t->- -v .'^iz' ,'.*»/: -sr&t.' '• > «•>,•'''.'.;-r'r^&:- ?£■••*,•/, NATIONAL LIBRARY OF MEDICINE Bethesda, Maryland Gift of Michael J. North 1 V/ ■i *■ 3** t. nos; ■A V. ■3 H- LITERARY AND SCIENTIFIC CLASS BOOK, EMBRACING THE LEADING FACTS AND PRINCIPLES OF SCIENCE. Xllufitratetr t>2 3Stt(jcaUiH0S, WITH MANY DIFFICULT WORDS EXPLAINED AT THE HEADS OF THI LESSONS, AND QUESTIONS ANNEXED FOR EXAMINATION ; DESIGNS] AS EXERCISES FOR THE READING AND STDDY OF THE HIGHER CLASSES IN COMMON SCHOOLS. SELECTED FROM THE REV. JOHN PLATTS' Stterarg antr Scientific Class JSooft, AND FROM VARIOUS OTHER SOURCES, AND ADAPTED TO THE WANTS AND ' CONDITION OF YOUTH IN THE UNITED STATES. By LEVI W. LEONARD. gTKREOTYPED BY T. H. CARTER & CO. BOSTON. PUBLISHED BY JOHN PRENTISS, [Proprietor of the copy-right.] 1827." DISTRICT OF NEW-HAMPSHIRE, to wit. District Clerk's Office. Be it remembered, that on the twelfth day of November, A. D. 1825, and in the fiftieth year of the Independence of the United States of America, John Prentiss of the said District, has deposited in this office the title of a book, the right whereof he claims as pro- prietor, in the words following, to wit:— " The LITERARY AND SCIENTIFIC CLASS BOOK, embrac- ing the leading facts and principles of Science. Illustrated by engrav- ings, with many difficult words explained at the heads of the lessons, and questions annexed for examination ; designed as exercises for the reading and study of the higher classes in common schools. Selected from the Rev. John Platts' Literary and Scientific Class Book, and from various other sources, and adapted to the wants and condition of youth in the United States. By Levi W. Leonard." In conformity to the Act of the Congress of the United States, enti- tled, " An Act for the encouragement of learning, by securing the copies of maps, charts, and books, to the authors and proprietors of such copies, during the times therein mentioned ;" and also to an Act, entitled, f( An Act, supplementary to an Act, entitled, An Act for the encouragement of learning, by securing the copies of maps, charts, and books, to the authors and proprietors of such copies, dur- ing the times therein mentioned; and extending the benefits thereof to the arts of designing, engraving, and etching historical, and other prints " SAMUEL CUSHMAN, { **£*££« A true Copy of Record: r Attest SAMUEL CUSHMAN, Clerk. oy> ADVERTISEMENT. —QS©©~ The following Extracts are introduced as recommendatory of the design of the Literary and Scientific Class Book. In teaching the art of reading it is an obvious waste of the precious period, devoted to education, to confine the exer- cises in that art to mere combinations of words; or to compositions, the sole object of which is to prove the wit and genius of the writer;—to compositions which do not teach any thing, and which, after a volume of them has been pe- rused and re-perused for years> leave the mind in a state of listless curiosity. In proof of the justice of this remark, we need only appeal to the feelings of those persons, who, while they were at school, read no other books than the selections published under the titles of Speakers, Readers, Extracts, and Beauties. As exercises in elocution, and as examples of elegant composition, such books cannot be sufficiently S commended; but they are ill adapted to the more important objects of instruction, and with regard to the purposes of general knowledge, they bear the same relation that gilding bears to gold, or pastime to useful labour.----Rev. D. Blair. It is evident that want of time will prevent the great mass of mankind from pursuing a systematic course of education in all its details; a more summary and compendious method therefore must be pursued by them. The great majority iT ADVERTISEMENT. must be content with never goiUg'^b.eyond a certain point, and with reaching that point by the' ippst expeditious route. A few, thus initiated in the truths of Stjpice, will no doubt push their attainments further; and for these the works in common use will suffice; but for the multitude it will be most essential that works should be prepared adapted to their circumstances......It is not necessary that all who are taught or even a considerable proportion should go beyond the rudiments ; but whoever feels within himself a desire and an aptitude to go further will do so,—and the chances of dis- covery, both in the arts and in science itself, will be thus indefinitely multiplied. Edinburgh Review, No. 81. PREFACE. —a©©— The Literary and Scientific Class Book, by the Rev. John Platts of Doncaster, England, was published in the begin- ning of the year 1821. "The grand object aimed at," he says in his Preface, " is, that while the pupil reads his daily lesson, he shall not only learn to pronounce words, but shall also treasure up a valuable stock of ideas, to enlarge his mind, to interest his heart, and to prepare him for his future scenes on the theatre of life." The plan and leading title of the above-mentioned publi- cation have been adopted in the present work, and many of the lessons have been retained either in full, or in an abridged and altered form. The notes, appendix, and engravings, have been added; and such materials have been selected from other sources as were judged best adapted to improve the hearts and enlarge the minds of youth in this country. Most of the lessons have been selected with a particular reference to the instruction which they contain on important branches of knowledge. Although the work is designed for the higher classes, yet it is believed that all young per- sons, who are able to read with facility, and are acquainted with the rudiments of arithmetic and geography, may use it with advantage. The names of authors are given in many instances, but, in general, the quotations have been so much altered, or the same lesson taken from so many different sources, that it could not be done with convenience. The works consulted or from which extracts have been made, are noticed in the Appendix. A list of select books has been furnished for the use of those who wish to make further attainments. SELECT BOOKS. Locke's Conduct of the Understanding, 1 vol. 18mo. Watts' Improvement of the Mind, 12mo. Rett's Elements of General Knowledge, 2 vols. 12mo. Bezout's Elements of Arithmetic, 12mo. Legendre's Elements of Geometry, 8vo. Colburn's Introduction to Algebra upon the inductive me- thod of Instruction, 1 vol. 12mo. Joyce's Familiar Introduction to the Arts and Sciences, 1 vol. 12mo. Systematic Education, or Elementary Instruction in the various departments of Literature and Science, by Rev. W. Shepherd, Rev. J. Joyce, and Rev. L. Carpenter, 2 vols. 8vo. Cavallo's Elements of Natural aftd Experimental Philosophy, by F. X. Brosius, 2 vols. 8vo. Nicholson's Operative Mechanic 8vo. Nicholson's Popular Elements of pure and mixed Mathe- matics, 8vo. Ilutton's Recreations in Mathematics and Natural Philoso- phy, 4 vols. 8vo. Enfield's Institutes of Natural Philosophy, Theoretical and Practical, 4to. Ferguson's Lectures on select subjects in Mechanics, Optics, Astronomy, &c. edited by Dr. Brewster, 2 vols. 8vo. Ferguson's Astronomy, 2 vols. 8vo. edited by Dr. Brewster. Bonnycastle's Introduction to Astronomy, 1 vol. 8vo. Cotting's'Introduction to Chemistry, 12mo. Henry's Elements of Chemistry, 2 vols. 8vo. Macneven's Tabular View of the Modern Nomenclature and System of Chemistry. Mackenzie's One Thousand Experiments in Chemistry, ex- hibiting the applications of Modern Chemistry to all branches of the useful arts, 8vo. Cleveland's Mineralogy and Geology, 2 vols. 8vo. Lowry's Conversations on Mineralogy. vm SELECT BOOKS. Robinson's Catalogue of American Minerals, 8vo. Locke's Outlines of Botany, 12mo. Thornton's Elements of Botany, with 160 plates. Eaton's Manual of Botany for the Northern and Middle States, 12mo. Eaton's Botanical Exercises, including directions, rules, &c. 12mo. Davy's Agricultural Chemistry, 12mo. Brown's Compendium of Agriculture, 12mo. Dean's New England Farmer, or Georgical Dictionary, 8vo. Willich's Domestic Encyclopjedia, edited by Dr. Cooper, 3 vols. Svo. Benjamin's Rudiments of Architecture, Svo. Cabinet Maker's Guide. Gregory's Economy of Nature, 3 vols. 8vo. Buffon's Natural History, 2 vols. 8vo. Paley's Natural Theology, 12mo. Harris' Natural History of the Bible, 8v'o. Harlan's Description of the Mammiferous Animals of North America, Svo. Bewick's Quadrupeds, 1 vok 8vo. Kirby and Spence's Introduction to Entomology, 2 vols. Svo. Worcester's Sketches of the Earth and its inhabitants, 2 vols. 12mo. Malte-Brun's Universal Geography, or description of all parts of the world on a new Plan, 7 vols. 8vo. Bingley's Useful Knowledge, 3 vols. 12mo. Bigland's Letters on the Study of History, 8vo. Tytler's Elements of History, Ancient and Modern, 12mo. History of New England by Hannah Adams, 8vo. History of England, abridged from Hume and Smollet, by J. Robinson, D. D. Paley's Moral and Political Philosophy, Svo. Baker's Moral Philosophy, abridged from Paley, 18fflo. Parkhurst's Elements of Moral Philosophy, 12mo. Smith's Wealth of Nations, 2 vols. 8vo. The Federalist, by Madison, Jay, and Hamilton, 8vo. Say's Treatise on Political Economy, 8vo. The American Journal of Science and Aits. New-Haven. The Boston Journal of Philosophy and the Arts. New Edinburgh Encyclopaedia, edited by Dr. Brewster. CONTENTS, Lefleon. Pa6e- 1. Intellectual Pleasures, - - 1 2. Mental Improvement, - *» 3. Habit of Attentive Thought, - - 5 4. Cultivation of Memory, - - " e 5. Plan of Reading, - - " *j 6. Hymn to Science, - - - ' j" 7. Usefulness of Mathematical Studies, - 13 8. Imagination,—its Power illustrated, - 14 9. Beauty and Sublimity, Illustration of, - 16 10. Taste, Improvement and Pleasures of, - ■ 1° 11. Poetry,—its Object, - 20 12. Advantages of Studying History, - - ^l 13. Philosophy,—its leading Offices, - - 23 14. The Praise of Philosophy* - *5 15. General Properties of Bodies, - - " 16. Attraction of Gravitation. Sir Isaac Newton's Dis- covcrics - - - " o\j 17. Centre of Gravity. Pyramids of Egypt. Tower of Pisa - " 18. The Laws of Motion. Velocity, Momenta, Action and Re-action, - - - 35 19. Compound Motion. The Pendulum, - - 37 20. Mechanical Powers. The Lever, - - - 40 21. The Pulley, Wheel, and Axle, and Inclined Plane, 42 22. The Wedge and Screw. Friction, - - 44 23. The Laws of Fluids. Pressure of Fluids, - - 47 24. Specific Gravity of Bodies. Archimedes, - 50 25. Hydraulics. Syphon. Common Pump. Forcing Pump,......f2 26. The Diving Bell, and Steam Engine, - - 54 87. Nature and Properties of Air. The Air Pump, 56 28. The Barometer, Uses of, " " r? 29. Sound. Velocity of Sound. Echo, - - 61 30. Nature of Musical Sounds. Musical Barometer, 64 31. Optics. Reflection and Refraction of Light, -60 X CONTENTS. Lesson. „, Pag: 32. Different Kinds of Lenses. Burning Glass, - t>y 33. Mirrors. Convex Reflectors, - - -71 34. Colours. The Prism. - . - - 73 35. The Rainbow, Halo, and Parhelia, - -^ - 75 36. Structure of the Eye. Angle of Vision, - 78 37. Optical Instruments. Spectacles. Microscopes, 81 38. Microscopic Discoveries, - - " " f 39. The Telescope and Telegraph, - - - 86 40. Astronomy. Progress of this Science, - - 88 41. The Solar System. Galileo, . - - 91 42. The Sun, a magnificent habitable globe, - - 93 43. Mercury and Venus, - - - 95 44. The Earth, Ecliptic and Zodiac. Celestial Lati- tude and Longitude, - 97 45. Day and Night, causes of, - - 100 46. Changes of the Seasons, - 102 47. The Moon. Harvest Moon, - - 104 48. The Tides, explanation of, - - - 107 49. Eclipses of the Moon and Sun, - 108 50. Mars, Vesta, Juno, Pailas, and Ceres, - - 111 51. Jupiter--his Belts, Satellites, &c. - - - 113 52. Saturn, and Uranus. Saturn's Ring, - - 114 53. Comets. Pope Callixtus, - - - 115 54. The Fixed Stars. The Milky Way, - -117 55. The Constellations. Hymn to the North Star, 119 56. Forms and Divisions of Time. Equation of Time, 122 57. The Planetary System, 125 58. Chemistry, Importance and Use of, - - 127 59. General Principles of Chemistry. Chemical Af- finity, ......128 60. Caloric. Thermometer, - - - - 130 61. Atmospheric Air, Composition of. Oxygen. Nitro- gen, _------ 133 62. Water, Composition of. Hydrogen Gas, - - 135 63. The Earths and Alkalies. Uses of Lime, - 137 64. Acids and Salts. Mountains of Salt, - - v 140 65. Simple Combustibles. Carbon. Metals, - 143 66. Oxyds and Combustion. Exhilarating Gas, - 145 67. Electricity. Electrical Machine. Experiments, 148 68. Leyden Phial. Dr. Franklin's Discovery. Thun- der and Lightning, - 152 CONTENTS. XI Lesson. Page. 69. Falling Stars, Water Spouts, and Northern Lights, 154 70. Galvanism. Voltaic Battery, - 157 71. Galvanism (continued.) Prof. Hare's New De- jffagrator, - - - - 159 72. Mslfhetism. Variation of the Needle, - - 162 73. Magnetical Experiments. Amusing Deceptions, 164 74. Aerostation. Air Balloons. Parachute. Death ofRozier, . - - - - 166 75. Natural History,—its Objects, - 169 76. Mineralogy. Characters of Minerals, - - 172 77. Classification of Minerals. The Diamond, - 174 78. Gold,—its remarkable ductility, - - - 176 79. Silver and Mercury. Plating with Silver. Quick- silver Mine, - - - 178 80. Copper and Lead. Brass. White Lead, - 180 81. Iron and Tin. Importance of Iron. Use of Tin. Pewter, - - - - - 182 82. Zinc, Manganese, and Antimony, their Uses, 183 83. Study of Geology,—its objects and uses, - 185 84. Geology. Stratification. Sacred History confirmed, 186 85. Relative Situation of Rocks. Decomposition of Rocks,.....189 86. Biographical Sketch of Linnaeus, - - 191 87. Study of Botany, a Source of Mental Improve- ment, ----- 194 88. Texture of Vegetables. Bark. Wood. Pith. Age of Trees,.....196 89. Sap and Secretions. Flowing of the Sap. Sugar, 198 90. Process of Vegetation, ... 200 91. Roots, Stems, Buds, and Leaves. Effect of Light upon Plants, .... 202 92. Flower and Fruit, - - - - 205 93. Classification of Vegetables,its Importance and Use, 207. 94. Flowers. Insects in Flowers, - - 210 95. Animal Kingdom. Study of Zoology advanta- geous to the Young, - - - - 212 96. First Class of Animals (Mammalia,) Orders of, 213 97. Birds,—their Division into Orders. Moulting, 217 98. Reptiles and Fishes. Electrical Fishes, - 219 99. Structure and Transformation of Insects, - 221 100. Orders of Insects. The Gossamer, - - 225 xii CONTENTS. Lesson. ^aS** 101. Crustaceous and Molluscous Animals. Shells, 228 102. Vermes and Zoophytes. Leech. Polypes, - 230 103. Existence of the Deity, - - - - 232 104. Political Economy Progress of Civilization, - 233 105. Property, unequal Distribution of, - *fc 235 106. Division of Labour, ----- 237 107. Agriculture,—the Strength of Nations, - 239 108. Commerce and Manufactures, - 240 109. Money,—its abundance, not the cause, but the con- sequence of Wealth, - - - 242 110 Ship-building and Navigation, - 244 111. Architecture, Advantages of,—Orders of, - 246 112. Constitution of the United States, Sketch of, - 248 113. Excellence of our Republican Government, - 251 114. Intelligence of the People a Means of Safety to the Government, - - - - 252 115. The government of England. King. Parliament, 254 116. America : an Extract from Bryant's Poem of the Ages, _ . - 257 117. Structure of the Human Body, - - 258 118. Structure of the Human Body, (continued,) - 260 119. The Human Voice, wonderful Mechanism of, 262 120. Structure of the Ear, - - - 263 121. Music, Pleasures of,—Ear for, - - 265 122. Painting. Cartoons of Raphael, - - 267 123. Sculpture. Statuary. Casting in Plaster of Paris, 270 124. The Love of Nature, - - - 271 125. The Importance of Natural Philosophy, - 272 126. Mythology, - - - - - 274 127. Account of the Principal Heathen Gods, - 275 128. Account of the Principal Heathen Goddesses, - 278 129. Harmony of Science and Christianity, - 280 130. The Influence of an Early Taste for Reading, 281 131. The Mechanical Wonders of a Feather, - - 282 132. Art of Making Pins, - - - - 284 133. Clouds and Rain,.....285 134. Invention and Progress of Printing, - - 287 135. Hope, Influence of, - 288 THE LITERARY AND SCIENTIFIC CLASS BOOK, —qqg- LESSON 1 Intellectual Pleasures. Evolv'ed, unfolded, unrolled, thrown out, Transcen'dent, excellent, surpassing others. WHEN we think of what man is, not in his faculties only, but in his intellectual acquisitions, and of what he must have been, on his entrance into the world, it is difficult for us to regard this knowledge and absolute ignorance as states of the same mind. It seems to us almost as if we had to con- sider a spiritual creation or transformation, as wondrous as if, in contemplating the material universe, we were to strive to think of the whole system of suns and planets, as evolved from a mere particle of matter, or rising from nothing, as when originally created. We believe that they were so cre- ated, and we know that man, comprehensive as his acquire- ments are, must have set out in his intellectual career from absolute ignorance; but how difficult is it for us to form any accurate conception of what we thus undoubtingly believe! The mind, which is enriched with as many sciences as there are classes of existing things in the universe, which our or- gans are able to discern—the mind, which is skilled in all the languages of all the civilized nations of the globe, and which has fixed and treasured in its own remembrance, the beauties of every work of transcendent genius, which age after age has added to the stores of antiquity—this mind, we know well, was once as ignorant as the dullest and feeblest of those minds, which scarcely know enough, even to won- der at its superiority. That pleasure attends the sublime operations of intellect in the discovery of truth, or the splendid creations of fancy, 2 INTELLECTUAL PLEASURES. or the various arts to which science and imagination arc subservient, every one will readily admit, to whom these operations are familiar. But the great masters in science and art are few, and the pleasure which they feel in their noblest inventions, therefore, would be but a slight element in the sum of human happiness. The joy, however, is not confined to those, who have the pride of contemplating these great results as their own. It exists to all who have the humbler capacity of contemplating them merely as results of human genius. It is delightful to learn, though another may have been the discoverer; and perhaps the pleasure which a mind truly ardent for knowledge, feels in those early years, in which the new world of science is opened, as it were to its view, and every step, and almost every glance affords some new accession of admiration and power, may not be surpassed even by the pleasure which it is afterwards to feel, when it is not to be the receiver of the wisdom of others, but itself the enlightener of the wise.—Brown. Call now to mind what high, capacious powers Lie folded up in man; how far beyond The praise of mortals, may the eternal growth Of nature to perfection half divine, Expand the blooming soul: what pity then Should sloth's unkindly fogs depress to earth Her tender blossom ; choke the streams of life, And blast her spring! far otherwise designed Almighty wisdom; nature's happy cares The obedient heart far otherwise incline. Witness the sprightly joy when aught unknown Strikes the quick sense, and wakes each active power To brisker measures; witness the neglect Of all familiar objects, though beheld With transport once; the fond attentive gaze Of young astonishment; the sober zeal Of age, commenting on prodigious things. For such the bounteous providence of heaven, In every breast implanting this desire Of objects new and strange, to urge us on With unremitted labour to pursue Those sacred stores that wait the ripening soul, In truth's exhaustless bosom. Akensjde. MENTAL IMPROVEMENT". 3 LESSON 2. Mental Improvement. Par'aphrase, to explain in many words. Di'agram, delineation of a geometrical figure. No man is obliged to learn and know every thing, for it is utterly impossible; yet all persons are under some obliga- tion to improve their own understanding. Universal igno- rance or infinite errors will overspread the mind which is neglected, and lies without cultivation. Skill in the sciences is indeed the business and profession but of a small part of mankind; but there are many others placed in such a rank in the world, as allows them much leisure and large oppor- tunities to cultivate their reason, and enrich their minds with various knowledge. The common duties and benefits of society, which belong to every man living, and even our necessary relations to a family, a neighbourhood, or government, oblige all persons whatsoever to use their reasoning powers upon a thousand occasions; every hour of life calls for some regular exercise of our judgment as to times and things, persons and actions; without a prudent and discreet determination in matters be- fore us, we shall be plunged into perpetual errors in our con- duct. Now that which should always be practised, must at some time be learned. Besides, every son and daughter of Adam has a most im- portant concern in the affairs of a life to come, and therefore it is a matter of the highest moment for every one to under- stand, to judge, and to reason right about the things of re- ligion. It is vain for any to say, we have no leisure or time for it. The daily intervals of time, and vacancies from ne- cessary labour, together with the one day in seven in the Christian world, allow sufficient opportunity for this, if men would but apply themselves to it with half so much zeal and diligence as they do to the trifles and amusements of this life ; and it would turn to infinitely better account. There are five eminent means or methods whereby the mind is improved in the knowledge of things ; and these are observation, reading, instruction by lectures, conversation, and meditation, which last, in a peculiar manner, is called study. 4 MENTAL IMPROVEMENT. Observation is the notice that we take of all occurrence!) in human life, whether they are sensible or intellectual, whether relating to persons or things, to ourselves or others. It is this that furnishes us, even from ou*r infancy, with a rich variety of ideas and propositions, words and phrases. All those things which we see, hear or feel, which we perceive by sense or consciousness, or which we know in a direct man- ner, with scarce any exercise of our reflecting faculties or our reasoning powers, may be included under the general name of observation. There is no time or place, no trans- actions, occurrences, or engagements in life, which exclude us from this method of improving the mind. Reading is that means of knowledge, whereby we ac- quaint ourselves with the affairs, actions, and thoughts of the living and the dead, hi the most remote nations, and most distant ages. By reading, we learn not only the actions and sentiments of different nations and ages, but transfer to our- selves the knowledge and improvements of the most learned men, the wisest and best of mankind. It is another advan- tage of reading, that we may review what we have read; we may consult the page again and again, and meditate on it at successive periods in our retired hours. Unless a reader has an uncommon and most retentive memory, there is scarcely any book or chapter worth reading once that is not worthy of second perusal. Public or private lectures are such verbal instructions as are given by a teacher while the learners attend in silence. An instructer, when he paraphrases and explains other au- thors, can mark out the precise point of difficulty or contro- versy, and unfold it. When he teaches us natural philoso- phy, or most parts of mathematical learning, he can convey to our senses those notions, with which he would furnish our minds. He can make the experiments before our eyes. He can describe figures and diagrams, point to the lines and angles, and by sensible means make out the demonstration in a more intelligible manner. Conversation is that method of improving our minds, wherein by mutual discourse and inquiry we learn the sen- timents of others, as well as communicate our own. By friendly conference, not only the doubts which arise in the mind upon any subject of discourse are easily proposed and solved, but the very difficulties we meet with in books and HABIT OF ATTENTIVE THOUGHT. 5 in our private studies may find a relief. A man of vast reading, without conversation, is like a miser, who lives only to himself. Meditation or study includes all those exercises of the mind, whereby we render all the former methods useful, for our increase in true knowledge and wisdom. By meditation we fix in our memory whatsoever we learn, and form our own judgment of the truth or falsehood, the strength or weakness of what others speak or write. Neither our own observation, nor reading the works of the learned, nor at- tendance on the best lectures of instruction, nor enjoying the brightest conversation, can ever make a man truly know- ing and wise, without the labours of his own reason in sur- veying, examining, and judging, concerning all subjects upon the best evidence he can acquire.—Watts. Questions.—1. What will be the stale of the mind if unculti vated ? 2. To what exercise do the common duties of society oblige all persons? 3. What is the most important subject on which every one should reason correctly ? 4. What are the most suitable opportunities for this duty ? 5. What are the five eminent means of knowledge ? 6. What is observation ? 7. Reading ? 8. What ar« lectures ? 9. What is included in meditation or study ? 10. What are some of the advantages of each of these five means of knowledge f LESSON 3. Habit of Attentive Thought. Griffin, a fabled animal. Tal'isman, a magical character. It is of great importance to your intellectual improvement that you should acquire the habit of attentive thought. The primary recommendation of science is its utility; and if you are really desirous of advancing in it, you will not regard the occasional ruggedness of a road, which is far from being al- ways rugged. It may be allowed to him, who walks only for the pleasure of the moment to turn away from every path, in which he has not flowers and verdure beneath his feet, and beauty wherever he looks around. But in that know- ledge which awaits your studies, in the various sciences to which your attention may be directed, you have a noble prize before you; and, therefore, you should not hesitate occa- fATTUlVUF fit CULTIVAl'IUN 01' SlEMORV iionally to put forth all the vigour of your attention, at the risk of a little temporary fatigue. It will facilitate your ac- quisition of a reward, which the listless exertions of the*in- dolent can never obtain. It is in science, or philosophy, as in many a fairy tale. The different obstacles which the hero encounters, are not pro- gressively greater and greater; but his most difficult achieve- ments are often at the very commencement of his career. He begins, perhaps, with attacking the castle of some en- chanter, and has to force his way, unassisted, through the griffins and dragons that oppose his entrance. He finishes the adventure with the death of the magician—and strips him of some ring, or other talisman, which renders his sub- sequent adventures comparatively easy and secure. The habit of attentive thought, which the consideration of diffi- cult subjects necessarily produces, in those who are not too indolent to give attention to them, or too indifferent to feel interest in them, is more truly valuable than any talisman, of which accident or force might deprive you. The magic with which this endows you, is not attached to a ring, or a gem, or any thing external; it lives, and lives for ever, in the very essence of your minds.—Brown. LESSON 4. Cultivation of Memory. Super'fluo«6, unnecessary. Cha'os, confusion, ck in words from the Greek sound like k. Memory implies two things : first, a capacity of retaining knowledge; and, secondly, a power of recalling that know- ledge to our thoughts when we have occasion to apply it to use. When we speak of a retentive memory, we use it in the former sense; when of a ready memory, in the latter. Without memory, there can be neither knowledge, arts, nor sciences; nor any improvement of mankind in virtue, or morals, or the practice of religion. Without memory, the soul of man would be but a poor, destitute, naked being, with an everlasting blank spread over it, except the fleeting ideas of the present moment. CULTIVATION OF MEMORY. 7 There is one great and general direction, which belongs to the improvement of other powers as well as of the me- mory, and that is, to keep it always in due and proper exer- cise. Many acts by degrees form a habit, and thereby the capacity or power is strengthened and made more retentive and ready. Due attention and diligence to learn and know the things which we would commit to our remembrance, is a rule of great necessity. There are some persons, who com- plain they cannot remember what they hear, when in t*uth their thoughts are wandering half the time, or they hear with such coldness and indifference, and a trifling temper of spi- rit, that it is no wonder the things which are read or spoken make but a slight impression, and soon vanish and are lost. If we would retain a long remembrance of the things which we read or hear, we should engage our delight and pleasure in those subjects, and use proper methods to fix the atten- tion. Sloth and idleness will no more bless the mind with intellectual riches, than they will fill the hand with gain, the field with corn, or the purse with treasure. Some persons are conceited of their abilities, and trust so much to an acuteness of parts denominated genius, that they think it superfluous labour to make any provision before- hand, and they sit still, therefore, satisfied without endeavour- ing to store their understanding with knowledge. Such should remember that we are born ignorant of every thing. God has made the intellectual world harmonious and beauti- ful without us; but it will never come into our heads all at once; we must bring it home by degrees, and there set it up by our own industry, or we shall have nothing but darkness and chaos within, whatever order and light there may be in things without us. Others, on the contrary, depress their own minds, despond at the first difficulty, and conclude that getting an insight in any of the sciences, or making any progress in knowledge, farther than serves their ordinary business, is above their ca- pacities. The proper remedy here is to set the mind to work, and apply the thoughts vigorously to the business; for it holds in the struggles of the mind, as in those of war,—a persua- sion that we shall overcome any difficulties that we may meet with in the sciences, seldom fails to carry us through them. Nobody knows the strength of his mind, and the force of steady and regular application, until he has tried. 8 rLA^TpREADING All things are open to the searching eye Of an attentive intellect, and bring Their several treasures to it, and unfold Their fabric to its scrutiny. All life, And all inferior orders, in the waste Of being spread before us, are to him, Who lives in meditation, and the search Of wisdom and of beauty, open books, Wherein he reads the Godhead, and the ways He works through his creation, and the links That fasten us to all things, with a sense Of fellowship and feeling, so that we Look not upon a cloud, or falling leaf, Or flower new blown, or human face divine, But we have caught new life, and wider thrown The door of reason open, and have stored In memory's secret chamber, for dark years Of age and weariness, the food of thought, And thus extended mind, and made it young, When the thin hair turns gray, and feeling dies. Percival. Questions.—1. What does memory imply? 2. What general direction is given for the improvement of memory ? 3. What is a rule of great necessity ? 4. What is said of those who are conceited of their abilities ? 5. What is the proper remedy for those who de- spond at difficulties ? LESSON 5. Plan of Reading. Specula'tion, a train of thoughts formed by meditation. Discrimination, the act of distinguishing one from another. Desidera'ta, pi. some desirable things which are wanted. Lab'yrinth, a place formed with inextricable windings. The only method of putting our acquired knowledge on a level with our original speculations, is, after making our- selves acquainted with our author's ideas, to study the sub- ject over again in our own way ; to pause, from time to time, in the course of our reading, in order to consider what we have gained; to recollect what the propositions are, which the author wishes to establish, and to examine the different PLAN OP READING. & proofs which he employs to support them. Such reasonings, as we have occasion frequently to apply, either in the busi- ness of life, or in the course of our studies, it is of impor- tance to us to commit to writing, in a language and in an order of our own; and if, at any time, we find it necessary to refresh our recollection on the subject, to have recourse to our own composition, in preference to that of any other author. That the plan of reading, commonly followed, is very dif- ferent from that which is here recommended, will not be disputed. Most people read merely to pass an idle hour, or to please themselves with the idea of employment, while their indolence prevents them from any active exertion ; and a considerable number with a view to the display which they are afterwards to make of their literary acquisitions. From whichsoever of these motives a person is led to the perusal of books, it is hardly possible that he can derive from them any material advantage. If he reads merely from indolence, the ideas which pass through his mind will probably leave little or no impression; if he reads from vanity, he will be more anxious to select striking particulars in the matter or expression, than to seize the spirit and scope of the author's reasoning, or to examine how far he has made any additions to the stock of useful and solid knowledge. A proper selection of the particulars to be remembered is necessary to enable us to profit -by reading. When we first enter on any new literary pursuit, we commonly find our ef- forts of attention painful and unsatisfactory. We have no discrimination in our curiosity, and by grasping at every thing, we fail in making those moderate acquisitions which are suited to our limited faculties. As our knowledge ex- tends, we learn to know what particulars are likely to be of use to us, and acquire a habit of directing our examinations to these, without distracting the attention with others. It is partly owing to a similar circumstance, that most readers complain of a defect of memory, when they first enter on the study of history. They cannot separate important from trifling facts, and they find themselves unable to retain any thing from their anxiety to secure the whole. In order to give a proper direction to our attention to the course of our studies, it is useful before engaging in any par- ticular pursuits to acquire as familiar an acquaintance as 10 HYMN to science. possible with the great outlines of the different branches of science; with the most important conclusions which have hitherto been formed in them, and with the most important desiderata which remain to be supplied. By such general views alone we can prevent ourselves from being lost amidst a labyrinth of particulars, or can engage in a course of ex- tensive and various reading, with an enlightened and dis- criminating attention.—Stewart. Questions.—1. By what method may our acquired knowledge be put on a level with our original speculations ? 2. What reasonings is it important to commit to writing ? 3. What plan of reading is com- monly followed ? 4. What are its disadvantages ? 5. Why should a proper selection be made of the objects of knowledge ? 6. What is useful before engaging in any particular pursuits ? 7. What will an acquaintance with the great outlines of science prevent ? LESSON 6. Hymn to Science. Scholiast, a writer of explanatory notes. Soph'ist, a plausible but false reasoner. Science ! thou fair effusive ray From the great source of mental day, Free, gen'rous, and refined, Descend with all thy treasures fraught, Illumine each bewilder'd thought, And bless my lab'ring mind. But first with thy resistless light Disperse those phantoms from my sight, Those mimic shades of thee, The scholiast's learning, sophist's cant, The visionary bigot's rant, The monk's philosophy. Oh! let thy powerful charm impart The patient head, the candid heart, Devoted to thy sway ; Which no weak passions e'er mislead, Which still with dauntless steps proceed Where reason points the way. HYMN TO SCIENCE. 1 I Give me to learn each secret cause; Let numbers, figures, motion's laws, Reveal'd before me stand; Then to great nature's scenes apply, And round the globe and through the sky Disclose her working hand. Next to thy nobler search resign'd The busy restless human mind Through ev'ry maze pursue ; Detect perception where it lies, Catch the ideas as they rise, And all their changes view. Her secret stores bid Mem'ry tell, Bid Fancy quit her airy cell In all her treasures drest; While, prompt her sallies to control, % Reason, the judge, recalls the soul To truth's severest test. Say from what simple springs began The vast ambitious thoughts of man, That range beyond control, Which seek eternity to trace, Drive through the infinity of space, And strain to grasp the whole ? Then range through being's wide extent, Let the fair scale with just ascent And equal steps be trod, Till, from the dead corporeal mass, Through each progressive rank you pass To instinct, reason, God! There, Science, veil thy daring eye, Nor dive too deep, nor soar too high, In the divine abyss; To faith content thy beams to lend, Her hopes t* assure, her steps befriend, And light the way to bliss. Then downward take thy flight again, Mix with the policies of men, And social Nature's ties 12 ' HYMN TO SCIENCE. The plan, the genius, of each state, Its interest and its power relate, Its fortunes and its rise. Through private life pursue thy course Trace ev'ry action to its source, And means and motives weigh; Put tempers, passions, in the scale, Mark what degrees in each prevail, And fix the doubtful sway. The last, best effort of thy skill, To form the life, and rule the will, Propitious Pow'r! impart; Teach me to cool my passions' fires, Make me the judge of my desires, The master of my heart. Raise me above the vulgar breath, Pursuit of fortune, dread of death, And all in life that's mean : Still true to reason be my plan, And let my actions speak the man, Through ev'ry varying scene. Hail, queen of manners! test of truth! Hail, charm of age, and light of youth! Sweet refuge of distress ! E'en business you can make polite, Can give retirement its delight, Prosperity its grace. Of pow'r, wealth, freedom, thou the cause, Foundress of order, cities, laws, Of arts inventress thou! Without thee, what were human kind ! How vast their wants, their thoughts how blind I Their joys how mean, how few ! Sun of the soul! thy beams unveil 1 Let others spread the daring sail On fortune's faithless sea: While undeluded, happier I From the vain tumult timely fly, And sit in peace with thee. MATHEMATICAL STUDIES. 13 LESSON 7. Usefulness of Mathematical Studies. Ax'ioms, maxims, self-evident propositions. Anal'ogy, resemblance—see Hedge's or Jamieson's Logic. Phys'ics, natural philosophy, or the doctrine of natural bodiftS, their various appearances, affections, motions, operations, &c. Of all the sciences which serve to call forth the spirit of enterprise and inquiry, there is none more eminently useful than mathematics. By an early attachment to these elegant and sublime studies we acquire a habit of reasoning, and an elevation of thought, which fixes the mind, and prepares it for every other pursuit. From a few simple axioms, and evident principles, we proceed gradually to the most general propositions, and remote analogies : deducing one truth from another in a chain of argument well connected and logically pursued ; which brings us at last, in the most satisfactory manner, to the conclusion, and serves as a general direction in all our inquiries after truth. Mathematical learning is likewise equally estimable for its practical utility. Almost all the works of art and devices of man, have a dependence upon its principles, and are indebt- ed to it for their origin and perfection. The cultivation ot these admirable sciences is therefore a thing of the utmost importance, and ought to be considered as a principal part of every well regulated plan of education. They are the o-uideofour youth, the perfection of our reason, and the foundation of every great and noble undertaking. Mathematics are very properly recommended as the best remedy to cure an unsteady and volatile disposition. They teach us to reason in a clear and methodical manner. They give a manly vigour to our understanding, and free us from doubt and uncertainty on the one hand, and credulity and rash presumption on the other. These studies are calcu- lated to teach exactness and perspicuity in definition, con- nexion and conclusiveness in argument, carefulness in ob- servation, patience in meditation; and from no exercises can the scholar go better prepared and disciplined to the pursuit of the higher branches of knowledge. The benefit to be derived from them is thus stated by Mr Locke: " I have mentioned mathematics as a way to settle m the mind a 1*4 IMAGINATION. habit of reasoning closely, and in train ; not that I think it necessary that all men should be deep mathematicians; but that having got the way of reasoning, to which that study necessarily brings the mind, they might be able to transfer it to other parts of knowledge' as they shall have occasion." Mathematics, according to their proper definition, consti- tute the science of quantity, either as subject to measure or number. They are pure and mixed. The former consider cmantity abstractedly, without any regard to matter or par- ticular bodies; the latter treat of quantity as subsisting in bodies, and consequently they are intermixed with the con- sideration of physics, or experimental philosophy. Rett's Elements of General Knowledge. Questions.—1. What habit does an early attention to mathema- tical studies produce ? 2. What is said of their practical utility ? 3. What are they calculated to teach ? 4. How is the benefit to be derived from them stated by Mr. Locke ? 5. Give a definition of mathematics. C. How do pure mathematics consider quantity ? 7. Mixed ? Note. Pure mathematics are arithmetic, algebra, geometry, and fluxions: mixed consist chiefly of mechanics, pneumatics, hydro- statics, optics, and astronomy. LESSON S. Imagination. We do not merely perceive objects, and conceive or re- member them simply as they were, but we have the power of combining them in various new assemblages,—of forming at our will, with a sort of delegated omnipotence, not a single universe merely, but a new and varied universe, with every succession of our thought. The materials of which we form them are, indeed, materials that exist in every mind; but they exist in every mind only as the stones exist shapelessly in the quarry, that require little more than me- chanic labour to convert them into common dwellings, but that rise into palaces and temples only at the command of irchitectural genius. This power of combining our con- ceptions or remembrances in new assemblages is termed magination. The most sublime exertions of imagination are made by IMAGINATION. 15 the poet. But we must not conceive, merely because they are sublime, that they comprehend the whole office of ima- gination, or even its most important uses. It is of far more importance to mankind, as it operates in the common offices of life,—in the familiar feelings of every hour* What are all those pictures of the future, which are ever before our eyes, in the successive hopes, and fears, and designs of life, but imaginations, in which circumstances are combined that never perhaps, in the same forms and proportions, have ex- isted in reality, and which, very probably, are never to exist but in those very hopes and fears which we have formed ? The writer of romance gives secret motions and passions to the characters which he invents, and adds incident to inci- dent in the long series of complicated action which^ he de- velopes. What he does, we, too, are doing every hour;— contriving events that never are to happen,—imagining mo- tives and passions, and thinking our little romances, of which ourselves, perhaps, are the primary heroes, but in the plot of which there is a sufficient complication of adventures of those whom we love, and those whom we dislike. Our ro- mances of real life, though founded upon facts, are, in their principal circumstances, fictions still; and, though the fancy which they display may not be as brilliant, it is still the same in kind with that which forms and fills the history of imagi- nary heroes and heroines. It is well known, from experience, that the activity and consequent improvement of imagination, depend not a little upon the character of the objects with which it is first occu- pied. The great, the sublime, the beautiful, the new, and the uncommon, in external nature, arc not only striking and agreeable in themselves, but, by association, these qualities powerfully awaken the sensibilities of the heart, and kindle the fi^es of youthful imagination. If the student permit objects which are mean, low, or sensual, to usurp possession of his mind ; if the books which he reads, and the studies that he pursues, are contaminated with gross ideas, he has no right to expect that this omnipotent faculty shall ever draw from the polluted treasures of his memory, any thing noble, useful, or praiseworthy; or that his name shall ever be enrolled among those who have delighted, instructed, and honoured their native land and the world at large. By an excessive indulgence in the pleasures of imagina- le BEAUTY AND SUBLIMITY. tion, the taste may acquire a fastidious refinement unsuitable to the present situation of human nature; and those intel- lectual and moral habits, which ought to be formed by ac- tual experience of the world, may be gradually so accommo- dated to the dreams of poetry and romance, as to disqualify us for the scenes in which we are destined to act. But a well-regulated imagination is the great spring of human ac- tivity, and the principal source of human improvement. As it delights in presenting to the mind scenes and characters more perfect than those with which we are acquainted, it prevents us fro>n ever being completely satisfied with our present condition, or with our past attainments, and engages us continually in the pursuit of some untried enjoyment, or of some ideal excellence. Destroy this faculty, and the con- dition of man will become as stationary as that of the brutes. Questions.—1. What is imagination ? 2. By whom are its most sublime exertions made ? 3. Illustrate its operation in the common Qffices of life. 4. On what do the activity and improvement of ima- gination greatly depend P 5. What may be the consequence of an excessive indulgence in the pleasures of imagination ? 6. Why is a well-regulated imagination the great spring of human activity, and source of human improvement ? LESSON 9. Beauty and Sublimity. Emo'tions, vivid feelings arising immediately from the consider- ation of objects, perceived, remembered, or imagined. Cartoon', a painting or drawing upon several sheets of large paper pasted on canvass. The most celebrated are the cartoons of Raphael. See Lesson on Painting. Our emotions of beauty are various ; and, as they gra- dually rise, from object to object, a sort of regular progres- sion may be traced from the faintest beauty to the vastest sublimity. These extremes may be considered as united, by a class of intermediate feelings, for which grandeur might, perhaps, be a suitable term, that have more of beauty, or more of sublimity, according to their place in the scale of emotion. Let us imagine that '.ve see before us a stream gently gliding through fields, rich with all the luxuriance of summer, overshadowed at times by the foliage that hano-s BEAUTY AND SUBLIMITY. 17 over it, from bank to bank, and then suddenly sparkling in the open sunshine, as if with a still brighter current than before. Let us trace it, till it widens to a majestic river, of which the waters are the boundary of two flourishing em- pires, conveying abundance equally to each, while city suc- ceeds city, on its populous shores, almost with the same ra- pidity as grove formerly succeeded grove. Let us next be- hold it losing itself in the immensity of the ocean, which seems to be only an expansion of itself, when there is not an object to be seen but its own wide amplitude, between the banks which it leaves, and the sun that is setting, as if in another world, in the remote horizon;—in all this course, from the brook to the boundless waste of waters,—if we were to trace and contemplate the whole continued progress, we should have a series of emotions. The emotions which rose, when we regarded the narrow stream, would be those which we class as emotions of beauty. The emotions which rose when we considered that infinity of waters, in which it was ultimately lost, would be of the kind which we deno- minate sublimity; and the grandeur of the river, while it was still distinguishable from the ocean, to which it was pro- ceeding, might be viewed with feelings, to which, on the same principle of distinction, some other name or names might be given. The same progressive series of feelings, which may thus be traced as we contemplate works of nature, is not less evi- dent in the contemplation of works of human art, whether that art has been employed in material things, or be purely intellectual. From the cottage to the cathedral—from the simplest ballad air, to the harmony of a choral anthem—from a pastoral to an epic poem or tragedy—from a landscape to a cartoon,—in each case there is a wide interval, and you may easily perceive, that, merely by adding what seemed degree after degree, you arrive at last at emotions which have little apparent resemblance to the emotions with which the scale began. In the moral scene the progression is equally evident. Let us suppose, for example, that in the famine of an aimy, a soldier divides his scanty allowance with one of his com- rades, whose health is sinking under the privation. We feel in the contemplation of this action, a pleasure, which is thai of moral beauty. In proportion as we imagine the famine 18 TASTE. of longer duration, or the prospect of relief less-probable, the action becomes more and more morally grand and heroic. Let us next imagine, that the comrade, to whose relief the soldier makes this generous sacrifice, is one whose enmity he has formerly experienced on some interesting occasion; and the action is not heroic merely, it is sublime. It is in the moral conduct of our fellow men, that the spe- cies of sublimity is to be found, which we most gladly re- cognise, as the character of that glorious nature, which we have received from God,—a character which makes us more erect in mind, than we are in stature, and enables us not to gaze on the heavens merely, but to lift to them our very wishes, and to imitate in some faint degree, and to admire at least, where wc cannot imitate, the gracious perfection that dwells there.—Brown. Questions.—1. What illustration is given of the emotions of beauty and sublimity which arise from contemplating the works of nature ? 2. The works of human art ? 3. What is the, example for illustrating moral beauty and sublimity ? LESSON 10. Taste. Fine Arts, the arts generally distinguished by the appellation fine, are poetry, music, painting, sculpture, and engraving, with their several branches. To these may be added architecture and gardening. The word taste has two general significations : one literal or primitive relating to corporeal sensations; the other figu- rative, referring to mental discernment. This metaphor would not have been so general, had there not been a con- formity between mental taste, and that sensitive taste which gives us a relish of every flavour. The subject of this lesson is mental or intellectual taste. Without the emotions of beauty and sublimity, there would be no taste to discern the aptitude of certain means for pro- ducing these emotions. On the other hand, without the judgment, which discerns this order, in the relations of means and ends, there would be no voluntary adaptation of the great stores of forms and sounds, and colours, for producing TASTE. 19 them,—none of those fine arts which give as much happi- ness as embellishment to life. Reason and good sense have so extensive an influence on all the operations and decisions of taste, that a thorough good taste may well be considered as a power, compounded of natural sensibility to beauty, and of improved understanding. Frequent exercise and curious attention to its proper objects must greatly heighten its power. Nothing is more improveable than that part of taste, which is called an ear for music. At first, the sim- plest and plainest compositions only are relished. Our plea- sure is extended by use and practice, which teach us to re- lish finer melody, and by degrees enable us to enter into the intricate and compound pleasures of harmony. An eye for the beauties of painting is never acquired all at once. It is gradually formed by being conversant among pictures, and studying the works of the best masters. It is the same with respect to the beauty of composition or discourse : attention to the most approved models, study of the best authors, com- parisons of lower and higher degrees of the same beauties, operate towards the refinement of taste. In no part of nature is the pure benevolence of heaven more strikingly conspicuous than in our susceptibility of the emotions of this class. In consequence of these emotions, it is scarcely possible for us to look around, without feeling either some happiness or some consolation. Sensual plea- sures soon pall, even upon the profligate, who seeks them in vain in the means which were accustomed to produce them ; weary, almost to disgust, of the very pleasures which he seeks, and yet astonished that he does not find them. The labours of severer intellect, if long continued, exhaust the energy which they employ; and we cease, for a time, to be capable of thinking accurately, from the very intentness and accuracy of our thought. The pleasures of taste, however, by their variety of easy delight, are safe from the languor which attends any monotonous or severe occupation, and, instead of palling on the mind, they produce in it, with the very delight which is present, a quicker sensibility to future pleasure. Enjoyment springs from enjoyment; and if we have not some deep wretchedness within, it is scarcely pos- sible for us, with the delightful resources which nature and art present to us, not to be happy, as often as we will to be happy. 20 POETRY. Questions.—1. What are the two significations of the word taste ? 2. What does intellectual taste discern ? 3. How may a thorough good taste be considered ? 4. What effect have exercise and atten- tion upon taste ? 5. What examples of this are given i C. What is said of" sensual pleasures ? 7. Of the pleasures of taste ? LESSON 11. Poetry. The object of the philosopher is to inform and enlighten mankind; that of the orator, to acquire an ascendant over the will of others, by bending to his own purposes their judg- ments, their imaginations, and their passions : but the pri- mary and the distinguishing aim of the poet is to please ; and the principal resource which he possesses for this purpose, is by addressing the imagination. In poetry, we perceive every where what Akenside calls " The charm, That searchless nature o'er the sense of man Diffuses,—to behold, in lifeless things The inexpressive semblance of himself, Of thought and passion." The zephyrs laugh,—the sky smiles,—the forest frowns, —the storm and the surge contend together,—the solitary place not merely blossoms like the rose, but it is glad. All nature becomes animated. The poetic genius, like that soul of the world, by which the early philosophers accounted for all earthly changes, breathes its own spirit into every thing surrounding it. The world is full of poetry—the air Is living with its spirit; and the waves Dance to the music of its melodies, And sparkle in its brightness—earth is veiled, And mantled with its beauty; and the walls, That close the universe, with crystal, in, Are eloquent with voices, that proclaim ' The unseen glories of immensity. STUDY OP HISTORY. 21 'Tis not the chime and flow of words, that move In measured file, and metrical array; 'Tis not the union of returning sounds, Nor all the pleasing artifice of rhyme, And quantity, and accent, that can give This all-pervading spirit to the ear, Or blend it with the movings of the soul. 'Tis a mysterious feeling, which combines Man with the world around him, in a chain Woven of flowers, and dipped in sweetness, till He taste the high communion of his thoughts, With all existences, in earth and heaven, That meet him in the charm of grace and power. 'Tis not the noisy babbler, who displays, In studied phrase and ornate epithet, And rounded period, poor and vapid thoughts, Which peep from out the cumbrous ornaments, That overload their littleness. Its words Are few, but deep and solemn ; and they break Fresh from the fount of feeling, and are full Of all that passion, which, on Carmel, fired The holy prophet, when his lips were coals, His language winged with terror, as when bolts Leap from the brooding tempest, armed with wrath, Commissioned to affright us, and destroy.—Pehcival. Questions.—1. What is the object of the philosopher ? 2. Of the orator ? 3. Of the poet ? 4. What is the principal resource of the poet ? 5. To what is the poetic genius compared ? LESSON 12. Advantages of studying History. If we consider the knowledge of history with regard to its application, we shall find that it is eminently useful to us in three respects, namely, as it appears in a moral, a political, and a religious point of view. In a moral point of view, it is beneficial to mankind at large, as the guide of their conduct. In a political—as it suggests useful expedients to those who exercise the public offices of 22 STUDY OP history. the state; or as it enables us to form, by comparison with those who have gone before them, a just estimate of their merits. In a religious—as it teaches us to regard the Supreme Being as the governor of the universe, and sovereign disposei of all events. The faculties of the soul are improved by exercise; and nothing is more proper to enlarge, to quicken, and to refine them, than a survey of, the conduct of mankind. History supplies us with a detail of facts, and submits them to exami- nation before we are called into active life. By observation and reflection upon others we begin an early acquaintance with human nature, extend our views of the moral world, and are enabled to acquire such a habit of discernment, and cor- rectness of judgment, as others obtain only by experience. By meditating on the lives of sages and heroes, we exercise our virtues in a review, and prepare them for approaching ac- tion. We learn the motives, the opinions, and the passions of the men who lived before us; and the fruit of that study is a more perfect knowledge of ourselves, and a correction of our failings by their examples. Experience and the knowledge of history reflect mutual light, and afford mutual assistance. Without the former no one can act with address and dexterity. Without the latter no one can add to the natural resources of his own mind a knowledge of those precepts and examples, which have tended to form the character and promote the glory of eminent men. History contributes to divest us of many illiberal prejudices, by enlarging our acquaintance with the world. It sets us at liberty from that blind partiality to our native country, which is a sure mark of a contracted mind, when due merit is not allowed to any other. This study likewise tends to strengthen our abhorrence of vice ; and creates a relish for true greatness and solid glory. We see the hero and the philosopher repre- sented in their proper colours; and as magnanimity, honour, integrity, and generosity, when displayed in illustrious in- stances, naturally make a favourable impression on our minds, our attachment to them is gradually formed. The fire of enthusiasm and of virtuous emulation is lighted, and we long to practise what we have been instructed to approve. The love of our country naturally awakens in us a spirit of curiosity to inquire into the conduct of our ancestors, and to learn the memorable events of their history. Nothing that PHILOSOPHY. 23 happened to them can be a matter of indifference to us. We are their descendants, we reap the fruits of their public and private labours, and we not only share the inheritance of their property, but derive reputation from their noble actions. History, considered with respect to the nature of its sub- jects, may be divided into general and particular; and wkh respect to time, into ancient and modern. Ancient history commences with the creation, and extends to the reign of Charlemagne, in the year of our Lord eight hundred. Modern history, beginning with that period, reaches down to the pre- sent times. General history relates to nations and public af- fairs, and may be subdivided into ecclesiastical and civil, or ac- cording to some writers, into sacred and profane. Biography, memoirs, and letters, constitute particular history. Statis'tics refer to the present condition of nations. Geography and chronology are important aids, and give order, regularity, and clearness to all. Kett. Questions.—1. What is the advantage of history in a moral point of view ? 2. In a political ? 3. In a religious ? 4. What are the uses of history in respect to the mental faculties and the conduct of life ? 5. How does history divest us of illiberal prejudices ? 6. How does it tend to strengthen our abhorrence of vice, and create a relish for true greatness ? 7. What is said of the history of our ancestors i 8. How may history be divided ? 9. subdivided ? LESSON 13. Philosophy. Proposition, a sentence in which any thing is affirmed or denied. Demonstra'tion, a process of reasoning in which we perceive it to be impossible that the conclusion should not follow from the premises, or antecedent propositions. By philosophy we mean the knowledge of the reasons of things, in opposition to history, which is the bare knowledge of facts ; or to mathematics, which is the knowledge of the quantity of things, or their measures. These three kinds of knowledge ought to be joined as much as possible. History furnishes matter, principles, and practical examinations, and mathematics complete the evidence. All arts have their pe- culiar philosophy, which constitutes their theory. It is to be observed, that the bare intelligence and memory of philoso- 24 PHILOSOPHY. >hicalpropositions, without an ability to demonstrate them, a not philosophy, but history only. Where such propositions, lowever, are determinate and true, they may be usefully ap- tlied in practice, even by those who are ignorant of their de- nonstrations. Philosophy discovers and teaches those principles by means if which happiness may be acquired, preserved, and increased. Wisdom applies these principles to the benefit of individuals .nd of society. Knowledge which is applicable to no useful •urpose cannot deserve the name of wisdom. The sources >f that knowledge of truth which leads to the possession of lappiness are reason and revelation. To instruct men in .hose truths which God hath communicated to mankind by •evelation, is the province of theology. To teach them such truths, connected with their happiness, as are capable of being discovered by the powers of reason, is the province of philosophy. The leading offices of philosophy may be easily deduced from the general idea of its object. As the permanent en- joyment of real good is the end to be attained, the business of philosophy, therefore, will be to cultivate the understand- ing, and direct its operations; to correct and improve the will and affections; to inquire out the causes of natural an- pearances, and hence arrive at the knowledge of the first cause, under those characters and relations that are most interesting to mankind; to conduct men to such an acquaint- ance with the properties of natural bodies, and their recipro- cal pactions, as shall enable them to apply the objects around them to their own convenience; and, finally, to assist them in investigating the principles of social virtue, and thus pro- vide themselves with such rules of conduct as arise from mu- tual convenience and interest, from the natural sentiments 3f justice and humanity, and from the voluntary engagements )f civil society. ■iS^fkirVT1' Y1"^ meant b^ Pkilowphy? 2. What three , tit HiSS gt 1h0Uld hl J'°ined as much *s P°ss*le -? 3. What rJvfnce of tlS ?WCrn P^ophy and wisdom? 4. What is the rovince of theology? 5. Of philosophy ? 6. What are the leading ffices of phUosophy ? NoTE/The tfri great ob^cts oVoWlosotSf re God, man, and the universe. Philosophy is iometimes dTvlded »to three parts, intellectual, moral, and physical, ov La uTal! CHAISE OF PHILOSOPHY. 25 LESSON 14 The Praise of Philosophy. But now let other themes our care engage, For lo, with modest yet majestic grace, To curb imagination's lawless rage, And from within the cherish'd heart to brace, Philosophy appears. The gloomy race By Indolence and moping Fancy bred, Fear, Discontent, Solicitude, give place, And Hope and Courage brighten in their stead, While on the kindling soul her vital beams are shed Then waken from long lethargy to life The seeds of happiness and powers of thought; Then jarring appetites forego their strife, A strife by ignorance to madness wrought. Pleasure by savage man is dearly bought With fell revenge, lust that defies control, With gluttony and death. The mind untaught Is a dark waste, where fiends and tempests howl; As Phcebus to the world, is science to the soul. And Reason now through number, time, and space, Darts the keen lustre of her serious eye, And learns, from facts compared, the laws to trace, Whose long progression leads to Deity. Can mortal strength presume to soar so high! Can mortal sight, so oft bedimm'd with tears, Such glory bear!—for lo, the shadows fly From Nature's face ; confusion disappears, And order charms the eyes, and harmony the ears In the deep windings of the grove, no more The hag obscene and grisly phantom dwell; Nor in the fall of mountain-stream, or roar Of winds, is heard the angry spirit's yell; No wizard mutters the tremendous spell, Nor sinks convulsive in prophetic swoon; Nor bids the noise of drums and trumpets swell, To ease of fancied pangs the labouring moon, Or chase the shade that blots the blazing orb of noon 3 26 PRAISE OP PHILOSOPHY. Many a long-lingering year, in lonely isle, Stunn'd with th' eternal turbulence of waves, Lo, with dim eyes, that never learn'd to smile, And trembling hands, the famish'd native craves Of Heaven his wretched fare: shivering in caves, Or scorch'd on rocks, he pines from day to day : But Science gives the word; and lo, he braves The surge and tempest, lighted by her ray, And to a happier land wafts merrily away. And even where nature loads the teeming plains With the full pomp of vegetable store, Her bounty unimproved is deadly bane: Dark woods, and rankling wilds, from shore to shore, Stretch their enormous gloom ; which to explore Even Fancy trembles in her sprightliest mood; For there, each eye-ball gleams with lust of gore, Nestles each murderous and each monstrous brood, Plague lurks in every shade, and steams from every flood. 'Twas from Philosophy man learn'd to tame The soil by plenty to intemperance fed. Lo, from the echoing axe, and thundering flame, Poison, and Plague, and yelling Rage are fled. The waters bursting from their slimy bed, Bring health and melody to every vale : And from the breezy main, and mountain's head, Ceres and Flora to the sunny dale, To fan their glowing charms, invite the flutt'ring gale. What dire necessities on every hand Our art, our strength, our fortitude require ! Of foes intestine what a numerous band Against this little throb of life conspire ! Yet Science can elude their fatal ire Awhile, and turn aside death's levell'd dart Sooth the sharp pang, allay the fever's fire, And brace the nerves once more, and cheer the heart And yet a few soft nights and balmy days impart. Nor less to regulate man's moral frame Science exerts her all-composing sway. Flutters thy breast with fear, or pants for fame Or pines, to Indolence and Spleen a prey, GENERAL PROPERTIES OP BODIES. 27 Or Avarice, a fiend more fierce than they ? Flee to the shade of Academus' grove; Where Cares molest not, Discord melts away In harmony, and the pure passions prove How sweet the words of Truth breathed from the lips of Love. What cannot Art and Industry perform, When Science plans the progress of their toil! They smile at penury, disease, and storm; And oceans from their mighty mounds recoil. When tyrants scourge, or demagogues embroil A land, or when the rabble's headlong rage Order transforms to anarchy and spoil, Deep-versed in man, the philosophic sage Prepares with lenient hand their frenzy to assuage. 'Tis he alone, whose comprehensive mind, From situation, temper, soil, and clime Explored, a nation's various powers can bind And various orders, in one form sublime Of polity, that midst the wrecks of time, Secure shall lift its head on high, nor fear Th' assault of foreign or domestic crime, While public Faith, and public Love sincere, And Industry and Law maintain their sway severe. Beattie. LESSON 15. General Properties of Bodies. feymmet'rical, proportionate, having parts well adapted to each other. Cap'illary, a term applied to tubes of a very small bore, scarcely larger than to admit a hair, derived from capillus, the Latin word for hair. When we speak of bodies, we mean substances, of what- ever nature, whether solid or fluid; and matter is the ge- neral term used to denote the substance of which the diffe- rent bodice are composed. As we do not suppose any body 28 GENERAL PROPERTIES OP BODIES. to exist without certain properties, such as impenetrability, extension, figure, divisibility, inertness, and attraction, these, therefore, are called the general properties of bodies. By impenetrability, is meant the property which bodies have of occupying a certain space, so that, where one body is, another cannot be, without displacing the former; for two bodies cannot exist in the same place at the same time. A liquid may be more easily removed than a solid body ; yet it is not the less substantial, since it i? as impossible for a liquid and a solid to occupy the same space at the same time, as for two solid bodies to do so. If some water bq put into a tube closed at one end, and a piece of wood be inserted that accurately fits the inside of the tube, it will be impos- sible to force the wood to the bottom, unless the water is first taken away. The air is a fluid differing in its nature from liquids, but not less impenetrable. If you endeavour to fill a phial by immersing it in water, the air will rush out in bubbles in order to make way for the water; and if you reverse the phial, and plunge it perpendicularly into the wa- ter, so that the air will not be able to escape, the water will not fill it, though it will rise a little, because it compresses the air into a smaller space in the upper part of the glass. A body which occupies a certain space must necessarily have extension; that is to say, length, breadth, and depth. These are called the dimensions of extension, and we can- not form an idea of any body without them. The limits of extension are called figure or shape. A body having length, breadth, and depth, cannot be without form, either symme- trical or irregular; and this property admits of almost an in- finite variety. The natural form of mineral substances is that of crystals; many of them are very beautiful, and not less remarkable for their transparency and colour, than for their perfect regularity, as may be seen in the various mu- seums and collections of natural history. The vegetable and animal creation appears less symmetrical, but is still more diversified in figure than the mineral kingdom. Ma- nufactured substances assume the various arbitrary forms which the art of man designs for them. Divisibility is that property of matter, by which its parts may be divided and separated from each other; and of this division there can be no end. We can never conceive of a particle of matter so small as not to have an upper and under GENERAL PROPERTIES OF BODIES. 29 surface, which might be separated, if we had instruments fine enough for the purpose. A grain of gold may be ham- mered by the gold-beaters to such a degree of fineness, that the two millionth part of it may be seen by the naked eye; and by the help of a microscope the fifty millionth part will be visible. There are animals, it is said, so small that a single grain of sand is larger than four millions of them. But the natural divisions of matter are still more wonderful. The fragrance of a body is a part of the body itself, and is produced by very minute particles or exhalations which escape from it. How inconceivably small must be the odo- riferous particles of a carnation, which diffuse themselves through a whole garden, so that, in every part of it, its fra* grance is perceptible! The word inertness expresses the resistance which inac- tive matter makes to a change of state. It requires some external force to put a body which is at rest in motion; and an exertion of strength is also requisite to stop a body which is already in motion. If a ball were fired from a cannon with a certain velocity, and there were no resistance from the air, it would circulate round the earth perpetually, and never come to a state of rest. In this manner the moon goes round the earth. By attraction is meant the tendency that bodies have to approach each other, whatever be the cause of such tenden- cy. All bodies are composed of infinitely small particles of matter, each of which possesses the power of attracting or drawing towards itself any other particle, and of uniting with it, when sufficiently near to be within the influence of its attraction; but in minute particles this power extends to so very small a distance around them that its effect is not sensible, unless they are, or at least appear to be, in contact It then makes them adhere together, and is hence called the attraction of cohesion. It is by this principle that bodies preserve their forms, and are prevented from falling to pieces. The cohesive attraction of solids is much greater than that of fluids; and in elastic fluids, such as air, there is no cohesive attraction among the particles, and the utmost efforts of human art have proved ineffectual in the attempt to compress them, so as to bring them within the sphere of each other's attraction, and make them cohere. If two po- lished plates of marble, or of brass be but together with a 3* 30 ATTRACTION OF GRAVITATION. little oil between them to fill up the pores in their surfaces, they will cohere so powerfully as to require a very consi- derable force to separate them. Two globules of quicksil- ver, placed very nea/to each other, will run together, and drops of water will do the same. The ascent of water and other liquids in sugar, sponge, and all porous bodies is a spe- cies of this attraction, and is called capillary attraction. Some bodies appear to possess a power which is the re- verse of the attraction of cohesion. It is called repulsion, and is supposed to extend to a small distance around bodies, so as to prevent them from coming into actual contact. Water repels most bodies till they are wet. A small needle carefully placed on water will float. The drops of dew which appear in the morning on plants assume a globular form, from the mutual attraction between the particles of water; and upon examination it will be found that the drops do not touch the leaves, for they roll off in compact bodies, which would not be the case if there existed any degree of attraction between the water and the leaf. The repelling force between water and oil is so great that it is impossible to mix them in such a manner that they shall not separate again. Questions.—1. What is matter ? 2. What are the general pro- perties of bodies ? 3. What is impenetrability ? 4. By what experi- ments is this property of matter illustrated ? 5. Define extension and figure. 6. What is divisibility, and how illustrated ? 7. Define inert- ness ? 8. What is meant by attraction ? 9. Attraction of cohesion ? 10. What is said of the attraction of solids and fluids ? 11. What ex- periments illustrate cohesive attraction ? 12. What is capillary at- traction ? 13. What is repulsion, and by what experiments illus- trated. LESSON 16. Attraction of Gravitation. Rectilin'ear, consisting of right or straight lines. Curvilin'ear, consisting of crooked, or curved lines. Projec'tile, a body put in motion. Evaga'tion, a wandering deviation. Phenom'enon, (pi. phenomena) appearance, commonly expressive of some remarkable appearance in nature. The attraction of gravitation is only a modification of the ATTRACTION 0* GRAVITATION. 31 attraction of cohesion. The latter is not perceptible but in very minute particles, and at very small distances, the other acts on the largest bodies, and extends to immense distances. That very law which moulds a tear, And bids it trickle from its source, That law preserves the earth a sphere, And guides the planets in their course.—Rogers. The tendency which bodies have to fall is produced en- tirely by the attraction of the earth ; for the earth is so much larger than any body, on its surface, that it forces every body, which is not supported, to fall upon it. The following simple incident led to the most extensive and complicated calculations, and was productive of the most noble and won- I derful discoveries. Newton happening one day, in the year 1666, when only twenty-five years of age, to be sitting under an apple-tree, and an apple falling upon his head, it suggested a variety of reflections. The phenomena of falling bodies in particular engaged his attention; and, extending his re- searches to the heavens, he began to investigate the nature of motion in general. Because there is motion, he reason- ed, there must be a force that produces it. But what is this force ? That a body when left to itself, will fall to the ground, is known to the most ignorant; but if you ask them the rea- son of its thus falling, they will think you either an idiot or a madman. The circumstance is too common to excite their wonder, although it is so embarrassing to philosophers, that they think it almost inexplicable. It is the mark of a supe- rior genius to find matter for wonder, observation, and re- search, in circumstances which to the ordinary mind appear trivial, because they are common, and with which they are satisfied, because they are natural, without reflecting that nature is our grand field of observation, that within it is con- tained our whole store of knowledge; in a word, that to study the works of nature, is to learn to appreciate and ad- mire the wisdom of God. In applying his reflections on the nature of falling bodies to the celestial motions, Newton soon perceived that the force of gravity was not confined to the surface of our globe ; it being found to act alike at the bottom of the lowest valleys, and at the summit of the most lofty mountains. This led 32 ATTRACTION OP GRAVITATION. him to conjecture, that it might extend as far as the moon, and be the means of retaining her in her orbit. Imagine the moon, he reasoned, at the first moment of its- creation, to have been projected forward, with a certain velocity, in a rectilinear direction ; then, as soon as it began to move, gra- vity would act upon it, and impel it toward the centre of the earth. But as a body, impelled by two forces, will follow the direction of neither, the moon, so circumstanced, would neither proceed directly forward, nor fall directly downward, but keep a middle course, and move round the earth in a curvilinear orbit. This may be more fully illustrated, by at- tending to the motion of a shot, or any other projectile. A ball, shot from the mouth of a cannon, in a horizontal direc- tion, does not fall to the ground till it has proceeded to a considerable distance; and if it be discharged from the top of a high mountain, it will fly still further before it comes to the earth. Increase the force and the height, and the dis- tance will be augmented accordingly. And thus, in imagi- nation at least, we can suppose the ball to be discharged with such velocity, that it will never come to the ground, but return to the place whence it set out, and circulate con» tinually round the earth, in the manner of a little moon. Thus proceeding in his reflections, Newton discovered the admirable provision of the great Creator to prevent the eva- gation of the planets, and to retain them exactly within the bounds of their orbits. This he has demonstrated to be ef- fected by gravity, and that gravity and' motion completely solve all the phenomena of the planetary revolutions, both primary and secondary. By establishing this one principle in philosophy he has fully explained the system of the world, so far as it relates to this globe, and to all the rest of the pla- nets that regard the sun as their centre. Such is the New- tonian system of universal gravitation or attraction. But what is this principle, which gives life and motion to inani- mate beings, and how does it act? The effects are visible, but the agent that produces them is hidden from our senses. It eluded the search of Newton himself; he that soared to the utmost regions of space, and looked through nature with the eye of an eagle, was unable to discover it. This princi- ple of gravitation, has been styled " The constant impression of Divine power ;"—in every other sense the cause is likely to continue unexplored by man. It is, however, pretty ge- centre of gravity. 33 nerally agreed that the same principle of gravity, by which we see all bodies tend toward the centre of the earth, is a general law of nature, extended to all distances, and to every body, or substance, in the universe. For this the moon thro' heaven's blue concave glides, And into motion charms th' expanding tides, While earth impetuous round her axle rolls, Exalts her wat'ry zone, and sinks the poles.—Falconer. Questions.—1. What is the attraction of gravitation? 2. How is the tendency of bodies to fall produced ? 3. What incident led Newton to the most wonderful discoveries ? 4. How did he reason ? 5. What is considered the mark of a superior genius ? 6. What did Newton soon perceive respecting the force of gravity ? 7. What did this lead him to conjecture ? 8. How did he reason respecting the moon ? 9. What has this principle of gravitation been styled ? ip. What did Newton fully explain by it ? LESSON 17. Centre of Gravity. Perpendicularly, in the direction of a straight line up and down. Pyr'amid, a pillar ending in a point. The centre of gravity of a body is that point about which all its parts, in any situation exactly balance each other, so that if a body be suspended or supported by this point, it will rest in any position. Whatever supports the centre of gra- vity bears the weight of the whole body ; and while it is sup- ported the body cannot fall. We may consider, therefore, the whole weight of a body as centered in this point. If a line is drawn from the centre of gravity of a body, perpen- dicularly to the horizon, it is called the line of direction; because it is the line which the centre of gravity would de- scribe, if the body fell freely. The broader the base is upon which a body rests, the more difficult it will be to over- turn it, as it must be moved the more to bring the line of direction beyond the base. A cask is easily rolled along, and so is a ball, but a box is moved with greater difficulty. When a box is longer than it is broad, it is much more easily turned on its side than set on its end. A building in the 34 CENTRE OF GRAVITY. form of a pyramid is the most durable, because, as it becomes narrower and narrower as it ascends, each stone or brick is supported by those below. The pyramids of Egypt, both great and small, still remain, and without doubt will do so for thousands of years to come, while the vast temples are crumbling into ruin. In building, care is taken not to bring the upper rows of bricks beyond those below, and for this purpose a line and plummet are used. But it does not follow, because a building leans, that the centre of gravity does not fall within the base. There is a high tower at Pisa, a town in Italy, which leans fifteen feet out of a perpendicular di- rection ; strangers tremble to pass by it, still it is found by experiment that the line of direction fails within the base, and therefore it wiH stand while its materials hold together. -The higher the centre of gravity is, the more easily may a body be overturned. Hence, a wagon or cart with a high load is more in danger of being overturned than one with a heavy load laid lower. This proves the injurious effect of rising in a coach or boat in danger of oversetting, the centre of gravity being thereby raised, and the line of direction thrown out of the base. In such circumstances the proper course is to lie down in the bottom, so as to bring the line of direction, and consequently the centre of gravity, within the base, and thus remove the danger of oversetting. Rope- dancers perform astonishing feats by the assistance of a long pole with very weighty pieces of lead at each end, by which they balance themselves and recover firm footing, if likely to fall on either side. In our ordinary actions we regulate the motions of our bodies, as if we were most correctly studying the nature and effects of the centre of gravity. If a man wishes to rise from a chair, he throws his body forward. If be is likely to fall on one side he leans to the other. A cor- rect knowledge of the centre of gravity in bodies is of the utmost importance in the science of mechanics, as well as in many of the common actions of life. Questions.—1 What is the centre of gravity ? 2. The line of direction ? 3. When does a body stand most firmly ? 4. Why is a pyramid tbe most durable form of building ? 5. What occasions a body to be easily overturned ? b\ What is the proper course when a coach or boat is in danger ef oversetting ? 7. On what principle do we regulate our ordinary actions ? 8. Show by fig. 12. the common centre of gravity of two bodies. 9. Illustrate by fig. 4. the overturning *f a body, when the line of direction falls out of the base. ill*. LAWS OF MOTION- 35 LESSON 18. The Laws of Motion. Momentum, (pi. momenta) the force acquired by different masses of matter moving with different velocities. A body, twice the weight of another, moving with equal velocity, will strike with twice the momentum,—with twice the veloeity, with/owr times the momentum,—with three times the velocity, with six times the momentum, and so on. A body is in motion whenever it is changing its situation with regard to a fixed point, and the cause which produces mo- tion is calledforce. The causes of motion, or the motive powers are either muscular, as the action of men and other animals, or mechanical, as the force of wind, water, gravity, the pres- sure of the atmosphere or any elastic medium, and steam. The motion of a body acted upon by a single force is always in a straight line, in the direction in which it received the impulse; and the degree of .quickness with which it moves, or the velocity, must be proportional to the force by which it is impelled. If a given force, therefore, will produce a given motion, a double force will produce the double of that motion. If a new force be impressed upon a body in motion, its motion will be increased proportionably to the new force impressed. The velocity with which a body moves is mea- sured by the space passed over, divided by the time which.it employs in that motion; for if you travel one hundred miles in twenty hours, your velocity is five miles in each hour. You may reverse this rule and say, that the time is equal to the space divided by the velocity, for one hundred divided by five gives twenty hours for the time; and you may say also that the space is equal to the velocity multiplied by the time, for twenty multiplied by five gives one hundred miles for the space. Motion is uniform, accelerated, or retarded. Uniform motion is regular, and at an equal rate throughout. The hand of a watch is an example of uniform motion, for it passes over equal spaces in equal times. If neither gravity nor any other force opposed its motion, a ball thrown by the hand would proceed onwards in a right line, and with a uni- form velocity for ever. Perpetual motion, however, cannot be produced by art, for gravity ultimately destroys all motion 36 THE LAWS OP MOTION. that human powers can produce. A ccelerated motion takes place, when the motive power continues to act upon any body, so that its motion is continually increased. When a stone falls from a height, the impulse which it receives from gravity during the first instant of its fall, would be sufficient to bring it to the ground with a uniform velocity; but the stone is not acted upon by gravity merely at the first instant of its fall,—this power continues to impel it during the whole of its descent, and it is this continued impulse which acce- lerates its motion. It has been found by experiment that heavy bodies, descending from a height by the force of gra- vity, fall sixteen feet the first second of time, three times that distance in the next, five times in the third second, seven times in the fourth, and so on, regularly increasing their ve- locities according to the number of seconds during which the body has been falling. Retarded motion is that of a body which moves every moment slower and slower; and it is produced by some force acting upon a body in a direction opposite to that which first put it in motion, as when a stone is thrown upwards, its velocity is gradually diminished by the power of gravity. The force, or power, with which a body in motion strikes against another body, is called its momentum. It is composed of its quantity of matter, multiplied by its quantity of motion; or in other words, its weight and its velocity. A small body may have, a greater momentum than a large one, provided its velocity be sufficiently greater; the momentum of an arrow shot from a bow, for instance, must be greater than a stone thrown by the hand. The momentum of bodies is one of the most important points in mechanics; for you will find, that it is from opposing motion to matter, that machines de- rive their powers. When a body in motion strikes against another body, it meets with resistance from it j and the resistance of the body at rest will be equal to the blow struck by the body in mo- tion ; or to express the same in philosophical language, action and re-action will be equal and in opposite directions. It appears, therefore, that one body acting upon another, loses as much motion as it communicates, and that the sum of the motions of any two bodies in the same line of direction, can- not be changed by their mutual action. From the action and re-action of bodies we may learn in what manner a bird, COMPOUND MOTIO^ ^. 37 by the stroke of its wings, is able to support its weight in the air. If the force with which it strikes the air below it, is equal to the weight of its body, then the re-action of the air upwards is likewise equal to it, and the bird being acted npon by two equal forces in contrary directions, will rest be- tween them. If the force of the stroke is greater than its weight, the bird will rise with the difference of these two forces ; and if the stroke be less than its weight, then it will sink with the difference. In the act of rowing, the water is struck with the oars, in a direction opposite to that in which the boat is required to move ; and the boat is driven .along by the reaction of the water on the oars. Questions.—1. When is a body in motion? 2. What is force ? 3. What are the motive powers ? 4. In what direction is the motion of a body acted upon by a single force ? 5. What is velocity ? 6. To what is the velocity of a moving body proportioned ? 7. How do you calculate the velocity of a moving body ? 8. What is uniform motion ? 9. Accelerated? 10. Retarded? 11. Why cannot perpetual motion be produced by art ? 12. When a stone falls from a height, how does gravity accelerate its motion ? 13. What is said of the distances through which heavy bodies fall in successive seconds of time ? 14. What is an instance of retarded motion ? 15. What is the momentum of a body ? 16. Of what composed ? 17. Why is it so important with respect to mechanics ? 18. What is meant by the term reaction ? 19. To what is reaction equal? 20. Explain the manner in which birds support themselves in the air. LESSON 19. Compound Motion. Projec'tile. impelled forward in a right line. Horizon'tal, parallel to the horizon, on a level. Oblique', not direct, not perpendicular, not parallel. If a body be struck by two equal forces in opposite direc- tions, it will not move at all; but if the forces, instead of acting on the body in opposition, strike it in two directions inclined to each other, it will follow the direction of neither of the forces, but will move in a line between them. There are many instances in nature, of motion produced by several powers acting at the same time. If a ship at sea sail before the wind directly east, and a current set from the north, it will be driven in a direction between the south and east. 4 38 ^mfound motion. A ball fired from a cannon is acted upon by two forces, the one is that occasioned by the powder, the other is the force of gravity. Circular motion is the result of two forces on a body, by one of which it is projected forward in a right line, whilst by the other it is confined to a fixed point. When you whirl a ball, for instance, which is fastened to your hand with a string, the ball moves in a circular direction ; be- cause it is acted upon by two forces, that given it by your- self, which represents the force of projection, and that of the string which confines it to your hand. If during its motion the string were suddenly to break, the ball would fly off in a straight line; being released from confinement to the fixed point, it would be acted on but by one force, and motion produced by one force is always in a right line. The force which confines a body to a centre round which it moves, is called the centrip'etal force ; and that force which impels a body to fly from the centre, is called the centrifugal force. In circular motion these two forces constantly balance each other, otherwise the revolving body would either approach the centre, or recede from it, according as the one or the other prevailed. If any cause should destroy the centripetal force, the centrifugal force would alone impel the body, and it would fly off in a right line in the direction in which it was moving, at the instant of its release. When a stone, whirled round in a sling, gets loose, it flies off in a right line, called a tangent, because it touches the circumference of the circle in which the stone was revolving. It is by the laws of circular motion that the moon and all the planets revolve in their orbits. The moon, for instance, has a constant tendency to the earth, by the attraction of gravitation, and it has also a tendency to proceed in a right line, by that projectile force impressed upon it by the Crea- tor ; now, by the joint action of these two forces it describes a circular motion. If the projectile force were to cease, the moon must fall to the earth ; and if the force of gravity were to cease acting upon the moon, it would fly off into infinite space. When you throw a ball in a horizontal or oblique direc- tion, it describes a curve line in falling, and is acted upon by three forces; the force of projection, which you commu- nicated to it: the resistance of the air, which diminishes its THE PENDULUM. 39 velocity, without changing its direction; and the force of gravity, which finally brings it to the ground. The curve line which the ball describes is called in geometry a parabola. A pendulum consists of a line, or rod, to one end of which a weight is attached, and it is suspended by the other to a fixed point, about which it is made to vibrate. Without being put in motion, a pendulum, like a plumb line, hangs perpendicularly to the general surface of the earth, by which it is attracted; but if you raise a pendulum, gravity will bring it back to its perpendicular position. It will, how- ever, not remain stationary there, for the velocity it has re- ceived during its descent will impel it onwards, and it will rise on the opposite side to an equal height; from thence it is brought back by its gravity, and again driven by the im- pulse of its velocity. Were it possible to remove the ob- stacles occasioned by the resistance of the air, and by the friction of the part by which it is suspended, the motion of a pendulum would be perpetual, and its vibrations perfectly regular; being of equal distances, and performed in equal times. The metallic rods of pendulums are expanded by heat and contracted by cold; clocks therefore will go faster in winter, and slower in summer, for the longer a pendulum is, the slower are its vibrations. The common remedy for this inconvenience is raising or lowering the weight of the pendulum, by means of a screw, as occasion may require. Pendulums vibrate faster towards the poles, and slowest at the equator. This is accounted for by the earth's diameter being greater through the equator than through the poles. All bodies on the earth's surface are drawn to its centre by the force of gravity; and more powerfully as the square of their distance is less. Hence, if one portion of the earth's surface be farther from its centre than another, the force of gravity on a pendulum in one place must be less than in another; and consequently the pendulum will vibrate slower or faster according to its situation. And this is found to be actually the case. It was from observing the difference in the vibrations of pendulums of the same length, that the difference of gravity was discovered, and the true figure of the earth ascer- tained. Pendulums vibrating seconds, at London, are thirty-nine inches and two-tenths in length ; but at the equa- tor about thirtv-nine inches and one-tenth. Pendulums 40 MECHANICAL POWERS. of the same length vibrate in the same time however differ- ent in weight. Questions.—1. In what direction will a body move when impel- led by two forces ? 2. Describe the motion of a ship as impelled by the wind and a current. 3. What is circular motion ? 4. The ex- ample ? 5. Centripetal force ? 6. Centrifugal ? 7. What is said of these two forces ? 8. What is a tangent ? 9. What is said of the motion of the moon? 10. What is a parabola ? 11. A pendulum? 12. Describe the manner in which a pendulum vibrates. 13. Why is not the motion of a pendulum perpetual ? 14. Why do clocks go faster in winter than in summer? 15. Why do pendulums vibrate fester towards the poles than at the equator ? Note. The centrifugal force is stronger at the equator than at the poles; and as it tends to drive bodies from the centre, it is necessarily opposed to, and must lessen the power of gravity, which attracts them towards the centre. The equatorial diameter of the earth is stated by some to be 34 miles, and by others to be 26 miles longer than the polar diameter. 10. Illustrate by figure 1. the composition and re- solution of motion. LESSON 20. Mechanical Powers. Centre of motion is that point which remains at rest while all the other parts of a body move round it. Axis of motion is the line about which a revolving body moves. Equilibrium, equipoise, equality of weight. The mechanical powers are simple instruments or ma- chines in the hands of man, by which he is enabled to raise great weights, and o\rercome such resistances as his natural strength could never effect without them. They are six in number, the lever, the pulley, the wheel and axle, the in- clined plane, the wedge, and the screw, one or more of which enters into the composition of every machine. In order to understand the power of a machine, four things are to be considered ; the power that acts', which consists in the effort of men or horses, of weights, springs, running waters, wind, and steam; the resistance which is to be overcome by the power, which is generally a weight to be moved ; the centre of motion, or, as it is termed in mechanics, the fulcrum, which is the point about which all the parts of a body move ; and lastly, the respective velocities of the power, and of the re- sistance, which must depend upon their respective distances THE LEVER. 41 from the axis of motion. The power and weight are said to balance each other, or to be in equilibrium, when the effort of the one to produce motion in one direction, is equal to the effort of the other to produce it in the opposite direction. The power of a machine is calculated, when it is in a state of equilibrium, that is, when the power just balances the re- sistance opposed, and the momentum of each is equal. The lever is any inflexible bar of iron, wood, or other ma- terial, which serves to raise weights, while it is supported at a point by a prop or fulcrum, on which, as the centre of mo- tion, all the other parts turn. There are three different kinds of levers. The first kind has the fulcrum between the weight and the power, as in steelyards and scissors. It is the most common kind, and is chiefly used for loosening large rocks ; or for raising great weights to small heights, in order to place ropes under them. Let it be required to raise a body which weighs ten hundred pounds, by the strength of a man equal to a hundred pounds weight. Now as the man's strength is only equal to the tenth part of the weight of the body to be raised, the arm of the lever, to which his strength is to be applied, must be ten times as long as the other, in order that the power and weight may be in equilibrium. A balance is a lever of this kind, with equal arms; but if one arm be four times the length of the other, then it is a lever which gains power in the proportion of four to one, and a single pound weight, put into the scale which is suspended from the long arm, will balance four pounds in the other. The second kind of lever is when the prop is at one end, the power at the other, and the weight between them. It explains why two men carrying a burden upon a pole, may bear unequal shares according to their strength, by placing it nearer to the one than the other. He, to whom the burden is five times the nearest, will have to bear five times as much weight as the other. In the case of two horses of unequal strength the beam may be so di- vided, that they shall draw in proportion to their respective ability. The third kind of lever is when the prop is at one end, the weight at the other, and the power applied between them. To this kind are generally referred the bones of a man's arm, for when he lifts a weight by the hand, the mus- cle that exerts its force to raise that weight, is fixed to the bone about one-tenth part as far below the elbow as the hand 4* 42 the pulley. is. The elbow being the centre round which the lower part of the arm turns, the muscle, therefore, must exert a force ten times as great as the weight to be raised. At first view this may appear a disadvantage, but the loss of power is com- pensated by the gain of velocity, and by the beauty and com- pactness of the limb. Questions.—1. What are mechanical powers? 2. What four things are necessary to be considered in order to understand the pow- er of a machine ? 3. When do the power and weight balance each other ? 4. What is a lever ? 3. Describe the lever of the first kind. 6. What are some instances of it, and to what purposes are they applica- ble ? 7. What is said of a balance ? 8. Describe the second kind of lever. 9. What does it explain ? 10. What is the third kind of lever' 11. Show how the bones of a man's arm make a lever of this kind 12. How is the loss of power compensated ? 13. Give an ilWrntinn by fig. 7. of the first kind of lever/ 14. Of the secondlind,£S es 9 and 5. 15. Of the third kind, by figures 10 and 2 Y S LESSON 21. The Pulley, Wheel and Axle, and Inclined Plane. The pulley is formed by a small wheel, made of wood or metal, with a groove in its circumference, which is placed in a frame and turns on an axis. The wheel is usually called a she-eve, and is so fixed in the frame, or block, as to move round a pin passing through its centre. Pullies are of two kinds; fixed, which do not move out of their places • and moveable, which rise and fall with the weight. A single fixed pulley gives no mechanical advantage, but it is of great im- portance in changing the direction of power, and is much used in buildings for drawing up small weights, for a man may raise a weight to any height without the fatigue of as- cendmg a ladder. In the single moveable pulley, the advan- tage gained is as two to one ; that is, a power exerted by the hand often pounds will balance a weight of twenty pounds. Iw 1'Si °1 PUlUeSu the P0Wer ga^d mm be estimated, by doubling the number of pullies in the lower or moveable block So hat when the fixed block contains two pullies which only turn on their axes, and the lower block also con- tains two.which not only turn on their axes, but rise with the weight, the advantage gained is as four to one. In an THE INCLINED PLANE. 43 example of this kind, you will perceive, that by raising the weight an inch, there are four ropes shortened each an inch, and therefore the hand must have passed through four inches of space in raising the weight a single inch; which esta- blishes the maxim, tha"t what is gained in power is lost in space. The next mechanical power is the wheel and axle, which consists of a cylinder, and a wheel fastened to it, or of a cy- linder with projecting spokes. The power being applied at the circumference of the wheel, the weight to be raised ia fastened to a rope that coils round .the axle. The advantage gained is in proportion as the diameter of the wheel exceeds that of the axle. Suppose a wheel to be twelve feet diame- ter, and the axle one foot, the power acting at the circumfe- rence of the wheel moves over twelve times the space which the circumference of the axle does. Hence, twelve hundred weight may be raised with the power of one hundred weight. The wheel and axle may be considered as a perpetual lever, the centre of the axle being the fulcrum, half the diameter of the wheel the long arm, and half the diameter of the axle the short arm. Now, from this it is evident, that the greater the diameter of the wheel, and the smaller the diameter of the axle, the stronger is the power of this machine; but then the weight must rise slower in proportion. A useful appli- cation of the wheel and axle is the crane used on wharfs for drawing goods up from a ship. A man sets a great wheel in motion by pressing on the spokes at the rim, and the rope to which the goods are attached is wound round the axle. The wheel is sometimes put in motion by a man in the in- side, who is in an upright position, and keeps walking on the bars, as if ascending stairs, which keeps the wheel revolving. The inclined plane is nothing more than a slope, or de- clivity, frequently used to facilitate the drawing up of weights. The increase of the power is in the proportion of the length of the plane to its height; that is, the more the plane is lengthened, or its height shortened, the less is the resistance to be overcome. If a plane be twenty feet long, and the perpendicular height be four feet, or one-fifth of the length, then five hundred pounds would be balanced on it by one hundred, because the plane is five times the length of the perpendicular height to which the weight is to be raised. If the height be two feet, or one-tenth of the length, then fifty 44 the wedge and screw. -.*v pounds will balance the five hundred. It is much less labori- ous to ascend a hill by a winding gentle ascent than to climb up a steep declivity. In addition to there being a greater force required in ascending a hill, horses, that draw a load, are placed in a position in which they can exert but a small part of their usual strength. The principle of the inclined plane is applied to the construction of carriage-ways, for tlie conveyance of heavy loads up steep elevations. It is applied also in rail-ways, the use of which has been hitherto confined, almost exclusively, to coal-works, and other mines. Inven- tions, whose only recommendations are simplicity and use- fulness, are often suffered to lie long in a state of public neg- lect, while others of more imposing aspect are readily adopt- ed. It has been remarked with respect to Great Britain, that the time has at length arrived, when carriages moving on level surfaces, or on gently inclining planes, with little friction, and without obstructions, are fast spreading over the face of the country. Questions.—1. How is the pulley formed ? 2. What are the two kinds of pullies ? 3. What is said of the single fixed pulley ? 4. What advantage is gained in a single moveable pulley ? 5. How is the power gained to be estimated in a system of pullies ? C. How is this explained and what maxim does it establish ? 7. Describe the wheel and axle. 8. In what proportion is advantage gained in this mecha- nical power ? 9. What is the example ? 10. Why may the wheel and axle be considered as a perpetual lever ? 11. What application is made of this power ? 12. What is an inclined plane ? 13. In what proportion is the increasp of power ? 14. What is the example for illustrating this ? 15. What application is made of the principle of the inclined plane ? 16. What has been remarked concerning the use of rail-ways ? 17. With respect to Great Britain ? 18. Explain the single moveable pulley by fig. 13.—system of pullies by fig. 15. 19. Illustrate the power of the wheel and axle by fig. 11. 20. Inclined plane by fig. 8. LESSON 22. The Wedge and Screw. Percus'sion, the impression a body makes in falling or striking upon another, or the shock of two bodies in motion. Sili'ceous, flinty; see Lesson 63. The wedge may be considered as two equally inclined planes united at their bases. The advantage gained by it ia the screw. 45 in the proportion of the slant side to half the thickness of the back; so that if the back of a wedge be two inches thick, and the side twenty inches long, any weight pressing on ^the back will balance twenty times as much acting on ^ie sides. But the great use of a wedge lies in its being u^H, not by pressure, but usually by percussion, as by the b^^of a hammer or mallet; for the momentum of the blow is greater, beyond comparison, than the application of any dead weight, or pressure, such as is employed in the other mechanical powers. Hence it is used in splitting wood and rocks, and even a large ship may be raised to a small height by driving a wedge below it. As all instruments, which slope off to an edge on one side only, may be ex- plained by the principle of the inclined plane; so those that decline to an edge on both sides, may be referred to the prin- ciple of the wedge. A saw is a series of wedges, on which the motion is oblique to the resistance. A knife cuts best when it is drawn across the substance which it is to divide; and the reason is, that the edge of a knife is in reality a very fine saw,, and therefore acts best when used like that instru- ment. It is usual in separating large mill-stones from the siliceous sand-rocks, in some parts of Derbyshire, in Eng- land, to bore horizontal holes under them in a circle, and fill these with wedges made of dry wood, which gradually swell as they imbibe moisture, and in a day or two lift up the mill-stone without breaking it. The last mechanical power is the screw, which is a kind of perpetual inclined plane, the power of which is still farther assisted by the addition of a handle or lever, where the power acts; so that the advantage gained is in proportion as the circumference of the circle, made by the handle or lever, is greater than the distance between thread and thread in the screw. The screw may be conceived to be made by cutting a piece of paper into the form of an inclined plane, and then wrapping it round a cylinder. The edge of the paper will form a spiral line round the cylinder, which will answer to the thread of the screw. With the addition of the lever, the screw forms a very powerful machine, employed either for compressions, or to raise heavy weights. It is used by book-binders to press the leaves of books together; and is the principal machine used for coining money; for taking off copper-plate prints; and for printing in general. 46 THE SCREW. All machines are composed of one or more of the six me- chanical powers which we have examined. Their force is diminished in a considerable degree by friction, by which is meant the resistance with which bodies meet in rubbing against each other. There is no such thing as perfect smooth^ ness or evenness in nature : polished metals, thougb»^y wear that appearance more than any other bodies, arl^r from possessing it in reality, and through a good magnifying. glass their inequalities may frequently be perceived. When the surfaces of two bodies, therefore, come into contact, the prominent parts of the one will often fall into the hollow parts of the other, and occasion more or less resistance to motion. Friction is usually computed to destroy one third of the power of the machine. The application of oil lessens friction, because it acts as a polish by filling up the cavities of the rubbing surfaces, and thus making them slide over each other the more easily. There are two kinds of friction, the one occasioned by the sliding of the flat surface of a body, and the other by the rolling of a circular body. The re- sistance resulting from the first is much the most considera- ble ; whilst in the latter the rough parts roll over each other with comparative facility; hence it is that wheels are often used for the sole purpose of diminishing the resistance of friction. The power of a machine is considerably affected by the resistance of the air. In all machines what is gained in power is lost in time. If a man can raise, by a single fixed pulley, a beam to the top of a house in two minutes, he will be able to raise six such beams in twelve minutes; but with six pullies, the three lower ones being moveable, he will raise six beams with the same ease at once; but he will be six times as long about it, that is, twelve minutes, because his hand will have six times as much space to pass over. One capital advantage in the mechanical powers is, that if the six beams were in one piece, it might be raised at once, though it would be impos- sible to move it by the unassisted strength of a single man. Questions.—1. What is the wedge ? 2. The advantage gained by it? 3. In what does its great use lie ? 4. What is said of instru- ments ? 5. \ saw ? 6. A knife ? 7. How are mill-stones obtained in Derbyshire ? 7. What is the screw ? 8. What is the advantage fained by it ? 9. How may the screw be conceived to be made ? 10. or what uses is it employed ? 11. What is friction ? 12. What part of a machine's power does friction destroy? [Note. If 60 pound* LAWS OP FLUIDS. 47 ate required to balance any weight with a mechanical power, 80 pounds will be wanted to put the machine in motion.] 13. How does oil lessen friction? 14. What are the two kinds of friction? 15. How does it appear that in the pulley what is gained in power is lost in time ? 16. Explain the principle of the wedge by fig. 6. 17. Of the screw by fig. 3. **' + LESSON 23. The Laws of Fluids. Hydrostat'ics, a term formed of two Greek words, which signify water, and the science which considers the weight of bodies, viz. statics. Gas, all kinds of air differing from the atmosphere are called gas. Cu'bical, having six square and equal sides. Or'ifice, any opening or perforation. A fluid is a body, the parts of which yield to any impres- sion, and are easily moved among each other. Philosophers have generally imagined that the particles of which fluids are composed must be exceedingly small, because with their best glasses, they have never been able to discern them. And they contend that these particles must be round and smooth, since they are so easily moved among one another. This supposition will account for many circumstances which belong to them. If they are round, there must be vacant spaces between them. If a number of cannon balls were placed in a large vessel so as to fill it up even with the edge; though it would hold no more of these balls, yet a great number of smaller shot might be placed in the vacuities be- tween them: and when the vessel would contain no more small shot, a great quantity of sand might be shaken in, and between the pores of these, water or other fluids would readily insinuate themselves. In a similar manner, a certain quan- tity of particles of sugar can be taken up in water without increasing the bulk, and when the water has dissolved the sugar, salt may be dissolved in it, and yet the bulk remain the same. And this is easily accounted for, if we admit the particles of water to be round. Fluids are either non-elastic and incompressible, as water, oil mercury, and others, or elastic and compressible, as air, steam, and the different gases. The science which treats of 48 PRESSURE OF FLUIDS. the nature, gravity, pressure, and motion of fluids, in general, and of the methods of weighing solids in them, is called hy- drostatics. The non-elastic fluids are said to be incompres- sible, not because they are absolutely so, but because their compressibility is so very small as to make no sensible diffe- rence in calculations relative to their several propertied It has been found that water will find its way through the pores of gold, rather than suffer itself to be compressed into a smaller space. At Florence, a celebrated city in Italy, a globe made of gold was filled with water, and closed so ac- curately that none of it could escape. The globe was then put into a press, and a little flattened at the sides: the con- sequence of which was, that the water came through the fine pores of the golden globe, and stood upon its surface like drops of dew. It was concluded at that time that water was incompressible. Later experiments, however, have shown, that those fluids which were esteemed incompressible, are, in a very small degree, as, perhaps, one part in twenty thousand, capable of compression. Fluids are subject to the same laws of gravity as solids; but their want of cohesion occasions some peculiarities. The parts of a solid are so connected as to form a whole, and their weight is concentrated in a single point, called the centre of gravity; but the atoms of a fluid gravitate independently of each other. It is on this account that water always finds its level; for when any particle accidentally finds itself ele- vated above the rest, it is attracted down to the level of the surface, and the readiness with which water yields to the slightest impression, will enable the particle by its weight to penetrate the surface and mix with it. The particles of a fluid acting thus independently, press against each other in every direction, not only downwards but upwards, and late- rally or sideways, and in consequence of this equality of pressure, every particle remains at rest in the fluid. If you agitate the fluid you disturb this equality of pressure, and it will not rest till its equilibrium or level is .restored. The pressure downwards is the effect of gravity, and if there were no lateral pressure, water would not run out of an opening on the side of a vessel. The lateral pressure proceeds entirely from the downward pressure, or the weight of the liquid fthove; and consequently the lower an orifice is made in a ffessel, the greater will be the velocity of the water ruBhing PRESSURE OF FLCIDS, 49 out of it. In a cubical vessel the pressure downwards will be double the lateral pressure on one side; for every particle at the bottom of the vessel is pressed upon by a column of the whole depth of the fluid, whilst the lateral pressure diminishes from the bottom upwards to the surface, where the particles have no pressure. The upward pressure of fluids may be shown by a machine, called the hydrostatic bellows. It consists of two oval or round boards, covered with leather so as to rise and fall like the common bellows, but without valves. A long tube is fixed to the upper board and weights placed upon it. When the tube is supplied with water, it will, by its upward pressure, sustain and lift up the weights. The pressure of water and other fluids differs from the gravity or weight, in this respect; the weight is accord- ing to the quantity; but the pressure is according to the- perpendicular height. Dr. Goldsmith relates that he once saw a strong hogshead split by the following experiment. A strong small tube, made of tin, about twenty feet long, was cemented into it, and then water was poured in to fill the cask; when it was full and the water had risen nearly to the top of the tube, the vessel burst with a prodigious force. This extraordinary power may be greatly increased by a forcing piston placed in the tube. A similar method has been adopted in forming a machine, called a hydrostatic press, by which hay or cotton may be brought into a compass twenty or thirty times less than it usually occupies. Questions.—1. What is a fluid? 2. What have philosophers generally imagined respecting the particles of fluids ? 3. What il- lustration is given respecting the vacant spaces between the parti- cles of fluids ? 4. What are the two kinds of fluids ? 5. Define Hydrostatics. 6. Why are the non-elastic fluids said to be incompres- sible ? 7. Describe the experiment made at Florence. 8. What was concluded at the time, and what have later experiments shown ? 9. What is the difference between the gravity of fluids and solids ? 10. Why does water always find its level ? 11. What is said of the direc- tion in which fluids press ? 12. What is the cause of the downward and lateral pressure L 13. What is said of the lateral pressure in a cubical vessel? H.TIow may the downward pressure be shown? 15. How does the pressure of a fluid differ from the weight ? 16. What is related by Dr. Goldsmith ? 17. What is said of the hydro- static press ? 18. Illustrate the pressure of fluids by figures 25. 24. and 23. 19 What is said of what is called the hydrostatical paradox ? 50 SPECIFIC GRAVITY OF BODIES. LESSON 24. Specific Gravity of Bodies. By the specific gravities of bodies we mean the relative weights, which equal bulks of different bodies have to each other. And it is usual to compare them with that of water, as it is by weighing bodies in water that their specific gra- vities are found. A body immersed in a fluid will sink to the bettom, if it be heavier than its bulk of fluid; if it be suspended therein, it will lose as much of what it weighed in air, as its bulk of the fluid weighs. The instrument gene- rally used for obtaining the specific ^gravities is called the hydrostatical balance ; it does not differ much from the com- mon balance. The general rule for finding the specific gra- vity of a solid, heavier than water, as a piece of metal, is this : weigh the body first in air, in the usual way, then weigh it when it is plunged in water, and observe how much it loses of its weight in this fluid, and dividing the former weight by the loss sustained, the quotient is the specific gra- vity of the body, compared with that of water. As an ex- ample, it is usual to take a guinea, which weighs in air one hundred and twenty-nine grains, and when suspended by means of a fine hair, and immersed in water, it is found to balance one hundred and twenty-one grains and three-quar- ters, losing of its weight seven grains and a quarter; now one hundred and twenty-nine divided by seven and a quar- ter, gives about seventeen for the quotient; that is, the spe- cific gravity of a guinea compared with that of water, is as ahout seventeen to one. And thus, any piece of gold may be tried, by weighing it first in air, and then in water; and if, upon dividing the weight in air, by the loss in water, the quotient comes to be about seventeen, the gold is good ; if the quotient be eighteen, or between eighteen and nineteen, the gold is very fine; but if it be less than seventeen, the gold is too much alloyed with some other metal. The same principle is universal. Hence we see the reason why boats or other vessels float on water; they sink just so low, that the weight of the vessel, with its contents, is equal to the Jj^jantity of water which it displaces. The method of ascer- taining the specific gravities of bodies, was discovered by SPECIFIC GRAVITY. OF BODIES. 51 Archimedes, in the following manner. Hiero, king of Sy- racuse, having given to a workman a quantity of pure gold, of which to make a crown, suspected that the artist had kept part of the gold, and adulterated the crown with a baser metal. The king applied to Archimedes to discover the fraud. The philosopher long studied it in vain, and at length accidentally hit upon a method of verifying the king's sus- picion. Going one day into a bath, he took notice that the water rose in the bath, and immediately reflected that any body, of equal bulk with himself, would have raised the water just as much; though a body of equal weight, but not of equal bulk, would not raise it so much. From this idea he conceived a mode of finding out what he so much wished, and was so transported with joy, that he ran out of the bath, crying out in the Greek tongue, " I have found it, I have found it!" Now, since gold was the heaviest of all metals known to Archimedes, it occurred to him that it must be of less bulk, according to its weight, than any other metal; and he, there- fore, desired that a mass of pure gold, equally heavy with the crown when weighed in air, should be weighed against it in water, conjecturing that if the crown was not alloyed, it would counterpoise the mass of gold when they were both immersed in water, as well as it did when they were weighed in air. But upon making trial, it was found that the mass of gold weighed much heavier in water than the crown did : nor was this all—when the mass and crown were immersed separately in the same vessel of water, the crown raised the water much higher than the mass did ; which showed it to be alloyed with some lighter metal that increased its bulk. And upon this principle is the doctrine of the specific gravi- ties of bodies founded. Questions.—1. What is meant by the specific gravities of bodies ? 2. What is said of a body immersed in a fluid ? 3. What is the gene- ral rule for finding the specific gravity of a solid heavier than water ? 4. What example is given? 5. How may a piece of gold be tried? 6 Why do vessels float ? 7. What incident led to the method of dis- covering the specific gravities of bodies ? 8. Who made the disco- very, and how ? 9. Explain the method and the result. 10. Explain by fig. 14. the use of the hydrostatic balance. 11. Describe the hy- drometer. *f 52 THE SYPHON. LESSON 25. Hydraulics. Intermittent, coming by fits, not constant. Res'ervoir, a conservatory of water ; a store. Vac'uum, a space unoccupied by matter. The science of Hydraulics teaches how to estimate the velocity and force of fluids in motion. Upon the principle of this science all machines worked by water are constructed, as engines, mills, pumps, and others. Water can be set in motion by its own gravity, as when it is allowed to descend from a higher to a lower level; and by an increased pressure of the air, or by removing the pressure of the atmosphere, it will rise above its natural level. In the former case it will seek the lowest situation, and in the ratter, it may be forced to almost any height. The syphon is a pipe used to draw off water, wine, or other fluids, from vessels which it would be inconvenient to move from the place in which they stand. It is made of tin or copper, and bent in such a manner that one limb may reach down through the hole in the top of the vessel to be emptied, to its very bottom; the other limb should be the longest, so that when filled it may contain a heavier body of fluid than that within the vessel. The pressure of the atmosphere being taken off from that part of the surface of the liquor within the tube, the liquor rises above its natural level, and flows through the longer limb, and the contents of the vessel are drawn off to the last. There are intermittent springs in va- rious places of the world, which have been explained on the principle of the syphon. A passage for the water may have been formed in the soil, and when the internal cavity has been filled with water, so as to begin to run off by this passage, the pressure of the atmosphere will make the water flow till all is carried off. Of course the spring then ceases until the cavity is again filled with water, when the same phenomenon is repeated. Fluids may be conveyed over hills and valleys in bent pipes, to any height which is not greater than the level of the spring whence they flow. The Romans, either from their ignorance of the pressure of fluids, or from their love of magnificence, conveyed water across valleys by P0RCING PUMP. 53 straight-lined aqueducts, which were supported by immense arches or columns. The common pump consists of a large tube or pipe, called the barrel, whose lower end is immersed in the water which it is designed to raise. A kind of stopper, called a piston, is fitted to this tube, and is made to slide up and down by means of a metallic or wooden rod. In the piston, there is a valve, or little door, which opening upwards, admits the water to rise through it, but prevents its returning. A simi- lar valve is fixed in the body of the pump. When the pump is in a state of inaction, the two valves are closed by their own weight; but when the piston is made to ascend, it raises a column of air which rested upon it, and produces a vacuum between itself and the lower valve ; the air beneath this valve expands and forces its way through it; and the water, relieved from the pressure of air, ascends into the pump, being forced up by the weight of the surrounding atmosphere. When the piston now descends it is forced into the water, which, as it cannot repass through the lower valve, must rise through the valve of the moveable piston, by the ascent of which, it is lifted up and runs off at the spout. There must never be so great a distance as thirty-three feet from the level of the water in the well, to the valve in the piston, for in that case, the water would not rise through the valve, because the pressure of the atmosphere will not sus- tain a column of water above that height. But when the water has passed the valve in the moveable piston, it is not the pressure of the air on the reservoir which makes it ascend; it is raised by lifting it up, as you would raise it in a bucket, of which the piston formed the bottom. The forcing pump is not only used to raise water from a well to the.surface of the earth, but likewise to force it into reservoirs on the tops of buildings, from which pipes are laid to convey it to different parts as conveniency requires. It differs from the common pump by having the upper piston solid, and a pipe joined to the barrel just above the lower piston, through which the water passes into what is termed the air vessel. In the pipe which leads to the air vessel there is a fixed valve, which opens upwards and prevents the return of the water. Through the upper part of the air vessel a tube is inserted, which reaches nearly to its bottom. Now the air which is above the water in the vessel being 5* 54 THE DIVING BELE. confined, and condensed into a smaller bulk than its natural space, presses by its elasticity upon the surface of the water, and forces it violently up the tube in a continual stream. It is upon this principle that the engine for extinguishing fires is constructed. Questions.—1. What does the science of hydraulics teach ? 2. What machines are constructed on the principles of this science? 3. What are the different ways in which water may be set in motion ? 4. What is flic syphon ? 5. Describe the manner of its conveying fluids. 6. How are intermittent springs caused ? 7. Describe the common pump and show how it raises water. 8. How high can water be raised in a common pump ? 9. Describe the forcing pump. 10. What engine is constructed on the principle of the forcing pump ? 11. Describe the common pump by fig. 21. and show its action. 12. Forcing pump by fig. 22. and show how it acts in forcing up water. LESSON 26. The Diving Bell, and Steam Engine. Ver'tically, in a direction perpendicular to the horizon. Apparatus, utensils and appendages belonging to a machine If you take a glass tumbler, and plunge it in water with the mouth downwards, you will perceive that very little water will enter into it. The air which fills the glass prevents the entrance of the water ; but as air is compressible, it cannot entirely exclude the water, which, by its pressure, condenses the air in a slight degree. Upon this simple principle ma- chines have been invented, by which people have been able to walk about at the bottom of the sea, with as much safety as upon the surface of the earth. The original instrument of this kind was much improved by Dr. Halley, more than a century ago. The machine was made of copper in the shape of a bell. The diameter of the bottom was five feet, that of the top three feet, and it was eight feet high. To make the vessel sink vertically in water, the bottom was loaded with a quantity of leaden balls. Light was let into the bell by means of strong spherical glasses fixed in the top. Barrels filled with fresh air, were made sufficiently heavy, and sent down, from which a leathern pipe communicated with the inside of the bell, and a tube with a stop at the upper part Jet out the air which had become unfit for breathing The STEAM ENGINE. 55 divers are generally let down from a ship, and taking a rope with them, to which is fixed a bell in the vessel, they have only to pull the string, and the people in the ship draw them up; but if business requires it, they will stay several hours at the bottom of the sea without the smallest difficulty. By means of a strong globular cap with circular glasses in front to give light, it has been found practicable for a diver to go out of the engine to the distance of eighty or a hundred yards, the air being conveyed to him in a continued stream by small flexible pipes. Accidents, which through careless- ness have sometimes occurred, may be readily prevented, by a proper degree of attention, and people may descend to very great depths without danger. The diving bell has often been used in bringing up the goods from a vessel which has sunk in deep water, and in blowing rocks which impeded navigation. The Steam Engine is one of the most useful, curious, and important machines that have ever been invented. It con- sists of a large cylinder or barrel, in which is fitted a solid piston like that of the forcing pump. Steam is supplied from a large boiler, which in forcing up the piston, instantly opens a valve, through which cold water rushes, on the principle of the common pump. Other steam is then introduced above the piston, which forces it down, and drives the water out of the pipe. Steam raises the piston again, and again makes it fall, and thus produces an alternate motion, which is communicated, by an upright iron rod, to a large beam or lever, that is lifted up and pulled down with wonderful pre- cision and force. This regular and powerful motion is easily applied by the mechanic to all kinds of machinery. The apparatus has been varied by different persons, and for diffe- rent objects ; but the principle remains the same. By the admirable contrivances of Watt and Fulton, the steam-engine has become a thing stupendous alike for its force and flexibility,—for the prodigious power which it can exert, and the ease, and precision, and ductility with which it can be varied, distributed, and applied. The trunk of an elephant, that can pick up a pin or rend an oak, is nothing to it. It can engrave a seal, and crush masses of obdurate metal before it,—draw out, without,breaking, a thread as fine as gossamer, and lift up a ship of war like a bauble in ♦he air. It can embroider muslin and forge anchors,—cut 56 NATURE AND PROPERTIES OF AIR. steel into ribands, and impel loaded vessels against the fury of the winds and waves. It has armed the feeble hand of man, in short, with a power to which no limits can be as- signed ; completed the dominion of mind over the most re* fractory qualities of matter ; and laid a sure foundation for all those future miracles of mechanic power which are to aid and reward the labour of after generations. Questions.—1. What is the principle of the diving bell ? 2. What were the dimensions of Dr. Halley's diving bell ? 3. How was light let in ? 4. Fresh air? 5. How do divers make known their wish to be drawn up ? 6. Of what use is this invention ? 7. Describe the steam-engine. LESSON 27. Nature and Properties of Air. Den'sity, the degree of closeness and compactness of the parti- cles of a body, the property directly opposite to rarity. Absolutely, completely, without restriction, positively. Hemisphere, half a globe, or sphere. The science which treats of the mechanical properties of elastic or aeriform fluids, such as their weight, density, com- pressibility, and elasticity, is called Pneumatics. The air in which we live surrounds the earth to a considerable height, revolves with it in its diurnal and annual motion, and, toge- ther with the clouds and vapours that float in it, is called the atmosphere. The height to which the atmosphere extends has never been ascertained; but at a greater height than forty-five miles it ceases to reflect the rays of light from the sun. The air is invisible because it is perfectly transparent; but it may be felt on moving the hand in it, or when it moves and produces what we call wind. It is nearly nine hundred times lighter than water, but the whole atmosphere presses on all sides like other fluids, upon whatever is im- mersed in it, and in proportion to the depths. Its pressure upon a mountain is known to be less than in the plain or valley beneath. If a glass tumbler be completely filled with water, and covered with a piece of writing paper, so as to hold it tight, and accurately even, the water will not run out although the glass be inverted and the hand removed. The AIR PUMP 57 weight of the water is sustained by the upward pressure of the air upon the paper. The most essential point in which air differs from other fluids, is by its spring or elasticity, that is to say, its power of increasing or diminishing in bulk, according as it is more or less compressed. The elasticity of air differs from that of bodies in general; for when solid bodies are compressed they have an elastic power, which causes them to resume the same figure they possessed before compression : but on removing the pressure on air, it will not only resume its first bulk, but expand to an indefinite extent. With regard to animal and vegetable bodies, the gravity of the air is de- " stroyed by its elasticity. It is true, that the atmosphere presses with a weight of fifteen pounds upon every square inch of the earth's surface, when the air is heaviest, and that conse- quently a man's body, which contains nearly fifteen square feet, will sustain a weight equal to about fourteen tons and a half; but this pressure is so great that it would be absolutely insupportable, and even fatal to us, were it not equal in every part, and counterbalanced by the spring of that air which fills all the vesicles of the body, and reacts with an outward force equal to that with which the atmosphere presses inward. By means of an air-pump, the air may be drawn out of a large glass vessel, or receiver, and a vacuum produced, in which a great number of curious experiments may be per- formed, showing aLpnce the properties and usefulness of the air. We shall give%a brief description of the air-pump, though a view of the machine' itself will convey a much bet- ter idea of thqf important purposes to which it is applied, than any description can afford. Two brass cylinders are closely and firmly fastened down to the table or base of the machine, by means of what are qalled the head and the columns. The receiver is made to Jit very accurately on a brass circular plate, which ha| a hdje in the middle, through which the air passes from Ihe receiver into a tube made of brass, that communicates with the cylinders. Near the bottom of each cylinder is a valve opening upwards, and above these valves are two others in pistons which are moved up and down by - toothed rods that fall into a toothed wheel, to the axis of which a handle is fixed. On turning the handle one of the pistons is raised and the other depressed, consequently a ra«- 58 CONDENSING SYRINGE. refied space is formed between the upper and lower valve in one cylinder; then the air which is contained «i the receiver rushes through the brass tube and by its elasticity forces up the lower valve and enters the cylinder; then the valve closes and prevents the air from returning into the receiver. When the motion is reversed, the other piston ascends, and the first is depressed ; in its depression, the elasticity of the air contained between the two valves, forces open the up- permost valve, and it escapes into the upper part of the cy- linder ; then the valve closes and prevents its return. Whilst one piston, therefore, exhausts the air from the receiver, the other is discharging it from the top of the cylinder. Thus by continued exhaustion, the density of the air keeps de- creasing in the receiver, till its elasticity is no longer able to force up the lower valves, which terminates the effect of the machine. The air is admitted into the receiver again by unscrewing a small nut which is so situated as to communi- cate with the air channel. If the air be exhausted from a receiver, it will be held fast by the pressure of the external air. If a small receiver be placed under a larger, and both exhausted, the larger will be held fast, while the smaller will be easily moved. If a guinea and a feather be dropped from the top of the re- ceiver, they will reach the bottom at the same instant, be- cause there is then no resisting medium. Animals cannot live in an exhausted receiver, and the continuance of life varies according to the strength or size of the animal. A man requires a gallon of fresh air every minute. If a lighted candle be covered with a receiver containing* gallon of air, the candle will burn a minute ; arm then tffe flame, after having gradually decayed, will go ta$- A c/nstant supply of fresh air, therefore, is as necess?» to feed flame as to support life. If two brass hemispheres ojf three or foui inches in diameter be put together, aid the internal air ex- hausted, the pressure from without wil^equSe one hundred and fifty pounds to separate them; but iflfhe external air be taken away, they will separate of themselves. The Condensing Syringe has a solid piston, and a valve in the lower part of its barrel which opens downwards. By thrusting down the piston the air is forced through the valve, which is afterwards held close by the elasticity i>f the con- densed air. When the piston is raised up a vacuum is pro- THE BAROMETER. 50 duced, till it is raised above a small hole in the barrel, when the air rushes in, and is again discharged through the valve. An instrument of this kind is used to produce what is called the artificial fountain. Questions.—1. What is Pneumatics ? 2. What is the atmosphere ? 3. What is said of its height ? 4. What is wind ? 5. What is said of the weight and pressure of the atmosphere ? 6. What experiment illustrates the upward pressure of the atmosphere ? 7. How does the elasticity of air differ from the elasticity of bodies in general ? 8. What is the weight of the atmosphere upon a square inch ? 9. Upon the surface of a man's body ? 10. How is the pressure of the air upon the body counterbalanced? 11. Describe the air-pump. 12. Show the method by which the air is drawn from the receiver. 13. What are some of the experiments that may be performed by an air-pump ? 14. Describe the condensing syringe, and its action. 15. Look at fig. 16. and describe the aqr-pamp, and show its action. 16. Look at fig. 26. and describe the artificial fountain. LESSON 28. The Barometer^ Hermetically, a term applied to the closing of the orifice of a glass tube by fusion, so as to render it air-tight. • Respira'tion, the act of alternately inspiring air into the lungs, and expiring it from them. The Barometer is a very useful instrument for determin- ing-the variations of the weather. If a glass tube of about thiny-two or thirty-three inches long, hermetically sealed at one end, be filled with mercury, and then inverted in a basin or cup of the same fluid, the mercury in the tube will stand at an altitude above the surface of that in the basin between twenty-eight and thirty-one inches. The tube and the basin are fixed on a board, for the convenience of suspending it; the board is graduated for the purpose of ascertaining the hfeight at which the mercury stands in the tube; and a small [, moveable metallic plate, called a vernier, an inch of which is divided into a hundred equal parts, serves to show that height with greater accuracy. The height at which the mercury will stand depends upon the weight of the atmo- sphere, which varies much according to the state of the wea- ther. The air is heaviest, in dry weather, for it is then that the mercury is found to rise in the tube and consequently 60 THE BAROMETER. the mercury in the cup must be most pressed by the air. It is true that in damp weather the air feels heaviest, but it is on account of its being less salubrious. The lungs under these circumstances do not play so freely, nor does the blood circulate so well; and thus obstructions are frequently occa- sioned in the smaller vessels, from which arise colds, asthmas, and fevers. The thinness of the air in elevated situations is sometimes oppressive from being insufficient for respira- tion; and the expansion which takes place in the more dense air contained within the body is often painful. It oc- casions distension, and sometimes causes the bursting of smaller blood-vessels. ' The barometer has been used for the purpose of measur- ing the heights of mountains and towers> and of estimating the elevation of balloons. The weight of one hundred and three feet of air is equal to that of one tenth of an inch of mercury. If a barometer, therefore, be carried to any great eminence, the mercury will descend one tenth of an inch for every one hundred and three feet that the barometer ascends. When the surface of the mercury is convex, or stands higher in the middle than at the sides, it is a sign the mercury is then in a rising state ; but if the surface be concave, or hollow in the«middle, it is then sinking. In very hot weather, the falling of the mercury indicates thunder. In winter, the rising indicates frost, and in frosty weather if the mercury falls three or four divisions, there will be a thaw. But in a* continued frost, if the mercury rises, it will snow. In igfe, weather, when the mercury rises much and high, anofso continues for two or three days before the bad weather is entirely over, then a continuance of fair weather may be ex- pected. In fair weather, when the mercury falls low, and thus continues for two or three days before the rain comes, then much wet weather may be expected and probably high winds. The unsettled motion of the mercury denotes un- settled weather. The words engraved on the scale are not so much to be attended to, as the rising and falling of the mercury. It always sinks lowest of all for great winds, though not accompanied with rain; but it falls more for wind and rain together than for either of them alone. Ba- rometers are frequently made oPa tube with a curved neck and bulb, being more commodionpthan the basin and tube. To make these tolerably exact, however, the circular area SOUND. 61 of the bulb should be at least thirty or forty times larger than that of the tube; so that the mass of mercury may be as little affected as possible whilst it rises and falls ; for the height of the column is taken from the surface of the mer- cury in the bulb to its height in the tube. Questions.—1. What is the construction of the barometer? 2. Upon whaudoes the height of the mercury depend ? 3. Why is the air heavieswin dry weather ? 4. Why does it feel heaviest in damp weather ? 5„ How may the height of a mountain be ascertained by the barometer ? 6. What is indicated by the convexity and concavity of the mercury ? 7. Upon what other construction are barometers made than that first described ? LESSON 29. m Sound. Humidity, moisturg.' The degrees of moisture in the air are measured by an.^ instrument called a Hjgrom'eter, of which there .are varkiu^Jnds ; whatever contracts or expands by the moisture owdryness of the atmosphere is capable of being fonn^tnto one* ->'■ Sound arises from a tremulous or vibrating motion in elas- tic bodies, which is caused by a stroke or collision, and is carried to the e,ar through the medium of the air. The pro- duction of sound therefore depends upon three circumstan- ces, a sonorous body*to give the impression, a medium to convey it, and the ear to receive it. Sonorous bodies, how- ever, are merely the instruments by which a peculiar species of motion is corajlonicated to the air. It is true that when you ring a bell, botbfthe bell and the air are concerned in the pro- duction of sound : but sound, strictly speaking, is a perception excited in the mind by the motion of the air on the nerves of the ear; the air, therefore, as well as the sonorous bodies which put it in motion, is only the cause of sound,—the im- mediate" effect is produced by the sense of hearing: lor » without this sense, there would be no sound. The vibrating ^air strikes the ear, and causes in the mind the perception of' sound.' .■ If you endeavour to ring a small bell, after you have sus- pended it under the receiver in an air-pump, from which the air has been exhausted, no sound will be produced. By 6 62 VELOCITY OF SOUND. exhausting the receiver, you cut off the communication be- tween the air and bell; and the latter, therefore, cannot impart its motion to the air. It has been ascertained that liquids as well as air are capable of fconveying the vibrRory motion of a sonorous body to the organ of hearing ; for sound can be heard under water. Dr. Franklin imagined, that with his ear under water, he- heard the collision of stones in that medium, at the distance of a mnW, j The vibration of a sonorous body gives a tremulous mo- tion to the air around it, very similar to the motion commu- nicated to smooth water when a stone is thrown into it. This first produces a small circular wave around the spot in which the stone falls ; the wave spreads, and gradually com- municates its motion to the adjacent waters, producing simi- lar waves to a considerable extent. The same kind oT waves are produced in the air by the motion of a sonorous body, but with this difference, that asL air is an elastic fluid, the motion does not consist of regularly extending u^ves, but of vibrations, and are composed of a motion forwards and back- wards, similar to those of a sonorous body. They differ also in the one taking place in a plane, the ofljier in alifirections : the aerial undulations being spherical. The first sphere of undulations which are produced immediately round the so- norous body, by pressing against the contiguous air, con- denses it. The condensed air, though impelled forward by the pressure, reacts on the first set of. unduR^ions, drivirlg them back again. The second set of undulations which have been put in motion, in their turn communicate their motion, and are themselves driven back h^reaction. Thus there is a succession of waves in the air,"c. lllus' ttate the vibrations of a musical string by figures 17. 18, and 19. 6* 66 OPTICS. LESSON 31. Optics. Lu'minous, shining by its own light. Transparent, admitting rays of light to pass through. Opaque', stopping the rays of light. Zenith, a point in the heavens directly over our heads, the pole of the horizon. Na'dir is a point diametrically opposite to the Zenith, constituting the other pole of the horizon. Optics is the science which treats of light, and of the instruments by which it is applied to useful purposes. It is one of the most interesting branches of natural philosophy, but not one of the easiest to understand; it will be neces- sary, therefore, that you give to it the whole of your attention. Light, when emanated from the sun, or any other lumi- nous body, is projected forwards in straight lines in every possible direction ; so that the luminous body is not only the centre from whence all the rays proceed, but every point of it may be considered as a centre which radiates light in every direction. The particles of light are so extremely minute, that although they are projected in different direc- tions, and cross each other, yet they are never known to in- terfere, and impede each other's course. It is still a disputed point, however, whether light be a substance composed of particles like other bodies. In some respects it is obedient. to the laws which govern bodies ; in others, it appears to be independent of them: thus, though its course is guid- ed by the laws of motion, it does not seem to be influenced by the laws of gravity. It has never been discovered to have weight, though a variety of interesting experiments have been made with a view of ascertaining that point. Some suppose that the rays of light, instead of being particles, consist of the undulations of an elastic medium, which fills all space, and which produces the sensation of light to the eye, just as the vibrations of the air produce the sensation of sound to the ear. Most of the phenomena may be ac- counted for by either hypothesis, but that of their being par- ticles applies more happily to some of the facts respecting the modifications of light by refraction and reflection. When rays of light encounter an opaque body, part of them are absorbed, and part are reflected, and rebound just REFLECTION OF LIGHT. 6? as an elastic ball which is struck against a wall. A ray of light striking perpendicularly upon a plane mirror, is re- flected back in the same direction ; but those rays which strike it obliquely, are reflected back in an opposite direction, but with the same obliquity; the angle of reflection, there- fore, is exactly equal to the angle of incidence. If you stand directly before a looking-glass, you see your image reflected back to you. If you stand a little to the side, you cannot see yourself; but a person who stands just as far on the other side of it, can see your image in the glass, and you can see his. If you place a candle a little to one side, you must go as far on the other to see its image in the glass. This is the same rule which takes place in the collision of elastic bodies against any surface. If you strike an ivory ball or common marble perpendicularly against the wainscot, it returns to you ; but if you make it strike sideways, it goes off at the same angle with which it came to the wainscot. So it is with rays of light ; the incident ray, or the ray which falls upon a surface, makes an angle with a perpendicular line, drawn from the point where it strikes, equal to that which the reflected ray makes with it. With respect to a looking-glass, it is the silvering on the glass which causes the reflection, otherwise the rays would pass through it without being stopped, and if they were.not stopped they could not be reflected. No glass, however, is so transparent but it reflects some rays : if you put your hand near a window, you clearly see its image on the other side, and the nearer the hand is to the glass, the more evi- dent is the image. Whatever suffers the rays of light to pass through it is called a medium, and the more transpa- rent the body, the more perfect 4s the medium. But rays of light do not pass through a transparent medium, (unless they fall perpendicularly upon it) in precisely the same di- rection in which they were Moving before they entered it. They are bent out of their former course, and this is called refraction. When they pass out of a rarer into a denser medium, as from air into water or glass, they are always re- fracted towards a perpendicular to the surface, and the re- fraction is, more or lo.^s, in proportion as the rays fall, more or less, obliquely on the refracting surface. But when they pass from a denser into a rarer medium, as from glass or water into air, thrv move in a direction farther from the GS ^ REF11ACTION OF LIGHT. perpendicular. If you put a piece of money into an empty basin, and stand at such a distance that it may not be visi- ble ; then let another person pour water into the basin, and the money will be seen; for the rays of light, in passing from a denser into a rarer medium, are bent from the per- pendicular, and thus are directed to your eye. The follow- ing, therefore, may be established as a sort of axiom in op- tics : we see every thing in the direction of that line in which the rays approach us last. If you place a candle before a looking-glass, and -stand before it, the image of the candle appears behind it; but if another looking-glass be so placed as to receive the reflected rays of the candle, and you stand before this second glass, the candle will appear behind that; because the mind imagines every object to be in the direc- tion from which the rays come to the eye last. Hence, when the rays of light coming from the celestial bodies, arrive at our atmosphere, they are bent downward ; and those bodies appear, when in the horizon, higher than they are. The effect of this refraction is about six minutes of time, but the higher they rise, the less are the rays refracted ; and when they are in the zenith, they suffer no refraction. The sun is visible about three minutes before he rises, and about the same time after he sets; making in the course of a year about a day and a half. Twilight is occasioned partly by refraction, but chiefly by reflection of the sun's rays by the atmosphere,, and it lasts till the oUn is eighteen degrdis be- low the horizon. Were there no atmosphere to reflect and refract the surfs rays, only that part of the heavens would be luminous in which the sun is placed ; and if we could live without air, and should turn our backs to the sun, the whole heavens would appear as dark as in the ninht. In this case also, a sudden transition from the brightest sun- shine to dark night would immediately take place upon the setting of the sun. Questions.—1. What is said of optics ? 2. In what manner ia light projected from luminous bodies ? 3. What is still a disputed point, and what is said of it ? 4. How are rays of light reflected ? 5. How is it shown that the angle of reflection is equal to the angle of incidence ? 6. What is meant by the refraction of rays of light ? 7. How are they refracted in passing from a rarer into a denser medium ? 8. From a denser into a rarer ? pc consists of at least two lenses, by one of which an imag<~ is formed within the tube of the microscope ; and this image is viewed through the eye-glass, instead of the object itself The solar microscope is a kind of camera obscura, which, in a darkened chamber, throws the image on a wall or skreen. It consists of two lenses fixed opposite to a hole in a board or window-shutter. There is also a plane reflector or mirror placed without, which may be so regulated as to throw the sun's rays upon the outer lens. A magic lantern is constructed on the same prin- ciples. The light is supplied by a lamp instead of the sun, and it is used for magnifying paintings on glass, and throw- ing their images upon a white skreen in a darkened chamber. Questions.—1. In what ways may sight be defective? 2. For what are spectacles intended ? 3. How do they assist eyes^that are too flat ? 4. Too convex or round ? 5. Why do some persons bring objects close to their eyes, and others hold them at a distance ? 6 What are microscopes"? 7. Single microscopes ? 8. How is their magnifying power calculated ? 9. Describe the compound microscope. 10. Solar microscope. 11. Magic lantern. 12. Look on fig. 35. and describe the singlo microscope. 13. On fig. 34. and describe the com- pound microscope. LESSON 38. Microscopic Discoveries. Miniature, (pronounced min'e-ture,) representation in a small compass. Fil'ament, a slender thread. Ped'icle, a footstalk. Animal'cule, a small animal. Con'ical, consisting of a circular base or bottom and ending in a Tissue, (pron. tish'u,) a substance interwoven with threads, or variegated. The microscope has opened to us.a new world of insects and vegetables; it has taught us that objects, invisible to the naked eye, exist, having figure, extension, and different parts ; some examples of which we shall produce, that we may have more reasons for admiring and praising the wis- dom and power of God. A grain of sand when examined by the eye appears round, but with the help of a glass we 84 MICROSCOPIC discoveries. observe that each grain differs from the other, both in size and figure ; some of them are perfectly round, others square, some conical, and the greater part of an irregular form. By microscopes which magnify objects millions of times, we can discover in the grains of sand a new animal world ; for within their cavity dwell various insects. In the vegetable kingdom we are presented with a thick forest of trees and plants, bearing leaves, branches, flowers, and fruits. Mouldi- ness, when looked at by the naked eye, seems nothing but an irregular tissue of filaments; but the magnifying glass shows it to be a forest of small plants, which derive their nourishment from the moist substance which serves them as a base. The stems of these plants may be plainly distin- guished, and sometimes their buds, some shut and some open. They have much similarity to mushrooms, which, it is well known, are the growth of a single night; but those in miniature, of which we are speaking, seem to come to perfection in a much less space of time ; hence we account for the extraordinary progress which mouldiness makes in a few hours. A sort of dust, which covers some stones, has been found to consist of small mushrooms, raised on pedicles, the heads of which, round the middle, were turned up at the edges. Above their covering a multitude of small grains ap- pear, shaped like cherries somewhat flattened; and among them several small red insects, which probably feed upon them. A small drop of the green surface of water, that has stood for some time, has been found to be altogether composed of animalcules of several shapes and magnitudes. The most remarkable were those that gave the water the green colour ; they were oval creatures; they could contract and dilate themselves, tumble over many times together, and then shoot away like fishes. If you slightly bruise some corns of pepper, and infuse them in water for a few days, and then expose a drop of it to the microscope, a number of animalcules will be visible, in continual motion, going backwards and forwards in all di- rections, turning aside when they meet each other, or when their passage is stopped by some obstacle. In other infu- sions, as in that of new hay, differently shaped animalcules will be found. When the drop in which they swim, and which to them is like a pond, becomes .diminished by evapo- ration, they gradually retire towards the middle, where they MICROSCOPIC DISCOVERIES. 85 accumulate, and at length, when entirely deprived of moist- ure, perish. Previously to this they appear in great distress, writhe their bodies, and endeavour to escape from that state of uneasiness which they evidently feel. If the smallest quantity of sulphuric acid be put into a drop of the infusion which swarms with these insects, they immediately throw themselves on their backs and expire. Upon examining the edge of a very sharp lancet with a microscope, it will appear as broad as the back of a knife ; rough, uneven, full of notches and furrows. An exceed- ingly small needle resembles a rough iron bar. But the sting of a bee, seen though the same instrument, exhibits every where a most beautiful polish, without the least flaw, blemish, or inequality, and it ends in a point too fine to be discerned. The threads of fine lawn seem coarser than the yarn with which ropes are made for anchors. But a silk- worm's web appears perfectly smooth and shining, and every where equal. The smallest dot, that can be made with a pen, appears irregular and uneven. But the little specks on the wings or bodies of insects are found fo be most accu- rately circular. The finest miniature paintings appear be- fore the microscope rugged and uneven, entirely void of beauty, either in the drawing or colouring. The most even and beautiful varnishes will be found to be mere roughness. But the nearer we examine the works of God, even in the least of his productions, the more sensible shall we be of his wisdom and power. In the numberless species of insects, what proportion, exactness, uniformity, and symmetry do we perceive in all their organs! what a profusion of colouring ! azure green, and vermilion, gold, silver, pearls, rubies, and diamonds; fringe and embroidery on their bodies, wmgs, heads, and every other part! how high the finishing, how inimitable the polish we every where behold ! On the gay bosom of some fragrant flower They, idly fluttering, live their little hour; Their life all pleasure, and their task all play, AH spring their age, and sunshine all their day. Not so the child of sorrow, wretched man, His course with toil concludes, with pain began; That his high destiny he might discern, And in misfortune's school this lesson learn; 8 86 THE TELESCOPE. Pleasure 's the portion of th' inferior kind, But glory, virtue, Heaven for man designed. Barbauld. Questions.—1. What has the microscope done for us ? 2. What is the appearance of grains of sand when examined by the eye, and by the microscope ? 3. Mouldiness ? 4. What is said of the green surface of standing water ? 5. What is the appearance of animalcules in the infusions of pepper?—new hay ? 6. What appearance has tho edge of a lancet ? 7. Sting of a bee ? 8. Fine lawn ? 9. Silk worm's web ? LESSON 39. The Telescope and Telegraph. Sat'ellite, a small planet revolving round a larger, a moon. Octag'onal, having eight angles and sides. Oral, delivered verbally, not written. No invention in the mechanic arts has ever proved more useful and entertaining than the production of the telescope ; its utility both by sea and land is too well known to need observation ; and without such assistance the science of as- tronomy must have been far short of its present state. A telescope is useful, not only for discovering those distant objects that are invisible to the naked eye, but for rendering more clear and distinct those that are discernible; it is con- structed to act either by refraction or reflection. It is the sole business of all telescopes to enable the eye to see the object under a larger angle. For this purpose a new image of an object is produced by the object-glass of the telescope, and then this image is viewed by means of the eye-glasses. The first impression, conveyed to the mind by a telescope, is that of bringing the object nearer, which is only another mode of declaring that it is enlarged, or seen under a larger angle. To show objects in their natural posture, a telescope must have three eye-glasses. The two additional lenses simply give an erect position to objects. If you remove one of the eye-glasses from a common telescope, every thing will appear in an inverted position. The three eye-glasses have all their focal distances equal, and the magnifying power is found by dividing the focal distance of the object-glass by the focal distance of one of the eye-glasses. The two additional lenses THE TELEGRAPH. 87 are not necessary for astronomical telescopes; for no incon- venience arises from seeing the celestial bodies inverted. When very great magnifying power is required, telescopes are constructed with concave mirrors, and called reflecting telescopes. Mirrors are used in order to bring the image nearer the eye ; and a lens or eye-glass is for the same pur- pose as in the refracting telescope, that is, to magnify the image. The Newtonian reflecting telescope consists of a tube, towards the end of which a concave mirror is placed. The reflected converging rays, before they reach the focus, are made to fall upon a plane mirror placed at an angle of forty-five degrees, and thus are thrown upwards to the focus of a convex lens fixed in the upper side of the telescope, through which the eye looks down on the image. In the telescopes made by Dr. Herschel there is but one mirror, which is placed at the lower end of the tube, with such an inclination, that the rays are brought to a focus and the image formed near the edge of the upper end of the tube. The image, therefore, is formed by only one reflection, and its brightness, when viewed through the lens is, on this account, greater than that in the Newtonian telescope. The head of the observer, when a large aperture is wanted, may be placed entirely at one edge of the tube, so as not to intercept any of the rays at the time of making an observation; but as the eye looks down the tube, the back must be turned to the object. Dr. Herschel's grand telescope is nearly forty feet long, and four feet ten inches in diameter. The con- cave polished surface of the great mirror is forty-eight inches in diameter, and it magnifies six thousand times. This noble instrument was, in all its parts, constructed under the sole direction of Dr. Herschel: it was begun in the year 1785, and completed August 28th, 1789, on which day was dis- covered the sixth satellite of Saturn. The telegraph is a machine for communicating intelli- gence at a considerable distance, by making various signals, —which have been previously agreed upon between two parties,—to represent letters, words, or ideas. No machine for making signals can with propriety be called a telegraph, unless it is adapted to express a sufficient number of letters or words to form a complete language, and which can be made, therefore, to communicate any information which can be expressed by oral or written language. Less perfect sys~ 88 ASTRONOMY. terns of signals which extend only so far as to communicate intelligence of events which have been foreseen, and the appropriate signals, previously arranged, are called signal flags, signal lanterns, and signal guns or fires. Telegraphs have been constructed in various ways. What is called the English telegraph consists of six octagonal boards, each of which is poised upon an axis in a frame, and worked by means of ropes in the manner of bell-ropes, so that it can either be placed vertically, and appear with its full size to the observer at the nearest station, or it becomes invisible to him by being placed horizontally, so that the narrow edge alone is exposed, which from a distance cannot be seen. Six boards make thirty-six changes, by the most plain and simple mode of working; and they will make many more, if more were necessary; but as the real superiority of the te- legraph, over all other mpdes of making signals, consists in its making letters, it is not necessary that the changes should be more than the letters of the alphabet, and the arithme- tical figures. Telegraphs of this description are set up on eminences at the distance of eight, ten, or twelve miles; and a line of them, by repeating each other's signals, con- veys a message at the rate of a hundred miles in about five minutes. A telescope for the use of the observer is fixed in the watch-tower of each station. Questions.—1. Of what advantage is the telescope ? 2. Why does it seem to bring an object nearer ? 3. What is said of the eye-glasses and the magnifying power of telescopes ? 4. Why are mirrors used in reflecting telescopes ? 5. Describe the Newtonian telescope. 6. Describe the telescope as made by Dr. Herschel. 7. His grand tele- scope. 8. What is a telegraph ? 9. How is a proper telegraph dis- tinguished from other machines for making signals ? 10. Describe the English telegraph. 11. What is said of its number of changes ? 12. At what rate will such telegraphs convey a message ? 13. How may an idea of the Newtonian telescope be obtained by looking at fig. 27. LESSON 40. Astronomy. Locomo'tive, having the power of removing, or changing place. Astronomy is the science which teaches the magnitudes and motions, distances, periods, and order of the celestial ASTRONOMT. S9 bodies. It is the boldest find most comprehensive of all our speculations. It is the science of the material universe con- sidered as a whole. The wide-spreading firmament, while it lifts itself above all mortal things, exhibits to us that lu- minary, which is the light, and life, and glory of our world, and when this retires from our view, is lighted up with a tliousand lesser fires, that never cease to burn, that never fail to take their accustomed places, and never rest from their slow, solemn, and noiseless march. Among the objects more immediately about us, all is vicissitude and change. Plants arise out of the earth, flourish awhile and decay, and their place is filled by others. Animals also have their pe- riods of growth and decline. Even man is not exempt from the general law. Nations are like individuals, privileged only with a more protracted existence. The firm earth itself, the theatre of all this change, partakes in a degree of the common lot of its inhabitants, and the sea once heaved its waves where now rolls a tide of wealth and population. Situ- ated as we are, in this fleeting, fluctuating state, it is consol- ing to be able to dwell upon an enduring scene, to contem- plate laws that are immutable, an order that has never been interrupted, to fix, not the thoughts only, but the eye, upon objects that after the lapse of so many ages, and the fall of so many states, cities, human institutions, and monuments of art, continue to occupy the same places, to move with the same regularity, and to shine with the same pure, fresh, un- diminished lustre. Astronomy is the most improved of all the branches of knowledge, and that which does the greatest credit to the human understanding. We have in this obtained the object of our researches. We have solved the great problem pro- posed to us in the celestial motions ; and our solution is as simple and as grand as the spectacle itself, and is in every respect worthy of so exalted a subject. It is not the as- tronomer only, who is thus satisfied, but the proof is of a nature to carry conviction to the most illiterate and skep- tical. Our knowledge, extending to the principles and laws which the author of nature has chosen to impress upon his works, comprehends the future ; it resembles that which has been regarded as the exclusive attribute of supreme intelli- gence. We are thus enabled, not only to explain those unu- sual appearances in the heavens, which were formerly the DO ASTRONOMY. occasion of such unworthy fears, but to forewarn men of their occurrence; and by predicting the time, place, and circumstances of the phenomenon, to disarm it of its terror. There is, however, nothing perhaps so surprising in this science, as that it makes us acquainted with methods, by which we can survey those bright fields on which it is em- ployed, and apply our own familiar measures to the paths which are there traced, and to the bodies that trace them ; that we can estimate the form, and dimensions, and inequa- lities of objects so immense, and so far removed from the little scene of our labours. What would be the astonish- ment of an inhabitant of one of those bodies, of Jupiter for instance, to find that, by means of instruments of a few feet in length, and certain figures and characters still smaller. all of our own invention, we had succeeded in determining the magnitude and weight of this great planet, the length of its days and nights, and the variety of its seasons, that we had watched the motionsof its moons, calculated their eclipses, and applied them to important domestic purposes 1 What would be our astonishment to learn, that an insect, one of those for instance which serve sometimes to illuminate the waters of the ocean, though confined by the exercise of its proper organs and locomotive powers, to the sphere of a few inches, !iad, by artificial aids of its own contriving, been able to extend its sphere of observation to the huge monsters that move about it; that it had even attempted, not altogether without success, to fathom the depth of the abyss, in which it occupies so insignificant a place, and to number the beings it contains ? The first use of the telescope, about the commencement of the seventeenth century, opened a new and most brilliant era in the science of astr%omy. The defect of the natural organ with respect to the objects of this science had never been recognised. We had gazed upon them without com1 prehending what we saw. We had cast a vacant eye over the splendid pages of this volume, as children amuse them- selves with a book which they are unable to read. We had caught here and there a capital letter, or a picture, but we had failed to distinguish those smaller characters on which the sense of the whole depended. It is not the least of the ad- vantages of this wonderful instrument, that it has taught us the importance of those means of improvement and enjoy- THE SOLAR SYSTEM. 91 mtyit, which are placed within the reach of our own inge- nuity and skill. No one surely would have dreamed of pro- curing such an aid to the natural sight, any more than of creating a new sense. It would have seemed like changing the law of our being, and the condition in which we are placed. We have, by means of this instrument, emerged, as it were, from a prison. The mind has effected its enlarge- ment, as an insect bursts its little tenement, and flutters through the free air, and over the gay fields. Another change in this science, of the first importance, was wrought by the genius of Kepler, who died in the year 1.630. But the last and most important of all the revolutions that have taken place in it, is that achieved by Newton. There is no other instance of so signal a change in the opi- nions and pursuits of the philosophic world. It may be com- pared to those great and rapid conquests, by which new boundaries and new laws have been given to states and king- doms, and new directions to the industry and active employ- ments of men ; with this difference, however, that these have been made by violence, and with the aid and co-opera- tion of others, while the revolution in the sciences effected by Newton, was the silent, solitary work of an individual. Questions.—1. What is astronomy ? 2. What is said of the im- proved state of this branch of knowledge ? 3. What may be regard- ed as most surprising in it ? 4. What is said of the first use and im- portance of the telescope ? 5. What is said of Kepler ? 6. Of Newton ' [Note. Newton died March 1727, aged 85.] LESSON 41. The Solar System. Or bit, the path in which a celestial body moves. Car'dinal, one of the chief officers in the church of Rome. Inquisi'tion, a court established foF the detection of heresy. The true solar system consists of the sun and an unknown number of opaque bodies, which revolve round the sun, and some of which at the same time revolve round others. Those which revolve round the sun only, are called primary planets and comets. Those which revolve round a primary planet, at the same'time they are revolving round the sun 92 GALILEO. are called secondary planets, moons, or satellites. The number of comets is unknown. The sun is the centre of the system, and the eleven primary planets, at different dis- tances, and in different times, move round him, from west to east, in the following order, Mercury, Venus, the Earth, Mars, Vesta, Juno, Pallas, Ceres, Jupiter, Saturn, and Her- schel or Uranus. The Earth has one moon, Jupiter four, Saturn seven, and Uranus six. Venus and Mercury being nearer to the sun than our earth, are called inferior planets, and all the rest, which are without the earth's orbit, are called superior planets; some astronomers distinguish them by the terms interior and exterior, which seem preferable. The planets are retained in their orbits by the united operation of the centripetal force, by which a body is attracted to the centre of gravity, and the centrifugal force, by which it en- deavours to persevere in a straight line. These two powers, mutually balancing each other, compel them to make their respective revolutions. The time of performing their revo- lutions round the sun is called their year, and the time of performing their revolution on their axis, their day. The axis of a planet is an imaginary line conceived to be drawn through its centre, about which it revolves, and the extremi- ties of this line, terminating on opposite points of the planet's surface, are called its poles. The first material step in improving the science of astro- nomy was the establishment of the present arrangement of the sun and planets by Copernicus, who died in the year 1543. This doctrine, it is true, was held by Pythag'oras, but it was now presented in a new and stronger light, with its leading features more fully and distinctly unfolded. It is remarkable, that in so many instances, it should have ex- posed its authors and defenders to persecution. Pythagoras, we are told, made it known only to a select few; but one of his disciples, who had the courage to teach it publicly, was obliged to flee in order to escape the odium it excited. Copernicus meditated upon the subject for many years, be- fore he undertook to give his thoughts to the world, and scarcely surviving the publication of his work, he left to others to receive the shock that awaited those who espoused it. Galileo could not resist the accumulated evidence, that presented itself to his enlarged and philosophic mind, in favour of this refined scheme, and was accordingly destined THE SUN. 93 to bear the whole weight of indignation that was ready to burst upon the disturbers of a prejudice so old and so deeply rooted. He was arrested, and seven cardinals clothed with the authority of the church sat in judgment upon him, and sentenced him to the prison of the Inquisition for opinions, which they pronounced false in philosophy, heretical, and contrary to the word of God. After a year's confinement he was liberated, but continuing his discoveries, and apparently persevering in his opinions, he was imprisoned a second time. After being made to abjure what were deemed his errors, and to do penance for his offences, he was again re- stored to liberty. Indignant at the cruelty of this treatment, and the bigotry and blindness of his persecutors, he yet continued his pursuits; but in silence and fear. His ex- cessive application, and the constant use of his telescope, together with frequent exposure to the air by night, had such an effect upon him, that he lost his sight. He died in 1642, at the age of seventy-eight. Questions.—1. Of what does the solar system consist ? 2. What are primary planets ?—secondary planets ? 3. What is the order in which the eleven primary planets move round the sun ? 4. What planets have moons, and how many have each ? 5. What are interior and exterior planets ? 6. How are the planets retained in their orbits ? 7. Define year, day, axis, poles. 8. What was the first material step in the progress of astronomy ? 9. What is remarkable with respect to the true doctrine of the solar system ? 10. What course did Coper- nicus adopt ? 11. What is said of Galileo ? 12. Explain Engr. IV. LESSON 42. The Sun. Spher'oid, a body approaching to the form of a sphere, but not exactly round. Ellip'tical, oval,—an ellipse is produced from the section of a cone by a plane cutting both its sides, but not parallel to the base All the planets move round the sun in elliptical orbits, and the sun itself is situated in one of the foci of each ellipse : that focus is called the lower focus. See the Earth's orbit in fig. 40. Great source of day ! best image here below Of thy Creator, ever pouring wide, From world to world, the vital ocean round; 94 THE SUN. On nature, write with every beam, His praise. Soul of surrounding worlds !— 'Tis by thy secret, strong, attractive force, As with a chain indissolubly bound, Thy system rolls entire; far from the bourn Of utmost Herschel, wheeling wide his round Of eighty years ; to Mercury whose disk Can scarce be caught by philosophic eye, Lost in the near effulgence of thy blaze. Thomson. The sun is a fountain of light that illuminates the world; it is the cause of that heat which maintains the productive power of nature, and makes the earth a fit habitation for man. The figure of the sun is a spheroid, higher under the equator than about the poles ; and his diameter is computed to be nearly nine hundred thousand miles. His solid bulk is more than a million of times larger than that of the earth. The sun has two motions; the one is a periodical motion, in an elliptical or very nearly circular direction, round the com- mon centre of all the planetary motions ; the other is a revo- lution upon its axis, which is completed in about twenty-six days. That the sun has a rotation round his axis is made evident by the spots seen on his surface. Some of these spots have made their first appearance near the edge or margin of the sun, and have been seen some time after on the opposite edge; whence, after a stay of more than thir- teen days, they have re-appeared in their first place, and taken the same course over again. These spots were en- tirely unknown before the invention of telescopes, though they are sometimes of sufficient magnitude to be discerned by the naked e%e. Some have been so large, as by compu- tation to be capable of covering the continents of Asia and Africa, the whole surface of the earth, or even five times its surface. The sun has commonly been considered a globe of fire ; but this has been doubted by modern astrono- mers. The celebrated Herschel considers the sun as a most magnificent habitable globe, surrounded by a very extensive atmosphere, which consists of elastic fluids that are more or less lucid and transparent; and of which the lucid ones fur- nish us with light. The appearances, called spots in the sun, he considers as real openings in the luminous clouds of the solar atmosphere. MERCURY. 95 The sun is accompanied by a phenomenon called the zo- diacal light. It is a beam of light of a triangular form, visi- ble a little after sunset and before sunrise, with the base towards the sun. It is most clear about the beginning of March in the evening, and in September in the morning, but in the torrid zone it is constantly seen. It is generally supposed to proceed from the sun's atmosphere. Qukstions.—1. What is the figure of the sun? 2. Describe the motions of the sun. 3. How is it made evident that the sun has a rotation round his axis ? 4. What is said of the spots that have been seen in the sun ? 5. What does Dr. Herschel consider the sun to be? —The spots ? G. Describe the zodiacal light. 7. In what proportion do the planets receive light and heat from the sun ? (see Appendix.) 8. What rule is given ? 9. What is said of the attraction of bodies ? 10. What is the rule for finding the distances of the planets from the sun? 11. What was ascertained by Kepler? 12. What is the rule for finding how many times one planet is greater than another? [Note. When any body, revolving round the sun,is nearest to him, it is said to be in its perihe'lion; and when it is most distant, in its aphe'- lion (pron. af-e'Ie-un.) The common centre about which the sun re- volves in its periodical motion is always found to be exceedingly near the sun, and most commonly within it: it may, therefore, without any material error, be regarded as the centre of the planetary system] LESSON 43. Mercury and Venus. Elonga'tion, a planet's elongation, or its angular distance from the sun, is an angle formed at the earth by two lines, one drawn from the earth to the sun, and one from the earth to the planet. Disk, the face of the sun and moon, as it appears to us on the earth. Mkrcury is seldom visible to the inhabitants of the earth, for its greatest apparent distance from the sun, or its great- est elongation, is not more than twenty-eight degrees, and its reflected light is absorbed in the more powerful rays of the sun. He always appears on the same side of the heavens with the sun ; of course, he can be seen in the east, only in the morning a little before sunrise, and in the west in the evening a little after sunset. When viewed with a telescope of high magnifying power, he exhibits nearly the same pha- ses as the moon, and they are to be accounted for in the same manner. Mercury revolves round the sun at nearly 96 VENUS. the mean distance of thirty seven millions of mile", and com- pletes his revolution in about t.iree months. According to Sir Isaac Newton, the heat and light, of the sun on the surface of Mercury, are almost seven times as intense as on the sur- face of the earth in the middle of summer; which, as he found by experiments made for that purpose with a ther- mometer, is sufficient to make water fly off in steam and va- pour. Such a degree of heat, therefore, must render Mer- cury uninhabitable to creatures of our constitution ; and if bodies on its surface be not inflamed and set on fire, it must be because their degree of density is proportionably greater than that of such bodies is with us. When Mercury passes over the sun's face, or is between us and the sun, this is called his transit, and the planet appears like a black spot in the sun's disk. The light emitted by Mercury is a very bright white. Fair Venus next fulfils her larger round, With softer beams, and milder glory crowned ; Friend to mankind, she glitters from afar, Now the bright evening, now the morning star. Baker. Venus is computed to be sixty-eight millions of miles from the sun, and completes her annual rotation in about seven and a half months, turning on her axis in a little less than twenty four hours. The light, which this planet re- flects, is very brilliant, and often renders her visible to the naked eye in the day-time. When Venus is to the west of the sun, she rises before the sun, and is called the morning star ; when she appears to the east of the sun, she shines in the evening, and is then called the evening star. She is in each situation alternately, for about two hundred and ninety days; and, during the whole of her revolution, she appears, through a telescope, to have all the various shapes and ap- pearances of the moon. As the orbit of Venus is within that oi the earth, like Mercury, she sometimes passes over the sun's face, and her transits have been applied to one of the most important problems in astronomy,—that of determining the true distances of the planets from the sun. The atmo- sphere of Venus has been calculated to be fifty miles high ; this has been learned from observing her transits, when her atmosphere was seen to throw a shade on the sun's disk THE EARTH. 97 about five seconds before the more opaque part touched his edge. When the elongation of Venus is about forty de- grees, her lustre far exceeds that of the moon, at the same apparent distance from the sun. For though the moon re- flects more light to us than Venus does, yet this light is dull, and has none of the briskness which attends the beams of Venus. This difference is supposed to arise from the cir- cumstance of Venus having an atmosphere far more dense than that of the moon. Questions—1. What is the appearance of Mercury? 2. What is the length of his year ?—Distance from tbe sun ? 3. Why is it seldom seen ? 4. What is its greatest elongation ? 5. What calculation did Newton make with respect to the light and beat of Mercury ? 6. What must be the consequence of such a degree of heat ? 7.- What is called a transit of Mercury ? 8. What is the distance of Venus from the sun .'—Length of her year ?—Day ? 9. When is Venus evening and when morning star ?—How long in each situation ? 10. To what purpose have hertransits been applied? 11. What is said of her at- mosphere ? 12. When is the lustre of Venus greatest, and to what ie it attributed ? LESSON 44. The Earth. Merid'ian, a great circle passing through the poles of the world, and also through both zenith and nadir ; it crosses the equator at right angles, and divides the sphere into two hemispheres, the eastern and the western ; it has its poles at the east and west points of the horizon. The planet which we inhabit is called the earth. It re- volves about the sun at the mean distance of ninety-five, or, as some state, of ninety-three millions of miles. It com- pletes this revolution in a year, and turns on its axis in a day, or twenty-four hours. If the earth were seen from the sun, it would appear to describe, while revolving in its orbit, a circle among the stars. But to us on the earth, the sun ap- pears to describe precisely the same circle, only beginning at the opposite point. That imaginary great circle in the heavens, which the sun appears to describe in the course of the year, is called the ecliptic. The apparent diurnal, or daily motion of the sun is very different from the path which it appears to traverse in the course of a year. The former 98 CELESTIAL LATITUDE AND LONGITUDE. is observed by the most inattentive spectator; but the knowledge of the latter must be the result of patient ob- servation. The other primary planets, when seen from the sun, do not describe exactly the same circle among the stars, that the earth does; but are sometimes on one side of the ecliptic and sometimes on the other. But none of them, except Juno, Pallas, and Ceres, are ever farther distant from the ecliptic than eight degrees. So that within a zone or belt of sixteen degrees, that is, eight degrees on each side of the ecliptic, the planets, except those just named, are always to be found. This zone, or broad belt, is called the Zodiac. The ecliptic then is an imaginary circle in the heavens pass- ing through the middle of the zodiac, and situated in the plane of the earth's orbit. A plane is an even level surface. If you suppose a smooth thin solid plane cutting the sun through the centre, extending out as far as the fixed stars, and terminating in a circle which passes through the middle of the zodiac ; in this plane the earth would move in its re- volution round the sun; it is therefore called the plane of the earth's orbit. The points, where the orbit of any hea- venly body cuts the plane of the ecliptic, are called the nodes of that body. The point, where the body passes from the north side of the plane of the ecliptic to the south, is called its descending node; where it passes from the south to the north, its ascending node. The ecliptic, as well as every other circle, great or small, is divided into three hundred and sixty degrees ; but it has also another division into twelve signs, of thirty degrees each, called the twelve signs of the zodiac. These signs derive their names from clusters of stars, or constellations, which, as the ancients imagined, resembled certain animals. They are most commonly represented by characters, and the names given them should be made familiar; for the sun, as he ap- pears to move round in the ecliptic, seems to enter these clus- ters of stars, and is therefore said to be in this or that sign. If the axis of the earth be supposed to extend both ways to the starry heavens, its places or points among the stars are the celestial poles, one north and the other south, direct- ly over or beyond the poles of the earth of the same name. If the plane of the earth's equator were extended every way to the starry heavens, the circle it would make among thq CELESTIAL LATITUDE AND LONGITCDE. 99 Stars is called the celestial equator. Now the celestial equa- tor does not coincide with the ecliptic, but makes an angle with it of twenty-three degrees and twenty-eight minutes, that is, the axis of the earth is not perpendicular to the plane of the ecliptic, but is inclined twenty-three degrees and twenty-eight minutes. Thus we have two great circles, the ecliptic and equator, passing through the heavens eastwardly and westwardly, from either of which the latitude of the hea- venly bodies might be estimated. But astronomers have se- lected the ecliptic for this purpose, and have supposed lines or circles to cross it at right angles, as the meridians do the equator ; which lines or circles are called secondaries to the ecliptic. The points where all the secondaries meet, are called the poles of the ecliptic; which points are twenty-three degrees twenty-eight minutes from the celestial poles. Hence the latitude of a heavenly body is its distance from the ecliptic, measured on a secondary to the ecliptic ; and like latitude on the earth, it can never exceed ninety degrees. The longitude of a heavenly body is the distance of a se- condary to the ecliptic, reckoned from some given uniform secondary, called the prime secondary. But the longitude of heavenly bodies, unlike longitude on the earth, is reckon- ed only eashoard; it may extend, therefore, to three hun- dred and sixty degrees. It is usually stated in signs, degrees, minutes, and so forth ; and the prime secondary, from which it is reckoned, cuts the ecliptic in the beginning of the sign Aries, a point where the celestial equator crosses the ecliptic. If a secondary, for instance, passing through a heavenly body, cuts the ecliptic eighteen degrees in the sign Capri- corn, then, since the first point of Capricorn is nine signs eastward from the first point of Aries, the longitude of that body is nine signs, eighteen degrees. But it is often impor- tant to know the distance of a heavenly body from the celes- tial equator, as well as from the ecliptic. This distance is its declination, and is reckoned on a meridian, as latitude is on the earth. Its distance from the beginning of Aries, reckoned on the equator, is its right ascension; which, like celestial longitude, is reckoned through the whole circle, or three hundred and sixty degrees. Two planets are said to be in conjunction with each other, when they have the same longitude, or are in the same degree of the ecliptic on the saiiie side of the heavens, though their latitude be different: 100 DAY AND NIOHT. They are said to be in opposition, when their longitudes differ half a circle, or they are in opposite sides of the heavens. Questions.—1. What is the ecliptic ?—explain. 2. What is the zodiac ?—explain. 3. What is meant by the plane of the earth's orbit ? 4. What are nodes ? 5. What are the divisions of the ecliptic ? 6. What are the celestial poles ? 7. What is the celestial equator ? 8. How is the axis of the earth situated with regard to the plane of the ecliptic ? 9. What are the poles of the ecliptic ? 10. What is the la- titude of a heavenly body? 11. The longitude? 12. How is the longitude of a heavenly body reckoned and stated ? 13. What exam- ple is given ? 14. What is the declination of a heavenly body. 15. Right ascension ? 16. When are two planets said to be in conjunc- tion ? 17. In opposition ? [Note. The points at which the ecliptic cuts the celestial equator are called the equinoctial points. Those two points of the ecliptic farthest from the equator are called solstices. Ap'ogee, that point of the orbit of the moon which is farthest from the earth. Per'igee, that point which is nearest to the earth.] 18. Look at fig. 40. and point out the ecliptic, zodiac, and signs of the zodiac. LESSON 45. Day and Night. Ver'nal, belonging to the spring. Intersect', to cut, to divide each other mutually. By the diurnal motion of the earth, the same phenomena appear as if all the celestial bodies turned round it; so that in its rotation from west to east, when the sun or a star just appears on the eastern side of the horizon, it is said to be rising, and as the earth continues its revolution, it seems gradually to ascend till it has reached its meridiSTi ; here the object has its greatest elevation, and begins to decline till it set, or become invisible on the western side. In the same manner the sun appears to rise and run his course to the western horizon, where he disappears and night ensues, till he again illuminate the same part of the earth in another diurnal revolution. One half of the earth's surface is con- stantly illuminated, and by the regular motion of the earth on its axis, every place is successively brought into light and immersed in darkness. If the axis of the earth were always perpendicular to the plane of the ecliptic, the days would every where be of the same length, and just as long as the DAY AND NIGHT. 101 nights. For an inhabitant at the equator, and one on the same meridian towards the poles, would come into the light at the same time, and, on the other side, would immerge into darkness at the same time. And since the motion of the earth is uniform, they would remain in the dark hemisphere just as long as in the light; that is, their day and night would be equal;—the plane of the ecliptic would coincide with the plane of the equator. But as the ecliptic and equator make an angle with each other of twenty-three degrees and twenty- eight minutes, or in other words, as the axis of the earth has such an inclination to the plane of its orbit, it is manifest that, except the earth be in that part of its orbit where the ecliptic cuts the equator, an inhabitant at the equator and one on the same meridian towards the poles, will not come into the light at the same time, nor, on the other side? im- merge into darkness at the same time. And since the axis of the earth always preserves the same inclination, they will,—except at the points where the two great circles inter- sect each other,—remain in the dark and light hemispheres different times ; that is, their day and night will be unequal. The points where the equator cuts the ecliptic are at the be- ginning of the signs Libra and Aries. The earth is at these points of its orbit, or, as it is commonly said, the sun enters the sign Aries on the twentieth of March, and the sign Libra on the twenty-third of September. Hence at these periods, and at no others, the days and nights are equal all over the world; and on this account they are called equinoxes ; the first the vernal, and the second the autum- nal equiuox. At these seasons, the sun rises exactly in the east at six o'clock, and sets exactly in the west at six o'clock ; __the light of the sun is then terminated by the north and south poles, and as all parts of the earth turn round once in twenty-four hours, every place must receive the rays twelve hours, and be deprived of them for the same time. But at other seasons, when the rays of light are not terminated by the north and south poles, but extend over the one and do not reach the other, it must be manifest, from a moment's inspection of the circles drawn on globes, or common maps of the world, that day and night will be unequal in all places except those situated on the equator, where they will be always er/ual At the poles there is but one day and one niffht in a vcar, each of six months. The sun can never 9* 102 CHANGES OF THE SEASONS. shine beyond a pole farther than twenty-three degrees and twenty-eight minutes; for that is the extent of his declina- tion ; and when he has declination from the celestial equa- tor either north or south, he must shine beyond one pole and not to the other; the days, therefore, will be longest in one hemisphere when they are shortest in the other. The subject of this lesson may be illustrated, by hanging any round body above or below the level of a candle so as to correspond with the sun's declination. It will be seen, that the light shines over one pole and does not reach the other. If the ball be then turned round, it will be observed, that the circles performed by any parts of the surface are unequally divided by the light; that it will be constant day or night near the north pole, as the ball is depressed or ele- vated, and that all the phenomena will be reversed in the Other, or lower hemisphere. Questions.—1. What phenomena appear from the diurnal motion efthe earth ? 2 Under what circumstances would the days and nights bo every where of the same length ?—Why ? 3. Why is not the day and night always equal to an inhabitant at the equator, and to one on the same meridian towards the poles ? 4. At what points does the equator cut the ecliptic ? 5. When is the earth at those points of its orbit?—and what happens at these periods? 6. At other seasons ? 7. What is said of day and night at the poles? 8. How may the subject of this lesson be illustrated ? 9. Look at fig. 41), and illustrate the n a nations in the lengths of the days and nights. LESSON 46. Changes of the Seasons. ©bliq'uity of the Ecliptic, the angle which the ecliptic makes with the equator. Look nature through, 'tis revolution all; All change, no death. Day follows night, and night The dying day. Stars rise and set, and rise. Earth takes th example ; see, the summer gay, With her green chaplet and ambrosial flowers, Droops into pallid Autumn. Winter gay, Horrid with frost, and turbulent with storm, Blows Autumn and his golden fruits away ; Then melts into the Spring. Soft Spring, with breath Favonian, from warm chambers of the south, CHANGES TTTE SEASONS. 103 Recals the first. All, to reflourish, fades ; As in a wheel, all sinks, to reascend : Emblem of man, who passes, not expires.—Thomson. The orbit in which the earth revolves in his annual course round the sun is not a circle but an ellipse or oval ; and we are more than three millions of miles nearer to the sun in December about the time of the winter solstice, than we are in June about the time of the summer solstice. Now as heat and light from the sun are greater as the distance is less, it is manifest that this circumstance would occasion a variation in the temperature of the air, like that of our sea- sons, it'the equator always coincided with the ecliptic. But the seasons with us, in north latitude, are not in the least de- gree occasioned by this circumstance, but by the direction in which the sun's rays fall upon us. When they fall per- pendicularly, or most nearly so, the season is warmest; and when they fall most obliquely, or in a slanting manner, the season is coldest. The cause of the difference in the obli- quity of the sun's rays is the obliquity of the ecliptic. The effect of obliquity, in regard to rays will be evident, if a board be held perpendicularly before a fire. It will then re- ceive a body of rays equal to its breadth. But if it be placed obliquely, at an angle of forty-five degrees, then only half the rays will fall on its surface, and the other half will pass over it; so it is with the surface of the earth in summer and winter.' The circumstance also, that the days are longest, whether in north or south latitude, when the sun's rays fall in the greatest quantity and most directly at any place, con- tributes much to the warmth of summer and the cold of win- ter. In northern countries, where the days are eighteen or twenty hours long, or where the sun is above the horizon for any number of days together, the heat of summer is equal to that of any part of the world. Since the degree of heat from the sun increases as the earth's distance'diminishes, and this distance is least when it is summer in south latitude, and greatest when it is sum- mer in north latitude, a greater degree of heat, therefore, must be received in summer in south latitude, than in sum- mer in north latitude. But to compensate for a less degree of heat, the inhabitants in north latitude have longer sum- mers than those in south latitude. For as the sun is not m 104 THE MOON. the centre of an ellipse but in the focus, the earth must move farther in its orbit in one part of its revolution than in the other. It moves slower also as it is farther from the sun ; and our summers are found to be eight days longer than the summers in south latitude; that is, between the vernal and autumnal equinoxes there are eight days more, than between the autumnal and vernal. It is well known that the degree of heat is not greatest, when the days are longest. We have the warmest weather in the latter part of July, and in the first of August; and our coldest motith is January. To account for this it has been stated, that a body onoa heated does not .grow cold again instantaneously, but gradually; now as long as more heat comes from the sun in the day, than is lost in the night, the heat of the earth and air will be daily increasing, and this must evidently be the case for some weeks after the longest day, both on account of the number of rays which fall on a given space, and also from the perpendicular di- rection of those rays. It is for the same reason, that the warmest part of the day is not, when the sun is at the me- ridian, but about two or three o'clock in the afternoon. Questions.—1. When are those who livo in north latitude nearest the sun ? 2. What would be the consequence if the equator coincided with the ecliptic ? 3. What* occasions the seasons with us ? 4. How may the effect of obliquity in regard to the sun's rays be made evident ? 5. What contributes much to the warmth of summer ? 6. What is said of north and south latitudes as respects the degree of heat ?—Ex- fdain. 7. Why is not the degree of heat greatest when the days are ongest ? 8. Look at fig. 40, and illustrate the diversity of the seasons. LESSON 47. The Moon. Quadrature, the first and last quarter of the moon. Lu'nar, relating to the moon. Luna'tion, the revolution of the moon. The moon is a secondary planet, revolving round the earth in about twenty-nine days and a half, and is carried with the earth round the sun once a year. Its distance from the earth is about two hundred and forty thousand miles; and it turns on its axis in the same time that it per- THE MOON. 105 forms its revolution round the earth. The light of the sun illuminates one half of its surface, and leaves the other in darkness. Of this illumination we perceive different de- grees, according to the various positions of the moon, with respect to the sun and the earth. We see one half of its body enlightened, or a full moon, when it is placed in oppo- sition to the sun, or when the sun is in one part of the hea- vens, as west, and the moon in the opposite part, as east. When the moon is in conjunction with the sun, or in that part of its orbit which is between the earth and the sun, its enlightened surface is turned from us, which renders it di- visible ; this is the time of the new moon. When the moon appears in the intermediate part of its orbit, between the conjunction and opposition, it is in its quadratures, and about half of its illuminated surface is turned towards us. As the moon illuminates the earth by light reflected from the sun, so she is reciprocally illuminated by the earth which reflects the sun's rays to the surface of the moon. As the surface of the earth is more than thirteen times greater than that of the moon, the earth must appear to the inhabitants of the moon thirteen times larger than the moon does to us, and it will exhibit the same phases, but in an opposite order. As the rotation of the moon on her axis is performed in the same time that she goes once round the earth,—which is evident from her always presenting the same face to us dur- ing the whole of her monthly revolution,—it is plain that the inhabitants of one half of the lunar world are totally de- prived of a sight of the earth, unless they travel to the oppo- site hemisphere. The face of the moon appears to have shades of different colours. If viewed through an ordinary telescope, her sur- face will appear diversified with long tracts of mountains1 and cavities. It has been ascertained that these are moun- tains from the shadows which they cast, and some of them are supposed to be volcanic. The difference between the rising of the moon on one day and the preceding is generally about fifty minutes But in places of considerable latitude, there is a remarkable differ- ence about the time of harvest, when at the season of full moon she rises for several nights together only about twenty minutes later on the one day than on that immediately pre- ceding By thus succeeding the sun before the twilight m 106 THE HARVEST MOON". ended, the moon prolongs the light, to the great benefit of those who are engaged in gathering in the fruits of the earth; and hence the full moon at this season is called the harvest moon. It is believed that this was observed by per- sons engaged in agriculture, at a much earlier period than it was noticed by astronomers. The phenomenon may be easily explained by the assistance of a globe ; and it is oc- casioned by the moon's orbit lying sometimes more oblique to the horizon than at others. The Harvest Moon. All hail! thou lovely queen of night, Bright empress of the starry sky ! The meekness of thy silvery light Beams gladness on the gazer's eye, While from thy peerless throne on high Thou shinest bright as cloudless noon, And bidd'st the shades of darkness fly Before thy glory-^Harvest moon! In the deep stillness of the night, When weary labour is at rest, How lovely is the scene !—how bright The wood—the lawn—the mountain's breast. When thou fair moon of Harvest! hast Thy radiant glory all unfurled, , And sweetly smilest in the west, Far down upon the silent world. Shine on, fair orb of light! and smile Till autumn months have passed away, And labour hath forgot the toil He bore in summer's sultry ray; And when the reapers end the day, Tired with the burning heat of noon, They '11 come with spirits light and gay, And bless thee—lovely Harvest Moon !» W. Millar. Questions.—1. In what time does the moon revolve round the earth ? 2. At what distance is it from the earth ? 3. In what time does it turn on its axis ? 4. What is said of the illumination of the moon ? 5. How does the earth appear as seen from the moon ? 6. How does the face of the moon appear when viewed through a telescope ? 7. What is the Harvest Moon ? 8. By what is it occa^ pooed ?—9. Look at fig. 41, and illustrate the phases of the moon. THE TIDES. 107 LESSON 48 The Tides. The sea is observed to flow for certain hours from the south towards the north. In this motion, which lasts about six hours, the sea gradually swells ; so that entering the mouths of rivers, it drives back the waters towards their heads. After a continual flow of six hours, the sea seems to rest for about a quarter of an hour ; it then begins to ebb, or retire back again from north to south for six hours more; and the rivers resume their natural course. Then, after a seeming pause of a quarter of an hour, the sea again begins to flow, as before, and thus alternately. This regular and alternate motion of the sea constitutes the tides.. They are chiefly occasioned by the attraction of the moon, but are af- fected by that of the sun. There are two tides in about twenty-five hours ; and the time of high or low water is eve- rv day fifty minutes later than on the preceding day. The moon is supposed to draw the earth towards itself, and to act upon the solid parts of it, in the same manner as if its whole weight were in a single point in or near the centre. Now the waters at any place over which the moon is passing, will be more attracted than the earth ; and therefore will be heaped up under the moon. But the waters on the opposite side of the globe will be less attracted than the earth ; con- sequently the earth is drawn away from them ; and they are helped up, or, in other words, it is high water there. When he waters are elevated at the side of the earth under the moon and at the opposite side also, it is evident they must recede from the intermediate points, and thus the attraction of the moon will produce high water at two places and low water at two places on the earth at the same time. The des fifty minutes later everyday, because it,s twenty-four ours and fifty minutes before the same meridian on our LTobe returns beneath the moon. The earth revolves on its Ss in about twenty-four hours; if the moon, therefore, were stationary, the same part of our globe would return b, neat I it, every twenty-four hours ; but as during our daily revolution the moon advances in her orbit the earth must mike more than a complete revolution m order to bring the 108 eclipses. same meridian opposite the moon; we are fifty minutes iu overtaking her, and the tides are retarded for the same rea- son that the moon rises later on one day than on the pre- ceding. The tides, though constant, are not equal; but are great- est when the moon is in conjunction with the sun or in opposition to it, or at the time of new and full moon; and le-'st, when in quadrature to it. This increase and diminu- tion constitute the spring and neap tides. The attraction of sea- sons, nor difference in the length of their days and nights. At the equator there will be perpetual summer, and at the poles unceasing winter. The degree of light and heat is about twenty-five times less than at the earth. The satellites of Jupiter are invisible lo the naked eye, but through a telescope they make a beautiful appearance. As our moon turns round the earth, enlightening the nights by reflecting the rays of the sun, so these also enlighten the ni Jvts of Jupiter, and move round him in different periods ofrime, proportioned to their several distances. They often pass behind the body of the planet, and also into its shadow, and are eclipsed. These eclipses are of use for ascertaining the longitude of places. They have led to the discovery, that light is about eight minutes in coming from the sun to 10* 114 SATURN. the earth; for an eclipse of one of these satellites appears to us to take place sixteen minutes sooner, when the earth is in the part of her orbit nearest Jupiter, than when in the part farthest from him. Hence light is sixteen minutes in crossing the earth's orbit, and of course eight minutes in coming from the sun. An observer on Jupiter, with eyes constructed like ours, could never see Mercury, Venus, the Earth, or Mars, for, on account of the immense distance, they are always immersed in the sun's ray?. Questions.—1. What is tlic diameter of Jupiter?—distance from the sun ?—time of revolution round the sun ?—diurnal rotation ? 2 Describe the telescopic appearance of Jupiter. 3. What is the post tion of his axis, and the consequence of that position ? 4. What a said of Jupiter's moons ? 5. Of what use are their eclipses ? C. To what discovery have they led ?—how ? LESSON 52. Saturn and Uranus. Anom'aly, irregularity, deviation from rule. Hypoth'esis, a supposition, a system formed under some principle not proved. Saturn though not so brilliant as Jupiter, is a very con- spicuous planet. It shines with a pale light, and the degree of heat and light is eighty times less than at the earth. It revolves round the sun in little Less than thirty years, at the mean distance of nine hundred millions of miles. It turns on its axis in little more than ten hours, and its diameter is seventy-nine thousand miles. Saturn, as seen through a good telescope, is a beautifu' object, having seven moons, a double ring, and appearances similar to the belts of Jupiter. The ring is one of the greatest anomalies in our system. It is a thin, broad, opaque, circular body, encompassing the planet without touching it, like the wooden horizon of an artificial globe. Although the phenomenon is usually termed the ring, yet it consists of two, entirely detached from each other and from the body of the planet, one exactly without or beyond the other. Stars have been seen through the vacancy between them, and also between the inner ring and the planet. Concern- COMETS, 113 mg the nature and uses of the ring there have been various hypotheses. Dr. Herschel thinks it not less solid than the body of Saturn itself, and it is observed to cast a strong shadow upon it. The light of the ring is generally brighter than that of the planet, which has been attributed to its si- tuation above the region of mists and clouds. Both the pla- net and the ring perform their rotations about the same com- mon axis, and in nearly the same time. The ring disappears twice in every revolution of the planet round the sun ; that is, once in fifteen years, and Saturn appears quite circular for nine months together. Some have supposed that the use of the ring is to collect, refract, and transmit the rays of the sun to the body of the planet. The planet Uranus, or Herschel, completes a revolution round the sun in about eighty-four years. On account of its distance from the earth, which is eighteen hundred mil- lions of miles, its diurnal rotation has never been determined. Heat and light at Uranus are about three hundred and sixty times less than at the earth. It is scarcely visible to the naked eye, although its diameter is thirty-five thousand miles. Astronomers formerly considered it as a star, but on the 13th of March, 1781, Dr. Herschel discovered it to be a planet. Questions.—1. How far is Saturn from the sun? 2. What de- gree of light, and heat has it ? 3. How often does it revolve round the sun ? 4. On its own axis ? 5. What is the appearance of Saturn as seen through a telescope ? 6. Describe the ring. 7. What is said con- cerning the nature and uses of the ring. 8. In what time does Ura- nus complete a revolution ? 9. At what distance from the sun ? 10. What is the diameter of Uranus? 11. Degree of heat and light ? 12. When and by whom discovered? [Note. Saturn's inner ring is dis- tant from its body 21,100 miles. The breadth of the inner ring is 20,000 miles. The outer ring is distant from the inner ring 2,839 miles, and the breadth of the outer ring is 7,200 miles. Uranus is the name which has been given to the planet Herschel, or Georgium Si- dus, on the continent ofEurope.] LESSON 53. Comets. Hast thou ne'er seen the comet's flaming flight ? Th' illustrious stranger passing, terror sheds lib" COMETS. On gazing nations, from his fiery train Of length enormous; takes his ample round Through depths of ether; coasts unnumbered worlds Of more than solar glory ; doubles wide Heaven's mighty cape, and then revisits earth, From the long travel of a thousand years. Young. Besides the primary and secondary planets, there are other bodies which revolve round the sun, and consequently make a part of the solar system. These are called comets, and Appear occasionally in every part of the heavens. They are solid, opaque bodies, generally distinguished by a lucid train or tail, issuing from that side which is turned away from the sun. Most of them move in very elliptical orbits; at one time coming very near the sun, even nearer than M^frcury, and again receding to a distance far beyond the orbit of Uranus. The train is so transparent, that the fixed stars may be seen through it, and sometimes it extends to an immense distance in the heavens. The farther it reaches, the broader it seems to become, and at times it is divided into rays. Viewed through a telescope, comets appear full of spots and inequalities, and a vapour frequently renders it impos- sible to observe their figure. In a clear sky, however, the solid body of a comet often reflects a splendid light. That part of astronomy relating to comets is still imperfect, for the opinion once prevailed, that they were only meteors gene- rated in the air, like those we see in a clear night, vanishing in a few moments, and no care therefore was taken to ob- serve or record their phenomena with accuracy. The number of comets belonging to the solar system is unknown. More than five hundred have appeared since the commencement of the christian era. The orbits of ninety- eight comets, up to the year 1808, have been calculated ; but of all the comets the periods of only three are known with any degree of certainty, being found to return at inter- vals of seventy-five, one hundred twenty-nine, and five hun- dred and seventy-five years; and of these that which appear- ed in 1680 is the most remarkable. This comet, which will not appear again till the year 2225, at its greatest distance, is about eleven thousand two hundred millions of miles from the sun, while its least distance from the centre of the sun is about four hundred ninety thousand miles. In that part of / its orbit nearest the sun, it flies, according to Newton, with THE FIXED. STARS. 117 a velocity of eight hundred eighty thousand miles an hour ; but according to calculations made since the days of New- ton, its motion has been computed to be one million two hundred forty miles an hour. The comet of 1758 was looked for with great interest by astronomers, because its return had been predicted. But it is worthy of remark, that what, in this century, excited only the curiosity of astronomers and mathematicians, had been regarded four revolutions before, in 1456, with feelings of horror. Its long train spread consternation over all Europe, already terrified at the success of the Turkish arms, which had just destroyed the great empire. Pope Callixtus, on this occasion, ordered a prayer, in which the comet and the Turks were included in the same anathema. Questions.—1. What arc comets ? 2. How do they move ? 3. What is said of the train of a comet? 4. How do comets appear through a telescope ? 5. What is said of the number of comets ? 6. What is known of the orbits of comets ? 7. What is said of the comet of 1G80 ? 8. What is worthy of remark with respect to the comet of 1758 ? [Note. The comet of 1758 is expected to return in 1834.] LESSON 54. The Fixed Stars. Neb'ula, (plural, nebulae,) a cloud of obscure light in the heavens; some nebulas consist of clusters of telescopic stars, others ap- pear as luminous spots of different forms. Sir'ius, the dog-star. Those luminous bodies which always appear in the hea- vens at the same distance from each other, are called fixed stars; because, with the exception of a few, which, in a course of years, appear to change their places, it has not been discovered, that they have any proper motion of their own. When viewed through a telescope they appear as points of small magnitude ; they must be at such an immense distance, therefore, as to be invisible to the naked eye, if they borrowed their light; as is the case with the satellites of Jupiter and Saturn, although they appear of very distin- guishable magnitude through a telescope. The stars are probably suns, around each of which revolve primary and secondary planets, as about our sun. They are distinguish* able from the planets by their twinkling. 118 THE MILKY WAY. The magnitudes of the fixed stars appear to be different from one another, which difference may arise either from a diversity in their real magnitudes, or distances; or from both these causes acting together. The difference in the apparent magnitude of the stars is such as to admit of their being divided into six classes, the largest being called stars of the first magnitude, and the least which are visible to the naked eye, stars of the sixth magnitude. Stars that cannot be seen without the help of glasses are called telescopic stars. The number of stars, visible at any one time to the naked eye, is about one thousand ; but Dr. Herschel, by his skilful improvements of the reflecting telescope, has disco- vered that the whole number is great beyond all conception. Upon viewing the heavens during a clear night, we discover a pale irregular light, and a number of stars whose mingled rays form the luminous tract called the milky-way. The stars themselves are at too great a distance to be perceived by the naked eye; and among those which are visible with a telescope there are spaces apparently filled with others in immense numbers. Many whitish spots or tracts (called nebula;) are visible in different parts of the heavens, which are supposed to be milky-ways at an inconceivable distance, The distance of these remoter bodies is so vast and mea- sureless, that we can hardly speak of it except in relation to the inconceivable swiftness of light. The rays by which they are now made visible to the eye of the astronomer, the rapid motion of which might circle the earth while one is pronouncing a syllable, have been darting forward for thousands and ten thousands of years to reach us. All the events and revolutions, which history records, have taken place during their progress. They commenced their career, it has been computed, at a period of such remote antiquity, that, compared with it, the date of that time, when God gave the earth to man for a habitation, is but of yesterday. Dr. Herschel has calculated that the distance of the re- motest nebulae, exceeds that of the nearest fixed star at least three hundred thousand times. Upon this fact, he thus re- marks ; a telescope with a power of penetrating into space, like my forty feet one, has also, as it may be called, a power of penetrating into time past. To explain this we must consider that from the known velocity of light, it may be proved that when we look at the star called Sirius, the THE CONSTELLATIONS. 119 rays which enter the eye cannot have been less than six years and four months and a half coming from that star to the observer. Hence it follows that when we see an object at the calculated distance, at which one of these.very remote nebulae may still be perceived, the rays of light which con- vey its image to the eye, must have been more than nineteen hundred and ten thousand, that is, almost two millions of years on their way; and that, consequently, so many years ago, this object must already have had an existence in the sidereal heavens, in order to send out those rays by which we now perceive it. . But when we have reached the utmost distance to which the power of our instruments can penetrate, who will say, that we are approaching any limits of the creation 1 who will say, that if the disembodied spirit should travel forward through eternity, numberless systems would not be continual- ly spreading before it 1 All that part of the universe which we are able to discern, is peopled by inhabitants, who have the common want of heat and light; who will say, that there are not other parts of the material universe inhabited by beings of different natures, to whom these wants are un- known 1 It is only some portion, we know not how small, of the material universe' which is obvious to our senses; who will attempt to define the limits of the invisible world? who will attempt to set bounds to the works of infinite power and infinite goodness] Questions.—1. What are fixed stars?—why so called? 2 How does it appear that they do not borrow their light? 3. What is said of the magnitude of the stars? 4. Number? 5 Describe the milky- way (or galaxy.) 6. What calculations did Dr. Herschel make ? [Note. Many stars, single to the naked eye, appear double, triple, and even quadruple, through a telescope. Dr. Herschel found that in more than fifty double stars, a change of situation really takes place: it is concluded, therefore, that they describe orbits round a centre of gravity.] LESSON 55. The Constellations. The first people who paid much attention to the fixed stars were the shepherds in the beautiful plains of Egypt 120 THE CONSTELLATIONS. and Babylon. Endowed with a lively fanfty, they divided the stars into different companies or constellations, each of which they supposed to represent the image of some animal, or other terrestrial object. Of these ancient constellations there were fifty, to which the moderns have added about thirty others. Twelve of these constellations are in the zo- diac, bearing the same names with the signs of the zodiac or ecliptic. But these constellations and signs do not coin- cide, for the equinoctial points are not stationary, but move backward, and the sign Aries always begins at one of them, and all the other signs each succeed Aries in order ; it fol- lows therefore that all the signs of the ecliptic or zodiac move backward with the equinoxes. The distance which they move annually is about fifty seconds of a degree; so that with respect to the fixed stars the equinoctial points fall backwards thirty degrees, in about two thousand two hun- dred years, whence the stars will appear to have gone for- ward ihirty degrees, with respect to the signs of the ecliptic, which are always reckoned from the equinoctial points. This shows the importance of distinguishing between the signs of the zodiac and the constellations of the zodiac ; for stars, which are in one sign at one time, will be in the suc- ceeding one at another. Thus, the stars which were for- merly in Aries, are now in Taurus, and so on. When these names were given to the signs and constellations, it is sup- posed that each sign coincided with the constellation of the same name ; but on account of this moving of the equinoc- tial points, or, as it is termed, the precession of the equinoxes, there is now about one sign or thirty degrees difference. The period will be completed in about twenty-six thousand years. Among the northern constellations, none are more re- markable than that which is nearest to the north pole, and termed the little bear. The last star of its tail is but two de- grees from the pole ; hence it is called the polar star. It is easily distinguished from the neighbouring stars, because it scarcely appears to change its position, and is always in the same part of the heavens. By its fixed situation it becomes a guide to travellers, and particularly to mariners who are sailing on the open seas. Before the discovery of the com- pass sailors had no surer guide than the polar star; and i even now, when the sky is serene, they repose in many cases j HYMN TO THE NORTH STAR. 121 with greater certainty upon the direction of this star, than upon the magnetic needle. Hymn to the North Star. The sad and solemn night Has yet her multitude of cheerful fires; The glorious host of light Walk the dark hemisphere till she retires: All through her silent watches gliding slow, Her constellations come, and round the heavens, and go. Day, too, hath many a star To grace his gorgeous reign, as bright as they: Through the blue fields afar, Unseen, they follow in his flaming way. Many a bright lingerer, as the eve grows dim, Tells what a radiant troop arose and set with him. And thou dost see them rise, Star of the Pole! and thou dost see them set. Alone in thy cold skies, Thou keep'st thy old unmoving station yet, Nor join'st the dances of that glittering train, Nor dip'st thy virgin orb in the blue western main. There, at morn's rosy birth, Thou lookest meekly through the kindling air, And eve, that round the earth Chases the day, beholds thee watching there ; There noontide finds thee, and the hour that calls The shapes of polar flame, to scale heaven's azure walls', On thy unaltering blaze The half-wrecked mariner, his compass lost, Fixes his steady gaze, And steers, undoubting, to the friendly coast; , And they who stray in perilous wastes, by night, Are glad when thou dost shine to guide their footsteps right. And, therefore, bards of old, Sages, and hermits of the solemn wood Did in thy beams behold A. beauteous type of that unchanging good, 11 122 FORMS AND DIVISIONS OP TIME. That bright eternal beacon, by whose ray The voyager of time should shape his heedful way. Bryant. Questions.—1. What is said of the first division of the stars into oonstellations ? 2. Why do not the constellations and signs of the zodiac coincide ? 3. What is the present difference between them ? 4. At what rate does the change take place ? 5. Describe tne situa- tion of the polar star. LESSON 56. Foi*ms and Divisions of Time. As the form of the year is various among different na- tions, so is its beginning. The Jews, like most other na- tions of the East, had a civil year, which commenced wit|i the new moon in September; and an ecclesiastical year, which commenced from the new moon in March. The Persians begin their year in the month answering to our June ; the Chinese, and most of the inhabitants of India, begin it with the first moon in March ; and the Greeks with the new moon that follows the longest day. In England and America, the civil or legal year formerly commenced on the twenty-fifth of March, and the historical year on the first of January. But since the alteration of the style, which took place in 1752, the civil year in both countries has likewise begun on the first of January. The principal division of the year is into parts called months, which are either astronomical or civil. An astrono- mical or natural month is that which is measured exactly by the motion of the Earth or Moon, and is accordingly either lunar or solar. A lunar month is the time the moon takes to revolve round the earth, which she performs in twenty-seven days, seven hours, and forty-three minutes. A solar month is that space of time in which the earth runs through one of the signs of the zodiac ; as the earth con- stantly travels through the twelve signs in three hundred and sixty-five days five hours and forty-nine minutes, each solar month is found by dividing this number by twelve, to contain thirty days, ten hours, and twenty-nine minute? EQUATION OP TIME. 123 Civil months are those which are framed to serve the uses of life, and approach nearly to the quantity of astronomical months either lunar or solar ; being made, with the excep- tion of February, to consist of thirty and thirty-one days. To the days of a week, the Pagans gave the names of the sun, moon, and planets ; and for the first two days and last day of our weeks, those names are still retained. A natural ox solar day is the time which the sun takes in passing from the meridian of any place till it comes round to the same meridian again ; or it is the time from noon to noon. A sidereal day is the time in which the earth revolves once about its axis. The rotation of the earth is the most equable and uniform motion in nature, and is completed in twenty-three hours, fifty-six minutes, and four seconds, for any meridian on the earth will revolve from a fixed star, to that star again in this time. Sidereal days, therefore, are all of the same length ; but solar or natural days are not. The mean length of a solar day is twenty-four hours, but it is sometimes a little more, and sometimes less. The reason of the difference between the solar and sidereal day is, that as the earth advances almost a degree eastward in its orbit, in the same time that it turns eastward round its axis, it must make more than a complete rotation before it can come into the same position with the sun that it had the day be- fore ; in the same way, as when both the hands of a w,atch or clock set off together, as at twelve o'clock, for instance, the minute hand must travel more than a whole circle before it will overtake the hour hand, that is, before they will be in the same relative position again. It is on this account that the sidereal days are found to be, on an average, shorter than the solar ones by three minutes and fifty-six seconds. As a clock is intended to measure exactly twenty-four hours, it is evident that, when a solar day consists of more than twenty-four hours, it will not be noon by the sun till it is past noon by the clock ; in which case the sun is said to be slow of the clock. But when a solar day consists of less than twenty-four hours, it will be noon by the sun before it is noon by the clock ; and the sun is then said to be fast of the clock. Time measured by a clock is called equal or mean time, and that measured by the apparent motion of the sun in the heavens, or by a sun-dial, is called apparent time. The adjustment of the difference of time, as shown by a 124 EQUATION OF TIME. well-regulated clock and a true sun-dial is called the equa* Hon of time. Since the stars are found to gain three minutes and fifty-six seconds upon the sun every day, amouriting in a year to one diurnal revolution, it follows that, in three hundred and six- ty-five days as measured by the sun, there are three hundred and sixty-six days as measured by the stars. This regular return of the fixed stars to the meridian affords an easy method of determining whether our clocks and watches keep true time. For if through a small hole in a window-shutter, or in a thin plate of metal fixed for that purpose, it be ob- served at what time any star disappears behind a chimney or the corner of a building at a small distance; then if the star disappears the next night three minutes and fifty-six seconds sooner by the clock or watch than it did the night before, on the second night seven minutes fifty-two seconds sooner, and so on, it is a certain sign that the machine goes right; but if it does not observe this rule, it is evidently not accurate, and as the disappearing of a star is instantaneous, we may depend upon this information to half a second at most. Questions.—1. What is said of the form and commencement of the year among different nations ? 2. What is an astronomical month ? 3. Lunar month? 4. Solar month? 5. Civil month ? 6. Solar day ? 7. Sidereal day ? 8. How does it appear that sidereal days are all of the same length ? 9. Why is there a difference between the lengths of a solar and sidereal day ? 10. When is the sun said to be slow of the clock ? 11. Fast of the clock? 12. What is mean time? 13. Apparent time ? 14. Equation of time ? 15. What follows incon- sequence of the stars gaining upon the sun? 16. What is an easy method of determining whether clocks and watches keep true time ? [Note. The inequality of solar days, as caused by the eccentricity of the earth's orbit, and the obliquity of the ecliptic, is clearly illustrat- ed in Wilkins' Elements of Astronomy : the work has been recom- mended as containing a judicious selection and concise statement of the leading facts and principles of the science.] THE PLANETARY SYSTEM. 125 LESSON 57. The Planetary System A Fair star of eve, thy lucid ray Directs my thoughts to realms on high; Great is the theme, though weak the lay, For my heart whisper's ' God is nigh.' The Sun, vicegerent of his power, Shall rend the veil of parting night, Salute the spheres, at early hour, And pour a flood of life and light. Seven circling planets I behold, Their different orbits all describe ; Copernicus these wonders told, And bade the laws of truth revive. Mercury and Venus first appear, Nearest the dazzling source of day ; Three months .compose his hasty year, In seven she treads the heav'nly way. Next, Earth completes her yearly course ; The Moon as satellite attends ; Attraction is the hidden force, On which creation's laws depend. Then Mars is seen of fiery hue ; Jupiter's orb we next descry ; His atmospheric belts we view, And four bright moons attract the eye. Mars soon his revolution makes, In twice twelve months the sun surrounds; Jupiter, greater limit take?, And twelve long years declare his sounds. With ring of light, see Saturn slow, Pursue his path in endless space ; Py seven pale moons his course we know, And thirty years that round shai trace. 11* 126 THE TLANETARY system The Georgium Sidus next appears, By his amazing distance known ; The lapse of more than eighty y kin his account makes one alone JfjflErt&ns are his, by Herschel shown, ierscnl^of modern times the boast; ©iscovery here is all his own, Another planetary host 1 And lo! by astronomic scan, Three stranger planets track the skies, Part of that high majestic plan, Whence those successive worlds arise. Next Mars, Piazzi's orb is seen, Four years six months complete his round ; Science shall renovated beam, And gild Palermo's favoured ground. Daughters of telescopic ray, Pallas and Juno, smaller spheres, Are seen near Jove's imperial way, Tracing the heavens in destined years. Comets and fixed stars I see, With native lustre ever shine ; How great! how good ! how dreadful! He, In whom life, light, and truth combine. Oh ! may I better know his will, And more implicitly obey; Be God my friend, my father still, From finite—to eternal day. Mangnall. Note. The foregoing rhymes-were made, probably, before Vesta was discovered, and some of the facts, relating to the other new pla- nets, not so well ascertained as at present. Ceres is sometimes called Piazzi, after the discoverer. CHEMISTRY. 127 LESSON 58. Chemistry is an instructive, interesting, and valuable science. . Within the last sixty years its 'empire h* been wonderfully extended. There is scarcely an art of human life which it is not fitted to subserve ; scarcely a department of human inquiry or labour, either for health, pleasure, orna- ment, or profit, which it may not be made in its present im- proved state, eminently to promote. To the husbandman this science furnishes principles and agents of inestimable value. It teaches him the food of plants, the choice and use of manures, and the best means of promoting the vigour, growth, productiveness, and preservation of the various vege- table tribes. To the manufacturer chemistry has lately be- come equally fruitful of instruction and assistance. In the arts of brewing, tanning, dyeing, and bleaching, its doc- trines are important guides. In making soap, glass, pottery, and all metallic wares, its principles are daily applied, and are capable of a still more useful application, as they be- come better understood. Indeed, every mechanic art, in the different processes of which heat, moisture, solution, mix- ture, or fermentation is necessary, must ever keep pace in impruvement with this branch of philosophy. To the phy- sician this science is of still-greater value, and is daily grow- ing in importance. He learns from it to compound his me- dicines, to disarm poisons of their force, to adjust remedies to*dis*»ases, and to adopt general means of preserving health. To the student of natural history chemistry furnishes in- struction at every step of his course. Tp the public econo- mist it presents a treasure of useful information. By means of this science alone can he expect to attack with success the de- stroying pestilence, and to guard against other evils to which the state of the elements gives rise. And to the successful prosecution of numberless plans of the philanthropist, some acquaintance with the subject in question seems indispensably necessary. Finally, to the domestic economist this science abounds with pleasing and wholesome lessons. It enables him to make a proper choice of meats and drinks; it di- rects h>tn to those measures with respect to food, clothing, and 12$ GENERAL principles respiration, which have the best tendency to promote health, enjoyment, and cheapness of living; and it sets him on his guard against many unseen evils, to which those who are ig- norant Af its laws are continually exposed. In a word, from a speculative* science, chemistry, since the middle of the eighteenth century, has become eminently and extensively a practical one. From an obscure, humble, and uninteresting place among the objects of study, it has risen to a high and dignified station ; and instead of merely gratifying curio- sity, or furnishing amusement, it promises a degree of utility, of which no one can calculate the consequences or see the end. Questions.—1. What does chemistry do for the husbandman? 2. For the manufacturer ? 3. For the mechanic arts ? 4. For the physician ? 5. For the"student of natural history ? 6. For the public economist? 7. For the philanthropist? 8. lor the domestic eco- nomist ? LESSON 59. General Principles of Chemistry. The object of chemistry is to ascertain the ingredients of which bodies are composed,—to examine the compounds formed by those ingredients,—and to investigate the nature of the power which produces these combinations. The science therefore naturally divides itself into three parts : a description of the component parts of bodies, or of elementa- ry or simple substances as they are called,—a description of the compound bodies formed by the union of simple sub- stances,—and an account of the nature of the power which produces these combinations. This power is known in chemistry by the name of affinity, or chemical attraction. By simple substances is not meant what the ancient phi- losophers called elements of bodies, as fire, air, earth, and water, nor particles of matter incapable of farther diminu- tion or division. They signify merely bodies that have never been decomposed, or formed by art. The simple substances of which a body is composed are called the constituent parts of that body ; and, in decomposing it, we separate its con- ©F CHEMISTRY. 129 stituent parts. If, on the contrary, we divide a body by cut- ting it to pieces, or even by grinding it to the finest powder, each of these small particles will consist of a portion of the several constituent parts of the whole body : these are called the integrant parts. Compound bodies are formed' by the combination of two or more simple substances with each other. Attraction is that unknown force which causes bodies to approach each other. Its most obvious instances are, the gravitation of bodies to the earth ; that of the planets towards each other, and the attractions of electricity and magnetism. But that attraction, which comes under the more immediate cognizance of chemists, subsists between the particles of bodies ; and when it operates between particles of the same species, it is called the attraction of cohesion, or the attrac- tion of aggregation ; but when between the particles of dif- ferent substances, it is called the attraction of composition, chemical attraction, or chemical affinity. The attraction of cohesion, then, is the power which unites the integrant particles of a body : the attraction of composition that which combines the constituent particles. When particles are united by the attraction of cohesion, the result of such a union is a body of the same kind as the particles of which it is formed; but the attraction of composition, by combining particles of a dissimilar nature, produces compound bodies quite different from any of their constituents. If, for in- stance, you pour upon a piece of copper, placed in a glass vessel, some of the liquid called nitric acid (aqua fortis) for which it has a strong attraction, every particle of the copper will combine with a particle of acid, and together they will form a new body, totally different from either the copper or the nitric acid. If you wish to decompose the compound which you have thus formed, present to it a piece of iron, for which the acid has a stronger affinity than for copper; and the acid will quit the copper to combine with the iron, and the copper will be what the chemists call precipitated, that is to say, it will be thrown down in its separate state, and reappear in its simple form. In order to produce this effect, dip the blade of a knife into the fluid, and when you take it out you will observe that, instead of being wetted with a bluish liquid like that contained in the glass, it will be covered with a thin coat of copper. 130 CALORIC. The simple substances were said very lately to amount to more than fifty in number, but since the truly interesting and very important discoveries of Sir Humphrey Davy, and other eminent chemists, it is scarcely possible to say what substances are not compound bodies. But it will be most conducive to science to consider all those substances as simple, which no mode of decompounding has yet been dis- covered. Simple substances naturally divide themselves into two classes. Those which belong to the first class are of too subtile a nature to be confined in any of the ves- sels -which we possess. They do not sensibly affect the most delicate balance, and they have received therefore the name of imponderable bodies. The second class of bodies may be confined in proper vessels, may be exhibited in a separate state, and their weight and other properties may be deter- mined. They have received the name of ponderable bodies. The imponderable bodies at present supposed to exist are four, light, heat or caloric, electricity, and magnetism. The first three are intimately connected with chemistry, but mag- netism has with it no known connexion. Questions.—1. What is the object of chemistry? 2. How does the science divide itself? 3. What is meant by simple substances? 4. What is the difference, between decomposition and division ? 5. How are compound bodies formed ? 6. What is attraction and its most obvious instances ? 7. Define attraction of cohesion and attrac- tion of composition. 8. What are the results of each of these kinds of attraction ? 9. What example is given to illustrate chemical affini- ty or attraction ? 10. How may you decompose the body thus formed ? 11. Define the chemical term precipitate. 12. What is said of the number of simple substances? 13. Into what two classes are they di- vided? 14. What is stated as the ground of this division ? 15. What are the four imponderable bodies ? LESSON 60. Caloric. Chem'ically, when a mere mixture of two or more substances is made, they are said to be mechanically united ; but when each or either substance forms a component or constituent part of the product, the substances have formed a chemical union. Heat is a well known sensation which we perceive on touching any substance whose temperature is superior to CALORIC. 131" that of the human body. Chemists have agreed to call the matter of heat calorie, in order to distinguish it from the sensation which this matter produces. Caloric has a ten- dency to diffuse itself equally among all substances that come in contact with it. If the hand be put upon a hot body, part of the caloric leaves the hot body, and enters the hand; this produces the sensation of heat. On the contra- ry if the hand be put upon a cold body, part of the caloric contained in the hand leaves the hand to unite with the cold body ; this produces the sensation of cold. If you pour warm water into one basin, cold water into a second, and a mixture of hot and cold water into a third ; then put the one hand into the cold water and the other into the warm, for two minutes, and after that put both hands into the luke- warm water, to the one hand it will feel cold and to the other hot. Persons ascending from the burning shores of Vera Cruz, on the road to the mountain land of Mexico, will feel the climate become colder, and will put on their great coats, and yet they will meet people descending complaining of the heat. Cold therefore is nothing but a negative quality, sim- ply implying the absence of the usual quantity of caloric. Caloric'is uniform in its nature ; but there exist in all bodies two portions, very distinct from each other. The one is called sensible heat, or free caloric; the other latent heat, or combined caloric. Sensible caloric is the matter of heat disengaged from other bodies, or, if united, not chemi- cally united with them. Latent caloric is that portion of the matter of heat which makes no sensible addition to the tem- perature of the bodies in which it exists. Wrought iron, though quite cold, contains a large portion of latent caloric; and if it be briskly hammered for some time on an anvil, it will become red hot by the action of this species of caloric, which by the percussion of hammering is now evolved and forced out as sen*!Lie heat. Caloric per-ades all bodies; and this is not the case with any other substance with which we are acquainted. It com- bines with different substances, however, in very different proportions ; and for this reason, one body is said to have a greater capacity for caloric than another. When gaseous substances become liquid, or liquid substances solid, by this change of state the.} lose in a great measure their capacity for caloric. During the slaking of quick-lime, the caloric 132 THERMOMETER. which is evolved escapes from the water in consequence of its changing from a liquid to a solid form by its union with the lime. When solid bodies become liquid or gaseous, their capacity for caloric is proportionately increased. If you place a glass of water in a mixture of equal quantities of snow and salt, during their conversion to a liquid, the water will be frozen in consequence of parting with its ca- loric to supply the increased capacity of the mixture. The portion of caloric necessary to raise a body to any given temperature is called its specific caloric. - The instru- ment in common use for measuring the temperature of bodies is called a Thermometer. It consists of a glass tube con- taining a portion of mercury, with a graduated scale annex- ed to it. It is constructed in the following manner. A small bulb is blown on the end of the tube, and this bulb and a part of the tube are to be filled with mercury which is to be heated till it boils. This ebullition forces out the air and the tube is hermetically sealed while the mercury is boiling. The next object is to construct the scale. It is found by experiment, that melting snow or freezing water is always at the same temperature. If, therefore, a thermo- meter be immersed in the one or the other, the mercury will always stand at the same point. R has been observed, too, that water boils under the same pressure of the atmosphere at the same temperature. A thermometer, therefore, im- mersed in boiling water, will uniformly stand at the same point. Here, then, are two fixed points, from which a scale may be constructed, by dividing the intermediate space into equal parts, and carrying the same divisions as far above and below the two fixed points as may be wanted. When a ther- mometer is brought in contact with any substance, the mer- cury expands or contracts till it acquires the same tempera- ture ; and the height at which the mercury stands in the tube, indicates the exact temperature of the substance to which it has been applied. It will not show the absolute caloric in substances; for it cannot measure that portion which is latent, or chemically combined with any body. Caloric is the cause of fluidity in all substances capable of becoming fluid, from the heaviest metal to the lightest gas. It insinuates itself among their particles and invariably se- parates them in some measure from each other. Thus ice ft converted into water, and by a further portion of caloric,. atmospheric air. 138 into steam. We have reason to believe that every solid sub- stance on the face of the earth might be converted to a fluid, or even to a vapour or gas, were it submitted to the action of a very high temperature in peculiar circumstances. Some bodies give out their superabundant caloric much sooner than others. Iron is a quicker conductor of caloric than glass, and glass than wood. If you take a piece of iron in one hand, and a piece of wood in the other, the iron feels cold, the wood warmer, though the thermometer shows that their temperature is the same. Substances usually become more dense by the loss of caloric ; but the freezing of water is a striking exception to this general law of nature, and is a memorable instance of the wisdom and provident care of the Almighty, when he established the laws of the universe. Questions.—1. What is heat? 2. Why is the matter of heat called caloric ? 3. How are sensations of neat and cold produced ? 4. What is cold ? 5. What is sensible caloric ? 6. Latent caloric ? 7. What experiment illustrates this ? 8. Why is one body said to have a greater capacity lor caloric than another? 9. How do bodies lose their capacity for caloric ? 10. Why is caloric evolved during the slaking of quick-lime ? 11. When is a capacity for caloric increased ? 12. Describe the experiment. 13. What is specific caloric ? 14. Of what use is a thermometer ? 15. Of what does it consist ? IG. How is it constructed ? 17. How is calofic the cause of fluidity ? lb. What is said of conductors of caloric ? l'J. To what general law of nature is the freezing of water an exception ? 20. What are the different kinds of thermometers? (See Appendix.) 21. How is each gra- duated ? LESSON 61. Atmospheric Air. Gas. When solid substances are rendered permanently afiriform by heat, the air, thus produced, is culled a gas. All the gases are compounds of solid matter and caloric. It is caloric which separates the particles, and gives to the whole a gaseous form. The permanency of the gases appears to be owing to the strength of the affinity existing between caloric and their bases, which affinity resists every reduction of temperature. The atmosphere, which was formerly supposed to be a simple fluid, is composed of two distinct substances, termed oxygen gas and nitrogen gas. It is not a chemical com- pound, but a mere mixture of those gaseous substances in 1m 134 ATMOSPHERIC AIR. the proportion of 21 of the former and 79 of the latter. It contains also about one part in every thousand of carbonic acid gas, a considerable portion of water in a state of elastic vapour, and several adventitious substances. Oxygen is an element or simple substance generally dif- fused through nature, though like caloric it does not exist by itself It takes its name from two Greek words, signify- ing that which produces or generates acids, because one of its general properties is to form acids by combining with dif- ferent substances, which are called t.he bases of the several acids. Its different combinations are essential to animal life and combustion. Acted upon, or combined with caloric, it becomes oxygen gas, which is distinguished from all other gaseous matter by several important properties. Inflamma- ble substances burn in it under the same circumstances as in common air, but with infinitely greater vividness. If a taper, the flame of which has been extinguished, the wick only remaining ignited, be plunged into a bottle filled with it, the flame will instantly be re-kindled, and will be very brilliant, and accompanied by a crackling noise. If a steel wire, or thin file, having a sharp point, armed with a bit of wood in a state of inflammation, be introduced into a jar filled with the gas, the steel will take fire, and its combus- tion will continue, producing a most brilliant phenomenon. Oxygen gas is a little heavier than atmospheric air, and from its being absolutely necessary to the support of animal life, it has been called vital air. Nitrogen is a substance diffused through nature, and par- ticularly in animal bodies. It is not to be found in a solid or liquid state ; but combined with caloric, it forms nitrogen, or azotic gas, in which no animal can breathe, or any com- bustible burn. It is uninflammable and somewhat lighter than atmospheric air, and though, by itself, it is so noxious to animals, it answers an important end when mixed with oxy- gen gas in atmospheric air. Were it not for this large quan- tity of nitrogen in the atmosphere, the stimulating power of the oxygen would cause the blood to flow with too great rapidity through the vessels; the consequence of which wonld be, that the life of man would not be protracted to the length that it now is. The vermilion colour of the blood is owing to the inhalation of oxygen gas. When the dark purple blood of the veins arrives, at the lungs, it imbibes the WATER. 135 vital air of the atmosphere, which changes its dark colour to a brilliant red, rendering it the spur to the action of the heart and arteries, the source of animal heat, and the cause of sensibility, irritability, and motion. With regard to the nitrogen that is combined with atmospheric air, the great- est part of it is thrown out of the lungs at every respira- tion, and it rises above the head, that a fresh portion of air may be taken in, and that the same air may not be repeated- ly breathed. The leaves of trees and other vegetables give out during the day a large portion of oxygen gas, which, uniting with the nitrogen thrown off by animal respiration, keeps up the equilibrium, and preserves the purity of the atmosphere. In the dark, plants absorb oxygen, but the proportion is small, compared to what they exhale by day. Questions.—1. Of what is atmospheric air composed ? 2. What is the proportion of each, and what other substances does it contain ? 3. What is oxygen ? 4. Why is it thus named ? 5. How does it be- come oxygen gas ? 6. What are some of its important properties ? 7. Why has it been called vital air ? 8. What is nitrogen, and how does it form nitrogen or azotic gas ? 9. What are some of its properties ? 10. What important end does it answer, and how ? 11. How is the ver- milion colour of the blood produced ? 12. What becomes of the ni- trogen that is thrown out of the lungs ?—why ? 13. What tends to preserve the purity of the atmosphere? [Note. Nitrogen (pronounced Ni'tro-jen,) is called azote by the French chemists on account of its being so destructive of life. Oxygen, (pronounced ox'6-jen,) besides producing most of the acids, is necessary also to the production of the alkalies.] LESSON 62. Water. Cal'cine, to burn in the fire to a calx ;—calx is a substance easily reduced to powder. Efferves'cence, an intense motion which takes place in certain bodies, occasioned by the sudden escape of a gaseous substance. Water was formerly considered as a simple substance, and chemical philosophers were for a long time unwilling to allow of its being otherwise. Its compound nature, how- ever, has been fully proved. It is composed of eighty-eight parts by weight of ox}gen, and twelve of hydrogen, in every hundred parts of the fluid. It is found in four states, name- ly, solid or ice ; liquid or water; vapour or steam ; and in a 186 WATER. state of composition with other bodies. Its most simple state is that of ice, and the difference between liquid water or vapour and ice, is merely that water contains a larger portion of caloric than ice, and that vapour is combined with a still greater quantity than water. However long we boil a fluid in an open vessel, we cannot make it in the smallest de- gree hotter than its boiling point, for the vapour absorbs the caloric, and carries it off as fast as it is produced. It is owing to this, that all evaporation produces cold. An ani- mal might be frozen to death in the midst of summer, by repeatedly sprinkling ether upon him, for its evaporation would shortly carry off the whole of his vital heat. Water thrown on burning bodies acts in the same way ; it becomes, in an instant, converted into vapour, and by thus depriving them of a large portion of their caloric, the fire, as we term it, is extinguished. Vapour occupies a space eight hundred times greater than it does when in the form of water, and the expansive force of steam is found by experiment to be much greater than that of gunpowder. There is reason to believe that, in time, steam may be applied to many useful purposes of which at present we have no idea. Hydrogen is the base of the gas which was formerly called inflammable air, and when in the aeriform state, it is the light- est of all ponderable things. If you put a quantity of filings of zinc into a vessel which has a glass tube adapted to it, and then pour upon them sulphuric acid (oil of vitriol) di- luted with six or eight times its quantity of water ; an effer- vescence will immediately take place, the oxygen of it will become united to the metal, and the hydrogen gas will be disengaged, and may be conveyed by the glass tube into any proper receiver. While it is rushing through the tube, it may be kindled with a taper, and it will burn with a long iflame like a candle. In the burning of the gas, the hydro- gen unites with the oxygen of the atmosphere, and the result of the combination is flame and water. It has been sup- .posed that the torrents of rain, which generally accompany Ithunder storms, may arise from a sudden combustion of hy- -drogen and* oxygen gases by means of lightning. Hydrogen gas is only one fourteenth of the weight of atmospheric air, and occupies a space -fifteen hundred times greater than it possessed in its aqueous combination. It is continually emanating from vegetable and animal matters during their THE EARTHS. 137 decay, and is evolved from various mines, volcanoes, and other natural sources. From its great levity it has general- ly been used to fill air-balloons. Water is said to be in a state of composition with other bodies, because in many cases it becomes one of their com- ponent parts. It is combined in a state of solidity in marble, in crystals, in spars, in gems, and in many alkaline, earthy, and metallic salts, both natural and artificial, to all of which substances it imparts hardness, and to most of them transpa- rency. Near the poles water is eternally solid; there it is similar to the hardest rocks, and may be formed by the chisel of the stafuary, like stone. It becomes still more solid in the composition called mortar, and in cements, having parted with more of its caloric in that combination than it does in the act of freezing. If you take some ground plaster of Paris, fresh calcined, and mix it with a little water, the affini- ty of the plaster for the water is so great, that in a few minutes the whole will be converted to a solid. Questions.—1. Of what i.« water composed? 2. In what four states is it found ? 3. What is its most simple state ? 4. What is the difference between liquid water or vapour and ice ? 5. Why cannot water in an open vessel be made hotter than its boiling point ? 6. How may an animal be frozen to death in the midst of summer ? 7. Why would this happen ? r\ Explain the extinguishing of fire by water. 9. What space does vapour occupy ? 10. What is said of the expan- sive force of steam, and its probable application ? 1.1. What is hydro- gen, and how may hydrogen gas be obtained ? 12. What is the result of kindling hydrcgen gas on its rushinor from the glass tube ? 13. What is its weight and what space does it occupy ? 14. In what sub- stances is water combined in a state of solidity ? 15. Why does water become solid in mortar and in cements? [Note. Hydrogen (pron. Hi'drO-jen,) takes its name from two Greek words signifying to pro- duce water.] LESSON 63. The Earths and Alkalies. The earths are 6ilex, or silica, alumine, glucine, zircon, yttria, magnesia, barytcs, stroutites, and lime :—tli3 four last mention- ed are called alkaline earths. Stra'ta (plural of stratum) beds, layers. Earths are such incombustible substances as are not ductile, are mostly insoluble in water or oil, and preserve JO * 138 THE ALKALIT!* their constitution in a strong heat. Notwithstanding the varied appearance of the earth under our feet, and of the mountainous parts of the world, whose diversified strata pre- sent to our view substances of every texture and of every shade, the whole is composed of only nine primitive earths; and as three of these occur but seldom, the variety which is produced by the other six becomes the more remarkable. One of the most valuable earths with which we are acquainted is silex or pure flint. It is the most durable article in the state of gravel for the formation of roads ; it is a necessary ingredient in earthenware, porcelain, and cements ; it is the basis of glass, and of all vitreous substances. It is white, inodorous and insipid in its pure state, and the various colours, which it assumes in different substances, proceed from the different ingredients with which it is mixed. Alu- mine obtained its name from its being the base of the salt called alum. It is distributed over the earth in the form of clay, and on account of its aptitude for moulding into dif- ferent forms, and its property of hardening in the fire, is employed for various useful purposes. In making earthen- ware, a due proportion both of silex and alumine are neces- sary ; for if alumine alone were used, the ware could not be sufficiently burnt without shrinking too much, and even cracking ; and a great excess of silex would lessen the te- nacity and render the ware brittle. Lime is never found pure in nature ; it is obtained by decomposing calcareous matters by the action of fire, which deprives them of their acid. In its pure state it is used in many of the arts. It is employed by the farmers as a manure ; and by bleachers, tanners, iron-masters and others, in their several manufacto- ries, and in medicine. The use of lime in agriculture may be attributed to its property of hastening the dissolution of all animal and vegetable matters, and of imparting to the soil a power of retaining a quantity of moisture necessary for the nourishment and vigorous growth of the plants. Mag- nesia, besides being the basis of several salts, is of great use in medicine ; and is employed by the manufacturers of ena- mels and porcelain. The alkalies are distinguished by an acrid and peculiar taste ; they change the blue juices of vegetables to a green, and the yellow to a brown, and have the property of render- ing oils miscible with water. They form various salts by THE ALKALIES. 130 combination with acids, act as powerful caustics when applied to the flesh of animals, and are soluble in water. Potash and soda have been called fixed alkalies, because they will endure a great heat without being volatilized: and yet in a very high temperature they are dissipated in vapour. They were formerly considered to be simple sub- stances, but they are now found to be compounds of metallic substances, called potassium and sodium, with oxygen. They have various uses in surgery and medicine, and are employ- ed in large quantities by the glass-maker, the dyer, the soap- maker, the colour-maker, and by many other manufacturers. Ammonia is so extremely volatile as to exhale at all known temperatures. AVhen combined with carbonic acid, it takes a concrete form, and a beautiful white colour, and is known in commerce by the name of volatile salts. With muriatic acid it forms what is termed sal ammoniac, which is employ- ed in many of our manufactories, particularly by dyers to give a brightness to certain colours. In tinning metals it is of use to cleanse the surfaces, and to prevent them from oxydizing by the heat which is given to them in the opera- tion. Ammonia is furnished from all animal substances by decomposition. The horns of cattle, especially those of deer, yield it in abundance, and it is from this circumstance that a solution of ammonia in water has been called hartshorn. Questions—1. What are earths? 2. What the names of the nine earths ? 3. What is said of silex ? 4. Of alumine ? 5. Of lime? 6. Of magnesia ? 7. How are alkalies distinguished ? 8. Whv are potash and soda called fixed alkalies ? 9. Of what are they compounds t 10. What is said of their uses ? 11. From what is am- monia furnished ? 12. What is said of its combinations and uses ? TNote Besides the nine earths, above enumerated, we have now Ihorina, which is a rare earthy substance lately discovered. A new alkali called lithia, has recently been discovered, which, like potash and soda, is found to be a metallic oxyd : its base is called lithium. Three new vegetable alkalies have also been discovered, called mor- phia, picrotoxine, and vauqueline. Clay, as it exists in soils, is com- monly called argillaceous earth; and lime in Boils is called calcare- ous earth] 140 ACIDS. LESSON 64. Acids and Salts. Acids which contain different quantities of oxygen are distin- guished by their termination. The name of that which con- tains most oxygen ends in ic, the other in ous. Thus we say sulphuric acid, and sulphurous acid. All salts that are com- posed of acids ending in ic, take an ending in ate ; as sulphate of lime, a compound of lime with sulphuric acid. All salts composed of acids ending in ous, take an ending in ite, in- stead of ate; as sulphite of lime. When there is an excess of acid, the preposition super is added ; and when an excess of the base, then sub is prefixed, as super-sulphate of potash, or sub-borate of soda, {borax.) The name acid, in the language of chemists, has been given to all substances, whether liquids or solids, which pro- duce that sensation on the tongue which wc call sour. Most of the acids owe their origin to the combination of certain substances with oxygen ; and they have the property of changing the blue, green, and purple juices of vegetables to red, and of combining with alkalies, earths, or metallic oxyds, so as to compose those compounds termed salts. The acids were formerly divided into three classes, mineral, vegetable, and animal; but the more useful and scientific way of di- viding them is into two classes only. The undecomposable acids, and those which are formed with two principles, are comprised in the first class ; while those acids which are form- ed with more than two principles compose the second class. Sulphuric acid is procured by burning sulphur, in contact with some substance containing oxygen ; by which process the sulphur combines with the oxygen, and becomes acidi- fied. In commerce it is commonly called the oil of vitriol. That peculiar acid which is called muriatic is usually ob- tained from muriate of soda, which is the chemical name for common salt. Carbonic acid is a combination of carbon and oxygen. It was formerly called fixed air, on account of its being so intimately combined in chalk, lime-stone, and other substances. If you pour some diluted sulphuric acid over pulverized chalk or marble contained in a glass ves- sel, which has a tube connected with it, an effervescence will take place, and carbonic acid gas will escape through the tube. This gas is more destructive of life than any 3ALT». 141 Other, and it extinguishes flame instantaneously. Water may be made by pressure to absorb three times its bulk of this gas; by whicii it acquires an acidulous and not unpleasant taste. Soda water, cider, and other fermented liquors ow© their briskness and sparkling to the presence of this gas. Fatal accidents often happen from the burning of charcoal in chambers, for wherever charcoal is burned this gas is always formed. It so often occupies the bottoms of wells, that workmen ought not to venture into such places without previously letting down a lighted candle. If the candle burns they may enter it with safety; if not, a quantity of quick-lime should be let down in buckets, and gradually sprinkled with water. As the lime slakes, it will absorb the gas, and the workmen may afterwards descend in safety. The number of acids that are well known amounts to more than forty, and their uses are so many and important that it is impossible to enumerate them. They are indispensable lo various arts and manufactures; they are employed for oulinary purposes, and for medicine; they act an important part in the great elaboratory of nature, and form a great proportion of many of the mountainous districts of the globe in their various combinations. The precise number of the salts is not known, but they probably amount to more than two thousand. The different salts are known from each other by the peculiar figure of their crystals, by their taste, and other distinctive or specific characters. The separation of salts from the water in which they may be dissolved, is generally effected by evaporation and cooling. When a certain portion of the water of solu- tion is evaporated, and the remainder left in a proper tem- perature at rest, the salts will shoot into crystals, and will be found dispersed through the water at the bottom and at the sides of the vessel, and sometimes also on the surface of the solution. Their crystallization is owing to the abstraction of the heat or water by which they were dissolved. Crys- tallized salts are liable to changes in their appearance by exposure to atmospheric air. Some have so great an af- finity for water that they absorb it with avidity from the at- mosphere, and thus becoming moist or liquid, they are said to deliquesce. Others, having less affinity for water than atmospheric air has, lose their water of crystallization by exposure, and readily fall into powder. Such salts are said 142 SALTS. to effloresce. Salts have not only the property of dissolving in water, but by exposure to great heat they will melt, and they require different degrees of heat to put them in a state of fusion, as well as different quantities of water for their solution. Many of the salts are found native, and the carbonates, sulphates, and muriates are the most frequent. Chalk, limestone, and marble, are all included in the term carbo- nate of lime. Few salts are more copiously disseminated than the sulphate of lime, particularly in the vicinity of Pa- ris, and hence its name Plaster of Paris. Of the native mu- riates, muriate of lime occurs with rock-salt, and muriate of magnesia is found in abundance in sea-water; and muriate of soda not only exists in immense quantities in the ocean, but vast mountains in different parts of the world are en- tirely formed of this salt. Nitrate of potash, known by the more familiar name of nitre or salt-petre, is collected in va- rious parts of the globe. Phosphate of lime, which is the basis of all animal bones, exists native in Hungary, and composes several entire mountains in Spain. Mountains of salt were probably formed in very remote ages, and by processes of which we can form no idea. It may be sup* posed, however, that these changes have been slow and gradual, for several of the native salts exhibit marks of regu- larity and beauty in their crystallization, which cannot be imitated by art. Questions.—1. To what substances is the name acid given?.2 To what do most acids owe their origin ? 3. How do they form salts ? 4. What is said of the division of acids ? 5. How is sulphuric acid procured ? 6. Muriatic acid ? 7. What is carbonic acid ? 8. How may you obtain carbonic acid gas? 9. What are some of the proper- ties of this gas ? 10. Why do fatal accidents often happen from the burning of charcoal ? 11. How may it be destroyed at the bottom of wells? 12. What is said of the number and uses of the acids ? 13. How are the different salts known from each other ? 14. How may salts be separated from their water of solution ? 15. To what changes are crystallized salts liable on exposure to atmospheric air ? 1*3. What native salts are mentioned ? 17. What is said of salt mountains ? SIMPLE COMBUSTIBLES. 143 LESSON 65. Simple Combustibles. E tinits, volatile liquids formed by the distillation of some of the acids witli alcohol. Al'cohol, rectified spirit of wine. It is al- ways the same from whatever kind of spirit it is distilled : it is the* purely spirituous part of all liquors that have undergone the vinous fermentation. The combinations of sulphur are denominated sulpkurets; ot phosphorus, yhosphurets; of carbon, carburets; of hydrogen, lui'irurcts ; the sulphuret of iron, for instance, is the union ot sulphur with iron. Most of the simple substances are combustible, or bear some relation to combustion. Light and caloric arc evolved during combustion ; oxygen is the principal agent; and hy- drogen, sulphur, phosphorus, carbon, and the metals, are the subjects, or the true instruments of this process. Hydrogen gas may be combined with water, sulphur, phosphorus, or with carbon. When combined with phosphorus it forms phosphurettcd hydrogen gas, which takes fire whenever it comes m contact with atmospheric air. The elastic sub- stance, which is called carburetted hydrogen gas, is carbon dissolved in hydrogen ; it has likewise been cailed heavy inflammable air. It is this gaseous compound which has occasioned so many dreadful accidents to miners, who call it the lire-damp. This sas is procured from pit-coal by drv distillation; and from its inflammability and brilliant flame, it has been used for lighting streets, shops, manufac- tories and lioht-houses on the sea-coast. The rate at which it is procured is trifling compared to the expense of oil and tallow. , Phosphorus is a solid inflammable substance, which burns at a vr-v low temperature, when in contact with oxygen gas or atmospheric air. Many amusing experiments may be .performed with it, but it must be handled with extreme iau'ion. H you fix a piece of solid phosphorus in a quid, and write vv.th it upon paper, the writing, in a dark room will be beautifully luminous. If the face or hands be rubbed with phosplm etted ether, they will appear, in a dark place, as though on lire, without danger or sensation of heat. Pure carbc. is known only in the diamond ; but carbon in the state of charcoal may be procured by heating to red- 144 SAUBON. ness a piece of wood closely covered with sand in a crucible} so as to preserve it while in the fire, and afterwards, while cooling, from the action of the atmosphere. It is capable of foriiiing various combinations, but charcoal is that with which we are most familiar. Carbon is not only a compo- nent part, but it forms nearly the whole of the solid basis of all vegetables, from the most delicate flower in the garden to the huge oak of the forest. It not only constitutes the basis of the woody fibre, but is a component part of sugar, and of all kinds of wax, oils, gums, and resins, and of these again, how great is the variety ! It is imagined that most of the metals may be combined with carbon ; but at present we know only of its combination with iron. In one proportion it forms cast iron ; in another, steel; and in a third, plum- bago, generally, though improperly, called black lead. There is no lead in its composition. Cast iron contains about one forty-fifth of its weight of carbon,—steel is combined with about one part of carbon in two hundred of iron,—and plum- bago, or carburet of iron, has been found to consist of nearly nine parts of carbon to one of iron. Wrought iron differs from cast iron, in being deprived of its carbon and oxygen, by continued heat and repeated hammering, which render , the metal malleable. Steel is made of wrought iron by va- I 'rious processes, whereby the metal resumes a small portion of the carbon, and acquires a capacity of receiving different degrees of hardness. The metals are generally procured from beneath the sur- face of the earth, in a state of combination either with other metals, with sulphur, oxygen, or with acids ; though a few of them have occasionally been found in a state of purity. Metals are the great agents by which we are enabled to | examine the recesses of nature ; and their uses are so mul- 1 tiplied, that they are become of the greatest importance in every occupation of life. They are the instruments of all our improvements, of civilization itself, and are even sub- I servient to the progress of the human mind towards perfec- J tion. Tiiey differ so much from each other, that nature I seems to have had in view all the necessities of man, in or- der that she might suit every possible purpose his ingenuity can invent, or his wants require. We not only receive this 1 great variety from the hand of nature, but these metals are rendered infinitely valuable by various other properties they 0XYDS. 145 possess;—by their combustibility, their solubility in fluids, their combinations with various substances, and by their union with each other, whereby compounds or alloys are formed, extremely useful in a variety of arts, manufactures, and other requisites of life. By combining them with oxy- gen we can invest them with new properties, and are ena- bled to employ these to promote the progress of the fine arts, by imitating the master-pieces of creation in the production of artificial salts, gems, and crystals, of every colour and of every shade. Questions.—1. What are the simple combustibles? 2. What is Baid of phosphorus combined with hydrogen gas ? 3. What is carbu- retted hydrogen gas ? 4. What do miners call it ? 5. To what use may it be applied ? 6. What is phosphorus ? 7. What experiments may be performed with it ? 8. How may carbon be obtained in the state of charcoal ? 9. What is said of carbon with regard to vegeta- bles, sugar, wax, &c. 10. What is said of its combinations with iron ? 11. In what state are metals generally found ? 12. What is said of the utility of metals ? [Note. Chlorine (oxymuriatic acid,) boron and fluorine (the bases of the boric and fluoric acids,) and a substance of recent discovery, called iodine, have lately been added to the list of simple substances, (see Appendix.) Iodine and Chlorine are capa- ble of forming distinct and peculiar acids by combination with Hydro- gen. They form various other compounds, such as Iodides, Chlori- des ; Iodates, Chlorates ; Iodurets, Chlorurets, &c. LESSON 66. Oxyds and Combustion. As oxygen can combine in different proportions with the same sim- ple substance, the products have been designated by the names of protoxyd, deutoxyd, or tritoxyd, according as the oxygen en- tered into it, in one, two, or three proportions; and that has been called peroxyd, which was most oxydated, or oxydized. Retort', see description of fig. 46, in Appendix. Any metal or combustible body which is combined with less oxygen than is sufficient to render it acid, is usually called an oxyd. Whenever a substance is converted into an oxyd, we say it is oxydized; but if it becomes an acid by its union with oxygen, we say it is oxygenized. The mine- ral, the animal, and the vegetable kingdoms, all furnish mat- ters which are convertible into oxyds, by an union with oxygen. Metallic oxyds are formed in several ways, the chief 146 COMBUSTION. of which are by the access of atmospheric air, by the dev composition of water, and by the decomposition of acids. Iron may be mentioned as a familiar example of a metal be- coming oxydized by atmospheric air. It is well known that when this metal is exposed to air and moisture, it acquires rust, or in other words its surface is converted to an oxyd, in whicii state the metal will be found to have acquired an increase of weight. Common red lead, which is a true oxyd of lead, is made by melting that metal in ovens so constructed as to have a free access to atmospheric air. Gold, silver, and platina, cannot be oxydized, unless in a very high tem- perature ; and with respect to other metals, they not only differ in their capacity for oxygen, but also in their attrac- tion for it; so that one will often rob the other, thus reduc- ing the first oxyd to its primitive metallic form. If you dissolve some quicksilver in nitric acid, and after dropping a little of the solution upon a bright piece of copper, gently rub it with a piece of cloth, the mercury will precipitate it- self upon the copper, which will be completely silvered. With regard to the oxyds of nitrogen ; the first degree of oxydizement produces nitrous oxyd ;—a further portion of oxygen nitric oxyd, and they are both in a state of gas. Nitrous oxyd gas bears the nearest resemblance of any other to atmospheric air. It will support combustion even better than common air ; it is respirable for a short time, and it is absorbed by water. Persons who have inhaled this gas have felt sensations similar to those produced by intoxication. In some people it produces involuntary muscular motion and a propensity to leaping and running; in others, involuntary fits of laughter; and in all, high-spirits, and the most exquisite- ly pleasurable sensations, without any subsequent feelings of debility. It is readily procured by exposing crystals of ni- trate of ammonia, in a retort, to the heat of a lamp, by which means, the ammoniacal salt is decomposed, and this gas is evolved. Combustion may be defined to be a process by which cer- tain substances decompose oxygen gas, absorb its base, and Buffer its caloric to escape in the state of sensible heat. The ao-ency of oxygen in combustion is attributable to its affinity for combustible bodies. The combustible having a greater affinity to oxygen than oxygen has to caloric, the oxygen gas is decomposed, and its oxygen combines with the ignited COMBUSTION. 147 body, while its caloric, becoming free, is diffused among the surrounding bodies. Whenever we burn *a combustible body, a continued stream of atmospheric air flows towards the fire placed to occupy the vacancy left by the air that has undergone decomposition, and which, in its turn, becomes decomposed also. "Hence a supply of caloric is furnished without intermission, till the whole of the combustible is saturated with oxygen. As the combustible burns, light is disengaged, and the more subtile parts, now converted by caloric into gas, are dissipated in that state. When the combustion is over, nothing remains but the earthy parts of the combustible, and that portion which is converted, by the process, into an oxyd, or an acid. The smoke which arises from a common fire is chiefly water in the state of vapour, with a mixture of carburetted hydrogen and bitu- minous substances; part of the water comes from the mois- ture of the fuel; the other part is formed during combus- tion, by the union of the hydrogen of the combustible with the oxygen of the atmosphere. The agency of oxygen in combustion may be demonstrated by placing a lighted can- dle under a glass vessel inverted upon a plate of water. It will be seen that the candle will go out as soon as it has consumed all the oxygen contained in the included air, and that the water will rise up in the vessel to fill the vacancy. In the decomposition of atmospheric air by combustion, it is natural to ask what becomes of the nitrogen gas ? As -the oxygen becomes fixed in the combustible body, its caloric is disengaged, a part of which combines with the nitrogen, and carries it off in the form of rarefied nitrogen gas. When bodies are burnt, none of their principles are destroyed. We have reason to think that every particle of matter is inde- structible, and that the process of combustion merely decom- poses the body, and sets its several component parts at liberty, to separate from each other, to form other new and varied combinations. It was said of old, that the Creator weighed the dust, and measured the water, when he made the world. The first quantity is here still; and though man can gather and scatter, move, mix, and unmix, yet he can destroy nothing: the dissolution of one thing is a prepara- tion for the being, and the bloom, and the beauty of another. Something gathers up all the fragments, and nothing is lost. 148 EI.ECTUK'rTV. Questions.—1. What is an oxyd? 2. What are the principal ways by which metallic oxyds are formed ? 3. What is said of iron as an example ? 4. What is red lead and how is it made ? 5. What is said of the different capacity and attraction of metals for oxygen ? 6. What experiment is given for illustration? 7. What is said of the properties of nitrous oxyd gas ? 8. What effects does it produce on being inhaled ? U. How may it be procured ? 10. How may combus- tion be defined ? 11. How is the process of combustion explained? 12. What remains when the combustion is over ? 13. What is smoke ? 14. How may the agency of oxygen in combustion be demonstrated ? 15. What becomes of the nitrogen gas? 16. What is said of the in- destructibility of matter ? 17. What is a retort ? (see Appendix.) 18. How may chlorine be procured ? 1!». What is said of the attrac- tion of chlorine for the metals ? 20. How is combustion defined in the Appendix, and on what grounds is it so defined ? LESSON 67. Electricity. Elec'tric. The first electrical phenomena are supposed to have been observed in a mineral substance called ar.iber, in Greek elektrun, and hence the fluid or power has been denominated electric. The surface of the earth, and of all the bodies with which we are acquainted, is supposed to contain or possess a power of exciting or exhibiting a certain quantity of an exceed- ingly subtile agent, called the electric fluid or power. The quantity usually belonging to any surface, is called its natu- ral share, and then it produces no sensible effects ; but when any surface becomes possessed of more, or of less, than its natural quantity, it is electrified, and it then exhibits a variety of peculiar and surprising phenomena ascribed to the power called electric. If you take a stick of sealing-wax and rub it on the sleeve of your coat, it will have the power of at- tracting small pieces of paper, or other light substances, when held near them. If a clean and dry glass tube be briskly rubbed with the hand, or with a piece of flannel, and then presented to any small light substances, it will im- mediately attract and repel them alternately for a consider- able time. The tube is then said to be excited. If an ex- cited glass tube, in a dark room, be brought within about half an inch of the finger, a lucid spark will be seen between the finger and the tube, accompanied with a snapping noise, and a peculiar sensation of the finger. Dry flannel clothes, ELECTRICITY. 149 when handled in the dark, frequently exhibit a sparkling appearance, attended with the same kind of noise that is heard in the experiment of the glass tube. All those bodies which transmit or conduct electricity from one surface to another, are called conductors, and those surfaces that will not transmit the electric power, are called electrics or non-conductors. The general class of conduc- tors comprehends metals, ores, and fluids in their natural state, except air and oils. Vitrified and resinous substances, amber, sulphur, wax, silk, cotton, and feathers, are electrics or non-conductors. Many of these, such as glass, resin, and air, become conductors by being heated. When a sur- face is supposed to have more than its natural quantity of this fluid, it is said to be positively electrified; and when less than its natural share, to be negatively electrified. When any electrified conductor is wholly surrounded by non-con- ductors, so that the electric fluid cannot pass from it along conductors to the earth, it is said to be insulated. The hu- man body is a good conductor of electricity ; but if a person stand on a cake of resin, or on a stool supported by glass legs, the electric fluid cannot pass from him to the earth, and if he is touched by another person standing on the ground, the same sparkling appearance and noise, as men- tioned above, will be exhibited. Two surfaces, both posi- tively, or both negatively electrified, repel each other; and I two substances, of which one is positively, and the other I negatively electrified, attract each other. Opposite electrW cities always accompany each other, for if any surface be- come positive, the surface with which it is rubbed becomes.* negative ; and if any surface be rendered positive, the near* e;t conducting surface will become negative. When one side of a conductor receives the electric fluid, its whole sur- face is instantly pervaded; but when an electric or non- conductor is presented to an electrified body, it becomes! electrified on a small spot only. If to one' side of a pane of I glass, you communicate positive electricity, the opposite sidaj will become negatively electrified, and the plate is then saidl to be charged. These electricities cannot come together." unless a communication, by means of conductors, is mad between the sides of the glass; and if their union be mad through the human body, it produces ah affection of th nerves called an electric shock. 150 EXPERIMENTS. As the excitation which is produced by rubbing with the hand on a tube or plate of glass, is not only very laborious, but inadequate to the production of any material quantity of electric fluid, machines have been constructed of various forms for this purpose. Tim most common machine con- sists of a glass cylinder, supported by two glass pillars, and made to turn by a crank or handle. A rubber, or cushion, of leather, spread with an amalgam of mercury and zinc or tin is fastened to a spring, which proceeds from a socket ce- mented on the top of another glass pillar. A piece of black silk is fastened to the cushion and extended over the cylin- der, nearly to the receiving points, to prevent the fluid from flying off. A fourth glass pillar supports what is called the prime conductor, which is made of hollow brass or tin plate, arfd, at the end towards the cylinder, has a collection of pointed wires, and at the other end, a single wire terminated by a brass ball. A small chain is fastened to the cushion, one end of which extends to the floor or table. It serves to conduct the fluid in passing from the earth to supply the machine. When the cylinder is turned swiftly, the electric fluid passes from the rubber to the glass, and is thence con- veyed to the points of the prime conductor, which is thus positively electrified. While the electric fluid is collecting, it produces a crackling noise, and in a darkened room the flame will be seen spread on the surface of the cylinder. If a cylinder be made of resin, the electricity is the reverse of Lthat whicii is produced by the smooth glass cylinder and "rubber of the usual machines; for in this case the rubber V partakes of the positive, and the cylinder, and prime conduc- tor, is electrified with the negative. This difference be- % tween the resin and glass has given rise to what is called the '■ > double current, or vitreous and resinous electricity ; but it is jl> generally supposed that the difference arises more from the \ effect of the surfaces that act on each other, than from any ; peculiar qualities in the different bodies. ■ Some of the experiments which may be made with an i electrical machine are necessary for illustrating the laws of electricity, and others are merely entertaining. If the inside of a glass tumbler be electrified by presenting it to a pointed \ wke extending from the prime conductor, and then placed Stover a few pith-balls laid upon a table, the balls will immedi- ately begin to leap up along the sides of the glass, and then EXPERIMENTS. 151 back to the table; they are attracted and repelled by the electrified inside surface of the glass, the electricity of which they gradually conduct to the table. If a person having long hair, not tied up, be placed upon an insulated stand, and, by means of a chain be connected with the prime conductor, when the machine is put in motion, the hairs on his head, by repelling each other, will stand out in a most surprising man- ner. A piece of sponge, filled with water, and hung to a conductor, when electrified in a dark room, exhibits a most beautiful appearance. If a piece of sealing-wax be fastened to a wire, and the wire be fixed into the end of the conduc- tor, and the wax lighted, the moment the machine is worked, the wax will fly off in the finest threads imaginable. Take a two ounce phial, half full of olive-oil, pass a slender wire through the cork, and let the end of it be so bent as to touch the glass just below the surface of the oil; then place your thumb opposite the point of the wire in the phial, and if, in- that position, you take a spark from the charged conductor, the spark, in order to reach your thumb, will actually per- forate the glass. In this way holes may be made all round the phial. Questions.—1. What parts of bodies contain the electric fluid ? 2. When is a body said to be electrified ? 3. What experiment may be made with sealing-wax ? 4. When is a glass tube said te be ex- cited ? 5. What is said respecting an excited tube when in a dark room? 6. What are conductors of electricity ? 7. Electrics, or non- conductors ? 8. When is a surface positively, and when negatively electrified? 9. When is a conductor said to be insulated? 10. What is said of the human body as a conductor ? 11. When do surfaces repel, and when attract each other ? 12. What takes place when a conductor receives the electric fluid ?—non-conductor ? 13. When is a plate of glass said to be charged ? 14. What is an electric shock ? 15. Describe the electrical machine. 16. What are some of the experi-, ments that may be made with it ? (See Electrical Machine, fig. 49.) [Note. The earliest account of any known electrical effect is by the ancient naturalists, Thales and Theophrastus, who flourished, the first 600, and the latter 300 years before the present era.] 152 DR. FRANKLIN ,3 DISCOVERY. LESSON 68. Electricity (continued.) A queous, watery. Collapse', to fall together. The Leyden phial is a glass jar coated with tin foil on the inside and outside within about three inches of the top of its cylindrical part, and having a wire with a brass ball at its extremity. This wire passes through a cork or piece of wood, and at its lower extremity is a small chain, or wire, that touches the inside coating in several places, and serves as a conductor to charge the jar with electric fluid. On bringing the ball of the jar near the prime conductor, after a few turns of the machine, the jar will be charged. The discharging rod consists of two brass balls attached to the ends of a wire, bent in the form of a semicircle, and fixed to a glass handle. When one of the balls of the discharg- ing rod is applied to the ball of the jar, and the other to the outside coatino-, a communication is made between the out- «ide and inside of the jar, by which the equilibrium is in- stantly restored by the superabundant electricity passing from one side to the other, appearing in the form of a vivid flash, and accompanied with a loud report Any number of persons may receive the shock together by laying hold of each other's hands, the person at one end touching the out- ride of the jar, and the person at the other end bringing his hand near the ball of the jar. If there were a hundred per- sons so situated, they would every one feel the shock at the same instant. The electric fluid may be thus conveyed many miles in a moment of time. When great force is re- quired from the electric fluid, a number of jars of the above description are connected together by making a communi- cation between all their outsides, and another between all their insides. In this manner any number of jars may be charged with'the same facility as a single one, and from the powerful effect of the electric fluid, when it is thus collect- ed, it is called an electrical battery. The Leyden phial received its name from the birth-place of the discoverer, who was a native of Leyden in Holland. But the greatest discovery that was ever made in electricity was reserved for Dr. Franklin, in America. It had been THUNDER AND LIGHTNING. 153 imagined before his time that a similarity existed between lightning and the electric fluid; but Franklin brought this supposition to the test, and proved the truth of it by the sim- ple means of a boy's kite covered with a silk handkerchief instead of paper, and some wire fastened in the upper part, which served to collect and conduct the fluid. When he had raised this machine into the atmosphere, he drew elec- tric fluid from the passing clouds, which descended through the flaxen string of the kite as a conductor, and was after- wards drawn from an iron key which he tied to the line at a small distance from his hand. This important experiment immediately led to the formation of conductors to secure buildings from the effects of lightning. When aqueous vapour is condensed, the clouds formed are usually more or less electrical, and the earth below them be- ing brought into an opposite state, a discharge takes place when the clouds approach within a certain distance, consti- tuting lightning; and the collapsing of the air, whicii is ra- refied in the electrical circuit, is the cause of the thunder, whicii is moie or less intense, and of longer or shorter du- ration, according to the quantity of the air acted upon, and the distance of the place where the report is heard from the point of the discharge. In gloomy pomp, whilst awful midnight reigns, And wide o'er earth her mournful mantle spreads, Whilst deep-voiced Thunders threaten guilty heads, And rushing torrents drown the frighted plains, And quick-glanced Lightnings, to my dazzled 6ight, Betray the double horrors of the night: A solemn stillness creeps upon my soul, And all its powers in deep attention die ; My heart forgets to beat; my steadfast eye Catches the flying gleam ; the distant roll, Advancing gradual, swells upon my ear With louder peals, more dreadful as more near. Awake, my soul, from thy forgetful trance ! The storm calls loud, and meditation wakes; How at the sound pale Superstition shakes, Whilst all her train of frantic fears advance ! U4 FALLING STARS. Children of darkness, hence ! fly far from me ! And dwell with guilt and infidelity ! But come, with look composed, and sober pace, Calm Contemplation, come ! and hither lead Devotion, that bh earth disdains to tread ; Her inward flame illumes her glowing face, Her upcast eye, and spreading wings, prepare Her flight for heaven to find her treasure there. She sees, enraptured through the thickest gloom, Celestial beauty beam, and 'midst the howl Of warring winds, sweet music charms her soul; She sees while rifted oaks in flames consume, A Father God, that o'er the storm presides, Threatens, to save,—and loves, when most he chides. Chapone. Questions.—1. What is the description of the Leyden phial ? 2. How is it charged ?—how discharged ? 3. What experiment may ba made by it ? 4. What is an electrical battery ? 5. What great dis- covery did Dr. Franklin make,—and by what means ? (i. To what did this experiment lead ? 7. What is lightning ?—thunder ? (See Leyden phial, fig. 50.) LESSON C9. Falling Stars, Water Spouts, and Northern Lights. Lam'bent, playing about, gliding over. Glo'ry, a circle of rays which surrounds the heads of saints in pictures,—praise, celebrity, felicity of heaven. It is supposed to be owing to the electricity of the atmo- sphere, that we observe a number of curious and interesting phenomena, such as falling stars, water-spouts, and northern lights. What are called falling stars are seen chiefly in clear and calm weather: it is then that the electric fluid is pro- bably not very strong, and passing through the air it becomes visible in particular parts of its passage, according to the con- ducting substances with which it may meet. One of the most striking of this kind is recorded by Beccaria, an Ita- lian.—As he was sitting with a friend in the open air, an hour after sun-set, they saw a falling, or as it is sometimes V NORTHERN ltgitts. 150 called, a shooting star, directing its course towards them, growing apparently larger and larger,, till it disappeared not far from them, and, disappearing, it left their faces, hands, and clothes, with the earth, and neighbouring objects, sud- denly illuminated with a diffused and lambent light, attend- ed with no noise at all. lie concluded this to be the effect of electricity, because he had previously raised his kite, and found the air very much charged with the electric matter : sometimes he saw it advancing to his kite like a falling star; and sometimes he saw a kind of glory round it, which fol- lowed it as it changed its place. Water-spouts are often seen in calm weather ; and the sea seems to boil and send up smoke under them, rising in a sort of hill towards the spout. A rumbling noise is often heard at the time of their appearance, which happens gene- rally in those moiitltfLtliat are peculiarly subject to thunder- storms, and they are commonly accompanied or followed by lightning. When these approach a ship, the sailors present and brandish their swords to disperse them, which seems to favour the conclusion that they are electrical. The analogy between water-spouts and electricity maybe made visible by hanging a drop of water to a wire, communicating with the prime conductor, and placing a vessel of water under it. In these circumstances, the drop assumes all the various ap- pearances of a water-spout, in its rise, form, and mode of disappearing. It is inferred, therefore, that the immediate cause of this extraordinary phenomenon is the attraction of the lower part of the cloud for the surface of the water. The northern light (Aurora Boreaiis) is an extraordinary meteor, or luminous appearance, showing itself in the night, in the northern part of the heavens; and most frequently in frosty weather. It is usually of a reddish colour inclining to yellow, and sends out frequent coruscations of pale light, which seem to rise from the horizon in the form of a pyra- mid with undulating motion, and shoot with great velocity up to the zenith. This kind of meteor, which is more un- common as we apprqach towards the equator, appears with the greatest lustre in the polar regions, and during the long winter is almost constant. In Sweden and Lapland, the northern lights are not only singularly beautiful in their ap- pearance, but afford travellers by their almost constant ef- fulgence a very beautiful light during the whole night. In 156 NORTHERN LIGHTS. ~W Hudson's bay, they diffuse a variegated splendour, whicii is said to equal that of tne full moon. In the no.th eastern parts of Siberia, they have been described as beginning with single bright pillars, rising in the north, and almost at the same time in the north-east, whicii gradually increasing com- prehend a large space of the heavens, rush about from place to place with incredible velocity, and finally almost cover the whole sky. The northern lights are supposed to be electrical phenomena, because electricians can readily imitate the ap- pearance with their experiments. Dr. Franklin's idea is that they may arise from a discharge of electricity, accumulated in the atmosphere near the poles, into its rarer parts. On the Northern Lights. BY LOMONOSOV, A RUSSIAN POET--TRANSLATED BY J. BOW- RING. 40 Where are thy secret laws, O nature, where \ Thy north lights dazzle in the wintry zone : How dost thou light from ice thy torches there 1 There has thy sun some sacred, secret throne ? See in yon frozen seas what glories have their birth ; Thence night leads forth the day to illumine the earth. Come then, philosopher! whose privileged eye Reads nature's hidden pages and decrees ; Come now, and tell us whence, and where, and why, Earth's icy regions glow with lights like these, That fill our souls with awe; profound inquirer, say ; For thou dost count the stars and trace the planets' way! What fills with dazzling beams the illumined air? What wakes the flames that light the firmament ? The lightning's flash ? there is no thunder there— And earth and heaven with fiery sheets are blent; The winter night now gleams with brighter, lovelier ray Than ever yet adorned the golden summer's day. Is there some vast, some hidden magazine, Where the gross darkness flames supplies 1 Some phosphorus fabric, which the mountains screen, Whose clouds of light above those mountains rise? Where the winds rattle loud around the foaming sea, And lift the waves to heaven in. thundering revelry ? ' GALVANISM 157 Thou knowest not! 'tis doubt, 'tis darkness all! E'en here on earth our thoughts benighted stray, And all is mystery through this worldly ball— Who then can reach or read yon milky way 1 Creation's heights and depths are all unknown, untrod ; Who then shall say how vast, how great, creation's God .' Questions.—1. Why is it supposed that those meteoric appear- ances called falling stars owe their origin to electricity ? 2. How may the analogy between electricity and the water-spout be made visible ? 3. Describe the northern light. 4. What is Dr. Franklin's idea of it* [Note. A similar light called aurora australis has been long since ob* nrved towards the south pole.] LESSON 70. Galvanism. Mus'cle, the fleshy fibrous part of an animal body. Galvanism is another mode of exciting electricity. In electricity the effects are chiefly produced by mechanical action; but the effects of galvanism are produced by the chemical action of bodies upon each other. This branch of philosophy has been denominated galvanism, from Galva- ni, an Italian professor, whose experiments led to its dis- covery. In 1789, he was by accident led to the fact of electricity having the property of exciting contractions in the muscles of animals. After having observed that com- mon electricity, even that of lightning, produced vivid convulsions in the limbs of recently killed animals, he ascer- tained that metallic substances, by mere contact, under par- ticular circumstances, excited similar commotions. He found it to be essential that the forces of metals employed should be of different kinds. He applied one piece of metal to the nerve of the part, and the other to the muscle, and afterwards connected the metals, either by bringing them together, or by connecting them by an arch of a metallic substance ; every time this connexion was formed, the con- vulsions took place. The greatest muscular contractions were found to be produced by zinc, silver, and gold. A per- son may be made sensible of this kind of electric action by the following experiments. If he place a piece of one metal, as a half crown above, and a piece of some other metal, as 14 158 voltaic battery. zinc, below his tongue, by bringing the outer edge of these pieces in contact, he will perceive a peculiar taste, and in the dark will see a flash of light. If he put a slip of tin-foil upon the bulb of one of his eyes, and a piece of silver in his mouth, by causing these pieces to communicate, in a dark place, a faint flash will appear before his eyes. Galvani sup- posed that the virtues of this new agent resided in the nerves of the animal, but Volta, who prosecuted this subject with much greater success, showed that the phenomena did not depend on the organs of the animal, but upon the electrical agency of the metals, which is excited by the moisture of the animal, whose organs were only a delicate test of the pre- sence of electric influence. In exciting the electricity of the pieces of silver and zinc, the saliva of the mouth answers the same purpose as the moisture of the animal. The conductors of the galvanic fluid are divided into the perfect and imperfect. The perfect conductors consist of metallic substances and charcoal: the imperfect are water and oxydated fluids, as the acids and all the substances that contain these fluids. To render the Galvanic, or more properly the Voltaic power sensible, the combination must consist of three conductors of the different classes. When two of the three conductors are of the first class, the combi- nation is said to be of the first order; when otherwise, it is said to be of the second order. If a piece of zinc be laid upon a piece of copper, and upon the copper a piece of flan- nel, moistened with a solution of salt in water a circle of the first class is formed ; and then if three other pieces be laid on these in the same order, and repeated several times, the whole will form a pile or battery of the first order. The ef- fects may be increased to any degree, by a repetition of the same simple combination. The following is a cheap and easy method of constructing a Voltaic pile, for zinc is one of the cheapest of metals, and may be easily melted, like lead. Let a person cast twenty or thirty pieces of zinc, of the size of a cent, which may easily be done in moulds made of clay. Let him then take as many cents, and as many pieces of paper or woollen cloth cut in the same shape, and which he is to dip in a solution of salt and water. In building the pile, let him place a piece of zinc, wet paper, the supera- bundant water being pressed out, after which the copper; then zinc, paper, copper, and so on, until the whole be GALVANISM. 159 finished. The sides of the pile may be supported with rods of glass, or varnished wood, fixed in the board on which it is built. Having wet both hands, touch the lower part of the pile with one hand, and the upper part with the other, constant little shocks of electricity will be felt until one hand be removed. If the hand be brought back a similar repetition of shocks will be experienced. Hold a silver spoon in one hand, and touch with it the battery in the lower part, then touch the upper part with the tongue ; the bitter taste is extreme. If the end of the spoon be put under the eyebrow, close to the ball of the eye, a sensation will be felt like the burning of red-hot iron, but which ceases the instant the spoon is removed. The plates will soon become oxy- dated, and require cleaning in order to make them act. Questions.—1. What is galvanism ? 2. Give an account of the origin of this branch of philosophy. 3. How may a person be made sensible of this kind of electric action ? 4. What was the discovery of Volta? 5. What are perfect conductors of galvanic fluid ?—im- perfect ? 6. What is necessary in order to render the galvanic or vol- taic power sensible ? 7. When is the combination said to be of the first order ?—second order ? 8. How may a pile or battery of the first order be formed ? 9. What is a cheap and easy method of forming a voltaic pile ? 10. What experiments may be formed with such a pile? 11- Why do the plates require cleaning? (See Voltaic pile, fig. 47.) LESSON 71. Galvanism (continued.) Laboratory, a room fitted up with apparatus for the performance of chemical operations. Deflagrate, to burn rapidly: nitre thrown on hot coals defla- grates. When accompanied with a loud noise it is termed dgt- o-na'tion. The most convenient kind of galvanic battery consists of a trough made of baked wood, three inches broad, and about as deep; in the sides of the trough are grooves opposite to each other ; into each pair of grooves is fixed by cement, a plate of zinc and silver soldered together, and in the order of silver and zinc ; the cement must be filled in so as to pre- vent any communication between the different cells. The cells are to be filled with water and nitrous acid, and then H60 OALVANISM. if a communication be made between the first and last celf, by means of the hands, a strong shock will be felt, which will be repeated as often as the contact is renewed. Several persons, by joining hands, having first wetted them with wa- ter, may receive the shock. The spark from a powerful galvanic battery acts upon and inflames gun-powder, charcoal, cotton, and other inflam- mable substances, melts all metals and disperses diamonds. Fill the battery, described above, with water and nitrous acid in the proportion of nine parts of water and one of acid, and wipe the edges of the plates very dry ; then fasten two wires to pieces of copper, which are to be put into the outer cells, and in order to hold the wires they must be sur- rounded to a sufficient extent with little glass tubes. If the ends of the wires be brought together on a plate of glass, a spark will be perceived ; and if gun-powder be laid on the glass between the points of the wires, it will be exploded. The galvanic battery in the laboratory of the Royal Insti- tfution at London consists of two hundred instruments, con- nected together in regular order, each composed of ten double plates arranged in cells of porcelain, and containing in each plate thirty-two square inches; so that the whole number of double plates is two thousand, and the whole sur- face one hundred and twenty-eight thousand square inches. This battery, when the cells are filled with sixty parts of water, mixed with one part of nitric acid, and one part of sulphuric acid, affords a series of impressive and brilliant effects. When pieces of charcoal, about one inch long and One-sixth of an inch in diameter, are brought near each other, a bright spark is produced, and more than half the volume of charcoal becomes ignited to whiteness, and by withdraw- ing the points from each other, a constant discharge takes place through the heated air, in a space equal at least to four inches, producing a most brilliant ascending arch of light, broad and conical in form in the middle. When any sub- stance is introduced into this arch, it instantly becomes ig- nited ; platina melts as readily in it as wax in the flame of a common candle ; fragments of diamond, and points of char- coal, and plumbago, rapidly disappear, and seem to evaporate in it. Such are the decomposing powers of electricity, that not even insoluble compounds are capable of resisting their energy j for glass, when moistened and placed in contact NEW DEFLAGRATOR. 161 with electrified surfaces from the voltaic apparatus is slowly acted upon, and the alkaline, earthy, or acid matter carried to the poles in the common order. Not even the most solid aggregates, nor the firmest compounds, are capable of re- sisting this mode of attack ; its operation is slow, but the results are certain ; and sooner or later, by means of it, bodies are resolved into simpler forms of matter. The effects of galvanism on metallic bodies are greatly increased by using plates of a large size; and on the con- trary, the shock is increased by multiplying the pairs of plates. The shock of a battery containing eighty or a hun- dred pairs of plates, of three or four inches in diameter, is such as few persons would be willing to bear more than once. At the same time such a battery produces but feeble effects when passed through a metallic wire. On the contrary, if one or two pairs of plates containing the same extent of sur- face be used, the sensation it gives is hardly to be felt, while it will deflagrate a metpllic wire of considerable size. Professor Hare, of Philadelphia, has invented a new me- thod of extricating the Voltaic influence, by so connecting the plates, that, in effect, only two great surfaces of the metals are presented to each other. By this arrangement, the gal- vanic action on different substances has presented some new phenomena, and the common theory of galvanism must un- dergo, it is thought, a radical change. The calorific princi- ple is immensely increased, while the electric shock is hardly to be perceived. Charcoal exposed to the effects of this new deflagrator melts into globules resembling diamond, and the process is attended with a most intense light. If mercury be placed in the hand, and the back side of the hand be ap- plied to the negative pole, and the positive pole be brought to the surface of the mercury, it will be inflamed, and the hand will be affected with no disagreeable sensation, till the mass of mercury becomes heated. The new view, which Professor Hare has been induced to offer, is, that galvanism is a compound of electricity and caloric, and this is thought to be confirmed by the action of his machine. Questions—1. What is the most convenient kind of galvanic battery ?• 2. What is the effect of a powerful galvanic battery upon inflammable substances ? 3. Describe the battery at the Royal Insti- tution in London. 4. What effect does it produce upon charcoal?— other substances ? 5. What is said of the effects of galvanism by 14* 162 M.Vt.NETlS.M. using plates of a large size ?—by multiplying the pair* of plates ? 6. What is the invention of Prof. Hare ?' 7. What experiments may be performed with it? 8. What new view of the subject has Prof. Hare offered ? (See the galvanic or voltaic battery described at the begin- ning of this lesson, fig. 40.) [Note. Prof. Hare has named his new apparatus Catorimotor, or heat mover.] LESSON 72. Magnetism. Polar'ity, that property of a magnet, by which, if left at liberty, it will point towards the poles of the earth, or nearly so : the same end always points to the same pole. Although the phenomena of the magnet have, for many ages, engaged the attention of natural philosophers, not only by their singularity and importance, but also by the obscu- rity in which they are involved; yet very few additions have been made to the discoveries of the first inquiries into the subject. No hypothesis has hitherto been framed, that will account in an easy and satisfactory manner, for all the va- rious properties of the magnet, nor have the links of the chain, which connect it with the other phenomena of the universe, ever been pointed out. It is certain, indeed, that both natural and artificial electricity will give polarity to needles, and even reverse a given polarity ; and hence it may be inferred that there is a considerable affinity between the electric and magnetic powers, but in what manner elec- tricity acts in producing magnetism, is still utterly unknown. The ancients were acquainted with the attractive and re- pulsive powers of the magnet; but it does not appear that they knew of its tendency to the pole: this very fortunate di^overy was made about the beginning of the fourteenth century, when the spirit of exploring distant regions was gradually forming in Europe. The use which might be made of it in directing navigation was immediately perceived, and that most valuable, but now familiar instrument, the mariner's compass, invented. When navigators found that they could, at all seasons, and in every place, discover the north and south with the greatest ease and accuracy, it be- came no longer necessary to depend, like the voyagers of former ages, merely on the light of the star?, and the obser- MAGNETISM. 163 vation of the sea-coast. They gradually abandoned their ancient timid and lingering course along the shore and ven- tured boldly into the ocean. Relying on this new guide, they could steer in the darkest night, and under the most cloudy sky, with a security and precision till then unknown. The compass may be said to have opened to man the do- minion of the sea, and to have put him in full possession of the earth, by enabling him to visit every part of it. Nearly half a century elapsed, from the time of this dis- covery, before navigators ventured into any seas which they had not been accustomed to frequent. But in the course of the fifteenth century, discoveries were made far beyond the conception of all former ages. In the first voyage of Co- lumbus, the Spaniards were struck with an appearance, not less astonishing than new. They observed that the mag- netic needle, in their compasses, did not point exactly to the polar star, but varied toward the west; and, as they proceeded, this variation increased. This appearance, which filled the companions of Columbus with terror, and which still remains one of the mysteries of nature, is that deviation from the meridian which is called the variation of the needle. It is different in different parts of the world; being west at some places, east at others, and in parts where the variation is of the same name, its quantity is very dif- ferent. It is the same to all needles in the same place ; and for a long time, it was thought to be invariably the same, at the same place, in all ages ; but it was discovered, about the year 1625, that it was different at different times, in the same place. From subsequent observations, it appears, that this deviation was not a constant quantity, but that it gra- dually diminished ; and at last, about the year 1660, it was found that the needle at London pointed exactly north. At present the declination at London is about twenty-four de- grees west. For some years, it has been nearly stationary; but it is understood now to be returning in an easterly di- rection. Knowing the variation, or declination of the mag- netic needle, that is, the angle which the magnetic meridian makes with the meridian of the place, mariners are able to sail by the compass with as much accuracy as if it pointed. exactly north. The inclination, or dipping of the magnetic needle, ex-. . presses the property which the magnet possesses of inclining 164 MAGNETICAL EXPERIMENTS. one of its poles towards the horizon, and of elevating the other pole above it. This property was discovered in the year 1576. It is found to be always the same at the same place, but different in different places. Questions.—1. When was the polarity of the magnet discovered ? 2. What use was made of this property of the magnet ? 3. When and by whom was the deviation of the needle from the meridian discovered ? 4. What is said of this variation with respect to the same place ?—to different places ? 5. What is said of the declination of the needle at London? G. What is the inclination or dipping of the magnetic needle ? LESSON 73. Magnetical Experiments. The natural magnet, or loadstone, is found in the earth, generally in iron mines, in a hard and brittle state, and for the most part, more vigorous in proportion to the degree of hardness. Artificial magnets, which must be made of hard or highly tempered steel, are now generally used in prefer- ence to the natural magnet; not only, as they may be pro- cured with greater ease, but because they are far superior to the natural magnet in strength, communicate the magnetic virtue more powerfully, and may be varied in their form more easily. In making artificial magnets, care should be taken to apply the north polejpf the natural magnet or mag- nets to that extremity of the steel which is required to be made the south pole, and to apply the south pole of the mag- net to the opposite extremity of the piece of steel. Very powerful magnets may be formed by first constructing several weak magnets, and then joining them together to form a compound one. The north or south poles of two magnets repel each other; but the north pole of one attracts the south pole of another. The attraction between the magnet and iron is mutual, for the iron attracts the magnet as much as the magnet attracts the iron; since if they be placed on pieces of wood, so as to float upon the surface of the water, it will be found that the iron advances towards the magnet as well as the magnet to- wards the iron, or, if the iron be kept steady, then the mag- net will move towards it. magnetic experiments. 165 Magnetic attraction will not be destroyed by interposing obstacles between the magnet and iron. If you lay a small needle on a piece of paper, and put a magnet under the pa- per, the needle may be moved backwards and forwards; and with a piece of glass or board the effect will be the same. This property of the magnet has afforded the means of seve- ral amusing deceptions. A small figure of a man has been made to spell a person's name. The hand, in which was a piece of iron, rested on a board, under which a person, con- cealed from view, with a powerful magnet, contrived to carry it from letter to letter, until the word was made up. If the figure of a fish, with a small magnet concealed in its mouth, be thrown into the water, and a baited hook be suspended near it, the magnet and iron by mutual attraction will bring the fish to the bait. If you lay a sheet of paper, covered with iron filings upon a table, with a small magnet among them, and then shake the table a little, at the two ends or the poles, the particles of iron will form themselves into lines, a little sideways, which bend, and then form complete arches, peaching from some point in the northern half of the magnet to some other point in the southern half. If you shake some iron-filings through a gauze sieve upon a paper that covers a bar magnet, they will be arranged in beautiful curves. Soft iron is attracted by the magnet more forcibly than steel, but it is not capable of preserving the magnetic pro- perty so long. The gradual addition of weight to a magnet kept in its proper situation, increases the magnetic power, but heat weakens it, and great heat destroys it. Bars of iron that have stood long in a perpendicular situation, are generally found to be magnetical; this circumstance, toge- ther with the phenomena of the compass and the dipping needle, leaves no room to doubt but that the cause exists within the earth. Questions.—1. Where is the natural magnet found? 2. Why are artificial magnets used in preference to natural ? 3. How may very powerful magnets be formed ? 4. How do the poles of a mag- net attract and repel each other ? 5. How does it appear that the at- traction between the magnet and iron is mutual ? 6. How docs it appear that magnetic attraction will not be destroyed by the interpo- sition of bodies ? 7. What amusing deceptions has the attractive pro- perty of the magnet afforded ? 8. How may the magnetic power be weakened or destroyed ? 9. From what is it concluded that the. cav:sa of magnetism exists in the earth ? 16i aerostation. LESSON 74, Aerostation. Wick'er, made of email sticks. A'eronaut, one who sails through the air. Meteorological, relating to the phenomena of the atmosphere, such as the alterations of its weight and temperature, changes produced by evaporation and rain, its excessive agitations, its electricity, &c. Aerostation, in the modern application of the term, sig- nifies the art of navigating through the air, both in its prin- ciples and practice. Hence also the machines which are employed for this purpose, are called aerostats, or aerostatic machines ; and on account of their round figure, air-balloons. Air-balloons are of two kinds, those filled with rarefied air, and those filled with hydrogen gas. The best forms for bal- loons are globular or oval. Large balloons, for hydrogen gas, must be made of silk, and varnished over so as to be air-tight. The car, or boat, is made of wicker-work, cover- ed with leather, well varnished or painted, and is suspended by ropes proceeding from the net which goes over the bal- loon. The hydrogen gas for filling the balloon is procured by putting a quantity of iron-filings, or turnings, with some sulphuric acid diluted with water, into casks lined with lead. From the top of these casks tin tubes proceed, which unite into one that is connected with the silk tube of the balloon. Balloons of oiled silk cannot- be made smaller than five or six feet in diameter, as the weight of the material is too great for the air to buoy it up. In 1729, Bartholomew Gusman, a Jesuit of Lisbon, caus- ed an aerostatic machine, in the form of a bird, to be con- structed, and made it ascend, by means of a fire kindled un- der it, in the presence of the king, queen, and a great con- course of spectators. Unfortunately, in rising, it struck against a cornice, was torn, and fell to the ground. The inventor proposed renewing his experiment; but the people had denounced him to the inquisition as a sorcerer, and he withdrew into Spain, where he died in an hospital. In 1766, the Honourable Henry Cavendish discovered that hydrogen gas (then called inflammable air,) was at least seven times lighter than common air. It occurred soon afterwards to AIR BALLOONS. 167 the celebrated Dr. Black, that if a thin bag were filled with this gaseous substance, it would, according to the establish- ed laws of specific gravity, rise in the common atmosphere; but he did not pursue the inquiry. The same idea was con- ceived by Mr. Cavallo, to whom is generally ascribed the honour of commencing the experiments on this subject. He had made but little progress, however, in these experiments, when the discovery of Stephen and John Montgolfier, paper- manufacturers of France, was announced in 1782, and en- gaged the attention of the philosophical world. Observing the natural ascent of smoke and clouds in the atmosphere, those artists were led to suppose that heated air, if enclosed in a suitable covering, would also prove buoyant. After se- veral smaller experiments, by which this idea was fully con- firmed, they inflated a large balloon with rarefied air, which immediately and rapidly rose to the height of six thousand feet, and answered their most sanguine expectations. It was soon found that machines of this kind might be so contrived, as to convey small animals, and even human be- ings through the air with ease. The first adventurer in this aerial navigation was Pilatre de Rozicr, a daring Frenchman, who rose in a large balloon from a garden in the city of Pa- ris, on the 15th of October, 1783, and remained a consider- able time suspended in the air. He made several aerial voyages afterwards of greater extent, and in two of them was attended by other persons. In a short time, however the use of rarefied air in aerostation was for the most part laid aside, as inconvenient and unsafe. On recurring once more to the discovery of Mr. Cavendish, the philosophers of Paris con- cluded that a balloon, inflated with hydrogen gas, would an- swer all the purposes of that contrived by the Montgolfiers, and would also possess several additional advantages. 1 hey made their first experiment in August, 1783, which was at- tended with complete success. Since that time, air-balloons filled with rarefied air have not been generally used. The first aerial voyage in England was performed by V in- cent Lunardi, a native of Italy. The diameter of his bal- loon was thirty-three feet. Soon after, Mr. Blanchard as- cended, carrying up a pigeon, which flew away from the boat laboured for some time with its wings to sustain itselt in the air, and finally returned and rested on one side ot the boat. He ascended so high as to experience great difficulty 168 ^lEATII OP ROZIER. of breathing, but percei ing the sea before him, he descend*- ed near Ramsey, about seventy-five miles.from London, hav- ing travelled at the rate of nearly twenty miles an hour. The singular experiment of ascending into the atmosphere with a balloon, and of descending with a machine, called a parachute, in the form of a large umbrella, was performed by Mr. Garnerin in 1802. The weather was clear and plea- sant, and the wind was gentle. In about eight minutes the balloon and parachute had ascended to an immense height, and Mr. Garnerin in the basket, could scarcely be perceived. While the spectators were contemplating the grand sight before them, Mr. Garnerin cut the rope, and in an instant he was separated from the balloon, trusting his safety to the parachute. Before the parachute opened, he fell with great velocity ; but as soon as the parachute was expanded, which took place a few moments after, the descent became very gentle and gradual. It was observed that the parachute, with the appendage of cords and basket soon began to vi- brate like the pendulum of a clock, and the vibrations were so great, that more than once the parachute, and the basket with Mr. Garnerin, seemed to be on the same level, or quite horizontal; the extent of the vibrations, however, diminish- ed as he descended. On coming to the earth, he experi- enced some strong shocks, but soon recovered, and remained without any material injury. The fate of Rozier, the first aerial navigator, and of his companion Romain, has been much lamented. They as- cended with an intention of crossing the channel to England. Their machine consisted of a spherical balloon, filled with hydrogen gas, and under this balloon, a smaller one filled with rarefied air, designed to diminish the specific gravity of the whole apparatus. For the first twenty minutes they seemed to pursue the proper course ; but the balloon ap- peared to be much inflated, and the aeronauts appeared anxious to descend. Soon, however, when they were at the height of three quarters of a mile, the whole apparatus was in flames, and the unfortunate adventurers fell to the ground, and were killed. The invention of balloons cannot be considered as having added much to the comfort or utility of man. The only practical purposes which it has been made to subserve, are those of aiding meteorological inquiries, and of inspecting NATURAL HISTORY. 169 the fortifications and reconnoitring the camp of an enemy, which could not be approached by other means. The diffi- culties, under which this species of navigation labours, ap- pear at present to be insurmountable ; .and the want of some means to control and regulate the movements of the aerial vessel is so essential, as to excite a fear that it cannot be sup- plied. Questions.—1. What is aerostation ? 2. What is the best form for a balloon ? 3. What are the two kinds of balloons? 4. How is a balloon filled with hydrogen gas? 5. Who invented the first ae"ro- Btatic machine, and what was the result? 6. What discovery did Cavendish make ? (Hydrogen gas is 14 times lighter than common air, —see Lesson on water.) 7. What afterwards occurred to Dr. Black ? 8. What idea did Cavallo conceive ?—what is ascribed to him ? 9. What discovery did the Montgolfiers make ? 10. Who was the first aerial navigator? 11. What was the next discovery in this science ? 12. What is said of the ascent of Mr. Blancliard ? 13. Describe the experiment of Mr. Garnerin. 14. What was the fate of Rozier and Romain ? 15. What is said of the advantages which have been derived from balloons ? 16'. Of the difficulties under which this spe- cies of navigation labours? [Note. Small balloons may be made of thin strips of bladder, or other membrane, glued together.] LESSON 75. Natural History. Pellu'cid, clear, transparent, not opaque. Those who with a philosophical eye have contemplated the productions of Nature, have all, by common consent, di- vided them into three great classes, called the Animal, the Vegetable, and the Mineral or Fossil kingdoms. These terms are still in general use, and the most superficial ob- server must be struck with their propriety. Animals have an organized structure which regularly unfolds itself, and is nourished and supported by air and food ; they consequently possess life, and are subject to death; they are moreover endowed with sensation, and with spontaneous, as well as voluntary, motion. Vegetables are organized, supported by air and food, endowed with life, and subject to death as well as animals. They have in some instances spontaneous, though we know not that they have voluntary motion. They are sensible to the action of nourishment, air, and light, and 15 170 NATURAL HISTORY. either thrive or languish according to the wholesome or hurtful application of these stimulants. The spontaneous movements of plants are almost as readily to be observed as their living principle. The general direction of their branch- es, and especially of the upper surface of their leaves, though repeatedly disturbed, to the light, the unfolding and closing of their flowers at stated times, or according to favourable or unfavourable circumstances, with some still more cu- rious particulars, are actions undoubtedly depending on their vital principle, and are performed with the greater facility in proportion as that principle is in its greatest vigour. Plants alone have a power of . Describe arsenic. 6. Give a general account of the seve'n classes of metals. (See Appendix to Lesson 65.) [Note. The de- scription of the metals properly belongs to the subject of Chemistry, (see Lesson (55) but for the sake of a little more variety it was thought Dcst to insert 4 brief account of the most important ones after Mine- ralogy.] LESSON 83. Study of Geology. Crude, unconnected, not well digested. Intersection, the point where lines cross each other. Geology has for its object the study of the earth in genes ral, of its plains, hills, and mountains ; and embraces the consideration of the materials of which it is composed, and the circumstances peculiar to its original formation, as well as the different states under which it has existed, and the various changes which it has undergone. Geology has now become an object of the attention and inquiries of many dis- tinguished philosophers. The discoveries of chemists and mineralogists, and the observations of intelligent travellers, have all tended to facilitate these inquiries, and to render them more enlightened and satisfactory ; and, although mo- dern times have produced many visionary theories, and crude conjectures on this subject, they have also given birth to some important acquisitions, and much correct philosophy, which will be highly prized by all who study the history and structure of our globe. The science of geology, indepen- dently of the healthy employment it affords, is of great im- portance in a practical point of view. It very nearly con- cerns the minef, engineer, and drainer, and even the farmer 18b" GEOLOGY. and architect; and discloses a variety of indications highly useful in their respective pursuits: to the miner, the rocks containing metallic veins and coals; to the engineer, the association of hard rocks with soft; to the drainer, the intersection of a country by hard dykes, or veins imper- vious to water ; to the farmer, the best places for finding lime-stone, marl, and clay; and to the architect, the most durable stones for buildings. The person who is attached to geological inquiries, can scarcely ever want objects of em- ployment and of interest. The ground on which he treads —the country which surrounds him—and even the rocks and stones, removed from their natural position by art, are all capable of affording some degree of amusement. Every new mine or quarry that is opened, every new surface of the earth that is laid bare, and every new country that is disco- vered, offers to him novel sources of information. In tra- velling, he is interested in a pursuit which must constantly preserve the mind awake to the scenes presented to it; and the beauty, the majesty, and the sublimity of the great forms of nature, must necessarily be enhanced by the contempla- tion of their order, their mutual dependence, and their con- nexion as a whole. Questions.—1. What is geology ? 2. What is said of the discove- ries of chemists and mineralogists? 3. Why is the science of geolo- gy important in a practical point of view ? 4. What are the advan- tages of studying geology ? LESSON 84. Geology. Stratification, the division of a mass of rock into many parallel portions, whose length and breadth greatly exceed their thick- ness. The surface of the globe, considered with relation to its inequalities, is divided into highland, lowland, and the bot- tom of the sea. The highland comprises alpine land, com- posed of mountain groups or series of mountain chains; mountain chains, formed by a series of those still more simple inequalities, called mountains: in the former we consider their length, height, form, and connexion ; the parts of the GEOLOGY. 187 latter are the foot, the acclivity, and the summit. Lowland comprises those extensive flat tracts which are almost entirely destitute of small mountain groups. To the bottom of the sea belong the flat, the rocky bottom, shoals, reefs, and islands. It is only after a diligent study of the inequalities just pointed out, that we can with advantage undertake to explore the means employed by nature to produce them ; and the first step is to proceed to the examination of the physical causes of the slow, but unceasing changes of the globe. Obser- vation teaches us, that most of the elevations and hollows we meet with on the surface of the earth owe their origin to the action of the atmosphere, to that of the ocean, and to volca- nic fire. These powerful agents may be considered with regard to their destroying, and, in consequence of this de- struction, with regard to their forming effects. All geologists are agreed that our present continents were once covered with water. This is proved by the remains of marine animals imbedded in the strata which lie on the sum- mits of the highest mountains. The structure of the globe, as far as we are acquainted with it from the intersections made by rivers, by the action of the sea upon the coast, and by mining operations, consists of beds of different kinds of stone, which generally increase in thickness as we descend deeper. Stratification, in its simplest form, may easily be conceived, by placing a closed book with the back resting upon the table, and raising the opposite edges a little; the book may represent a thick mineral bed, and the leaves a series of strata. In nature we frequently find the strata much broken, and thrown out of the original position. Where any series of strata are wanting, a question naturally arises, have they been carried away by some sudden inun- dation, before the upper strata were deposited, or have they never extended to that place ? In some instances it is certain that the strata have been carried away from particu- lar situations, as in some of the excavations which have formed valleys, in which the strata that terminated on one side of the valley may be discovered again in the hills on the opposite side. The substances of which the strata are composed, are argillaceous, calcareous, or siliceous earth, which are generally more or less intermixed or combined. The strata of clay, or argillaceous strata, being water-tight, give rise to springs, as they arrest the water that runs through 188 GEOLOGY. the porous strata, and convey it to other situations. The inclinations of the strata, with the breaks and inequalities, render the globe habitable, by distributing the waters over the surface. The strata to a great depth are generally characterized by the remains of animals or vegetables, in what is called a petrified state, the organic structure being distinctly visible, although the animal or vegetable matter is almost entirely removed, and its place generally supplied by calcareous or sili- ceous earth. These organic remains are more abundant in the upper than the lower strata; and in the lowest beds of rock which have yet been explored, no traces of organic existence have been found. These remains make us acquainted with the great changes which must have taken place in the con- dition of our planet in remote ages. The uppermost stratum in England and iy various parts of Europe, is formed of al- luvial soil. In this soil, the remains of quadrupeds of vast size, such as the elephant, the rhinoceros, and mammoth or mastodon, are frequently found. Many of these are differ- ent from any existing species, and they prove that dry land existed in the vicinity, and that Europe was then inhabited by species of animals at present unknown. The researches of modern geologists have given abundant confirmation to the sacred history, not only with respect to the general deluge, but also with regard to the age of the earth. Until very lately several geological phenomena were considered, by superficial inquirers, as indicating that the creation of the globe we inhabit was an event much more remote than the sacred history represents. This opinion was kept in countenance only as long as geology was in its infancy. Every successive step which has been lately taken in the improvement of this science has served to show its fallacy. The investigations of the latest and most accurate philosophers have afforded the strongest proofs, that the earth, in its present form, cannot have existed longer than appears from the Mosaic account. Questions.—1. How is the surface of the globe divided ? 2. What does the highland comprise?—lowland? bottom of the sea? 3. What does observation teach us ? 4. In what are all geologists agreed ? 5. How is this proved ? 0. What is said of the structure of the globe ? 7. How may stratification be conceived ? rt. What are the substances of which the strata are composed? 9. What is said of organic re- mains ? 10. What have modern geological researches confirmed ? ROCKS. 189 LESSON 85. Relative Situation of Rocks. Pseu'do, a prefix, which, put before words, signifies false, counter- feit. Lichen, (pronounced Lik'en) a cryptogamous plant, growing on rocks; in Ireland, a species of Lichen is prepared and used as food. Presented to the cultured eye of taste, No rock is barren, and no wild is waste. Rocky masses, variously placed over each other, com- pose the whole crust of the earth, to the gi^atest depth that the industry of man has been able to penetrate. Now these rocks, with respect to each other, occupy a determinate situation, which helds invariably in every part of the earth. Thus limestone is no where found under granite, but always above it. Werner has chosen this relative situation as the basis of his classification of rocks. He divides them into five classes which are called formations ; as primitive, transi- tion, fletz, alluvial, and volcanic. The primitive formations are of course the lowest of all, and the alluvial constitute the very surface of the earth; for the volcanic, as is obvious, are confined to particular points. Not that the primitive are always at a great depth under the surface, very often they are at the surface and constitute mountains. In such cases the other classes of formations are wanting altogether. In like manner the transition and other formations may, each in its turn, occupy the surface, or constitute the mass of a moun- tain. In some cases all the subsequent formations which ought to cover them are wanting in that particular spot. Each of these grand classes of formations consists of a greater or smaller number of rocks, which occupy a determinate position with respect to each other, and which like the great formations may often be wanting in particular places. The rocks which constitute the primitive formations are very numerous. They have been divided into several sets, such as granite, gniess, mica-slate, and others. It deserves attention, that the rocks constituting them are all chemical combinations, and generally crystallized ; that they contain no petrifactions ; and that the oldest formations contain no carbonaceous matter. Transition rocks are not so mj. 190 ROCKS. merous. In these, petrifactions first make their appearance, and they usually consist of species of corals and zoophytes, which do not at present exist, and are therefore supposed to be extinct. Fletz rocks are disposed in flat or horizontal strata. They contain abundance of petrifactions ; and these much more various in their nature than those which occur in the transition formations, consisting of shells, fish, and plants. The alluvial formations constitute the great mass of the earth's surface. They have been formed by the gra- dual action of rain and river water upon the other forma- tions. They consist of the component parts of previously existing rocks, separated by the influence of air, moisture, and change of temperature, and deposited in beds. Sand, gravel, loam, and petrifactions of animals and vegetables, are often found in this class. Volcanic formations are pseudo- volcanic, or such minerals as are altered in consequence of the burning of beds of coal situated in their neighbourhood; and true volcanic, or such as are actually thrown from the crater of a volcano. The expansion of water in the pores or fissures of rocks by heat, or congelation, is a physical cause of the separation of their parts. The solvent power of moisture exerted upon alkaline or calcareous matter, in rocks, is another cause of their decomposition. Electricity, which is shown, by ex- periments with the voltaic apparatus, to be a most powerful agent of decomposition, seems to assist in all these changes; electrical powers being almost constantly exhibited in the atmosphere. The production of a bed for vegetation is effected by the decomposition of rocks. As soon as the rock begins to be softened, the seeds of lichens, which are con- stantly floating in the air, make it their resting-place. Their generations occupy it, till a finely-divided earth is formed, which becomes capable of supporting mosses and heath: acted upon by light and heat, these plants imbibe the dew, and convert constituent parts of the air into nourish- ment. Their death and decay afford food for a more per- fect species of vegetable ; and, at length, a mould is formed, in which even the trees of the forest can fix their roots, and which is capable of rewarding the labours of the cultivator. The decomposition of rocks tends to the renovation of soils, as well as their cultivation. Finely-divided matter is carried by rivers from the higher districts to the low countries, and LINN^ES. 191 alluvial lands are usually extremely fertile. The quantity of habitable surface is constantly increased by these opera- tions ; precipitous cliffs are gradually made gentle slopes, lakes are filled up, and islands are formed at the mouths of great rivers. In these series of changes, connected with the beauty and fertility of the surface of the globe, small quan- tities of solid matter are carried into the sea ; but this seems fully compensated for by the effects of vegetation in absorb- ing matter from the atmosphere, by the production of coral rocks and islands in the ocean, and by the operation of vol- canic fires. What does not fade ? the tower, that long had stood The crash of thunder, and the warring winds, Shook by the slow but sure destroyer, Time, Now hangs in doubtful ruins o'er its base ; And flinty pyramids and walls of brass Descend : the Babylonian spires are sunk; Achaia, Rome, and Egypt, moulder down. Time shakes the stable tyranny of thrones, And tottering empires rush by their own weight. This huge rotundity we tread grows old , The sun himself shall die, and ancient night Again involve the desolate abyss. Armstrong. Questions.—1. What is the basis of Werner's classification of rocks ? 2. Into what five classes does he divide them ? 3. What is said of primitive rocks? 4. Transition? 5. Fletz? 6. Alluvial? 7. Volcanic? 8. How does the decomposition of rocks produce a bed for vegetation ? 9. Tend to the renovation of soils ? [Note. Some knowledge of geology is daily becoming more necessary, for without it, scarce a volume of travels or topography, a review or a journal, can be read with all the interest it demands. The structure of the country and the stratification of its mountains, are now as often and as minutely described, as the plants and the animals which are found upon their acclivities.] LESSON 86. Biographical Sketch of Linnaus. Charles Li.vn.eus, the founder of modern botany, was born in 1707, at a small village in Sweden, where his father 192 LINN.EIS. resided as a clergyman. His father was attached to his gar- den, which he had stocked with some of the rarer plants in that climate, and it is to the delight with which this spot inspired Charles, from his earliest childhood, that he himself ascribes his botanical passion. He was not distin- guished for his proficiency in the ordinary studies of a lite- rary education ; but he made a rapid progress in the know- ledge of plants, which he ardently pursued, both by frequent excursions in the fields, and by the unwearied perusal of such books on the subject as he was able to procure. When his father, who designed him for his own profession, came to the seminary, at which he was placed, for the purpose of inquiring into his improvement, he was much mortified to find his son declared utterly unfit for a learned profession by the tutors, who advised that he should be put to some manual occupation. In this perplexity he applied to the physician, Rothman, who was also lecturer in natural philosophy. This person discovered in young Linnaeus, talents, which, though not fitted to make him a theologian, were not ill adapted for another profession, and he proposed that of a physician. He took the youth gratuitously into his own house, gave him private instructions, and put him into a systematic me- thod of studying botany. In 1727, Linnaeus entered the University of Lund. He lodged in the house of Stoboeus, a physician, who pos- sessed a good library, and a museum of natural history. He paid for his entertainment by various little services, and it was only by accident that his host came to know the extent of his sfidious ardour. The mother of Stoboeus having ob- served that the candle in his chamber was burning at unsea- sonable hours, was induced, through fear of fire, to complain of it to her son. Stoboeus, therefore, entered his chamber at a lata hour, and found him diligently occupied with read? ing. Struck with this proof of his thirst after improvement, he gave Linnaeus the free use of his library, and admission to his table. The advice of Rothman, however, caused him, in 1728, to quit Lund, and to remove to Upsal, for the sake of the superior advantages it afforded. His father advanced him the sum of about eight pounds sterling, which he was informed was all the paternal assistance he was to expect. Thus he was turned out upon the world while yet but a learn- er in the profession by which he was to obtain his bread. His LINNAEUS. 193 little patrimony was soon exhausted, and he was reduced to depend upon chance for a meal. Unable to pay even for the mending of his shoes, he was obliged to patch them himself with folded paper. At length, in the autumn of 1729, as he was intently exa- mining some plants in the garden of the university, he was accosted by Celsius, professor of divinity, and an eminent naturalist, who was then engaged in preparing a work on the plants mentioned in the scripture. A little conversation soon apprised him of the extraordinary botanical acquisitions of the student, and perceiving his necessitous circumstances, he took him to live in his own house. It was in this year that Linnams conceived the idea of a new systematic ar- rangement of plants. He drew up a treatise, which was shown to Celsius, and by him to the botanical professor, who had the liberality to bestow on it his warmest approbation. As the professor's advanced age made him desirous of an as- sistant in the office of lecturing, Linnaeus was appointed. He was afterwards invited by the Academy of Sciences at Upsal, to explore the cold regions of Lapland, and the ala- crity with which this proposal was accepted, and the faith- fulness with which the objects of his journey were secured, were equally creditable to his zeal and perseverance. He visited Holland, and the most richly stored gardens of Eng- land and France. The great object of his wishes had always been the professorship of botany at Upsal, and through the kindness of an eminent Swedish statesman, he at length was chosen to that station, and he entered upon the duties of his office in the autumn of 1741. His increasing fame at- tracted students from every quarter, among whom were se- veral, who imbibed, and diffused throughout the civilized world, a taste for the science over which Linnaeus presided. His father who had so often grieved at the perverseness of his son's disposition for hunting after plants and insects, for- tunately lived to see him, not only professor of botany, but dean of the College of Physicians at Upsal, caressed by the noblemen of Sweden, and honoured by all the learned men of Europe. His opulence was such as to enable him to pur- chase an estate near Upsal, which was his chief summer re- sidence during the last fifteen years of his life. His views of nature impressed him with the most devout sentiments towards its author, and a glow of unaffected piety is conti- 194 STUDY OF BOTANY. nually breaking forth throughout his writings. A general mourning took place at his death, in 1778, and his body was attended to the grave with every token of respect. Qukstions.—1. To what circumstance docs Linnaeus ascribo hia passion for botany? 2. What is said of his early proficiency? 3. How was his thirst for improvement discovered at the University of Lund ? 4. What is said of his pecuniary means on his removal to Upsal ? 5. In what manner did he come into notice at Upsal ? 6. By what means was a taste for natural history diffused throughout the civilized world? LESSON 87. Study of Botany. Botany is that branch of natural history which treats of the vegetable kingdom. The study of this science is not a trifling employment, undeserving the time and attention be- stowed upon it. Can we for a moment conceive that the works of God are unworthy the attention of man 1—that those productions which bear such evident marks of the wis- dom and power of the Creator, are too contemptible for the examination of his creatures ? Whoever has had the curio- sity to crop the humblest flower of the field, and to observe the wonderful conformation of its parts, combining the unit- ed purposes of elegance and utility, will not hastily despise the study of nature. But when these observations are ex- tended through the immense variety of productions which compose the vegetable kingdom; when the different offices of each particular part of the plant, every one essentially contributing towards its existence and propagation, are coni sidered; when we advert to the variety of modes by which these ends are effected, and the infinite contrivance which is exhibited in their accomplishment, a wide field for instruc- tion and admiration'is opened before us. We need not labour to prove how delightful and instruct* ive it is to " Look through nature up to nature's God ;" neither, surely, need we attempt to show, that if any judi- cious or improved use is to be made of the natural bodies STUDY OP BOTANY. 195 around us, it must be expected from those who discriminate their kinds and study their properties. Of the benefits of natural science in the improvement of many arts, no one doubts. Our food, our medicine, our luxuries are improved by it. By the inquiries of the curious n*w acquisitions are made in remote countries, and our resources 6T various kinds are augmented. We find that gardening, the most elegant, and agriculture, the most useful of all arts, are improved only In those countries in which botany is made subservient to their advancement. And when a knowledge of this science is more generally diffused throughout our own country, we may expect to see it more frequently enriched with fields and adorned with gardens, which while they bestow honour on their possessors, shall prove a pleasant recreation to the old, and a useful study to the young. Nor should its influ- ence on the moral character be disregarded. The late Pre- sident Dwight was an eminent champion of the virtue which he practised. He often directed the attention of his pupils to Sweden, to point out the influence of natural history on the moral character of man. In that country botany is taught in the schools, and the habitation of her excellent children presents a cheering picture of domestic felicity. Their piety and their patriotism both flow from the'same source; for while they examine the productions of their country, they become attached to its soil, and while they contemplate the works of their Maker, they are animated with the glowing spirit of devotion. Botany deserves our highest regard as the source of mental improvement. Nothing so powerfully attracts the notice of the young observer, as the gay, though fleeting beauty of flowers; yet these interesting objects serve to produce an accuracy of discrimination, which is the foundation of cor- rect taste and sound judgment. To those whose minds and understandings are already formed, this study may be re- commended, independently of all other considerations, as a rich source of innocent pleasure. Some people are ever in- quiring what is the use of any particular plant? They con- sider a botanist with respect, only as he may be able to teach them some profitable improvement, by which they may quickly grow rich, and be then perhaps no longer of any use to mankind or to themselves. They would permit their children to study botany, only because it might possibly lead 196 TEXTURE OF VEGETABLES. to professorships, or other lucrative preferment. These views are not blameable, but they are not the sole end of human existence. Is it not desirable to call the soul from the feverish agitation of worldly pursuits, to the contempla- tion of divine wisdom in the beautiful economy of nature? Is it not desirable to walk with God in the garden of crea- tion, and hold converse with his providence ? If such ele- vated feelings do not lead to the study of nature, it cannot be far pursued without rewarding the student by exciting them. The more we study the works of the Creator, the more wisdom, beauty, and harmony become manifest; and while we admire, it is impossible not to adore. " Soft roll your incense, herbs, and fruits, and flowers, In mingled clouds, to Him, whose sun exalts, Whose breath perfumes you, and whose pencil paints!" Questions.—1. What is Botany ? 2. Why is the study of this science not a trifling employment ? 3. What renders it a field for in- struction and admiration ? 4. What may we expect when a know- ledge of this science is more generally diffused ? 5. Why did Dr. Dwight often direct the attention of his pupils to Sweden ? 6. How is botany a source of mental improvement ? 7. How do some people regard a botanist ? 8. How are these views to be considered, and wha$ reply is made to them ? LESSON 88. Texture of Vegetables. Longitudinally, running in the longest direction- Concen'tric, having one common centre. Every part of a living plant is covered with a skin or mem- brane called the cuticle. In the root and trunk it is coarse and hard, while in the leaves, flowers, and tender shoots, it is a fine, colourless, and transparent film, not thicker than a cobweb. It is porous and admits of the passage of fluids from within as well as from without, but in a due and defi- nite proportion in every plant. It not only protects the young tree from external injury, but it preserves our choicest fruit from premature decay, and without it, the leaf would lose its verdure, the flower its fragrance, and their transitory beauty would become ^till more evanescent. To wheat, TEXTTRE OF VEGETABLES. 197 rye, and most kinds of grass, the cuticle is of the highest importance, for it supports their stalks and secures them from injuries. In these, and still more abundantly in some others, Sir Humphry Davy has discovered the existence of a flinty earth; and it is this which makes the ashes of burnt straw one of the best materials whicii can be employed in giving it.^ finest polish to marble. The fruit of the peach and the leaf of the mullein have a cuticle covered with dense and rather harsh wool. Immediately under the cuticle of leaves and young stems is found a substance called the cellular integument. It is of a pulpy texture and the seat of colour. No plants are destitute of it, for it is the seat of operations indispensably necessary to healthy vegetation. When the cellular integu- ment is removed, the outer surface of the bark presents it- self, which in plants or branches that are only one year old, consists of one simple layer; but in the older branches and trunks of trees, it consists of as many layers as they are years old. The bark contains a great number of woody fibres, running for the most part longitudinally, which give it tenacity, and in which it differs very essentially from the parts already described. In the bark, the peculiar virtues or qualities of particular plants chiefly reside. Here we find in appropriate vessels the resin of the Fir, the astringent principle of the Oak, the fine and valuable bitter of the Pe- ruvian Bark, and the exquisitely aromatic oil of the Cinna- mon. Immediately under the bark is situated the wood, which forms the great bulk of trees and shrubs. When cut across it is found to consist of numerous concentric layers. Linnaeus and most writers believe that one of these circular layers is formed every year, the hard external part being caused by the cold of winter ; consequently, that the exact age of a sound tree when felled may be known by counting these rings. That the bark produces wood seems to have been proved beyond dispute, for plates of tin-foil have been introduced under the barks of growing trees, the wounds carefully bound up, and after some years, on cutting them across, the layers of new wood have been found on the out- side of the tin. The centre or heart of the vegetable body, within the wood, contains the pith. Its texture is precisely similar to that of the cellular integument, being composed of ceils 17* ~ 198 SAP AND SECRETIONS. which are seen to best advantage in the centre. These cells, which arc unusually large in the Elder, are filled with fluids when young, but in old branches the fluids are gone and the cells are empty. Of its Uses in the economy of vegetation, but little is known. Questions.—1. What is the cuticle of a plant ? 2. How is it de- scribed and what are its uses ? 3. Describe the cellular integument. 4. The bark. 5. The wood. 6. The pith. 7. What chiefly resides in the bark of plants ? 8. What is said of the circular layers of wood ? 9. How has it been shown that the bark produces the wood ? LESSON 89. Sap and Secretions. Odoriferous, fragrant, perfumed. Propul'sion, the act of driving forward. Es'culent, good for food, eatable. That the whole vegetable body is an assemblage of tubes and vessels is evident to the most careless observer; and those who are conversant with the microscope and books relating to it, have frequent opportunities of observing how curiously these vessels are arranged, and how different spe- cies of plants, especially trees, differ from each other in the structure and disposition of them. It is familiar to every one that plants contain various substances, as sugar, gum, acids, odoriferous fluids, and others, to which their various flavours and qualities are owing ; and a little reflection will satisfy us that such substances must each be lodged in proper cells and vessels to be kept distinct from each other. They are extracted, or secreted, from the common juice of the plant, and called its peculiar or secreted fluids. Various experiments and observations prove also that air exists in the vegetable body, and must likewise be contained in ap- propriate vessels. Besides these, we know that plants are nourished and invigorated by water, which they readily ab- sorb, and which, by proper tubes or vessels, is quickly con- veyed through their stalks and leaves. It is observed, moreover, that all plants, as far as any experiment has been made, contain a common fluid, which at certain seasons of the year is to be obtained in great quantity, and this is proper- SAP ANi> SECRETION!?, 199 ly called the sap. It is really the blood of the plant, by whicii its whole body is nourished, and from which the pecu- liar secretions are made. The great motion, called the flowing of the sap, which is to be detected principally in the spring, and slightly in the autumn, is totally different from that constant propulsion of it which is going on in every growing plant. Its facility to run is the first step towards the revival of vegetation from the torpor of w inter. Its exciting cause is heat, and the ef- fect of heat is in proportion to the degree of cold to which the plant has been accustomed. The same principle accounts for the occasional flowing of the sap in autumn after a slight frost. Such a premature cold increases the sensibility of the plant to any warmth that may follow, and produces, in a degree, the same state of its constitution as exists after the long and severer cold of winter. The sap in its passage through the leaves and bark be- comes quite a new fluid, possessing the peculiar flavour and qualities of the plant, and not only yielding woody matter for the increase of the vegetable body, but furnishing various secreted substances. These are chiefly found in the bark, and often in large and conspicuous vessels, as the turpen- tine-cells of the Fir tribe. In herbaceous plants, whose stems are only of annual duration, the perennial roots fre- quently contain these fluids in the most perfect state, noT are they,*in such, confined to the bark, but deposited through- out the substance of the root, as in Rhubarb and Gentian. It may be useful to enumerate some of the most distinct se- cretions of vegetables. Gum or mucilage, a viscid sub- stance of little flavour, exudes from many trees in the form of large drops or lumps, as in Plum, Cherry, and Peach trees. Resin is a substance soluble in spirits, and it differs ac- cording to the peculiar tree from which it is obtained. The more refined and volatile secretions of a resinous nature are called essential oils, and they are often highly aromatic and odoriferous. They exist in the highest perfection in the perfumed effluvia of flowers, some of which, capable of combination with spirituous fluids, are obtainable by dis- tillation, as that of the Lavender and Rose. The bitter secretion of many plants does not seem exactly to accord with any of the foregoing. Some facts would seem to prove it of a resinous nature, but it is often perfectly 500 PROCESS OF VEGETATION. soluble in water like gum or mucilage. Acid secretions are well known to be very general in plants. The astrin- gent principle would seem to be a sort of acid, of which there are many different forms, or kinds, and among them the tanning principle of the Oak, Willow, and others. To the secretion of plants we owe the existence of sugar. In tropical countries it is commonly obtained from the ex- pressed juice of the sugar-cane, but the Maple of the North yields it equally pure and scarcely less abundant. It exists also in the roots of some, and in the esculent fruit of many plants, communicating a sweet and usually an agreeable taste. To the foregoing secretions of vegetables may be added those on which their various colours depend. We can but imperfectly account for the green so universal in their herbage, but we may gratefully acknowledge the beneficence of the Creator in clothing the earth with a colour the most pleasing and the least fatiguing to our eyes. We may be dazzled with the brilliancy of a flower-garden, but we repose at leisure on the verdure of a grove or meadow. Questions.—1. What is said of tlie whole vegetable body? 2. What are called the peculiar or secreted fluids of plants? 3. What u said of the sap ? 4. The flowing of the sap ? 5. What arc some of the most distinct secretions of vegetables ? 0. What is said of those se- cretions on whicii the colours of vegetables depend ? LESSON 90. Process of Vegetation. Ineip'ient, just beginning. Suc'culent, juicy, moist. When a seed is committed to the ground, it swells by the moisture which its vessels soon absorb, and which, in con- junction with some degree of heat, stimulates its vital prin- ciple. Atmospherical air is also necessary to incipient vegetation, for seeds in general will not grow under water, except those of aquatic plants, nor under an exhausted re- ceiver. Seeds buried in tiie ground to a greater depth than is natural to them, do not vegetate, but they often retain the power of vegetation for an unlimited period. Earth taken from a considerable depth will, when exposed to the air, be PROCESS OF VEGETATION. 201 soon covered with young plants, though no seeds have been allowed to have access to it. The young root is the first part of the infant plant that comes forth, and by an unerring law of nature, it is sent downwards, to seek out nourishment as well as to fix the plant to .the ground. In sea-weeds, it seems merely to answer the latter purpose. In the Dod- der, the original root lasts only till the stems have established themselves on some vegetable, on whose juices they feed by means of other roots or fibres, and then it withers away. Wrhen the young root has made some progress, the two lobes, commonly of a hemispherical figure, which compose the chief bulk of the seed, swell and expand, and are raised out of the ground by the ascending stem. These lobes are called the Cotyle'dons, and between them is seated the Em- bryo, or germ of the plant. The leaves of the germ being of a succulent nature, assist the plant by attracting from the atmosphere such particles as the tender vessels are fitted to eonvey. These particles, however, have not in their own nature a sufficiency of nutriment for the increasing plant. The substance or farina of the lobes becomes soft and sweet, being converted into sugar, and is conveyed as long as it lasts to the tender plant, by means of innumerable small vessels, which are spread through the lobes; and which, uniting into one common trunk, enter the body of the germ, and thus supply that balmy liquor, without which the plant must inevitably have perished ; its root being then too small to absorb a sufficiency of food, and its body too weak to as- similate it into nourishment. Such is the general course of vegetation in plants furnished with two lobes or cotyledons. But there is a very distinct tribe, which have but one lobe, and are called monocoty- ledons. These are the grass and grain tribe, and many others, in which the body of the seed does not ascend out of the ground. The preservation of the vital principle in seeds is one of those wonders of nature which pass unre- garded, from being every day under our notice. Some may be sent round the world through every vicissitude of climate, or be buried for ages deep in the ground, and yet, in favour- able circumstances, they will vegetate. Others in order to succeed must sow themselves, in their own way, and at their own time. Great degrees of heat, short of boiling, do not im- pair their vegetative power, nor do we know any degree of 292 ROOTS. cold that has such an effect. Those who convey seeds from dis- tant countries, should be instructed to keep them dry ; for if they receive aay damp sufficient to cause an attempt at vege- tation, they necessarily die, because the process cannot, as they are situated, go on. It is usual with gardeners to keep melon and cucumber seeds for a few years, in order that the future plants may grow less luxuriantly, and be more abundant in blossoms and fruit. Dr. Darwin accounts for this from the damage which the lobes may receive from keeping, by which their power of nourishing the infant plant, at its first ger- mination, is lessened, and it becomes stinted and dwarfish through its whole duration. Questions.—1. What takes place when a seed is committed to tin ground? 2. What is said of the young root ? 3. Of sea-weeds? 4. Of Dodder ? 5. What are the two lobes called ? C. The germ ? 7. How do the leaves of the germ assist the plant ? 8. To what use is the farina of the lobes applied ? 9. What are plants called that have only one lobe ? 10. What is said of the preservation of the vital principle in seeds? 11. Why do gardeners sometimes keep melon and cucum- ber seeds for a few years ? 12. How does Dr. Darwin account for this ? LESSON 91. Roots, Stems, Buds, and Leaves. Rad'icle, the minute branch of a root. Physiol'ogy, the doctrine of the constitution of the works of nature. Perspire', to give out moisture. Absorb', to take in moisture. The root of a plant consists of two parts, the body of the root, and the fibre. The latter only is essential, being the part which imbibes nourishment. Roots are either of annual, biennial, or perennial duration. The first belong to plants which live only one year, or rather one summer, as barley; the second to such as are produced one season, and, living through the ensuing winter, produce flowers and fruit the following summer, as winter-rye and wheat; and the third to those which live and blossom through many succeeding seasons to an indefinite period, as trees and many herbaceous plants. Botanists distinguish several different kinds of roots, which are necessary to be known, not only for botanical purposes, but as being of great importance in agriculture and LEAVES. 208 gardening. Barren and thin soils are best suited to the wide spreading roots, which creep extensively on the surface ; dry and sandy plains are adapted to those which penetrate deep for nourishment, and are supplied with bulbs for its preservation, or with downy radicles for its abundant ab- sorption. Linnn^us enumerates seven kinds of trunks, stems, or stalks of vegetables. These are necessary to be known for botanical distinctions, though some are more important than others. About midsummer the progress of vegetation seems to be suspended, and for several days the vital energies of the tree are exerted in the formation of buds. We no longer observe the vigorous growth of spring, but if we examine the young branches, we shall find the newly formed buds at the base of the leaf-stalk, immediately above the place of their inser- tion. After the fall of the leaves they are more conspicuous, and during the winter we may perceive a gradual enlarge- ment, corresponding to the developement of the tender germs which they enclose. Plants, as is well known, may be pro- pagated by buds, and in that sense each bud is a separate being, or a young plant in itself; but such propagation is only the extension of an individual, and not a re-production of the species, as by seed. Leaves are eminently ornamental to plants from their pleas- ing colour, and the infinite variety as well as elegance of their forms. Their different situations, insertions, forms, and surfaces, which are of the greatest possible use in sys- tematical botany, cannot here be described. A knowledge of their real use with regard to the plant is a curious branch of vegetable physiology. That leaves give out moisture, or are organs of insensible perspiration, is proved by the simple experiment of gathering the leafy branch of a tree, and im- mediately stopping the wound at its base with wax to pre- vent the effusion of moisture in that direction. In a very short time the leaves droop, wither, and are dried up. If the same branch, partly fadod, though not dead, be placed in a very damp cellar, or immersed in water, the leaves revive, by which their power of absorption is also proved. A know- ledge of the perspiring and absorbing power of leavco is often pf great practical importance. It teaches us that plants droop, in consequence of the excess of the former, and are 304 LEAVES. lo be revived by diminishing their discharge, or increasing their absorption. The former is accomplished by confining the air around them, and the latter by sprinkling water over the leaves; and when plants have recently been removed, such management is frequently required. Air is not less essential to the healthy existence of ani- mals than of plants. One great use of leaves is to perform, in some measure, the same office for the support of vegeta- ble life, that the lungs of animals do for the support of ani- mal life. Light has a very powerful effect upon plants, and the green colour of leaves is so much owing to it, that plants raised in darkness are of a sickly white Light acts bene- ficially upon the upper surface of leaves, and hurtfully upon the under side ; hence the former is always turned towards the light, in whatever situation the plant may be placed. A great number of leaves follow the sun in its course, and a familiar instance of this is a clover-field. The leaves of some plants, when the light is withdrawn, fold over each other, or droop as if dying; and this is called by Linnaeus the sleep of plants. Some leaves display an extraordinary sensibi- lity to the touch of any extraneous body, or to any sudden concussion, as those of the sensitive plant. An impression made, in the most gentle manner, upon one of its leaflets, is communicated in succession to all of them, evincing an ex- quisite irritability. The moving plant of India exhibits such powers as to excite the astonishment of every beholder. If its motion be impeded, no sooner does it regain its liberty than its operations are renewed with increased activity, as if it were necessary to redeem the time which it had lost. Its winged leaves seem to disdain to rest, and to exhibit a most astonishing example of industry. Questions.«S-1. What are the two parts of the root of a plant ? 3. How are roots divided with regard to their duration ? 3. Give the examples. 4. What is said of buds ? 5. How is it proved that leaves are organs of perspiration, and of absorption ? 6. What ofBce do leaves perform for plants ? 7. What is the effect of light upon plants, and leaves? 8. What is said of the sensitive plant? 9. Of the moving plant of India? 10. Describe' the several kinds of Roots, (nee Appendix.) 11. What is said of the root of common herds grass ? 12 What are the seven kinds of trunks or stems ? 13. What are the several kinds of appendagos to a plant ? 14. What are the several kinds of Inflorescence ? FLOWER AND FRUIX. 2Q5 LESSON 92. Flower and Fruit. Fil'iform, thread like, or very slender. Ves'icle, a small cuticle, filled or inflated, or a little bladder. Go, mark the matchless working of the Power That shuts within the seed the future flower ; Bids these in elegance of form excel, In colour these, and those delight the smell; Sends nature forth, the daughter of the skies, To dance on earth, and charm all human eyes. Cowper. Lin\.ei:s classed the flower and fruit together, and defined them to be a temporary part of vegetables, destined for the reproduction of the species, terminating the old individual and beginning the new. These constitute the reproduc- tive organs, by which the species have been hitherto pre- served from extinction, and by which alone they will be re- newed, so long as seed time and harvest continue. There are seven of these organs, some of which are essential to the very nature of flower or fruit, others not so indispensably necessary, and therefore not universal. The student, who wishes to gain an adequate idea of these organs, should dis- sect different flowers, and bestow upon each part a separate examination. He will find externally the cal'yx or flower- cup, usually of a green colour, and often wanting; the corolla, or as it is sometimes termed the blossom, assuming various shades of colour, exhibiting a more delicate texture than the preceding, and like it sometimes wanting; the steimens, which are filiform organs arranged interior to the corolla, and are never wanting; tne pistils, arising from the centre of the flower, containing the rudiments of the fruit, and of course essential; the seed-vessel, of a pulpy, woody, or leathery texture, enclosing the seeds, but wanting in many plants ; the seed, the perfecting of which is the sole end of all the other parts; and the receptacle, or base, which is the point of connexion, and must necessarily be present in some form or other. The corolla constitutes the chief beauty of a flower, and includes two parts, the Petal and the Nectary. The former 18 206 FLOWER AND FRUIT. is either simple, as in the primrose and bell shaped flowers, in which case the corolla is said to be monopet'alous; or compound, as in the rose, in which it is polypet'alous. The whole use and physiology of the corolla have not yet been fully explained. The nectary contains or secretes honey; and there can be no doubt that the sole use of the honey with respect to the plant is to tempt insects, who in procuring it fertilize the flower, by disturbing the dust of the stamens, and even carry that substance from the barren to the fertile blossoms. A stamen commonly consists of two parts, the Filament and Anther, the former being merely what sup- ports the latter, which is the only essential part. The an- ther is generally of a membranous texture, consisting of two cells or cavities. It contains the Pollen, or Dust, which is thrown out chiefly in warm dry weather, when the coat of the anther contracts and bursts. The Pollen, though to the naked eye a fine powder, and light enough to be wafted along by the air, is so curiously formed, and so various in different plants, as to be an interesting and popular object for the microscope. Each grain of it is a round or angular, rough or smooth vesicle, which remains entire till it meets with any moisture, being contrary in this respect to the na- ture of the anther; then it bursts with great force, discharg- ing a most subtile vapour. The Pistil consists of three parts : the Germen, or rudi- ment of the young fruit and seed ; the style, various in ? igth and thickness, sometimes altogether wanting, and when present serving merely to elevate the third part, which is called the Stigma. This last is indispensable. It is very generally downy, and always more or less moist. The moisture is designed for the reception of the pollen, which explodes on meeting with it, and hence the seeds are fertilized and rendered capable of ripening, which they would not otherwise be, though in many plants fully formed. The ways in which insects serve the purpose of perfecting the seeds in plants are innumerable. These active little beings are peculiarly busy about flowers in bright sunny weaiher, when every blossom is expanded, the pollen in per- fection, a»d all the powers of vegetation in their greatest vigour. Then we see the rough sides and legs of the bee, laden with the goHen dust which it shakes off, and collects anew, in its visits to the honeyed stores inviting it on every CLASSIFICATION OF VEGETABLES. 20? -,ide. All nature is then alive, and a thousand wise ends are then accomplished by innumerable means that " seeing we perceive not;" for though in the abundance of the crea- tion there seems to be a waste, yet in proportion as we un- derstand the subject, we find the more reason to conclude that nothing is made in vain. Questions. 1. How did Linnaeus define the flower and fruit ? 2 What do these constitute ? 3. What is said of the number and im- portance of these organs ? 4. Describe the several parts belonging to the flower and fruit. 5. What two parts does the corolla include ? 6. When is the corolla termed monopetalous ? 7. Polypetalous ? 8. What is the use of the honey with regard to the plant ? 9. What are the parts of a stamen termed ? 10. Describe the anther. 11. Th« Pollen. 12. What are the parts of the Pistil ? 13. Describe the stig- ma. 14. What are the seven kinds into which the calyx is divided? (see Appendix) 15. What arc the seven kinds of seed vessels ? 16. What are some of the parts of which the seed itself is composed ? 17. Look at Engr. VII. and describe the parts of the flower and fruit of the Lily, (see the description in Appendix to Lesson 93.) LESSON 93. Classification of Vegetables. Gc nus, (plural gen'era) a set of plants, animals, or other things, comprehending many species. Nomencla'ture, a term employed to denote the language peculiar to any particular science or art: a vocabulary. All the known vegetable productions, upon the surface of the globe, have been reduced by naturalists to Classes, Orders, Genera, Species, and Varieties. The classes are composed of orders; the orders of genera; the genera of species; and the species of varieties. We may attain a clearer idea of them, by comparing them with the general divisions of the inhabitants of the earth. Vegetables resem- ble Man ; Classes, nations of men ; Orders, tribes, or divisions of nations ; Genera, the families that compose the tribes; Species, individuals of which families consist; and Varieties, individuals under different appearances. Linnams, dissatisfied with every system invented before his time, undertook to form a new one. With an eye which could at a Hiigle glance discern the peculiar features of an object; with firmness to encounter, and with talents to overcome, 208 CLASSIFICATION the greatest difficulties, he planned and accomplished more than all his predecessors, and his works which remain at this day unrivalled, will probably long continue unequalled. The number, situation, and proportion of the stamens were the foundation of his primary divisions. These organs, so con- stant, so essential to the completion of the flower, so neces- sary for the preservation of the vegetable kingdom, were happily selected to furnish each of his Classes with an ob- vious immutable character. The Orders into which his classes are subdivided, are established on a basis equally constant, on the number and situation of the pistils, or on some other circumstance equally obvious and invariable. A Genus is a subdivision of an order, and includes such plants as agree with each other in the form and situation of their flowers and fruits. A Species con'sists of such as agree in these particulars, but differ in the form of their root, stem, leaves, and other parts. A remark, which has sometimes been made to the preju- dice of the study of Botany, is, that it is a mere nomencla- ture, tending only to burden the memory with an immense list of names, without imparting to the student any degree of real and useful knowledge. But is it a small gratifica- tion, or of small importance, to be enabled to distinguish, at first sight, the productions of the vegetable kingdom, and to refer them to their proper classes, families, and stations ? The disadvantages resulting from the neglect of this study, are seldom more seriously felt than in the perusal of those narratives of voyages and travels, which are now so profuse- ly published. In passing through countries which have seldom been visited, it is in the highest degree desirable, that the adventurer should be able to avail himself of the opportunities afforded him, so as to render his labours of substantial service to mankind : but how is this to be effected, unless he be previously furnished with sufficient knowledge to distinguish those natural productions which it may be thought important either to procure or describe ? For want of this knowledge, which would enable him to acquaint us in two words with the name of any known plant, and to re- fer to its proper station every one which is unknown, we have endless descriptions of unknown and surprising vegetables, which either give us no precise idea, or by a long and cir- cuitous track, enable us at length to recognise an old and OF VEGETABLES. 209 familiar acquaintance. A striking instance of this may be found in the celebrated Kotzebue's narrative of his banish- ment to Siberia, in the course of which he discovered a plant which attracted in a high degree his admiration, and whicii he has described at great length, as one of the most beautiful flowers he had ever met with. A very moderate acquaintance with botanical science would however have in- formed him, that this plant was already known to most parts of Europe ; and the only doubt which remains is, as to the particular species of the plant, a doubt which his description does not after all enable us to clear up. The natural history of animals, though in many respects more interesting than botany to man as an animated being, and more striking in some of the phenomena which it dis- plays, yet, in other points, is less pleasing to a tender and delicate mind. In botany all is elegance and delight. No painful experiments are to be made. Its pleasures spring up under our feet, and, as we pursue them, reward us with health and serene satisfaction. None but the most foolish or depraved could derive any thing from it but what is beau tiful, or pollute its lovely scenery with unamiable or unhal- lowed images. Those who do so, either from corrupt taste or malicious design, can be compared only to the fiend en- tering into the garden of Eden. Questions.—1. How have naturalists arranged vegetables? 2. Give the illustration. 3. What are the foundations of the Linnrean Classes ?—Orders ? 4. What does a genus include ? 5. A Species ? 6. What remark has been made to the prejudice of the study of bota- ny ? 7. What is said to obviate this objection? 8. What is related of Kotzebue ? 9. What is said of botany as compared with the natural history of animals ? 10. What are the names of the twenty-four classes? 11. Of the orders of the first thirteen classes? 12. Give an example of the divisions of classes, orders, &c. 13. How is the spe- cies of a plant distinguished ? (For answers to the four last questions, see Appendix ) 14. Look at Engr. VII. and describe the parts of the flower and fruit of the geranium. 18* 310 FLOWERS LESSON 94. Flowers. Carna'tion, a fine and fragrant flower whose varieties of colour and luxuriance are innumerable. Class Decandria, order Digynia, genus Dianthus. The infinite variety of flowers is not less a subject of ad- miration than their regular succession, and equally evinces consummate wisdom and design. This diversity is not dis- cernible only in the different families of flowers, but it is to be seen in the individuals. - In a bed of tulips or carnations, there is scarcely a flower in which some difference may not be observed in its structure, size, or assemblage of colours; nor can any two flowers be found in which the shape and shades are exactly similar. Flowers have not only furnished the poets with inexhaustible description, but the philoso- phers in every age with a variety of moral sentiments. Those who have gathered a rose, know but too well how soon it withers; and the familiar application of its fate to that of human life and beauty is not more striking to the imagina- tion than philosophically and literally true. The following interesting account has been given by Sir John Hill of what appeared on examining a carnation. Its fragrance led me to enjoy it frequently and near; the sense of smelling was not the only one affected on these occasions; while that was satisfied with the powerful sweet, the ear was constantly attacked by an extremely soft but agreeable mur- muring sound. It was easy to know that some animal within the covert, must be the musician, and that the little noise must come from some little creature suited to produce it. I instantly distended the lower part of the flower, and placing it in a full light, could discover troops of little in- sects frisking with wild jollity among the narrow pedestal that supported its leaves, and the little threads that occupied its centre. What a fragrant world for their habitation! What a perfect security from all annoyance, in the dusky husk that surrounded the scene of action ! Adapting a mi- croscope to take in at one view the whole base of the flower, I gave myself an opportunity of contemplating what they were about, and this for many days together, without giving them FLOWERS. 2U the least disturbance. Thus I could discover their economy, their passions, and their enjoyments. The microscope had given, on this occasion, what nature seemed to have denied to the objects of contemplation. The base of the flower ex- tended itself under its influence to a vast plain ; the slender stems of the leaves became trunks of so many stately cedars ; the threads in the middle seemed columns of massy structure, supporting at the top their several ornaments ; and the nar- row spaces between were enlarged in walks, parterres, and terraces. On the polished bottoms of these, brighter than Parian marble, walked in pairs, alone, or in larger companies, the winged inhabitants; these from little dusky flies, for such only the naked eye would have shown them, were raised to glorious glittering animals, stained with living pur- ple, and with a glossy gold that would have made all the labours of the loom contemptible in the comparison. I could at leisure, as they walked together, admire their ele- gant limbs, their velvet shoulders, and their silken wings; their backs vieing with the empyrean in its blue ; and their eyes each formed of a thousand others, out-glittering the little planes on a brilliant: above description, and too great almost for admiration. I could observe them here singling out their mates, entertaining them with the music of their buzzing win^s, with little songs formed for their little or- gans, leading them from walk to walk among the perfumed shades, and pointing out to their taste the drop of liquid nec- tar just bursting from some vein within the living trunk; here were the perfumed groves, the more than myrtle shades of the poet's fancy realized. Here in the triumph of their little hearts, they skipped from stem to stem among the painted trees; or winged their short flight to the close shadow of some broader leaf— " All formed with proper faculties to share The daily bounties of their Maker's care." Note. The night-flowering cereus (cactus grandiflorus) is one of our most splendid hot-house plants, and is a native of Jamaica and some other of the West India Islands. Its stem is creeping, and thickly set with spines. The flower is white and very large, some- times nearly a foot in diameter. The most remarkable circumstance with regard to the flower is the short time it takes to expand, and the rapidity with which it decays. It begins to open late in the even- ing, flourishes for an hour or two, then begins to droop, and before morning is completely dead. 212 ANIMAL KINGDOM. LESSON 95. Animal Kingdom. Zo-ol'ogy, that branch of natural history which treats of animals. Ver'tebre, (pronounced ver'te-bur,) a joint of the spine. Few departments of knowledge are more interesting than the natural history of animals, and the attention given to it in the present age furnishes the best evidence that its claims to notice begin to be fully estimated. In our own country the inducements to its cultivation are peculiarly strong, for our immense lakes, forests, and mountains, have as yet been but imperfectly explored by naturalists, and the little that is known of their productions leads to the belief, that they con- tain abundance to encourage and reward the labours of science. The study of Zoology is particularly advantageous to the young, from its direct tendency to cultivate one of the most useful habits of the mind, that of attentive observation of things of common and daily occurrence. Its objects are every where around us,—swimming in the waters, flying in the air, walking the earth, and burrowing beneath it. One set provides our food and clothing, another purloins and de- stroys them. Some attack, and others protect us. Their forms are continually before our eyes, and their voices always sounding in our ears. In order to treat clearly of the animal kingdom, it is ne cessary to consider it according to some method of arrange- ment, by which those animals which most resemble one ano- ther are connected together for the convenience of descrip- tion. This arrangement is founded upon their form and structure, and separates them into various divisions and sub- divisions, according to their degree of similarity, and the points in which their structures correspond. Such a system of arrangement is called a classification of the animal king- dom ; and an accurate acquaintance with the principles on which it is founded will be of great assistance to the student of natural history. All animals are divided in the first place into two grand divisions, namely, into vertebral, embracing those that have a spine, or vertebres, and into invertebral, comprehending all FIRST CLASS 0F ANIMALS. 213 those that are destitute of a spine, or vertebral column. The vertebral animals are subdivided into four classes, and the invertebral into five. (See Appendix.) Each of the classes is divided into a greater or less number of orders, distinguish- ed by some important, clear, and remarkable peculiarities of conformation and structure, which are common to all the animals included under each of them. Orders are subdivid- ed into genera. These comprehend animals that have a ge- neral external resemblance to each other, a kind of family likeness. Genera are made up of species. Each distinct kind of animal constitutes a species, and they are known from one another by their size, colour, form, and various other circumstances of external appearance. Each kind of animal, then, constitutes a distinct species; a number of species taken together form a genus; those ge- nera which have important and well defined points of resem- blance in structure and conformation common to all, are placed together in an order ; whilst upon a similar principle, but more extensive in its application, these orders are mar- shalled into separate classes. Questions—1. What are the inducements to trie study of Zoolo- gy in our own country ? 2. Why is this study advantageous to the young ? 3. Upon what is a classification of the animal kingdom founded ? 4. What are the first two grand divisions ? 5. How are these subdivided ? 6. What are classes ? 7. Orders ? 8. Genera ? 9. Species? 10. Give a general definition of species, genus, order, and class. 11. What are the nine classes of the animal kingdom ? 12. How many and what are the classes according to Linnaeus ? [Note. In the exercise of reading, the words included in parentheses and italicized should be passed over. They are placed in the lessons that the atten- tion of pupils may be particularly directed to them. Pupils should mention them in answering the questions.] LESSON 96. The first Class of Animals (Mammalia.) The animals of this class are distinguished for a more perfect bodily structure, for more varied faculties, more de- licate sensations, a more elevated intelligence, and greater capability of improvement by imitation and education, than those of anv other. It is to this class that man, considered 314 MAN. as an object of natural history, properly belongs. He is ar- ranged with the animals of this class, because he nearly re- sembles them in structure and organs, though raised in reality far above them by the possession of intellectual and moral powers almost infinitely superior. The structure of an animal is always found to correspond to its character, mode of life, and food; and those, there- fore, which have a similar structure, resemble one another to the same extent in other particulars. From the formation of the anterior extremities of an animal, we may judge of the degree of address of which he is capable, and of the kind of motions he is able to perform ; and from the structure of his teeth, what is the nature of his food. Thus, the fore-feet of animals may be either enveloped in hoofs, or armed with claws, or furnished with slender nails ; and the perfection of the sense of touch will be in proportion to the delicacy of these organs respectively. Thus too, there are three kinds of teeth ; the incisive or cutting teeth, the canine or lacerating teeth, and the molar or grinding teeth; but all animals have not each of these kinds of teeth, nor are they of the tame chap*, and formation in all animals. It is principally from a regard to these parts, that natural- ists have proceeded in the arrangement of this class of ani- mals. The orders thus formed are nine in number. (See Appendix.) Of the first order (Biman'a) man is the only example. In point of adroitness, skill, and address, the structure of his body and the faculties of his mind give him great advantages over other animals. In consequence of his erect position, he has the free use of his hands, and his arms have unincumbered and various motions in every direction. . There are several distinct races of mankind inhabiting diffe- ■ rent portions of the earth, which differ one from another more or less in form, in features, in complexion, and in cha- racter. The cause of these varieties has never been satis- factorily pointed out. They have been attributed to climate, to situation, and to manner of life, but none of these circum- stances appear sufficient to produce them, and we therefore still remain in ignorance on the subject. But notwithstand- ing the differences in man, he maintains every where a de- cided rank, far above that of any other animal. He is the only one which has the power of communicating its thought* and feelings by articulate speech; the only one which can > 0R»ERS OF MAMMALIA, 213 properly be said to avail itself of the' advantages of society * and the only one that, strictly speakings educates its young. It is in consequence of these advantages, particularly that derived from association, that he has been enabled under all circumstances, to acquire and preserve a dominion over other animals, to protect himself against the severity of cli- mates, and thus spread his species over every part of the earth. Naturally tender and defenceless, he could only ex- ist in the most equable and temperate climates; but, aided by the inventions and discoveries of social life, he is enabled to brave the cold of the polar circle, as well as the overpow- ering heat of the regions on the equator. The second order (Quadruman'a, apes, baboons, Sfc.) of this class of animals forms a numerous tribe, and compre- hends a great variety of species. They maintain the erect position with difficulty ; it is a constrained one. Their structure evidently fits them for climbing) and their usual places of habitation are trees, on the fruits of which they feed. The third order is subdivided into several tribes or fami- lies, accordingly as they are more or less carnivorous. The first tribe is that of the Bats, distinguished by their wings, which are formed of a thin fold of skin, extending between* the two limbs of the same side. By means of this apparatus, many of them are able to fly with a force and rapidity equal to that of birds ; but in others it answers only the purpose of a parachute to break their fall from lofty places, or to ena- ble them to perform great leaps in their passage from tree to tree. The second tribe includes a number of small animals, which feed principally upon insects, and are called insec- tivorous, as the shrew-mouse and the mole. The third tribe possesses the characteristics of carnivorous animals in the highest degree. They are endowed not only with an appe- tite for animal food and a structure adapted for its mastica- tion and digestion, but with strength and courage for seizing and retaining it; as the wolf, fox, lion, panther, and others. A fourth tribe of this order comprehends the amphibious animals, as the Seal and the Morse. They live almost en- tirely in the sea, but they cannot remain constantly under water. The fourth order (Rod-en'tia, gnawers) are remarkably qualified by the arrangement of their, teeth for penetrating 216 UIIDERS ©F MAMMALIA. very solid substances; and they frequently feed upon wosdy fibres and the bark of roots and trees. Of this order, among •thers, are the beaver, the squirrel, and the various species of hare and rabbit. Beavers are aquatic animals, and they aonstruct themselves habitations upon waters which are suf- ficiently deep never to be frozen to the bottom. The fifth order (Edenta'ta, toothless) are remarkable for a great degree of torpor, listlessness, and indisposition to motion ; but some more than others. The sloth, the ant- eater, and the armadillo are among them, and of each of these there are several species. The three-toed sloth is an animal whose very aspect is painful and disgusting. The expression of its countenance, and its whole attitude, indeed, eonvey to the beholder the impression, that its very existence is a burden. Ruminating animals form the sixth order of this class, and examples may bo found in the camel, antelope, deer, ox, and sheep. They have been more valuable to man than any } others. Their flesh furnishes a large proportion of our ani- mal food. They are mild, docile, and easily domesticated. The seventh order (Pachydcr'mata, thick-skinned) em- braces all the animals with hoofs which do not ruminate, as the elephant, the tapir, the horse. The Hippopot'amus, or River-Horse, inhabits principally the rivers of the south of 1 Africa. It walks with ease at the bottom of the water, though J obliged, occasionally, to rise to the surface for breath. * Animals of the whale kind, or cetaceous animals, form the \ eighth order. They are usually confounded with the class . of fishes, which they resemble in many particulars of exter- nal appearance, as well as in the circumstance of residing always in the water. In point of structure, however, they elearly belong to the present class, since they breathe air by means of lungs, are warm-blooded, produce their young alive, and nourish them with milk. The Marsu'pial animals, which form the ninth order, are distinguished from all others by the possession of a recep- tacle, formed by a duplicature of the skin, for the purpose »f holding their young, or of receiving them on the approach of danger. Such are the Kanguroo and Opossum. •» Questions.—1. By what are animals of the class Mammalia dis- tinguished ? 2. Why is man, as an object of natural history, arranged with this class ? 3. From a regard to what parts of animals of thi( j BIRD8. '217 claas have naturalists arranged them into orders? 4. Describe the first order of mammalia,—gccond, &c. 5. What are the orders of mammalia according to Linnaeus? [Note. The distinctive charac- ters of the Linntcan orders of mammalia, with the exception of the last, depend on the kind, position, and number of the teeth, and thus animals of very different habits were brought together, from a resem- blance in one comparatively unimportant particular.] LESSON 97. Birds. Ornithol'ogy, that branch of natural history which describes the structure, economy, habits, &c. of birds. Vis'cid, glutinous, tenacious. The immense catalogue of the species of birds, and the variety and beauty of their external characters, have made them favourite objects of investigation with the natural his- torian. The extraordinary degree of instinct displayed in all their habits and economy, more especially in the con- struction of their nests, the care of their young, and the conduct of their migrations, have called forth the admiration of the philosopher and the lover of nature. The splendid colouring of their plumage, the powers of melody, and the liveliness and docility of many species, have given them value as objects of beauty and entertainment. The class of birds is divided, according to their structure and habits of life, into six orders. Birds of prey, or rapa- cious birds (accip'itres) correspond, in many respects, with the carnivorous animals among quadrupeds. They are dis- tinguished by their strong, hooked beaks, and their crooked and powerful talons. They are particularly remarkable for the very great distance at which they perceive their prey, and the accuracy with which they direct their flight towards it. Besides the upper and under eye-lids, all birds have a third which is semi-transparent, and serves the purpose of protecting the eye from the contact of external bodies, or from too powerful light, whilst at the same time it does not prevent them from distinguishing the objects around them. This membrane is situated at the inner angle of the eye, and is drawn over the globe of it, like a curtain, at will. It 19 218 BIRDS. is by means of this protection, that the eagle is enabled t« look steadily at the sun. Sparrows (Pas'sercs) form the most extensive and nume- rous order, embracing a great variety of species, which differ so much among themselves, as to be hardly capable of an intelligible description, common to them all. To this order belong those species which are most celebrated for the sweet- ness and harmony of their notes; and in general the organ of voice in them is larger and better formed, than in any others. Among them are the robin, the swallow, the linnet, the humming-bird, and the nightingale. The third order (Scanso'res, Climbers) includes those birds that have the external toe upon each side turned backwards, which enables them to grasp substances more firmly, and affords them a more sure support, than other birds. Among them are the woodpecker, the cuckoo, and the parrot. Woodpeckers are furnished with a long and slender tongue, covered towards its tip with spines or bristles, which are turned hackwards, and coated with a thick viscid secretion. They run in every direction around the trunks and branches of trees, striking them with their beaks, and thrusting their tongues into holes and clefts, for the purpose of drawing out their food. t The Gallinaceous birds (Gallina'tern) have short and weal J wings, and, of course, they are not constructed for long and continued flight. Of this order are the peacock, the turkey, the pigeon and the common fowls. The pigeons form in I some particulars an exception to the general characteristics I of their order. They fly very well, live in pairs, and build | their nests upon trees or in the clefts of rocks. The most •'" remarkable species among them is the crowned pigeon of l the Molucca islands, which is equal in size to a turkey. Its voice is exceedingly loud and harsh, and is said to have frightened sailors who landed on the islands which it in- habits, by its resemblance to the yells of the savage natives.tJi The Waders (Gral'la,) otherwise called shore birds are A distinguished by their very long and naked legs, which per- . mit them to wade to a considerable depth in the water with^ j out wetting their feathers. All birds with this structure are not, properly speaking, waders in their habits, though they are ranked in this order. Among them are the heron, plo? ver, oxeye, and ostrich. The ostrich is almost incapable op i REPTILES. 219 flight, but runs with immense rapidity. Its height varies from six to eight feet; it is the most lofty of birds and the swiftest of all animals. The toes of Web-footed birds (An'seres,) are connected together by a membrane, which fits them for being used as oars. Their whole structure is such as to adapt them for swimming; their legs are situated far back upon their bodies, their feathers are thick, smooth and oily, and their skin be- neath covered with a layer of close down, which effectually protects them from the contact of water. Most of them are capable of lofty and long continued flight, as the wild goose and duck ; whilst others from the shortness of their wings can scarcely raise themselves into the air, but are principal- ly confined to the surface of the water. As quadrupeds cast their hair, so all birds every year ob- tain a new covering of feathers; this is what is termed moulting. During its continuance, they always appear sickly and disordered; no feeding can maintain their strength, for their nourishment is now consumed and ab- sorbed in administering a supply to the growing plumage. It is worthy of observation, that of the vast number of birds which inhabit the globe, it has never been discovered that a single one is of a poisonous nature. They differ very much in being more or less salutary and palatable, as an article of diet; but none of them are pernicious. Sea-faring people and travellers eat every species of egg without the smallest hesitation. Questions.—1 What renders birds objects of interest to the natu- ralist and philosopher ? 2. Describe the first order of birds. 3. Second. 4. Third. 5. Fourth. C. Fifth. 7. Sixth. H. What is said of their moulting ? 9. What is worthy of observation respecting them ? 10. What are tjhe Linncean orders of birds? (see Appendix.) LESSON 98. Reptiles and Fishes. Icthyol'ogy, that branch o'f natural history which treats of fishes. Reptiles have less intelligence, fewer faculties, and less in- stinct, than either quadrupeds or birds. They are, in general, sluggish and indolent in their habits of life, and obtuse in their sensations. In cold countries they pass the greater 229 FISHES'. part of the winter in a dormant state. They are arranged in four orders. The Tortoises (Ckelo'nia) have a covering consisting of an upper and under shell, joined at their sides into one, which permits only their head and other extremi- ties to be extended without it. They have no teeth but their jaws are armed with a tough horny substance which supplies their place. The order of Lizards (Sau'ria) in- cludes a very considerable variety. The greater part of them have four feet, but a few are possessed of only two. They have nails and teeth, and their skin is covered with scales. Among them are the crocodile, the alligator, the chameleon, the true lizards and the dragons. The crocodile is the most celebrated. It is from twenty to thirty feet in length including the tail, and is covered with a coat of scales, which on the back form an armour proof against a bullet, and have an appearance like that of carved work. The Serpents (Ophid'ia) are distinguished by their long and slender bodies without limbs, and by the great extensi- bility of their jaws, mouth and throat. They are divided into the venomous and those that are not venomous. The number of the latter is the greatest and includes the largest animals. The venomous serpents are generally armed with fangs for the specific purpose of infusing poison into the wounds they inflict. When the tooth pierces the flesh of any animal, the poisonous fluid is injected into the opening. When broken or injured, these fangs are renewed, and when not employed, are hidden from the sight by a fold or projection of the gum. Serpents cast their'skins annually, and the beauty and lustre of their colours are then highly augmented. The reptiles of the fourth order (Batrach'ia, frog, salamander, &c.) are principally remarkable for a ' transformation which takes place in their offspring after leaving the egg. When first hatched, they are strictly an aquatic animal, and capable of breathing and living only under water. In this state they are seen by thousands, of a dark colour, with round bodies, swimming about in brooks and small ponds. After a certain period, their form and structure are altered, and they become at once animals capable of breathing only in air. Fishes being destined to inhabit only the water, are pro- vided with organs and a structure adapted to the element in which they reside. Since they cannot breathe pure air, they STRUCTURE OP INSECTS. 221 have a peculiar modification of the organs of respiration and circulation. A current of water is constantly passed over the gills by the action of the mouth of the animal, and by means of the air it contains, exerts an influence over the blood circulating in them, and produces the same changes in it as are produced in the lungs of other animals by the air they breathe. A few fishes, one of which is called the tor- pedo, are possessed of a very remarkable means of defence, which consists in the power of inflicting upon whatever liv- ing creature comes in contact with them, a powerful elec- trical shock. These shocks are so powerful, that in South America, horses driven into the pools which some fishes of this kind inhabit, have sometimes been stunned and even killed. The shocks become weaker and weaker upon con- tinued repetition, till the animal is exhausted, and loses for some time the power of producing any effect. Questions.—1. What is said of reptiles? 2. Describe the first order. 3. The second. 4. The third. 5. The fourth. 6. Describe the organs of respiration and circulation in fishes. 7. What remark- able means of defence have some fishes ? [Note. Fishes are divided into orders and genera, according to certain differences in the forma- tion, structure, and situation of their mouth, gills, gill-coverings, fins, &c.:—and they are called Apodes, as eels ; Jugulares, as cod ; Tho- racic/, as perch; Abdominalcs, as pike and salmon.] LESSON 99. Structure and Transformation of Insects. Fa'cet a little face or side of a body cut into a number of angles. Hexag onal, having six sides, or angles. Lu'bricated, made smooth so as easily to glide over any part. Entomol'ogy, that branch of natural history which treats of insects. The animals of this class are remarkable for a greater variety of powers and a more wonderful display of instinct and intelligence, than any other of the invertebral animals. They are distinguished by many peculiarities of form. In- stead of a heart, insects have a vessel or reservoir situated along the back, extending from one end of their bodies to the other, and filled with a transparent fluid, which is sup- posed to answer the purpose of blood, and to be conveyed, by absorption, to the various organs. They have no parti- 19* {>•»•> TRANSFORMATION OF INSECTS cular organ for respiration, but their bodies are penetrated in every direction by tubes, through which the air is trans- mitted to every part. These tubes communicate externally by openings called spiracles. To serve the purpose of a brain and nervous system, they are furnished with two knotted cords running the length of their bodies. They possess the senses of seeing, tasting, smelling, and feeling ; but organs of hearing, if they exist, have not yet been discovered. They are provided with a hard external covering which differs in different species; in some it forms a complete case of a horny or shell-like substance ; and in others it consists merely in a tough muscular coat, divided into rings which surround the body. Their heads are furnished withanten'na: or feel- ers, which are a kind of filaments composed of joints, de- signed probably as the organs of the sense of touch, or of sensations still more delicate and of a nature totally unknown to us. The mouth of insects varies much in construction, ac- cording to the nature of their food. Some are armed with a sort of lancet, and others with a trunk or probos'cis, which in the butterflies is capable of being rolled up in a spiral form. Their eyes may be considered among the most sur- prising of nature's works. They differ much in form and colour in the different insects; but they are not, as might be at first supposed, mere hemispherical bodies of plane sim- ple surfaces, for examination proves them to be composed of an immense assemblage of highly wrought hexagonal facets, each furnished with its proper optic nerve, retina, and other parts necessary for vision : the number of these facets dif- fers in different species; eight thousand have been counted in the eye of the common fly, and twelve thousand in that of the dragon fly. How sweet to muse upon His skill displayed ! Infinite skill! in ail that he has made, To trace in Nature's most minute design The signature and stamp of Power Divine ; Contrivance exquisite expressed with ease, Where unassisted sight no beauty sees; The shapely limb, and lubricated joint Within the small dimensions of a point; Muscle and nerve miraculously spun, TRANSFORMATION OF INSECTS. 223 His mighty work who speaks, and it is done. Th' Invisible in things scarce seen revealed; To whom an atom is an ample field. Cowper. The greater part of insects are winged. Those which are not winged, continue, during their whole existence, of the same form and structure as at birth. Those which are winged undergo certain changes of form, which are called their mctamor'phoses. They differ in number in different kinds of insects. For an example we may take the tribe of the Butterfly. From the egg of this insect is hatched an animal differing entirely from its parent. Its body is long and cylindrical, and divided into numerous ring?. It is pro- vided with a large number of very short legs, with jaws, and with several small eyes. It is familiarly known to us by the name of caterpillar. It lives in this state a considerable time, subsisting upon such food as is adapted to its nature. At length it casts off its skin, and appears in another form without limbs. It ceases to feed or to move. It seems to be totally without life. This is called the chrys'alis. After a while, by examining it closely, the imperfect shape of a but- terfly may be distinguished through its surface ; and finally the envelope is broken and the animal escapes. Its wings are at first short, weak, and moist, but they soon unfold to a greater size, and become strong ; and the insect is in a state. to fly. It has now 6ix long legs, a spiral trunk, two antenna?, and eyes differing entirely from those of the caterpillar. In short, it is an animal totally different, delighting us by the beauty of its spots and the variety of its colours; and yet these wonderful changes are only the successive unfolding of parts contained one within another in the original em'bryo. In the first state the animal is called the larva; in the se- cond the chrysalis or nympha; and the third is called the perfect state. A considerable portion of the insect tribes pass through these three changes of existence. But many only undergo what is called a demi-metamorphosis. Their larva resembles the perfect insect, except that it has no wings. And the only change they experience is, that in the nymph state they have the rudiments of wings, which finally on casting their skins, are changed into complete ones. Such are grasshoppers and many others. When about to pass into the chrysalis state, which is a 224 TRANSFORMATION OF INSECTS. state of imbecility, insects select the most proper places and modes of concealing themselves from their enemies. Some, as the silk-worm and others, spin silken webs round their bodies, by which the animal form is completely disguised. Others leave the plants upon which they formerly fed, and hide themselves in little cells which they make in the earth. Some fix themselves by a gluten, and spin a rope round their middle to prevent them from falling. Others attach them- selves to walls, with their heads higher than their bodies, but in various inclinations. In this state many remain motion- less and seemingly inanimate, during the whole winter. Behold the insect race, ordained to keep The lazy Sabbath of a half year's sleep ; Entombed, beneath the filmy web they lie, And wait the influence of a kinder sky. When vernal sun-beams pierce their dark retreat, The heaving tomb distends with vital heat; The full formed brood impatient of their cell, Start from their trance and burst their silken shell; Trembling, awhile they stand, and scarcely dare To launch at once upon the untried air: At length assured, they catch the favouring gale, And leave their sordid spoils and high in ether sail. Barbauld. Questions—1. For what are insects remarkable ? 2. What have they, instead of a heart i 3. What have they to answer the purpose of a respiratory organ? 4. Brain and nervous system? 5. What is s-aid of their senses and external covering ? 6. What are antennie ? { 7. Describe th» eyes of insects. B. What are the changes called f which winged insects undergo ? 9. Give a description of these changes in the example of the butterfly. 10. What is the animal called in its first—second—third state? 11. Describe what is called demi-metamorphosis. 12. What are some of the artifices of insects when about to enter the chrysalis state ? [Note. All insects have six legs, with the exception of the millepedes, (pronounced rnil'le- (' pedz, or mil-lep'e-dez) which have always more, and the number in- creases also with their age. Aurelia and Chrysalis are synonymous < words, both alluding to the metallic or golden splendour of the case in which insects are enclosed during that state. This brilliancy how- ever seems to be confined to the butterfly tribe. The name Pupa has lately been substituted for chrysalis and aurelia, because many insects in this state are thought to resemble an infaat in swaddling clothes. oroers of insects. 225 LESSON 100. Orders of Insects. Perforator, a part of some insects with which they bore various substances in order to admit their eggs. Farina'ceous, mealy, resembling the farina of flowers. Linnajus divided insects into seven orders. His divisions are founded upon the presence or absence of wings, their number, their texture, their arrangement, and the nature of their surface. The first order (colcop'tera) has four wings. The upper pair consist of a hard, crustaceous or horny sub- stance, and cover or defend the under pair, which are of a more soft and flexible texture, and are folded beneath them. This is the most numerous and best known kind of insects; and many of them are very remarkable for the singularity of their forms and the beauty of their colours. The various insects known under the name of beetles and winged bugs are included in this order. The second order (hcmip'tera) has likewise four wings ; but the upper pair is not of so hard a texture as those of the beetle tribe. They are more like fine vellum, and, at their extremities, terminate with a membraaous edge, which re- sembles the substance of the under pair. They cover the body horizontally, and do not meet in a straight line or ridge, as they do in the first order. Among them are found the grasshopper and the locust. The third order (lepidop'tera) has four wings and com- prehends the various kinds of moths and butterflies. Their wings are covered with a farinaceous powder, or rather with scales or feathers, disposed in regular rows, nearly in the same manner as tiles arc laid upon the roofs of houses. The elegance, the beauty, the variety of colours, exhibited in their wings, are produced by the disposition and tincture of these minute feathers. When the feathers are rubbed off, the wings appear to be nothing more than a naked and often a transparent membrane. The fourth order (neurop'tera) has four naked membra- nous wings, which are so interspersed with delicate veins, that they have the appearance of a beautiful net work. They have no sting. Of this order are the various species oC 22C ORDERS OF INSECTS. dragon fly, large and well known insects that frequent lakes and pools of stagnant water ; the Ephem'eral flies, which pass two or three years in the states of larva and chrysalis, but whose existence as winged and perfect in- sects is limited to a single day; and the Ant-lion and Ter'- mites, the former celebrated as the destroyer of the common ant, and the latter for the ravages they make in some tro- pical countries. The fifth order (hymenop'tcra) has four naked mem- l branous wings, but destitute of that delicate, netted struc- ture, which belongs to the last order. The females have j either a perforator or a sting. In the domestic economy and mode of propagation of some of the species, there are circumstances which excite our admiration and astonish- ment. The ant, wasp, and bee belong to this order. They live in societies, greater or less in extent and number; and prepare habitations and nourishment for themselves and offspring, with a forethought and provident care, excelled only by man himself. In some of the tribes of this order, there is, beside the males and females, a third sort called neuters, as among the ants and bees. The sixth order (dip'tera) has only two wings, but be- neath them are two cylindrical projections, which seem as if they were the rudiments of another pair. These have been called balancers or poisers, from being supposed to aid j them in preserving an equilibrium during their flight. Be- tween them and the wings themselves are found small mem- i branous scales, one upon each side, against which the J balancer strikes with great rapidity, whilst the insect is in motion, and causes that buzzing which is then observed. To this order belong some of the most troublesome and an- noying of the whole animal creation, such as the various species of gnat, and the common, fly. They are found in almost every part of the globe. The seventh and last order of insects (ap'tera) includes a great variety that are destitute of wings. It is true that in the preceding orders are arranged many sorts of insects that are destitute of wings, but they are so arranged because in( \ their general structure and habits of life they resemble the other members of the order. The Aptera, however, have no such resemblance, and are therefore placed by them- selves. Some animals of this order cover the surface of i I OftBF.RS OF INSECTS. 227 plants so completely as to produce the appearance of a dis- coloured change of structure. The family of spiders (ara'nea) is not always arranged among insects, and strictly speaking their structure is dif- ferent in some important particulars. They are distinguish- ed from all other insects by the absence of the antenna?. They have generally eight legs, and are furnished with six or eight eyes, which enable them to see objects in several different directions at once. They are nourished generally by living prey, which they secure by means of a web, spun with much ingenuity. The threads, of which the web is composed, are produced from six little fleshy bunches, or muscular instruments, each of which contains about a thousand tubes, or outlets of threads, so extremely minute that many hundreds of them must be united before they form one of those visible ropes, of which the spider's web is composed. By means of their webs, many species of spi- ders, particularly when young, are able to transport them- selves to a considerable distance through the air. In order to effect this, they ascend some eminence, and throw out a number of webs. These are raised up and carried along by the wind, and the animal being buoyed up by them is conveyed sometimes to a great height. In order to alight, they have only to disengage themselves from a part of their web, and suffer themselves to descend gradually to the ground. It is probable that they have recourse to this expedient, in part at least, for the purpose of catching insects for food. In autumn, the air is often full of the cobwebs which have been made use of for this singular mode of conveyance. This fine filmy substance is called Gossamer; and it is seen not only in the air, but is more observable in stubble fields, and upon furze and other low bushes. Those who have ascend- ed eminences for the purpose of observing the phenomenon, have frequently seen spiders floating by in the air, supported in the manner which has been described. To the Insect of the Gossamer:—By C. Smith. Small, viewless aeronaut, that by the line Of Gossamer suspended, in mid air Float'st on a sunbeam. Living atom, where Ends thy breeze-guided voyage ? With what design In ether dost thou launch thy form minute, 328 CRUSTACEOUS ANIMALS. Mocking the eye ? Alas ! before the veil Of denser clouds shall hide thee, the pursuit Of the keen swift may end thy fairy sail. Thus on the golden thread that fancy weaves Buoyant, as Hope's illusive flattery breathes, The young and visionary poet leaves Life's dull realities, while seven-fold wreathes Of rainbow light around his head revolve. Ah ! soon at Sorrow's touch the radiant dreams dissolve. Questions.—1. Upon what is the division of insects into orders ' ounded ? 2. What are the characteristics of the first order ? 3. Se- cond ? 4. Third? 5. Fourth? G. Fifth ? 7. Sixth ? 8. Seventh ? 9. Describe the wings of butterflies. 10. Describe ephemeral flies? 11. What is worthy of notice in ants, wasps, and bees ? 12. How is the buzzing of flies produced? 13. How do aptera insects often ap- pear on plants ? 14. How are spiders distinguished from all other insects ? 15. How is the web of the spider produced ? 16. Describe the aerial excursions of spiders. 17. What is the gossamer, and where seen ? LESSON 101. Crustaceous and Molluscous Animals. Mu'eous, slimy, viscous or glutinous. ' The Crustaceous animals have been sometimes included / an the class of insects, to which they have indeed many 1 strong points of resemblance. They deserve, however, a I separate consideration, both on account of their size and im- portance, and of some anatomical differences of structure. They have articulated limbs, antenna?, and jaws, similarly formed to those of insects. But they breathe by means of J gills, and have a regular, double circulation ; in which par-* J ticulars they differ from insects. Among the most familiar examples of this class are the lobster, craw-fish, and what} is usually called the horse-shoe. They are covered by a ' pretty thick, firm shell, which envelopes them completely.' j As this shell is incapable of growth, it is occasionally chang- ed, to make room for the constant increase in size of the animal. It is thrown off, and their bodies remain for a time entirely naked, and exposed in a soft and defenceless state. , MOLLUSCOUS ANIMALS. 22* In this case, the animal generally retires to some place of concealment and security, and remains till the shell is re- stored by the deposition of calcareous matter on the exter- nal membrane of the skin, which becomes hard and firm, and finally takes the place of the old shell. The Molluscous animals form a large and extensive class, but their structure, residence, and habits, are obscurely and imperfectly known. Among them are the cuttle-fish, oyster, clam, snail, and, in short, nearly all the testaceous animals, or shell-fish, as they are usually called, although they have no resemblance to fishes, and do not all inhabit the water. They are destitute of bones and articulated limbs. Their bodies are generally of a soft texture, and frequently, at first sight, appear to be little else than a simple mucous mass, without parts and almost without organization. In most in- stances they are completely enveloped in a fold or reflection of the skin, which is called their mantle. Sometimes there is only this simple membranous covering; but more fre- quently there is a hard external shell, which serves as a re- treat into which the animal may withdraw itself, and which it can carry about in all its changes of place. These shells differ exceedingly in shape, colour, and texture, in different species, and among them are found some whose form, polish, and splendid tints place them among the most beautiful ob- jects in nature. Questions.—1. In what points do crustaceous animals resemble in- sects ? 2. In what do they differ ? 3. What are examples of this class? 4. What is said of the growth and casting of their shell ? 5. What are examples of molluscous animals ? 6. What description of them is given ? 7. What is said of their shells? [Note. The study of those animals in the class mollusca which are characterized by a Bhell or calcareous covering has obtained the distinct scientific name of Conchology. The objects of conchology are separated into three divisions, namely, multivalves, or shells with many valves; bivalves, er shells with two valves; univalves, or shells with one valve.J 20 . 230 ZOOTHYTES. LESSON 102. Vermes and Zoophytes. Tentac'ula, often called feelers; organs supplying the place of hands and arms to some animals, and intended also for feeling. (Singular, Tentaculum.) The term Ver'mes has been used with great vagueness in natural history, and employed to designate animals to which the name was not appropriate. It is now, however, more restricted in its application, and is made to include only a ' small class of animals. Their bodies are of a cylindrical, elongated shape, divided into a great number of rings. In some species, certain black points appear around the head, whicii hare been supposed to be eyes, but this is doubtful. They are the only invertebral animals which have red blood. It circulates in a double system of vessels, but there is no distinct fleshy heart to give it motion. They breathe by means of gills, which are sometimes within and sometimes without their bodies. They have no limbs, but on each of the rings cf which their bodies are composed, are little spines or bristly projections which answer in some sort the purpose of feet. All, except the earthworm, inhabit the water. Many of them bury themselves in the sand ; some form themselves a sort of tube or habitation of sand, or other J materials ; and others exude from their surfaces a calcareous f matter, which produces a shell around them. When cut ; through the middle, each portion becomes a distinct in- j dividual. There are several species of the leech,' of which the me- dicinal leech is the most valuable. It has three jaws or ra- ther lancets, with which it pierces the skin of animals, in order to draw their blood. Its tail is furnished with a shal- . low cup, by which it is able to fix itself firmly to different 1 objects, while obtaining its nourishment; and by means of i - the same organ it moves from place to place. The class of Zo'ophytes is the last division of the animal kingdom, and the lowest in the scale of the animated crea- tion. It includes an immense number of individuals but imperfectly known, and having but few points of resem- blance and connexion with one another. In general, they have no nervous system, no complete vascular circulatioq, ZOOPHYTES. 231 no distinct apparatus for respiration, and no sense but that of feeling and perhaps that of tasting. This is not true, however, without exception; for, in some instances, traces of a nervous system, of a circulation, and of respiratory or- gans, may be detected, as in the sea-urchin, the common star-fish, and the sea-egg. These Zoophytes are the most perfect in their structure, and are endowed with a curious set of organs for the purpose of motion. Their shells are pierced with a large number of holes, regularly arranged, through which project the feet of the animal, or rather the instruments answering the purpose of feet. These are little hollow cylinders, filled with a liquid, and terminating in a kind of knob, which is also hollow. By forcing the liquid into these cylinders, or by exhausting it from them, the ani- mal can either lengthen or shorten them. The knob, when exhausted, is drawn into a cup-like form, and thus may be firmly fixed to whatever object it is applied, like a cupping- glass ; and when the liquid is again thrown into it, it is again loosened. Pol'ypes have a hollow, cylindrical, or conical body, with one extremity open which serves for their mouth, and is sur- rounded by a number of organs, (tentacula) by which they seize their prey. Many of them have been celebrated on account of the fact, that when one is divided into several pieces, each piece becomes a distinct animal, perfect in all its parts. The immense beds of coral and the different kinds of sponge, are nothing but the habitations of infinite numbers of these little animals, and arc produced by their labour. Corals grow in such quantities, and to such heights in some seas, as to create islands. The Friendly Islands, in the Pacific Ocean, were thus raised by corals from the depth of that sea. Ships have often been lost by striking on coral-rocks. Questions.—1. What is said of the former and present application of the term Vermes ? 2. What is said of the structure of Vermes ? 3. Of the circulation of their blood and of their respiration? 4. Of their in- struments of motion, and their habitations ? 5. Describe the medici- nal Leech. G. What is said of the general structure of Zoophytes ? 7. Describe the organs of motion in the most perfect Zoophytes. 8. What is the structure of Polypes? 9. For what celebrated ? 10. How are corals and sponge produced ? 11. What is said of the growth of corals in some seas ? [Note. To the class of Zoophytes belong In- testinal worms, sea-netiles, or sea-anem'ones, Medusre. orsunfish, and 238 EXISTENCE of the deity. Animalcules, which have been called infusorial animals, (Infusoria,) because they are principally found in some animal and vegetable fluids and infusions.] 12. What are the orders of Vermes according to Linnaeus ? (see Appendix.) 13. In treating of a particular animal, how are naturalists accustomed to designate it ? 14. Give examples. LESSON 103. Existence of the Deity. Gon and the world which he has formed are our great objects. Every thing which we strive to place between these is nothing. We see the universe, and seeing it, we believe in its Maker. The universe exhibits indisputable marks of design: it is not, therefore, self-existing, but the work of a designing mind. From the great masses that roll through space, to the slightest atom that forms one of their impercep- tible elements, every thing is conspiring for some purpose. I shall not speak of the relations of the planetary motions to each other,—of the mutual relations of the various parts of our globe,—of the different animals of the different ele- ments, in the conformity of their structure to the qualities of the elements which they inhabit,—of man himself in all the nice adaptation of his organs :—to these splendid proofs, it is scarcely necessary to do more than to allude. But when we think of the feeblest and most insignificant of living things,—the minutest insect which it requires a microscope ^j to discover, when we think of it as a creature, having limbs i that move it from place to place,—nourished by little vessels, j that bear to every fibre of its frame, some portion of the food which other organs have rendered fit for serving the pur- poses of nutrition ;—having senses, as quick to discern the objects that bear to it any relative magnitude as ours,— and not merely existing as a living piece of most beautiful . mechanism, but having the power, whicii no mere mechan- ism, however beautiful, ever had, of multiplying its own f existence, by the production of living machines exactly re- ■' sembling itself;—when we think of all the proofs of con- trivance which are thus to lie found in what seems to us a single atom, or less than a single atom, and when we think of the myriads and myriads of such atoms, which inhabit even the smallest portion of that earth, which is itself bvt POLITICAL ECONOMY. 233 almost rfli invisible atom, compared with the great system of the neaven?,—what a combination of simplicity and grandeur do we perceive ! It is one universal design, or an infinity of design;—nothing seems to us little, because nothing is so little as not to proclaim the omnipotence which made it;—and I may say too that nothing seems to us great in itself, because its very grandeur speaks to us of that immensity, before which all created greatness is scarcely to Ik; perceived. On particular arguments of this kind, however, that are as innumerable as the things which exist, it is not necessary to dwell. Those whom a single organized being, or even a single organ, such as the eye, the ear, the hand, does not convince of the being of a God,—who do not see him, not more in the social order of human society, than in a single instinct of animals, producing unconsciously, a result that is necessary for their continued existence, and yet a result which they cannot have foreknown—will not see him in all the innumerable instances that might be crowded together by philosophers and theologians. The world, then, toas made ;—there is a designing Power whicii formed it—a Power whose own admirable nature ex- plains whatever is admirable on earth, and leaves to us in- stead of the wonder of ignorance, that toonder of knowledge and veneration which is not astonishment, but love and awe. Bitoww, LESSON 104. Political Economy. Tcch'nical, belonging to arts; not in common or popular use. The language of science is frequently its most difficult part, but in political economy there are few technical terms, and those easily comprehended. It may be defined as the science which teaches us to investigate the causes of the wealth and prosperity of nations. In a country of savages, you find a email number of in- habitants spread over a vast tract of land. Depending on the precarious subsistence afforded by fishing and hunting, they are frequently subject to dearths and famines, which cut 20* 234 POLITICAL ECONOMY- them off iii great numbers. As soon as they begtn'to apply themselves to pasturage, their means of subsistence are brought within narrower limits, requiring only that degree of wandering necessary to provide fresh pasturage for their cattle. Their flocks ensuring them a more easy subsistence, their families begin to increase ; they lose in a great mea- sure their ferocity, and a considerable improvement takes place in their character. By degrees the art of tillage is discovered, a small tract of ground becomes capable of feeding a greater relative number of people ; the necessity of wandering in search of food is superseded; families begin to settle in fixed habitations; and the arts of social life are introduced and cultivated. In the savage state scarcely any form of government is established; the people seem to be under no control but that of their military chiefs in time of warfare. The possession of flocks and herds in the pastoral state introduces property, and laws are necessary for its security ; the elders and lead- ers therefore of these wandering tribes begin to establish laws, to violate which is to commit a crime and to incur a punishment. This is the origin of social order ; and when in the third state the people settle in fixed habitations, the laws gradually assume the more regular form of a monarchical or republican government. Every thing now wears a new aspect; industry flourishes, the arts are invented, the use of metals is discovered; labour is subdivided; every one ap- plies himself more particularly to a distinct employment, in which he becomes skilful. Thus, by slow degrees, this peo- ple of savages, whose origin was so rude and miserable, be- come a civilized people, who occupy a highly cultivated country, crossed by fine roads, leading to wealthy and popu- lous cities, and carrying on an extensive trade with other countries. The whole business of political economy is to study tho causes which have thus co-operated to enrich and civilize a nation. This science, therefore, is essentially founded upon history,—not the history of sovereigns, of wars, and of in- trigues,—but the history of the arts, and of trade, of discove- ries, and of civilization. We see some countries, like Ame- rica, increase rapidly in wealth and prosperity, whilst others, like Egypt and Syria, are impoverished, depopulated, and falling to decay ; when the causes which produce these va- PROPERTY. 235 rious effects are well understood, some judgment may be formed of the measures which governments have adopted to contribute to the welfare of their people; whether certain branches of commerce should be encouraged in preference to others ; whether it be proper to prohibit this or that kind of merchandise ; whether any peculiar encouragement should be given to agriculture ; whether it be right to establish by law the price of provisions or the price of labour, or whether they should be left without control; and whether many other measures, which influence the welfare of nations, should be adopted or rejected. It is manifest, therefore, that political economy consists of two parts—theory and practice; the science and the art. The science comprehends a knowledge of the facts which have been enumerated ; the art relates more particularly to legislation, and consists in doing whatever is requisite to con- tribute to the increase of national wealth, and avoiding what- ever would be prejudicial to it. Mits. Bryan. Questions.—1. What is political economy ? 2. What is the state of savage life ? 3. What is the consequence of attending to pasturage ? 4. What is the effect of discovering the art of tillage ? 5. What in- troduces property ? 6. What is the origin of social order ? 7. What follows after the laws assume the regular form of a government? 8. On what is the science of political economy founded ? 9. How may some judgment be formed of the measures of governments ? 10. What •'oestne science of political economy comprehend? 11. The art? LESSON 105. Property. When we consider the multitude who are in possession of means of enjoyment, that are to them the means only of selfish avarice or of profligate waste, and when, at the same time, we consider the multitudes, far more numerous, to whom a small share of that cumbrous and seemingly unprofitable wealth, would in an instant diffuse a comfort, that would make the heart of the indigent gay in his miserable hovel, and be like a dream of health itself to that, pale cheek, which is slowly waging on its wretched bed of straw, in cold and darkness, __it might almost seem to the inconsiderate., at least for a 436 PROPERTY. moment, that no expression of the social voice could be so beneficial, as that which should merely say, let there be no restraint of property, but let all the means of provision for the wants of mankind, be distributed according to the more or less imperious necessity of those wants, which all partake. It requires only the consideration of a moment, however, to perceive, that the very distribution, would, itself, be the most injurious boon that could be offered to indigence,—that soon, under such a system of supposed freedom from the usurpa- tions of the wealthy, there would only be one general penury, without the possibility of relief; and an industry, that would be exercised, not in plundering the wealthy, for there could not then be wealth to admit of plunder, but in snatching from the weaker some scanty morsel of a wretched aliment, that would scarcely be sufficient to repay the labour of the struggle, to him who was too powerful not to prevail. There would be no palaces, indeed, in such a system of equal ra- pine,—and this might be considered as but a slight evil, from the small number of those who were stripped of them; but when the chambers of state had disappeared, where would be the cottage, or rather the whole hamlet of cottages, that might be expected to occupy its place? The simple dwell- ings of the unhappy peasant might be the last, indeed, to be* invaded ; but when the magnificent mansion had been strip- ped by the first band of plunderers, these too would soon find plunderers as rapacious. No elegant art could be ex- ercised, no science cultivated, where the search of a preca- J rious existence for the day, would afford us no leisure for | studies or exercises beyond the supply of mere animal wants; and man, who, with property, is what we now behold him, and is to be, in his glorious progress even on earth, a being far nobler than we are capable, in our present circumstances, of divining,—would, without property, soon become, in the lowest depth of brutal ignorance and wretchedness, what it . is almost as difficult for our imagination to picture to us, as it would be for it to picture what he may become on earth, after the many long ages of successive improvement. The great inequality of property, strange as it may seem to be at any one moment, is only the effect of that security and absolute command of property, which allows the con- tinual accumulation of it by continued industry. If all things had been common to all,—instead of that beautiful DIVISION OP LABOUR. 237 and populous earth which we behold,—where cities pour wealth on the fields, and the fields, in their turn, send plenty to the cities,—where all are conferring aid and receiving aid, and the most sensual and selfish cannot consume a sin- gle luxury, without giving, however unintentionally, some comfort, or the means of comfort to others,—instead of this noble dwelling-place of so many noble inhabitants, we should have had a waste or a wilderness, and a few miserable strag- glers, half famished on that wide soil which now gives abun- dance to millions. Brown. Question.—What reasons may be given for the institution of pro* perty ? LESSON 100 Division of Labour. Smclt'ing, the melting of ore in a furnace so as to extract the metal. In the more precious metals this is called refining. That separation of employments, which, in political eco- nomy, is called the division of labour, can take place only in civilized countries. In the flourishing states of Europe and America we find men not only exclusively engaged in the exercise of one particular art, but that art subdivided into numerous branches, each of which forms a distinct occupa- tion for the different workmen. Observe the accommoda- tion of the most common artificer or day-labourer in a civiliz- ed and thriving country, and you will perceive that the number of people, of whose industry a part, though but a small part, has been employed in procuring him this accommodation, exceeds all computation. The woollen coat, for example, which covers the labourer, though it may appear coarse and rough, is the produce of the joint labour of a great number of workmen. The shepherds, the sorter of the wool, the carder, the dyer, the spinner, the weaver, the fuller, the dresser, with many others, must all join their different arts to complete even this ordinary production. How many merchants and carriers, besides, must have been employed in transport- ing the materials from some of those workmen to others who often live in a distant part of the country! How much com- 288 DIVl>ION OP LABOUR. merce and navigation in particular, how many ship-builders, sailors, sail-makers, rope-makers, must havp been employed, in order to bring together the different drugs made use of by the dyer, which often come from the remotest corners of the world ! What a variety of labour too is necessary in order to produce the tools of those workmen! To say no- thing of such complicated machines as the ship of the sailor, the mill of the fuller, or even the loom of the weaver, let us consider only what a variety of labour is requisite to form that very simple machine, the shears with whicii the shepherd clips the wool. The miner, the builder of the furnace for heating the ore, the burner of the charcoal to be made use of in the smelting house, the brick-maker, the brick-layer, the workmen who attend the furnace, the mill-wright, the forger, the smith, must all of them join their different arts in order to produce them. Were we to examine, in the same manner, all the different parts of his dress and household furniture, the different hands employed in preparing his food, the glass window which lets in the heat and the light, and keeps out the wind and the rain, with all the knowledge and art requisite for preparing that beautiful and happy inven- tion, together with the tools of all the different workmen employed in producing those different conveniences ; if we examine all these things, and consider what a variety of la- bour is employed about each of them, we shall be sensible, that without the assistance and co-operation of many thou- sands, the very humblest person in a civilized country could / not be provided for, even according to what we falsely ima- / gine the easy and simple manner in whicii he is commonly | accommodated. Compared, indeed, with the more extrava- gant luxury of the great, his accommodation must no doubt appear extremely simple and easy; and yet it may be true, perhaps, that the accommodation of an European prince does not always so much exceed that of an industrious and frugal ^ peasant, as the accommodation of the latter exceeds that of many an African king, the absolute master of the lives and liberties of ten thousand naked savages. AGRICULTURE. 239 LESSON 107. Agriculture. Agriculture is the science which explains the means ot making the earth produce, in plenty and perfection, those vegetahlcs which are necessary to the convenience or sub- sistence of man. Its practice demands a considerable know- ledge of the relations subsisting between the most important objects of nature. It is eminently conducive to the advan- tage of those engaged in it, by its tendency to promote their health, and to cherish in them a manly and ingenuous cha- racter. Every improvement made in the art must be consi- dered as of high utility, as it facilitates the subsistence of a greater proportion of rational and moral agents; or if we suppose the number to be unincreased, furnishes them with greater opportunities than could be possessed before, of ob- taining that intellectual and moral enjoyment, which is the most honourable characteristic of their nature. The strength of nations is in proportion to their skilful cultivation of the soil; and their independence is secured, and their patriotism animated, by obtaining from their native spot all the requi- sites for easy and vigorous subsistence. Not only to raise vegetables for the use of man, but for those animals also whicii are used as food, is obviously, therefore, part of the occupation of the husbandman; and to assist him in his operations, other animals are to be reared and fed by him, to relieve his labours by their strength and endurance of ex- ertion. In cold, and comparatively infertile climates, the services of these creatures are particularly important, if not absolutely indispensable, and their health and multiplication become, therefore, objects of great and unremitted attention. Since the errors of ancient husbandry have been correct- ed, and vulgar superstitious traditions exploded, agriculture has been gradually improving. A solid and rational system of the art has been founded upon clear and intelligible prin- ciples. The application of natural history and chemistry to it has greatly accelerated its improvements. Inquiries have been made into the causes of the fertility and barrenness of land, the food and nutriment of vegetables, the nature of soils, and the best modes of meliorating them with various 240 COMMERCE. manures. Foreign seeds have been introduced, and the methods of cultivation adopted from the nations whence they were borrowed. The intelligent farmer, profiting by the wider diffusion of knowledge, derives assistance from the , philosopher, and is furnished with the useful principles of every art in the least degree conducive to the improvement and success of his occupations. Questions.—1. What is agriculture ? 2. What does the practice demand ? 3. Why is it advantageous to those who engage in it ? 4. Why must every improvement in the art be considered of high utili- 1 ty? 5. What is said of agriculture with regard to nations ? G. What I belongs to the business ofthc husbandman besides the raising of vege-^ tables ? 7. What is said of modern improvements in agriculture ? j LESSON 108. Commerce and Manufactures. Gap'ital, the fund or stock of a trading company, or corporation; the stock which a merchant or tradesman employs in business on his own account. Commerce is the interchange of commodities, or the dis- { posal of produce of any kind for other articles, or lor some representative of value for which other articles can be pro- cured, with a view of making a profit by the transaction. , The term is usually restricted to the mercantile intercourse I between different countries. The internal dealings between J individuals of the same country, either for the supply of lm- f mediate consumption, or for carrying on manufactures, is ' more commonly denominated trade. Those who engage their capitals in commerce or trade, act as agents between the producers and the consumers of the fruits of the earth; they purchase them of the former, and sell them to the latter, and it is by profits on the sale / that capital so employed yields a revenue or income. Com- / merce or trade increases the wealth of a nation, not by rais- •' ing produce, like agriculture, nor by working up raw mate- rials like manufactures; but it gives an additional value to commodities by bringing them from places where they are plentiful to those where they are scarce: and by providing the means for their more extended distribution, both the. manltactures. 241 agricultural and manufacturing classes are incited to greater industry. Agriculture never arrives at any considerable, much less at its highest, degree of perfection, where it is not connected with trade, that is, where the demand for the produce is not increased by the consumption of trading cities. But it should be remembered that agriculture is the immediate source of human provision ; that trade conduces to the production of pro1, ision only as it promotes agricul- ture ; and that the whole system of commerce, vast and various as it is, has no other public importance than its sub- serviency to this end. Manufactures are the arts by which natural productions are brought into the state or form in which they are con- sumed or used. They require in general great expenses for their first establishment, costly machines for shortening manual labour, and money and credit for purchasing mate- rials from distant countries. There is not a single manu- facture of Great Britain which does not require, in some part of its process, productions from the different parts of the globe; it requires, therefore, ships and a friendly inter- course with foreign nations, to transport commodities ana" exchange productions. They would not be a manufacturing unless they were a commercial nation. The two sciences which most assist the manufacturer, are mechanics and chemistry;—the one for building mills, Working mines, and in general for constructing machines, either to shorten the labour of man by performing it in less time, or to perform what the strength of man alone could not accomplish; the other for fusing and working ores, for dyeing and bleaching, and extracting the virtues of various substances for particular occasions. It is more common to see merchants and manufacturers accumulate large and rapid fortunes than farmers. They are a class who generally employ capital upon a much larger scale, hence their riches make a greater show. Yet, upon the whole, trade and manufactures do not yield greater profits than agriculture. It must be observed that though a farmer does not so frequently and rapidly amass wealth as a merchant, yet neither is he so often ruined The risks a man encounters in trade are much greater than in farming. The merchant is liable to severe losses arising from contin- gencies in trade; he must have therefore a chance of making 242 MONEY. proportionally greater profits. The chances of gain muM balance the chances of loss. If he be so skilful or so for- tunate as to make more than his average share of gains, he will accumulate wealth with greater rapidity than a farmer ; but should either a deficiency of talents or of fortunate cir- cumstances occasion an uncommon share of losses, he may become a bankrupt. The rate of profits, therefore, upon any employment of capital is proportioned to the risks with which it is attended; but if calculated during a sufficient period of time, and upon a sufficient number of instances to * afford an average, these different modes of employing capital will be found to yield similar profits. It is thus that the dis- tribution of capital to the several branches of agriculture commerce, and manufactures, preserves a due equilibrium, which, though it may be accidentally disturbed, cannot. whilst allowed to pursue its natural course, be permanently deranged. A remarkably abundant harvest may occasional- ly raise the rate of agricultural profit^, or a very bad season may reduce them below their level. The opening of a trade - with a new country, or the breaking out of a war which im- pedes foreign commerce, will affect the profits of the mer- < chant: but these accidents disturb the equal rate of profits. as the winds disturb the sea; and when they cease, it re- turns to its natural level. Questions.—1. What is commerce? 2. Trade? 3. How does commerce or trade increase the wealth of a nation ? 4. To what end is the whole .system of commerce subservient ? 5. What are manu- factures ? 6. What is said of the connexion of manufactures with trade ? 7. How do the sciences of mechanics and chemistry assist . the manufacturer ? 8. What is said of the profits arising from agricul- ture, commerce, and manufactures ? LESSON 109. Money. Spe'cie, gold and silver coin, distinguished from paper money. Gold and silver, when first introduced into commerce were probably bartered like other commodities, by bulk merely; but shortly, instead of being given loosely by bulk, every portion was weighed in scales, but weight was no se- MONEE 243 CUrity against mixing gold and silver with base metals. To prevent that fraud, pieces of gold and silver are impressed with a public stamp, vouching both the purity and the quan- tity ; and such pieces are termed coin. This was an im- provement in commerce, and at first, probably, deemed com- plete. It was not foreseen that these metals wear by much handling in the course of circulation, and consequently, that in time the public stamp is reduced to be a voucher of the purity only, not of the quantity. This embarrassment is remedied by the use of paper money; and paper money is attended with another advantage, that of preventing the loss of much gold and silver by wearing. Before the invention of money, men were much at a loss how to estimate the value of their property. In order to ex- press that value they were necessarily obliged to compare it to something else/and having no settled standard, they would naturally choose objects of known and established value. Accordingly we reag both in Scripture and in the ancient poets, of a man's property being worth so many oxen and so many flocks and herds. We are informed that even at the present day the Calmuc Tartars reckon the value of a coat of mail from six to eight, and up to the value of fifty horses. In civilized countries every one estimates his capital by the quantity of money it is worth ;—he does not really possess the sum in money, but his property, whatever be its nature or kind, is equivalent to such a sum of money. It is common to imagine that the more money a country possesses, the more affluent is its condition. And that is usually the case. But the cause is often mistaken for the effect. A great quantity of money is necessary to circulate a great quantity of commodities. Rich flourishing countries require abundance of money, and possess the means of obtaining it; but this abundance is the consequence, not the cause of their wealth, which consists in the commodities cir- culated, rather than in the circulating medium. The in- crease of European comforts, of affluence, of luxury, is at- tributed to the influx of the treasures of the new world—and with reason; but those treasures are the sugar, the coffee, the indigo, and other articles, which America exports, to obtain which Europe must send her commodities that have been produced by the employment of their people. Gold and silver, though they have greatly excited their avarice 244 SHIP BUII.1>!N( and ambition, have eventually contributed but little to stimu- late their industry. It has been remarked of Spain, that the gold and silver of America, instead of animating the country and promoting industry, instead of giving life and vigour to the whole community, by the increase of arts, of manufac- tures, and of commerce, had an opposite effect, and produced in the event weakness, poverty, and depopulation. The wealth which proceeds from industry resembles the copious yet tranquil stream, which passes silent, and almost invisible, enriches the whole extent of country through which it flows ; but the treasures of the new world, like a swelling torrent, were seen, heard, felt, and admired; yet their first opera- tion was to desolate and lay waste the spot on which they fell. The shock was sudden ; the contrast was too great. Spain overflowed with specie, whilst other nations were comparatively poor in the extreme. The price of labour, of provisions, and of manufactures, bore proportion to the quantity of circulating cash. The consequence is obvious; in the poor countries industry advanced; in the more wealthy it declined. Questions.—1. What is probable respecting gold and silver on their first introduction ? 2. Why were gold and silver coined ? 3. To what is the public stamp in time reduced ? 4. What is the advantage of paper-money ? 5. How did men estimate the value of their proper- ty before the invention of money ? G. How is capital estimated in civilized countries ? 7. What is said of an abundance of money ? 8. What has been remarked of Spain ? LESSON 110. Ship-building and Navigation. No art or profession has appeared more astonishing and marvellous than that of navigation, in the state in which it is at presenl. This cannot be made more evident than by taking a retrospective view of the tottering, inartificial craft to which navigation owes its origin : and by comparing them with the noble and majestic edifices now in use, containing a thousand men* with their provisions, drink, furniture, wearing-apparel, and other necessaries for many months, besides a hundred pieces of heavy ordnance, and carrying NAVIGATION. 245 »li this vast apparatus safely, on the wings of the wind, across immense seas. These majestic floating structures are the result of the ingenuity and united labour of many hundred of hands, and are composed of a great number of well-proportioned pieces of timber, nicely fastened together by means of iron nails and bolts, and rendered so tight with tow and pitch, that no water can penetrate into any part. To give motion to these enormous machines, lofty pieces of timber called masts, have been fixed upright in them; and sails of linen cloth are placed for the purpose of catch- ing the wind, and receiving its propelling power. It has been requisite also to add vast quantities of cordage and tackling. Yet all these would be insufficient for the perfect government and direction of the vessel, if there were not fastened to the hinder part of it, by means of hinges and hooks, a moveable piece of wood called the rudder, very small in proportion to the whole machine, but the least in- clination of which to either side is sufficient to give imme- diately a different direction to the enormous mass ; so that two men may direct and govern this floating town, with the same or with greater ease than a single man can direct a boat. Even the vaulted part of the fabric, together with its sharp termination underneath, is proportioned according to the nicest calculations; and the length, width, and strength of the sails and tackling, are all in due proportion to one ano- ther, according to certain rules founded upon the principles of the art of ship-building. A large ship carries at least 2200 tons burden, that is, 4,500,0001b., and at the same time is steered and governed with as much ease as the smallest boat. And yet if such a ship sailed along the coast only, and, like the navigators of old, never lost sight of the shore, we might still look on navigation as an easy business. But to find the shortest way across an ocean from 4000 to 6000 miles in width, sailing by day or by night, in fair weather or in foul, as well when the sky is overcast, as when it is clear, with no other guide than the compass, or the height of the sun, the moon and stars, with exactness and precision, is the extraordinary and surpris- ing task of him who is skilled in the science of navigation. A violent storm of wind will make us tremble with fear in 21 * 246 * ARCHITECTURE a well-built house, in the midst of a populous city ; but the seaman, provided he has a good ship, rides with unshaken courage, amidst the enraged waves, when the whole surface of the ocean presents to the eye an awful scone of immense watery mountains and bottomless precipices. LESSON 111. Architecture. Amongst the various arts cultivated in society, some are only adapted to supply our natural wants or assist our in- firmities ; some are instruments of luxury merely, and cal- culated to flatter our pride, or gratify our desires : whilst others tend at once to secure, to accommodate, delight, and give consequence to the human species.—Architecture is of this latter kind ; and when viewed in its full extent, may truly be said to have a very considerable part in almost every comfort or luxury of life. Houses are among the first steps towards civilization, and have great influence both on the J body and mind. Secluded from each other, and inhabitants ,' of woods, of caves, or of wretched huts, men are generally indolent, dull, and abject, with faculties benumbed, and views limited to the gratification of their most pressing ne- ^ cessities; but wherever societies are formed, and commo- dious dwellings are found, in which, well sheltered, they may breathe a temperate air, amid the summer's heat or win- ter's cold ; sleep when nature calls, at ease and in security ; \ study unmolested; converse and taste the sweets of social enjoyments; there they are spirited, active, ingenious, and enterprising; vigorous in body, speculative in mind; agri- culture and arts improve ; the necessaries, the conveniences, and soon even the luxuries of life become abundant. The immediate and most obvious advantages of building are, employing many ingenious artificers, many industrious workmen, and labourers of various kinds ; converting ma- terials of little value into the most stately productions of * human skill; beautifying the face of countries ; and multi- plying the comforts of life. But these, however great, are rot the most considerable : that numerous train of arts and V; 1. JLZ-' A-RCHiTI-ciure. ' "* ■** 247 manufactures, contrived to furnish and adorn the works of architecture, which occupies thousands, and constitutes many lucrative branches of commerce; that certain con- course of strangers, to every country celebrated for stately structures, who extend your fame, and create a demand for your productions, are considerations of the highest conse- quence. Nor is architecture less useful in defending, than prosperous in adorning and enriching countries ; she guards their coasts with ships of war, secures their boundaries, fortifies their cities, and by a variety of useful construc- tions, controls the ambition and frustrates the attempts of foreign powers; curbs the insolence, and averts the danger, ; nd the horror of internal commotions. Materials in architecture are like words in phraseology. They have separately but little power, but they may be so arranged, as to excite ridicule, disgust, or even contempt; yet when combined with skill, and expressed with energy, they actuate the mind with unbounded sway. An able writer can move even in common language, and the master- ly disposition of a skilful artist, will dignify the meanest ma- terials.; while the weak efforts of the ignorant render the most costly materials despicable. To such the compliment of Apelles may justly be applied, who, on seeing the pic- ture of a Venus magnificently attired, said to the operator, " Friend, though thou hast not been able to make her fair, thou hast certainly made her fine," The five orders of architecture were successively invent- ed in ancient Greece and Italy ; they are called the Tuscan, the Doric, the Ionic, the Corinthian, and the Composite ; and are to be found in all the principal buildings of the Christian world. The Saxons had a simple style of archi- tecture, distinguished by semi-circular arches and massive plain columns. The Normans too invented a beautiful style of architecture, called the Gothic ; distinguished by its light- ness and profuse ornaments; by its pointed arches, and by its pillars, carved to imitate several conjoined. A knowledge of the several species of architecture may be conveyed more effectually by engravings, than by any verbal descriptions. Questions.— 1. To what objects are the arts adapted ? 2. What is man in a state of seclusion ? 3. Of society ? 4. Describe the ad- vantages of architecture. 5. Why are materials in architecture like words in phraseology ? 6. What arc the five orders of architecture'?!. 248 CONSTITUTION OF THE UNITED STATES. LESSON 112. Constitution of the United States. As all the youth of America ought to be well acquainted with the constitution of the country in which they live, and to which they must be subject, it will be proper to exhibit its general outlines. A strong sense of the value and blessings of union induc- ed the people at a very early period to institute a federal go- vernment to preserve and perpetuate it. They formed it almost as soon as they had a political existence; (1778) nay, at a time when their habitations were in flames, when many of them were bleeding in the field, and when the pro- gress of hostility and desolation left little room for those calm and mature inquiries and reflections which must ever pre- cede the formation of a wise and well balanced government for a free people. It is not to be wondered at, that a go- vernment instituted in times so inauspicious, should, on ex- periment, have been found greatly deficient, and inadequate to the purpose it was intended to answer. The people per- ceived and regretted these defects. They observed the dan- ger which threatened their union, and more remotely their liberty; and being persuaded that ample security for both could only be found in a national government more wisely framed, deputies from the several states met in convention at Philadelphia (1787,) to take the important subject into consideration. In the mild season of peace, with minds un- occupied with other subjects, they passed many months in cool uninterrupted and daily consultations ; and finally, with- out having been awed by power, or influenced by any pas- sion except love for their country, they presented and recommended to the people the constitution or form of go- vernment produced by their joint and very unanimous councils. The government of the United States is called republican. It is a representative democracy. All power resides ulti- mately in the people; but they exercise it by means of their representatives, or persons chosen by them for that purpose. All the departments of the government are bound to conform CONSTITUTION OF THE UNITED STATES. 249 td the provisions of the constitution, and the act of any one of them, even an act of Congress, if contrary thereto, is void. The most fundamental article in every form of government is the legislative branch, which has the power of making all the laws and regulations to which the whole community must be subject. This, in the United States, consists of a senate and house of representatives, jointly called the Congress, which must be assembled at least once every year. The senate consists of two members from each of the separate states, chosen by the legislatures of each state to serve for six years. The seats of one third of the senators are vacated every two years. The senate tries all persons impeached by the house of representatives ; but they can only punish by deprivation of office, or disqualification in future ; and the conviction must be by the votes of two thirds of the mem- bers present at any trial. The Vice-president presides in the senate, but without a vote, except in case of an equal di- vision of the votes of the other members. No person can be a senator who has not attained to the age of thirty years. The members of the house of representatives must be twenty-five years of age, and they are chosen by the people at large every two years. The number of the representative body varies according to the number of the separate states, and the population of each state. For this purpose an enu- meration of all the people must be made every ten years,, and the number of representatives must never exceed one for every thirty tliousand, but each state shall have at least one representative. The senators and representatives re- ceive a compensation for their services, to be ascertained by law, and paid out of the treasury of the United States. All bills for raising revenue must originate in the house of re- presentatives ; but the senate may propose or concur with amendments as on other bills. The judicial power is vested by the constitution in a su- preme court, and such inferior courts as Congress shall from time to time appoint; and all the judges hold their office during good behaviour. Besides the ordinary exercise of its power of deciding controversies, it is incident to the judicial power of the United States to pass upon the acts of Congress and decide upon their constitutionality; a power essential to the-rights of the people, but not known in any of the go* lernments of Europe. 230 CONSTITUTION OF THE UNITED STATES. The executive power is vested in a President, who is cho- sen every fourth year by electors appointed in the methods prescribed by the constitutions or legislatures of the separate states. If no person have a majority of the votes of the elec- tors, then from the persons having the highest numbers not exceeding three on the list of those voted for, the house of representatives shall choose the president by ballot. But in choosing the president, the votes must be taken by states, the representatives from each state having one vote. If no person have a majority of the votes of the whole number of electors for vice-president, then from the two highest num- bers on the list, the senate shall choose the vice-president. The president must be thirty-five years of age, and ho may be re-elected as often as the people please. He is liable to be impeached and removed from office for misbehaviour. He is the commander in chief of the army and navy : and by and with the advice and consent of the senate, makes treaties, appoints judges, foreign ministers, and other officers. If the president disapprove of any bill presented to him, after having had the concurrence of both houses, he must give his objections to it; and if two thirds of each house still \ abide by their first vote, the bill passes into a law, notwith- ■ standing his rejection of it. . — —0.....j • Besides the general government, whose power For many purposes extends over the whole union, each state has a se- parate local government, whose jurisdiction is confined to the regulation of its own concerns. These separate govern- ments are all republican, and consist generally of a governor, and two legislative branches, though the powers of the diffe- rent departments are variously modelled in the several states. Questions.—1. When did the people of the United States first form a government ? 2. What served to render this government de- ficient ? 3. When did a convention meet to form our present consti- tution ? 4. Under what advantages did the members deliberate ? 5. How do the people of the United States exercise their power ? 6. What power ha3 the legislative branch of government ? 7. Of what does this consist in the United States ? 8. Describe the senate. 9. House of representatives. 10. Where is the judicial power vested ? j 11. The executive ? 12. Describe the manner of choosing the pre- sident and vice-president. 13. What are some of the powers which the constitution gives the president ? 14. What is said of the go- vernments of the separate states ? [Note. The principal subordinate officers in the executive department, are the secretaries of state, of tin treasury, of war, and of tho navy.] EXCELLENCE OF OUR REPUBLICAN GOVERNMENT. 251 LESSON 113. Excellence of our Republican Government It is the just pride of the peopie of the United States, that they have attempted a mode of government which di- vests itself of all the support which is derived from the ho- nest weaknesses and attachments of the human mind; which, disclaiming all alliance with reverence of ancient authority, or the deep-rooted habits of unthinking obedience, trusts itself, with no other attractions than its own moral worth and dignity, to the custody of our virtues. By subjecting legis- lative bodies to rule, and holding them under the restraints of those fundamental principles and enactments, which we call the constitution, we have given a new dignity and a higher duty to law, and realized the noble idea of a moral supremacy, clothed with power, to hold not only subjects of the government to a just performance of their various indi- vidual duties, but also the government itself, in all its depart meats, in its proper place and sphere. * In the brighter moments of our hopes for the future for- tunes of our country, we may exclaim with Sir William Jones— What constitutes a state ? Not high raised battlement or laboured mound, Thick wall or moated gate ; Not cities proud, with spires and turrets crowned ; Not bays and broad armed ports, Where laughing at the storm rich navies ride; Not starred and spangled courts, Where low browed baseness wafts perfume to pride. No ! Men, high minded men, With powers as far above dull brutes endued, In forest, brake, or den, As beasts excel cold rocks and brambles rude; Men, who their duties know, But know their rights, and knowing, dare maintain, Prevent the long aimed blow, And crush the tyrant while they rend the chain : These constitute a state; 252 INTEL LICENCE OF THE PEOPLE. And sovereign laic, that state's collected will, O'er thrones and globes elate, Sits empress, crowning good, repressing ill. We may be told that this is a vision ofa perfect common- wealth ; and so it is :—still the hopes of patriots and sages, amid discouragement and defeat, gather about and rest upon it, with something of that gladness of heart, which the tired traveller feels, when he first descries the sun light upon the distant towers of the happy valley. Although the dangers of American liberty may arise and press upon us from every side, to chastise our hopes and our confidence, the duty of its friends is not doubtful. They must labour to augment that moral force, to which its very existence is committed. N. Am. Review. LESSON 114. Intelligence of the People a means of safety to the Govern- ment. In a government like ours, where the supreme control depends on the opinion of the people, it is important certainly that this opinion should be enlightened. " There is no power on earth which sets up its throne in the spirit and souls of men, and in their hearts and imaginations, their assent also and belief, equal to learning and knowledge ; and there is scarce one instance brought of a disastrous govern- ment, where learned men have been seated at the helm." Now the most certain mode of making learned rulers, is to extend as far as possible the influence of learning to the people from whom the rulers are taken. But intelligence not only makes good rulers, it makes peaceable citizens. It causes men to have just views of the nature, value, and re- lations of things, the purposes of life, the tendency of actions, to be guided by purer motives, to form nobler resolutions, and press forward to more desirable attainments. Laws will be obeyed, because they are understood and rightly estimat- ed. Men will submit cheerfully to good government, and consult the peace of society, in proportion as they learn to INTELLIGENCE OF THE PEOPLE. 253 > respect themselves, and value their own character. These I things are the fruit of knowledge. But ignorance is a soil which gives exuberant growth to discords, delusions, and the dark treacheries of faction. While the people are ignorant, they are perpetually subject to false alarms, and violent pre- judices, ready to give a loose rein to the wild storms of their passions, and prepared to yield themselves willing victims to the seductions of every ambitious, turbulent, treacherous, and faithless spirit, who may choose to enlist them in his cause. Knowledge will work upon this charm with a potent efficacy, lay the hideous spectres which it calls up, and pre- serve the soundness and growing strength of the social and political fabric. It should be considered the glory, and the duty of the go- vernment, to aid in establishing morals and religion. The firef step in accomplishing this purpose is to fix the princi- ples of virtue, and impress the importance of religious prac- tice, by enlarging the sphere of mental light, touching the springs of curiosity, opening the channels of inquiry, and pouring into the mind new materials of thought and reflec- tion. All branches of intellectual improvement will lead to moral goodness. The mind, whicii is taught to expatiate throughout the works of God, to ascend to the heavenly worlds and find him there, to go into the deep secrets of na- ture and find him there, to examine the wonders of its own structure, and look abroad into the moral constitution of things, and perceive the hand of an invisible, Almighty Be- ing, giving laws to the whole, will be impressed with a sense \ of its own dependence, and feel something of the kindling flame of devotion. It is not in human nature to resist it. ' And so the man who begins to study the organization of sr> > ciety, the mutual relations and dependencies of its parts, its objects, and the duties it imposes on those who enjoy its be* nefits, will soon be made to respect its institutions, value its privileges, and practise the moral virtues, in which its very existence consists. The more extensively these inquiries are encouraged, and these principles inculcated, in the elements of education, the greater will be the certainty of moral elevation of character, and the brighter the prospects of a virtuous community. In regard to religion, ignorance is its deadliest Lane. It gathers the clouds of prejudice from all the dark corners of the mind, and causes them to brood 22 254 THE GOVERNMENT OF ENGLAND. over the understanding, and too often the heart, with a dis- mal, chilling influence. It gives perpetuity to error, defies the weapons of argument and reason, and is impassive even to the keen sword of eternal truth. To bring'into salutary action these two great instruments of human happiness, mo- rals and religion, nothing is of so much importance, as to multiply the facilities of education, and quicken the spirit of enlightened inquiry. Through the medium of education the government may give a stronger impulse to the arts, and help to build up the empire of the sciences. Before men can invent, or make profound discoveries, they must be taught to think. Savages never advance a step farther in inventions and discoveries, than they are compelled by their wants. The external com- forts of civilized life depend on the useful arts, which an improved state of the intellect has brought to light. In the sciences, and in literature, we have a vast uncultivated field before us. In the arts of traffic, and the mysteries of gain, we may perhaps be contented with the skill we possess. But to be contented with our progress in the sciences and literature, and all those attainments, which chiefly dignify and adorn human nature, would argue an obtuseness and apathy altogether unworthy of a people, who are blessed with so many political, civil, and local advantages of various kinds, as the inhabitants of the United States. North American Review. Questions.—1. What are some of the advantages of knowledge with regard to rulers and the people ? 2. What are some of the ef- fects of ignorance ? 3. How may government aid in establishing morals and religion ? 4. How does intellectual improvement promote devotional feelings ? 5. What will be the effect of studying the or- ganization of society ? 6. What is the effect of ignorance m regard to religion ? LESSON 115. The Government of England. The government of England, which has sometimes been called a mixed government, sometimes a limited monarchy, !■ formed by a combination of the three regular species of THE GOVERNMENT OF ENGLAND. 255 government; the monarchy, residing in the king ; the aris* tocracy in the house of lords; and the republic being repre- sented by the house of commons. The crown of the united kingdom of Great Britain and Ireland is hereditary, and its rightful inheritor is bound, by the conditions of his inheri- tance, to the discharge of certain duties, as well as vested with certain powers and privileges. By the oath adminis- tered to the sovereign at his coronation, he solemnly engages to govern according to law, to execute judgment in mercy, and to maintain the established religion. To the king be- longs the sole power of sending and receiving ambassadors; and it is his prerogative also to enter into treaties, and to form alliances with foreign princes and states, to make wair or peace, to raise and regulate fleets and armies, to erect fortifications, to coin money, to regulate commerce, and to establish courts of judicature. He is the fountain of honour, office, and privilege, and he can grant letters of nobility and erect corporations. The king has an absolute negative upon the acts of parliament, his person is sacred, and he is not v accountable for misconduct. It is a principle of the consti- tutional law that " the king can do no wrong;" but it is pro- vided, that for all his public acts, his ministers and advisers are responsible to the nation at large by the medium of the parliament, and other legally constituted assemblies. The house of peers is composed of the lords spiritual and the lords temporal. The former consist of two archbishops, and twenty-four bishops, who are a kind of representatives of the clergy of England and Wales ; and of four b'shops, who are taken by rotation from the eighteen bishops of Ire- land. With regard to England the number of temporal peers is unlimited. The Scotch peers are sixteen in num- ber, and are elected by their own body for one parliament only. The lords temporal are divided into dukes, marquises, earls, viscounts, and barons, who hold their respective ranks in the foregoing order, by hereditary descent or by creation. In its aggregate capacity, the house of peers has a right to a negative upon all legislative proposals. The representatives, who constitute the house of com- mons, or the lower house of parliament, are divided into two classes, knights of the shire, or representatives of counties ; and citizens and burgesses, or representatives of cities and boroughs. The qualification for voting for county members, jjob THE GOVERNMENT OF ENGLAND. is the possession of a freehold of the value of forty shillings per annum or upwards. The right of election in boroughs is various, depending upon the charters or immemorial usage of each place, or upon decisions made by committees ap- pointed by the house of commons. " There is nothing in the British constitution so remarkable," says Paley, " as the irregularity of the popular representation. If my estate be situated in one county of the kingdom, I possess the ten thousandth part of a single representative ; if in another, the thousandth; if in a particular district, I may be one in twenty who choose two representatives; if in a still more favoured spot, I may enjoy the right of appointing two my- self. To describe the state of national representation as it exists, in reality, it may be affirmed, I believe with truth, that about one half of the house of commons obtain their seats by the election of the people, the other half by pur- chase, or by the nomination of single proprietors of great estates." He acknowledges this to be a flagrant incongrui- ty in the constitution ; but he doubts whether any new scheme of representation would collect together more wis- dom, or produce firmer integrity. The house of commons enjoys the privilege of a negative upon all the laws which may be proposed for its consideration, and exercises the right of originating all bills, which levy money upon the subject by way of taxes or assessments. The English regard this as the principal safeguard of their liberties, and the main barrier against the inordinate increase of the power of the crown, for the commons can at any time check measures of folly or guilt, by withholding the supplies, and without money the strength of the executive is paralyzed. The king, however, is invested with a power to dissolve the parliament, and thus, by submitting th:;ir conduct to the revision of their constituents, to appeal against them to the nation at larg ;. Questions.—1. How is the government of England formed? 2. What is the import of the oath wHich the king takes at his coronation ? 3. What are some of the prerogatives of the king? 4. Describe the house of peers. 5. House of commons ? 6. What are the remarks of Paley respecting the house of commons ? 7. What do the English regard as tbc principal safeguard of their liberties ? AMERICA. 257 LESSON 116. America. Here the free spirit of mankind at length Throws its last fetters off; and who shall place A limit to the giant's unchained strength, Or curb his swiftness in the forward race. For, like the comet's way through infinite space, Stretches the long untravell'd path of light Into the depths of ages ; we may trace, Afar, the brightening glory of its flight. Till the receding rays are lost to human sight. Europe is given a prey to sterner fates, And writhes in shackles; strong the arms that chain To earth her struggling multitude of states ; She too is strong, and might not chafe in vain Against them, but shake off the vampyre train That batten on her blood, and break their net. Yes, she shall look on brighter days, and gain The meed of worthier deeds; the moment set To rescue and raise up, draws near—but is not yet. But thou, my country, thou shalt never fall, But with thy children—thy maternal care, Thy lavish love, thy blessings shower'd on all— These are thy fetters—seas and stormy air Are the wide barrier of thy borders, where Among thy gallant sons that guard thee well, Thou laugh'st at enemies : who shall then declare The date of thy deep-founded strength, or tell How happy, in thy lap, the sons of men shall dwell. Bryant 22* 258 STRUCTURE OF THE HUMAN BODT. LESSON 117. Structure of the Human Body. Car'tilage, gristle. Ad'ipose, fatty. Ten'dons, hard, insensible cords, by means of which muscular fibres are attached to bones. Dr. Hunter gives the following beautiful representation of the structure of the human body, with reference to all the wants and requisites of such a being as man, in answer to a supposed objector, who asks why a more simple, less deli- cate, and less expansive frame had not been adopted. First, says he, the mind, the thinking, immaterial agent, must be provided with a place of immediate residence, whicii shall have all the requisites for the union of spirit and body; ac- cordingly, she is provided with the brain, where she dwells as governor and superintendent of the whole fabric. In the next place, as she is to hold a correspondence with all the material beings around her, she must be supplied with or- gans fitted to receive the different kinds of impression which they will make. In fact, therefore, we see that she is pro- vided with the organs of sense, as we call them; the eye is adapted to light; the ear to sound ; the nose to smell; the mouth to taste ; and the skin to touch. Further, she must be furnished with organs of communication between herself in the brain> and those organs of sense ; to give her infor- mation of all the impressions that are made upon them; and she must have organs between herself in the brain, and every other part of the body fitted to convey her commands and influence over the whole. For these purposes the nerves are actually given. They are soft white chords which rise from the brain, the immediate residence of the mind, and disperse themselves, in branches, through all parts of the body. They convey all the different kinds of sensations to the mind in the brain ; and likewise carry out of thence all her commands to the other parts of the body. They are in- tended to be occasional monitors against all such impressions as might endanger the well-being of the whole, or of any particular part; which vindicates the Creator of all things, in having actually subjected us to those many disagreeable and painful sensations which we are exposed to from a thou- sand accidents in life. STRUCTURE of the human body. 250 r The mind, in this corporeal system, must be endued with the power of moving from place to place; that she may have intercourse with a variety of objects; that she may fly from such as are disagreeable, dangerous, or hurtful; and pursue such as are pleasant and useful to her. And accordingly she is furnished with limbs, with muscles and tendons, the instru- ments of motion, which are found in every part of the fabric where motion is necessary. But to support, to give firmness and shape to the fabric ; to keep the softer parts in their proper places; to give fixed points for, and the proper di- rections to, its motions, as well as to protect some of the more important and tender organs from external injuries, there must be some firm prop-work interwoven through the whole. And, in fact, for such purposes the bones are given. The prop-work is not made with one rigid fabric, for that would prevent motion. Therefore there are a number of bones. These pieces must all be firmly bound together, to prevent their dislocation. And this end is perfectly well answered by the ligaments. The extremities of these bony pieces, where they move and rub one upon another, must have smooth and slippery surfaces for easy motion. This is most happily provided for, by the cartilages and mucus of the joints. The interstices of all these parts must be filled up with some soft and ductile matter, which shall keep them in their places, unite them, and at the same time allow them to move a little upon one another ; these purposes are an- swered by the cellular membrane, or adipose substance. There must be an outward covering over the whole appara- tus, both to give it compactness, and to defend it from a thousand injuries; which, in fact, are the very purposes of the skin and other integuments. Questions.—1. How does the soul correspond with material be- ings ? 2. What are the nerves, and their use ? 3. Of what use are the bones ? 4. The ligaments, cartilages, and mucus? 5. Cellular membrane ? 6. Skin and other integuments i 260 structure of the human body. LESSON 118. Structure of the Human Body (continued.) Secre'tion, the process by which various fluids are separated from the blood by means of the glands. Vas'cular, full of ves- sels. The mind being formed for society and intercourse with beings of her own kind, she must be endued with powers of expressing and communicating her thoughts by some sensi- ble marks or signs, which shall be both easy to herself, and admit of great variety ; and accordingly she is provided with the organs and the faculty of speech, by which she can throw out signs with amazing facility, and vary them without end. Thus wc have built up an animal body which would seem to be pretty complete ; but as it is the nature of matter to be altered and worked upon by matter, so in a little time such a living creature must be destroyed, if there is no provision for repairing the injuries which she must commit on her- self, and those to which she must be exposed from without. Therefore a treasure of blood is actually provided in the heart and vascular system, full of nutritious and healing par- ticles, fluid enough to penetrate into the minutest parts of the animal; impelled by the heart, and conveyed by the ar- teries, it pervades every part, builds up what was broken down, and sweeps away the old and useless materials. Hence we see the necessity or advantage of the heart and arterial system. The heart consists of four cavities, from one of which, the blood is driven into the arteries through the body, by another, it is received back again by the veins : it then passes into the third, whence it is forced into the lungs. Having there been revivified by coming in contact with the air, it is carried back by a set of veins into the fourth cavity, and thence into that in which it began its course : it is then again forced into the arteries, brought back by the veins, and thus circulates till the end of life. Each cavity of the heart is generally called into action four thousand times every hour. The arteries, into which the blood is forced, branch in every direction through the body, like the roots, branches, and leaves of a tree, running through the substance of the bones, and every part of the animal, till they are lost in such fine tubes as to be wholly invisible. In this man- STRUCTURE OF THE HUMAN BODY. 26l uer, they distribute nourishment, supply perspiration, and renew all the waste of the system ; and by passing through glands in every part of the body, all the various animal se- cretions are elaborated. In the parts where the arteries are lost to the sight, the veins take their rise, and in their com- mencement are also imperceptible. The blood is then of a dark colour. In this discoloured state it has lost some of its vital power ; but on being driven through the lungs its colour is restored. All this provision, however, would not be suffi- cient, for the store of blood would soon be consumed, and the fabric would break down, if there was not a provision for fresh supplies. And we actually find that on its passage from the lungs to the heart the blood receives a supply of a new fluid extracted from the food by myriads of fine tubes which carry it to a larger one, that empties itself into a large vein, and being mixed with the blood is conveyed to the heart. We see, therefore, by the very imperfect survey whicii we have been able to take of this subject, that the animal man must necessarily be complex in his corporeal system, and in its operations. He must have one great and general system, the vascular, branching through the whole circula- tion ; another, the nervous, with its appendages the organs of sense, for every kind of feeling ; and a third for the con- nexion and union of all these parts. Besides these primary and general systems, he requires others which may be more local or confined. One for strength, support, and protec- tion ; another for the requisite motion of the parts among themselves, as well as for moving from place to place, the muscular system; another to prepare nourishment for the daily recruit of the body, the digestive organs; and others for the various purposes of existence. Questions.—1. What are the uses of the blood? 2. Describe the circulation of the blood. 3. Describe the arteries. 4. What changes does the blood undergo in the course of its circulation ? 5. How is provision made for a fresh supply of blood ? [Notk That cavity of the heart from which the blood is driven into the arteries is called the left ventricle ; the next is called the right auricle ; the third the right icntrkle ; and the fourth the left auricle.] 262 THE HUMAN VOICE* LESSON 119. The Human Voice. Epiglot'tis, a small and thin piece of cartilage, placed at the back of the tongue, and having the office of closing the glottis, when the food is passing. The parts employed in the production of the voice are three in number, the trachea, or wind-pipe, by which the air passes to and from the lungs; the larynx, which is a short cylindrical canal at the head of the trachea ; and the glottis, which is a small oval opening between two semicir- cular membranes. The glottis being very narrow compared with the size of the trachea, the air can never pass through it without acquiring a considerable degree of velocity; so that the air thus compressed and forced on communicates, aa it passes, a vibratory motion to the particles of the two lips of the glottis, which produces the sound. The sound thus produced is reverberated through the different parts of the mouth; and it is the mixture of different reverberations, well proportioned to one another, which produces in the human voice a harmony, whicii no instrument can equal. The most wonderful part of the mechanism of the voice is the contraction and dilatation of the glottis. It is these changes which produce all the variety of tone. The diame- ter of the glottis never exceeds one tenth of an inch: now suppose a person capable of sounding twelve notes—to which the voice easily reaches,—there must be the difference of the hundred and twentieth part of an inch for each note. I But if we consider the subdivision of notes of which the voice is capable, the motion of the sides of the glottis ap- pears still more minute. Suppose that a voice can divide a note into one hundred pj.rts; it will follow that the different openings of the glottis will be twelve hundred in one tenth of an inch, and it is known that each of these will produce i sounds perceptibly different to a good ear. But the move- \ ment of each side of the glottis being equal, it is necessary (' to double this number, and the side of the glottis, therefore, actually divides the tenth of an inch into twenty-four hun- dred equal parts. Speech is articulated voice, that is, voice modified by the action of the palate, teeth, tongue, and lips. All animals I the ear. 263 I have a voice, but man alone speaks in the sense now alluded !} to. Some animals, it is true, have been taught to pronounce ■ a few words ; but they express no thoughts by these sounds. I It is believed that no sufficient reason can be drawn from mere organization, why man invariably should possess, and animals invariably want the power of speech. If we consider speech simply as a medium of the reciprocal ex- pressions of present feelings to the little society of citizens and friends of which we are a part, even in this limited view, of what inestimable value does it appear! To communicate to every one around us, in a single moment, the happiness which we feel ourselves,—to express the want, which we have full confidence, will be relieved as soon as it is known, —or to have the still greater privilege of being ourselves the ministers of comfort to wants, which otherwise could not have been relieved by us, because they could not have been discovered,—when the heart which we love is weighed down with imaginary grief, to have it in our power, by a few sim- ple sounds, to convert anguish itself into rapture,—these are surely no slight advantages ; and yet compared with the bene- fit which it affords to man as an intellectual being, even these are inconsiderable. By means of language, spoken or writ- ten, the opinions which are perishing in one mind, are rising in another; and often, perhaps, at the last fading ray of the flame of genius, that may have almost dazzled the world by excess of brilliancy, some star may be kindling, which is to shine upon the intellectual universe with equal light and gfory- Quf.stions.—1. What are the parts employed in the production oft lie voice? 2. How is the sound produced ? 3. What is the most wonderful part of the mechanism of the voice ? 4. What is said of the divisions and subdivisions of the glottis in sounding twelve notes >r 5. What is speech ? 6. What is said of the voice of animals ? LESSON 120. The Ear. Trun'cated, divided. Sen'tient, perceiving. The ear is adapted in an eminent degree to the purpose* It is designed to execute: and it offers an inviting subject 264 the ear. to such as are disposed to investigate the minute mechanism of an organ, which contributes remarkably to some of our most exquisite and refined enjoyments. Though the rapid glance of the eye, and the immense distance to which it enables us to carry our perceptions have given rise to some of our most pleasurable and magnificent sensations, still the sense which we are now considering has contributed most efficiently to the daily happiness of life. It enables us to hold communication with our fellow creatures; to improve and exalt our understandings by the mutual interchange of ideas ; and thus to increase the circle not only of our physi- cal, but of our moral relations. The charms of eloquence and the pleasure resulting from the concord of sweet sounds are other sources of intellectual enjoyment, which contribute to place this sense among the most delightful as well as the most important we possess. The organ of hearing, in its simplest form, consists of the expansion of a nerve, gifted with its peculiar sensitive quali- ties, over the surface of a delicate membrane. In man and the more perfect animals, there is an additional apparatus connected with this, the design of which is to collect and modify those pulses of the air which are finally to be im- pressed on the nervous membrane. In man this apparatus consists of a piece of cartilage, seated externally to the head, which contracts into a tube leading to the intern.il parts. The bottom of this tube is truncated obliquely, and its aper- ture closed by a firm membrane stretched across it, called the drum of the ear, which separates the external part from the succeeding, or middle portion of the organ. Beyond, or on the opposite side of this membrane, we meet with a small cavity, hollowed out in bone. Of the several openings into it, there is one more particularly demanding attention. It is the internal aperture of a tube, the other extremity of which opens behind and above the palate. By means of this communication, the external air is admitted into the* cavity, and equipoises the weight of the atmosphere on the other side of the membrane. Across the cavity there is extended, though by no means in a straight line, a series of little bones, the exterior one of which is attached to the membrane we have just mentioned, the most internal set being firmly con- nected with another membrane, which, in conjunction with it, shuts up the entrance to a still more deepened cavity, MUSIC. 265 called the labyrinth of the ear. This last hollow, excavated as it were in the solid bone, consists of a middle portion of irregular figure, and of different channels, which proceed from it in various directions, and, finally, return, with one exception to the same chamber. All these passages are lined by a membrane, on which the sentient extremity of the auditory nerve is expanded in different shapes; from these it is collected into one trunk and goes on to join a particular part of the brain, and thus completes the com- munication between the external agent and the sensorial organ. Questions.—1. What is the organ of hearing in its simplest form ? 2. What apparatus is connected with this in man ? 3. De- scribe the tube and cavity beyond it. 4. What opening deserves par- ticular attention ? 5. What is the use of it ? 6. What extends across tho cavity ? 7. Of what does the labyrinth consist ? 8. On what is the auditory nerve expanded ? and what does it join when collected into one trunk ? LESSON 121. Music. Music is the art of combining tunable sounds in a man- ner agreeable to the ear. It is an expression of feeling, which, almost like verbal discourse, may be said to be a lan- guage, since it is the utterance of thought and emotion from heart to heart. But music has a voice, as independent of the mere arbitrary forms of speech, as the tears of gratitude, or the smiles of love, that may indeed, give eloquence to words, but require no words to render them eloquent. Though, when very strictly considered, even the pure and almost spiritual delight of music, may perhaps be counted only a pleasure of sense, yet it approaches, by so many striking analogies, to the nature of our intellectual enjoy- ments, that it may almost be said to belong to that class. In its relation to the general pleasures of common minds, it is not to be considered as a mere pastime or relaxation ; it as- sumes a far higher character, and it may be said, at least, to be the intellectual luxury of those, who are incapable of any other luxury that deserves so honourable a name. And it is well, that there should be some such intermediate pleasure 23 266 MUSIC. *r of this sort, to withdraw for a while the da!l and the sensual, from the grosser existence in which they may be sunk, and to give them some glimpses, at least, of a state of purer en- joyment, than that which is to be derived from the sordid gains, and sordid luxuries of common life. Of the influence, which music has upon the general character, when cultivated to great refinement, there are different opinions. But of its temporary influence, as a source of tranquillizing delight, there can be no doubt. Who ne'er has felt her hand assuasive steal Along his heart—that heart will never feel. 'Tis hers to chain the passions, sooth the soul, To snatch the dagger, and to dash the bowl From Murder's hand; to smooth the couch of Care, Extract the. thorns, and scatter roses there. To her, Religion owes her holiest flame: Her eye looks heaven-ward, for from heaven she came'. And when Religion's mild and genial ray, Around the frozen heart begins to play, Music's soft breath falls on the quivering light; The fire is kindled, and the flame is bright; And that cold mass, by either power assail'd, Is warm'd—made liquid—and to heaven exhal'd. Pierpont. The phenomena of music, in addition to their general in- terest, are truly worthy of our astonishment, from that striking diversity of organic power in the perception of melody and still more of harmony which they exhibit in dif- ferent individuals, in whom all other circumstances are ap- parently the same. This diversity has often attracted the attention of philosophers, and has led even those who have no great tendency to speculation of any kind, to wonder at least, which is the first step of all philosophizing. In the present instance, however unfortunately, this first step is the " only step which philosophers have been able to take. If . the want of a musical ear had involved either a general. de- I feet of hearing, or a general slowness of discrimination in other cases of nice diversity, the wonder would not 'have been great. But those who are without ear for music per- ceive as readily as others the faintest whisper;—they dis- tinguish like them, the faintest shades of difference in the PAINTING. 267 mere articulations of sound which constitute the varieties of language, nor the articulations only, but the differences also of the mere tones of affection or displeasure, grief or gayety, which are so strikingly analogous to the varied expression of musical feeling;—and their power of discrimination in every other case in which the judgment can be exercised, is not less perfect. That the ear may be improved by cultivation, or in other words, by nice attention to the differences of musical sound, every one knows; and if this attention can enable us, even in mature life, to distinguish sounds as different in them- selves, which, but for the habitual attention, we should have regarded as the same, it may well be supposed that continued inattention, from earliest infancy, may render us insensible of musical relations still more obvious and precise, than those which we have thus only learned to distinguish ;—or, which is the same thing, that continued attention from in- fancy to slight musical differences of sound may render us capable of distinguishing tones as very dissimilar, the dif- ferences of which, however obvious at present, we should scarcely, but for such original attentive discrimination, have been able to detect. Questions.—1. What is music? 2. What renders the phenomena of music worthy of astonishment ? 3. What may be supposed to result from inattention to the differences of musical sounds ? 4. Attention ? LESSON 122. Painting. Pen'cil, an instrument used by painters for laying on colours; the finer sorts are made of camels' hair, or sometimes of the down of swans. The art of distributing lights and shades is called clair obscure, or chiaro-scuro. The art of painting gives the most direct and expressive representation of objects; and it was, doubtless, for this reason employed by many nations, before the art of writing was invented, to communicate their thoughts, and to convey intelligence to distant places. The pencil may be said to write a universal language; for every one can instantly un- derstand the meaning of a painter, provided he be faithful to 268 painting. the rules of his art. His skill enables him to display the various scenes of nature at one view; and by his delineation of the striking effects of passion, he instantaneously affects the soul of the spectator. Silent and uniform as is the ad- dress which a good picture makes to us, yet it penetrates so deeply into our affections, as to appear to exceed the powers of eloquence. Painting is the most imitative of all the arts. It gives to us the very forms of those, whose works of genius, or of vir- tue, have commanded or won our admiration, and transmits them from age to age, as if not lrfe merely, but immortality flowed in the colours of the artist's pencil; or, to speak of its still happier use, it preserves to us the lineaments of those whom we love, when separated from us either by distance or the tomb. How many of the feelings, which we should most regret to lose, would be lost but for this delightful art, —feelings that ennoble, by giving us the wish to imitate what was noble in the moral hero or sage, on whom we gaze, or that comfort us, by the imaginary presence of those whose affection is the only thing dearer lo us, than even our admi- ration of her'oism and wisdom. The value of painting will, indeed, best be felt by those who have lost, by death, a pa- rent or much-loved friend, and who feel that they should not have lost every thing, if some pictured memorial had still remained. Paintings in regard to their sublets are called historical, idhdscape, or portrait; and in regard to the painters, they are divided into schools or countries;- as the Italian, Ger- man, French, English, and other schools. Each of the schools has treated the practice of painting in its peculiar manner, and each with exquisite beauty and admirable ef- fect. The great component parts of painting are, invention, or the power of conceiving the materials proper to be intro- duced into a picture ; composition, or the power of arranging them; design, or tjie power of delineating them ; the manage- ment of lights and shades; and the colouring. Invention consists principally in three things, the choice of a subject properly within the scope of the art; the seizure of the most striking and energetic moment of time for representation; and the discovery and selection of such objects, and such probable incidental circumstances, as, combined together, may best tend to dcvelope the story, or augment the interest PAINTiNer. 2G9 of the piece. In this part of the art, there is a cartoon of Raphael, which furnishes an example of genius and sagacity. It represents the inhabitants of Lystra about to offer sacri- fice to Paul and Barnabas. It was necessary to let us into the cause of all the motion and hurry before us; according- ly, the cripple, whom they had miraculously healed, appears in the crowd : observe the means which the painter has used to dintinguish this object, and of course to open the subject of his piece. His crutches, now useless, are thrown to the ground ; his attitude is that of one accustomed to such sup- port, and still doubtful of his limbs; the eagerness, the im- petuosity, with which he solicits his benefactors to accept the honours destined for them, point out his gratitudentnd the occasion of it. During the time that he is thus busied, an elderly citizen of some consequence, by his appearance, draws near, and lifting up the corner of his vest, surveys with astonishment the limb newly restored; whilst a man of middle age and a youth, looking over the shoulder of the cripple, are intent on the same object. The wit of man could not devise means more certain of the end proposed; such a chain of circumstances is equal to a narration. In the cartoon of Paul preaching at Athens, the elevated situation, and energetic action of the apostle, instantly de- note him the hero of the piece, whilst the attentive but astonished circle gathered around him, receive, as it were, light from him, their centre, and unequivocally declare him the resistless organ of divine truth. Questions.—1. What are paintings in regard to their subjects i 2. To the painters ? 3. What are the great component parts of paint- ing ? 4. In what three things does invention consist ? 5. What car- toon of Raphael is an example in this part of the art? [Note. En- gravings, taken originally from the cartoons of Raphael, are sometime! inserted in Bibles. That of Peter and John healing the cripple at the beautiful gate of the temple, and that of Paul preaching at Athena, are common] 23* 270 SCULPTURE: LESSON 123. Sculpture. Consist'ence, degree of density or rarity. To ascertain when the art of sculpture was first practised, and by what nation, is beyond human research. We may safely conjecture, however, that it was almost one of the original propensities of man.' This will still appear in the ardent and irresistible impulse of youth to make represen- tations of objects in wood, and the attempts of savages to em- body their conceptions of their idols. A command from the author of our being was necessary to prevent the ancient Is- raelites from making graven images ; and the inhabitants of the rest of the earth possessed similar propensities. The de- scriptions in the Scriptures demonstrate that the art had been brought to great perfection at the period of which they treat. It is necessary to make a distinction between carving and sculpture : the former belongs exclusively to wood, and the latter to stone or marble. It is probable that every essay at imitating animated objects was in each nation made original- ly in wood. But they soon discovered, doubtless, that wood was incapable of a durability commensurate with their wishes; they adopted, therefore, a close grained and beau- tiful granite, which not only required tools of iron, but those of the most perfectly tempered steel, to cut it; and with such they have left us at this very distant time vast num- bers of excavated figures, as complete and as little injured as if executed within our own memory. The acknowledged masters of the sublime art of sculpture are the ancient Greeks, to whom every nation of the earth still pays a willing homage, and from whose matchless works each sculptor is happy to concentrate and improve his observations on the human figure, presented by them to his contemplation in its most graceful perfection. Such have been the excellence and correctness of their imitations of nature, and the refined elegance of their taste, that many of their works are men- tioned, as efforts never to be exceeded or perhaps equalled. Statuary is a branch of sculpture employed in the making of statues. The term is also used for the artificer himself PhidiajS was the greatest statuary among the ancients, and THE LOVE OP NATURE. 271 Michael Angelo among the moderns. Statues are not only formed with the chisel from marble, and carved in wood, but they are cast in plaster of Paris, or other matter of the same nature, and in several metals, as lead, brass, silver, and gold. The process of casting in plaster of Paris is as follows: the plaster is mixed with water, and stirred until it attains a pro- per consistence ; it is then poured on any figure, for instance, a human hand, or foot, previously oiled in the slightest man- ner possible, which will prevent the adhesion of the plaster : after a few minutes the plaster will dry to the hardness of soft stone, taking the exact impression of every part, even the minutest pores of the skin. This impression is called the mould. When taken from the figure that producq^t, and slightly oiled, plaster, mixed with water as before, may be poured into it, and it must remain until it is hardened ; if it be then taken from the mould, it will be an exact image of the original figure. When the figure is flat, having no deep hollows or high projections, it may be moulded in one piece, but when its surface is much varied, it must be moulded in many pieces fitted together, and held in one or more outside or containing pieces. This useful art supplies the painter and sculptor with exact representations from nature, and multiplies models of all kinds. It is practised in such per- fection, that casts of the antique statues are made so pre- cisely like the originals in proportion, outline, and surface, that no difference whatever is discoverable, excepting in co- lour and materials. Questions.—1. What is said of the origin of sculpture ? 2. How does sculpture differ from carving ? 3. What is said of this art as it existed among the ancient Greeks ? 4. Define the word statuary in both senses. 5. How are statues formed ? 6. What is the process of casting in plaster of Paris ? 7. Of what use is the art of casting to the painter and sculptor ? LESSON 124. The Love of Nature. When the mind becomes animated with a love of nature, nothing is seen tha does not become an object for curiosity 272 THE IMPORTANCE OF NATURAL PHILOSOPHY. and inquiry. A person under the influence of this principle can converse with a picture, and find an agreeable com- panion in a statue. He meets with a secret refreshment in a description ; and often feels a greater satisfaction in the prospect of fields and meadows, than another does in the possession. It gives him indeed a kind of property in every thing he sees ; and makes the most rude uncultivated parts of nature administer to his pleasures; so that he looks upon the world, as it were, in another light, and discovers in it a multitude of charms, that conceal themselves from the gene- rality, of mankind. A river is traced to its fountain; a flower to its seed; and an oak to its acorn. If a marine uw§il lies on the side of a mountain, the mind is employed in the endeavour to ascertain the cause of its position. If a tree is buried in the depths of a morass, the history of the world is traced to the deluge ; and he who grafts, inoculates, and prunes, as well as he who plants and transplants, will derive an innocent pleasure in noting the habits of trees and their modes of culture; the soils in which they delight; the shapes into which they mould themselves; and will enjoy as great a satisfaction from the symmetry of an oak, as from the symmetry of an animal. Every tree that bends, and every flower that blushes, even a leafless copse, a barren plain, the cloudy firmament, and the rocky mountain, are objects for his attentive meditation. For, To him who in the love of Nature holds Communion with her visible forms, she speaks A various language; for his gayer hours She has a voice of gladness, and a smile And eloquence of beauty, and she glides Into his darker musings, with a mild And gentle sympathy, that steals away Their sharpness, ere he is aware. Bryant. LESSON 125. The Importance of Natural Philosophy. With thee, serene Philosophy, with thee, And thy bright garland, let me crown my song: THE IMPORTANCE OF NATURAL PHILOSOPHY. 273 Effusive source of evidence and truth ! Without thee, what were unenlightened man ? A savage roaming through the woods and wilds, In quest of prey ; and with the unfashioned fur Rough clad : devoid of every finer art, And elegance of life. Nor happiness Domestic, mixed of tenderness and care, Nor moral excellence, nor social bliss, Nor guardian law were his; nor various skill To turn the furrow; nor to guide the tool Mechanic ; nor the heaven-conducted prow Of navigation bold, that fearless braves The burning line, or dares the wint'ry pole. ThomsoWt What can be more gratifying than to become acquainted with the wonderful laws of matter and motion ; with the grand mechanical powers; and the ingenious and admirable application of them to numberless purposes of human in- dustry, convenience, and comfort? What more pleasing than to know the nature and properties of the element in which we live ; to understand the laws on which the motion and pressure of fluids depend ; to be able to ascertain the specific gravities, or the relative weight of different bodies; and to be made acquainted with those newly-discovered principles, by means of which the aspiring genius of man has uareu io soar through the trackless regions of the air, and to explore, unhurt, the capacious bosom of the deep 1 What can be more interesting or more delightful, than to accompany the rays of light in their rapid journey from the sun ; to observe the various effects of reflection and refrac- tion ; to analyze distinctly the principle of light; to grasp the fading colours of the rainbow; to understand the laws of vision ; and to view the wonderful and happy application, which has been made of the grand principles of optics, to the promotion of physical and astronomical science ? What more astonishing than the exquisite nature of that most sub- tile, all-pervading fluid, which, when collected, produces 6iich powerful effects upon the human frame, which sports in the northern lights, and flashes amidst the storm; and which, by the penetrating genius and art of man, has even been rendered tractable and obedient to his will ? To be 274 MYTHOLOGY. made acquainted with the surprising laws of magnetic bodies, with the polarity of the needle, and the amazing changes which a knowledge of this most remarkable property has efr fected in the widely-extended intercourse of different na- tions by means of improved navigation, are certainly objects of the greatest utility, and interesting and instructive in the highest degree. While you contemplate the admirable laws of the planetary system, you will, doubtless, be struck with reverence and awe at the great First Cause, which originally established, and which continually maintains them in order and in being. Curious to search what binds old Ocean's tides, ^^ What through the various year the seasons guides, ^* What shadows darken the pale queen of night, Whence she renews her orb and spreads her light. You will take a pleasing survey of those grand movements in the heavenly bodies, to which the sweet interchange of day and night, the grateful succession of the seasons, the occurrence of eclipses, and the regular flowing and ebbing of the tides, may be justly ascribed. With the mind's eye you will even cast a glance into that universe of worlds, which, orbit within orbit, system combined with system, the daring genius of philosophy has ventured to descry in the regions of infinite space; and while absorbed in these sub- lime speculations, you will be ready to exclaim with the in- spired poet of Israel, " The heavens declare the glory of God, and the firmament proclaimeth his handy work :'-' or to break forth in the beautiful strains of Thomson— " These, as they change, Almighty Father, these Are but the varied God j the rolling year is full of Thee!" LESSON 126. Mythology. Mythology comprehends all those fabulous details con- cerning the objects of worship, which were invented and propagated by men who lived in the early ages of the world, and transmitted to succeeding generations, either ACCOUNT OP THE PRINCIPAL HEATHEN GODS. 275 by oral traditions, or written records. Fable is a creature of the human imagination, and owes its birth to that love of the marvellous, by which man is so peculiarly distinguished. Many circumstances conspired to extend and establish the empire of fable. The legislature employed fiction as the most effectual means of civilizing a rude world; philoso- phers, poets, and musicians, made this a vehicle of instruc- tion to the savage tribes. A fondness for fable, and her at- tendants allegory and personification, early characterized the Orientals. The boldness and the extravagance of their mythology are to be attributed, in a great measure, to the genial warmth of the climate, and to the fertility of the soil; to the face of nature perpetually blooming around them; and to the opportunity they had of contemplating the heave* ly bodies, continually shining under a cloudless sky. These were soon considered as the residence of Divine intelligence, and worshipped, together with the elements, as deities. The historians of antiquity were all poets. _ To immortalize the heroes, Whose deeds they described, they elevated them to the skies, and bestowed on them the names of the celestial: luminaries. The sculptor and the painter exercised all their ; skill to encourage this strange delusion. The use of hiero- glyphics was another fertile source of error. The minutest - animals and plants were worshipped as emblems of Deity. Questions.—1. What does mythology comprehend? 2. What is Fable ? 3. By whom, and for what ends, was fiction employed ? 4. What characterized the Orientals, or eastern nations? 5. What oc- casioned their peculiar mythology ? 6. Why didfBnclent historians encourage mythology ? 7. To what other causes is this delusion to be attributed? j. *- LESSON 127. Account of the principal Heathen Gods. Before the birth of our Saviour, the Jews were the only nation of the world who worshipped the true God. All the other nations worshipped different imaginary beings, which existed only in their absurd and ridiculous fancies. Most of these false gods, however, have now become forgotten, together with the nations that believed in them; but it is 276 ACCOUNT OP THE PRINCIPAL HEATHEN GODS. necessary to preserve a knowledge of the gods and goddesses worshipped by the Greeks and Romans, as they arc much spoken of in the finest writings of antiquity, and are still frequently mentioned both in poetry and in p' ,«e. The most ancient of their gods were Cha'os, and his son Er'e- bus; or confusion, and darkness. Saturn, one of their de- scendants, is the same as Time : his reign is called the Golden Age; and it is said, that the earth then produced corn and fruits without labour, and justice prevailed among all mankind. Saturn was deposed by his son Jupiter, called also Jove; who then divided his father's power between himself and his two brothers, Neptune and Pluto. Jupiter was to reign over heaven ; and he was said to hold his court, or council of the gods, on the top of Olym'pus, a mountain in Thes'saly. He is called by the ancient poets, the king of gods and men; and the eagle is represented as being the bearer of his thunderbolts. Neptune, the god of the sea, is represented with a trident, or fork with three teeth in his hand instead of a sceptre. He was drawn in his chariot by sea-horses, with his son Triton blowing a trumpet made of a shell, and dolphins playing round him. The dominions of Pluto, the god of the infernal regions, were divided into two parts, called Tar'tarus and Elys'ium. Tartarus was the place where the souls of the wicked were punished, and Elysium was the scene of perpetual happiness allotted to the good. The passage from the earth to these regions was across the river A'cheron, over which the de- parted spirits were conveyed by an old boatman, named Cha'ron ; and the further bank was also guarded by a dog with three heads, named Cer'berus. There were two re* markable rivers of Tartarus: one named Styx, which the gods used to swear by when they intended to make their oath very solemn ; and another named Le'the, which caused whoever bathed in it to forget every thing that was past. Mars, the son of Jupiter, was the god of war. Apol'Io, like- wise the son of Jupiter, was the god of music, poetry, and medicine. He is also represented as driving the chariot of the sun, drawn by four horses abreast; or rather, he is the sun itself. As a mark of affection, he intrusted this chariot one day to his son Phaeton ; who was killed by being thrown out of it, but not till after he had set a part of the earth on fire. Apollo is called also Phoebus, and Hype'rion ; and is ACCOUNT OF THE PRINCIPAL HEATHEN GODS. 277 represented as a beautiful young man, without a beard, and with graceful hair. Mercury, a son of Jupiter, was the messenger of the gods; and is therefore represented with wings to his cap and his feet. He was said to be the in- ventor of letters, and hence he is the god of eloquence ; and was the god of trade, and thence also of thieves. He was called also Her'mes; and is represented as carrying a wand, called cadu'ceus, with two serpents twisting round it. Vul- can, the god of fire and of smiths, was the artificer of heaven ; and made the thunderbolts of Jupiter, and the armour and palaces of the gods. It is said that one of his principal forges was within Mount Etna. He is called also Mul'ci- ber. The foregoing are the principal gods, but there were many of a second or still lower order, Bac'chus was the god of wine, and was crowned with leaves of the vine and the ivy. E'olus was the god of the winds : the north wind was called Bo'reas, the south wind Au'ster, the east wind Eu'rus, and the west wind Zeph'yrus. Mo'mus was the god of satire, and likewise of laughter and jokes. Plu'tus was the god of riches. Hy'men was the god of marriage : he is represented with the burning torch. Cu'pid was the god of love : he is represented as a beautiful child, but blind or hoodwinked, and carries a bow and arrows. Ja'nus, a god with two faces, looking forward and backward, had a temple which was open in time of war, and shut in peace. Escula'pius was an inferior god of medicine, below Apollo: he is represented as accompanied by a serpent, which was thought the most long-lived of all animals. Pan was the god of shepherds; and he is represented as having horns, and as carrying the musical instrument, now called Pan's pipes. There were other rural deities called Sat'yrs, Fauns, and Syl'vans: their figures were half man and half goat, and they dwelt chiefly in forests. Every river also was sup- posed to have its own god; who was drawn with a long beard, a crown of reeds, and leaning on an urn. There were likewise a great number of demi-gods, or half-gods; the principal one of these was Her'cules; who was accounted the god of strength, from his having performed some wonder- ful undertakings, called his Twelve Labours. He is repre- sented leaning on a large club, and wearing a lion's skin. 24 278 ACCOUNT OF THE PRINCIPAL HEATHEN GODDESSES. LESSON 128. Account of the principal Heathen Goddesses. Ju'no was the wife of Ju'piter, and was of course the queen of heaven. She is represented as drawn by peacocks in a chariot of gold. Her favourite messenger was I'ris the goddess of the rainbow. Miner'va, a daughter of Jupiter, was the goddess of wisdom and of war. She was repre- sented in complete armour, bearing a shield, called aegis, with a head on it, so terrible, that every one who looked on it was turned into stone. She was likewise the patroness of spinning, needle-work, and embroidery. She was called also Pal'las, and her principal emblem was the owl. Dian'a was the twin sister of Apollo; and as he drove the chariot of the sun, so she presided in that of the moon. She was the goddess of hunting; and is drawn as carrying a bow and arrows, with a half moon as an ornament on her fore- head, and attended by several nymphs as her companions, and by her hounds. She is called dso Phoebe ; and Cyn'- thia, from having been born on Mount Cynthus, and she had a very famous temple at Eph'esus, which is mentioned in the New Testament, in the 19th chapter of the Acts. Venus was the goddess of beauty and of love; and the wife of Vulcan, and mother of Cupid ; her chariot was drawn by doves, and the myrtle was sacred to her. She was said to have sprung from the sea, near the island of Cythe'ra; and her most celebrated temple was at the city of Pa'phos, in the island of Cyprus ; hence she is called also Cythere'a; and the Pa'phian, or the Cyp'rian, goddess. Ves'ta was the goddess of the earth and of fire. In her temple at Rome, a perpetual fire was maintained, which was kindled from the rays of the sun, and was constantly watched by priestesses chosen from the most noble families. They were called vestal virgins, and had very great honours and privileges. Ce'res was the goddess of corn and of harvest. Cyb'ele was one of the most ancient of the goddesses, being the wife of Saturn ; and in some respects represents the earth. She is displayed as crowned with towers, holding a key in her hand, and drawn in her chariot by lions. Pros er- pine was the wife of Pluto, and of course the queen of the infernal regions. She was the daughter of Ceres. Amphi- ACCOUNT OF THE PRINCIPAL HEATHEN GODDESSES. 2"9 tri'te was the wife of Neptune. Her sister was The'tis, another sea-goddess; and hence, when the sun sets, she is said to sink into Thetis's lap. The foregoing are the prin- cipal goddesses. Flo'ra was the goddess of flowers, and Pomo'na was the goddess of fruits. Bello'na was an inferior goddess of war. Auro'ra was the goddess of the morning, or rather of day- break. Thc'mi.s, the sister of Sa'turn, was the goddess of righteousness and justice : her daughter Astre'a also repre- sents justice ; she is sometimes called the Virgin, and in this character has a place among the stars, being denoted by the constellation Vir'go, or the Virgin. Hyge'ia was the goddess of health, lie'be was the goddess of youth, and was cup-bearer to Jupiter. A'te was the goddess of mis- chief. The Muses were nine virgin-goddesses who pre- sided over every kind of learning, and in that character at- tended on Apollo. They were sisters; the principal of them were Cli'o, who was the muse of history ; Thah'a, of comedy, Melpom'ene, of tragedy ; Terpsic'hore, of dancing; and Ura'nia, of mathematics and astronomy. They are sometimes called merely the Nine, in reference to their number. , 5 Parnas'sus and Hel'icon were two mountains feucred to Apollo and the Muses; at the feet of which flowed two streams, whose waters were supposed to communicate the inspiration of prophecy, or of poetry. Peg'asus was a winged horse of the Muses. The Graces were three sisters, who were supposed to give its attractive charms to beauty of every kind, and to dispense the gift of pleasing. The Furies were three sisters of a very different character; they were the most deformed and horrible of all the deities. In- stead of hair, they had snakes hanging from their heads. They carried chains, and whips with lashes of iron or of scorpions in one hand, and lighted torches in the other. They were the bearers of the vengeance of heaven. 1 he Destinies or Fates, were also three sisters, of whom one was represented as holding a distaff; another drawing from it a thread, signifying the life of man ; and the third with a pair of shears, ready to cut the thread whenever she should choose. The Dry'ads and Ham'adryads were rural god- desses, each having a single tree in her charge. 1 he na- iads were goddesses presiding over springs, wells, and loun- 280 HARMONY OF SCIENCE -WD CHRISTIANITY. tains; each, in the same manner, having one under hef care. The Ne'reids were inferior goddesses of the sea. From Baldwin's Pantheon/ LESSON 129. Harmony of Science and Christianity. After all-the- attacks of infidelity, and of theoretical phi- losophy, the religion of Christ, when contemplated through the medium of science, has had a complete and victorious triumph. It has been often objected to Christianity, that it is unfavourable lo the progress of knowledge; that it dis- courages scientific enterprises; that it is inimical to free inquiry, and has a tendency to keep the minds of men in blindness and thraldom. The history of Christianity, since the Reformation at least, demonstrates that the very reverse of what the objection states is the truth. Christian nations have been, of all others, most remarkable for favouring the , advancement of liberal knowledge. In those countries in which religion has existed in its greatest purity, and has enjoyed the most general prevalence, literature and science have been most extensively and successfully cultivated. It is also worthy of remark, that, among all the professions de- nominated learned, the clerical profession may be considered as having furnished as many, if not more authors of distinc- , tion than any other. And if we join to the clergy, those lay authors who have been no less eminent as Christians than as scholars, the predominance of learning and talents on the side of religion will appear too great to admit of com- parison. The discoveries made in mechanical and chemical philosophy have served to elucidate and confirm various parts of the Christian Scriptures. Every sober and well- directed inquiry into the natural history of man, and of the globe we inhabit, has been found to corroborate the Mosaic history, and the reports of voyagers and travellers have served to illustrate the sacred records, and to confirm the faith of Christians. Never was there a period in which so much light and evidence in favour of revelation were drawn from the inquiries of philosophy as in the present era ; nor THE INFLt f.nce of an early taste for reading. 281 was it ever rendered so apparent, that the information and the doctrines contained in the sacred volume perfectly har- monize with the most authentic discoveries, and the sound- est principles of science. Questions.—1. For what have christian nations been remarkable ? 2. What is said of the predominance of learning on the side of re- ligion ? 3. To what purpose have discoveries in philosophy been sub- servient ? 4. What is the character of the present period ? LESSON 130. The Influence of an early Taste for Reading. There is, perhaps, nothing that has a greater tendency to decide favourably or unfavourably respecting a man's fu- ture intellect than the question, Whether or not he be im- pressed with an early taste for reading. Books arc the depository of every thing that is most honourable to man. He that loves reading has every thing within his reach. He has but to desire, and he may pos- sess himself of every species of wisdom to judge, and power to reform. The chief point of difference between the man of talent and the man without, consists in the different ways in which their minds are employed during the same interval : they are obliged, we will suppose, to walk from Temple-bar to Hyde-park Corner : the dull man goes straight forward, he has so many furlongs to traverse: he observes whether he meets any of his acquaintance ; he inquires respecting their health and their family; he glances his eye, perhaps, at the shops as he passes; he admires, perchance, the fashion of a buckle, and the metal of a tea-urn. If he experience any flights of fancy, they are of a short extent; of the same na- ture as the flights of a forest bird clipped of his wings, and condemned to pass the rest of his life in a farm-yard. On the other hand, the man of talent gives full scope to his imagination. Unindebted to the suggestions of sur- rounding objects, his whole soul is employed. He enters into nice calculations; he digests sagacious reasonings. In imagination he declaims, or describes, impressed with the deepest sympathy or elevated to the loftiest rapture. «e 282 THE MECHANICAL WONDERS OF A F LATHER. makes a thousand new and admirable combinations, lie passes through a thousand imaginary scenes, tries his courage, tasks his ingenuity, and thus becomes gradually prepared to meet almost any of the many-coloured events of human life. If he observes the passengers, he reads their countenances, conjectures their past history, and forms a superficial notion of their wisdom or folly, their virtue or vice, their satisfac- tion or misery. If he observes the scenes that occur, it is with the eye of an artist. Every object is capable of suggest- ing to him a volume of reflections. The time of these two persons in one respect resembles; it has brought them both to Ilyde-park Corner. In every other respect how dissimilar ! Probably nothing has contributed so much to generate these opposite habits of mind, as an early taste for reading. Books gratify and excite our curiosity in innumerable ways. They force us to reflect; they present direct ideas of various kinds, and they suggest indirect ones. In a well-written book we are presented with the maturcst reflections, or the happiest flights of a mind of uncommon excellence ; and it is impossible that we can be much accustomed to such com- panions, without attaining some resemblance of them. Godwin. LESSON 131. The Mechanical Wonelers of a Feather. Lam'ina (plural lamina?,) thin plate, one coat laid over another. Every single feather is a mechanical wonder. If we look at the quill, we find properties not easily brought together, strength and lightness. I know few things more remarka- ble than the strength and lightness of the very pen with which I am now writing. If we cast our eyes towards the upper part of the stem, we see a material made for the pur- pose, used in no other class of animals, and in no other part of birds ; tough, light, pliant, elastic. The pith, also, which feeds the feathers, is neither bone, flesh, membrane, nor tendon. But the most artificial part of a feather is the beard, or as it is sometimes called, the vane: which we usually THE MECHANICAL WONDERS OF A FEATHER. 283 strip off from one side or both when we make a pen. The separate pieces of which this is composed are called threads, filaments, or rays. Now, the first thing which an attentive observer will remark is, how much stronger the beard of the feather shows itself to be when pressed in a direction per- pendicular to its plane, than when rubbed either up or down in the line of the stem; and he will soon discover, that the thread of which these beards are composed are flat, and placed with their flat sides towards each other; by which means, while they easily bend for the approaching of each other, as any one may perceive by drawing his finger ever so lightly upwards, they are much harder to bend out of their plane, which is the direction in whicii they have to encouru- ter the impulse and pressure of the air, and in which their strength is wanted. It is also to be observed, that when two threads, separated by accident or force, are brought together again, they immediately reclasp. Draw your finger round the feather whicii is against the grain, and you break, pro- bably, the junction of some of the contiguous threads; draw your finger up the feather, and you restore all things to their former state. It is no common mechanism by which this contrivance is effected ! The threads or lamina? above men- tioned are interlaced with one another ; and the interlacing is performed by means of a vast number of fibres or teeth which the threads shoot forth on each side, and which hook and >— . 3.2-3 22 o E 1© o o o © © © © © X CO © © © v-0 © © © © © o OI © © © 5 © o © S s © CO S © —< _c 5 a i w 9 ti S-s-Js !*if I ■ 1 g. If 01 © oi 0 co -It © © O 35 o o CO 1—1 a c b o CO cc o 2 35 o _l= ".'1= • 1- C5 . c * *' Je © © © © © § gS c - m - o* * —. 5 CO D © 1>» © X CO -* o # X O! 01 # © # © S3 X 0* o 35 © © in CO § = " O 3 O* f CO CO o* o* o* © CO -3* © O* © © 1-©| s s © © co" si i> (M # © © ©~ X *0 a .as s -5 X 31 35~ ©" c s s Time of revolving round the sun. 1> 00 © © ©" X © © © © 1© ©~|of X CO 35 CO — It* 1 © >o © I-H © QO" X © CO Dis-tance in Mill-ions. 1^ co Xi CO 35 >* CO 0? 0* CO m 01 01 **> 1© © 35 o* n< I © © 35 © I © X 1 £ 1 c 3 1 CO >> 9 o S 1 3 c > H 1 3 si > g 3 1 s l 5 c, 3 3 to 3 d D ) Note. The planets receive light and heat from the sun according to the square of their distances, that is, light and heat decrease as the square of the distance increases. If the distance of one planet be called 1, of another 2, and of a third 3, the heat and light received at the first is 1 X 1 = 1, at the second 2x2=4 times less, or \, at the third 3x3=z9 times APPEND**. 299 less, or f The following rule may be given; as the square of the distance of any planet from the sun is to 1, which re- presents the light and heat received at the earth, so is the square of the earth's distance from the sun, to the degree ot light and heat received at the planet in question. The attraction of bodies decreases as the square of the dis- tance increases; the attraction is mutual, and greater or less according to their solid contents. The following is the rule for finding the distances of the planets from the sun :—as the square of the earth's period ot revolution round the sun is to the cube of its distance, so is the square of any other planet's annual period of revolution to the cube of its distance ; and the cube root of the number thus found will be the planet's distance from the sun. It was ascertained by Kepler and demonstrated by Newton, that from the combined forces of attraction and rectilinear motion, the squares of the periodical times or revolutions ot the planets are, as the cubes of their distances. It was as- certained by Kepler also, that if a line were drawn from the sun to the earth, this line would, by the earth's motion, pass over equal spaces, or areas in equal times. To such pupils as are sufficiently acquainted with Arith- metic the instructer should explain at large the particulars mentioned in the above note. Questions may easily be pro- posed and worked out by the above rules:—for instance, if the period of Mercury be 88 days, what is its distance from the sun ?—If the heat and light at the earth be 1, what is the degree of heat and light at Mercury? and so of other planets. To find how many times one planet is greater than ano- ther the rule is, cube the diameter of each planet, and di- vide the neater number by the less, the quotient will give the proportional magnitudes, or the number of times the one is greater than the other. LESSON 44. Fie 40 Engraving V. S represents the sun, and N S is the earth in different parts of its orbit. The white circle in the dark space represents the ecliptic. The dark circular space filled with stars extending eight degrees from each side of the ecliptic represents the zodiac. The names ol the signs of the zodiac and the characters which represent 300 APPP.NDIX. them are placed around the zodiac, as Aries, Taurus, &c. At March 20th, the earth as seen from the sun appears at the beginning of the sign Libra; but the sun as seen from the earth, at that time, appears at the beginning of the sign Aries. Some of the particulars mentioned in Lesson 44 should be illustrated by the instructer by means of globes, if access to them can be obtained, or by such sensible objects as he can prepare for the purpose. LESSON 45. Day and Night. Fig. 40. If the line N S, which repre- sents the axis of the earth, were always in the circle that divides the light hemisphere from the dark one, the days and nights would be every where equal; for an inhabitant at the equator, and one on the same meridian towards the poles, would come into the light at the same time, and immerge into darkness at the same time. But the line N S is not in this circle, but has more or less of the positions as represented at the sign Cancer or Capricorn, that is, at Dec. 23d or June 21st. Here it is plain that an inhabitant at the equator does not come out of the dark hemisphere or immerge into it at the same time with an inhabitant on the same meridian to- wards the poles. But while the earth is at Capricorn, an in- habitant on the north side of the equator is in the light hemi- sphere longer than in the dark; that is, the day is longer than the night. But at Cancer, an inhabitant on the north side of the equator is in the dark hemisphere longer than in the light; that is, the night is longer than the day : whereas at the equator, in all situations of the earth, day and night are equal. LESSON 46. Changes of the Seasons. Fig. 40. The variety of the seasons depends (1,) upon the length of the days and nights ; and (2,) upon the position of the earth with respect to the sun. In what manner the seasons are affected by the different lengths of the days and nights must be evident from what has been said above ; and as to the other circumstance, it is manifest from a mere inspection of the figure, that in June the sun's rays will fall more perpendicularly upon an inhabitant on the north side of the equator than in Dec, for APPENDIX. 301 N is turned towards the sun in June and from it in Dec. : it is warmer therefore at the former season than at the latter. But to render the subject more plain it may be proper to trace the annual motion of the earth in its orbit. About the 20th of March the earth is in Libra, and consequently to its inhabitants the sun will appear in Aries, and be vertical to, or over the equator. The equator and all its parallels are then equally divided between the light and the dark, and consequently the days and nights are equal all over the world. As the earth pursues its journey from March to June, its northern hemisphere comes more into light, and on the 21st of that month, the sun is vertical to the tropic of Can- cer. All the circles parallel to the equator are then unequal- ly divided; those in the northern half have their greater parts in the light, and those in the southern have their longer parts in darkness ; it is summer therefore to the inhabitants of the northern hemisphere, and winter to the southern. Trace the earth now to September, and the sun is found vertical again to the equator, and, of course, the days and nights are again equal. And following the earth in its journey to December, or when it has arrived at Cancer, the sun appears in Capricorn ; and it is vertical to that part of the earth called the tropic of Capricorn, and now the southern pole is enlightened, and all the circles in that hemisphere have their longer parts in the light, and, of course, it is summer to those parts, and winter to us in the northern hemisphere. Note. Since it is summer to all those parts of the earth, where the sun is vertical, and we find the sun is vertical twice in the year to the equator, and every part of the globe between the equator and tropics, consequently there are two summers in a year to all those places; and in those parts near the equator, they have two harvests every year. LESSON 48. Figures 42 and 43. The Tides. S the sun, M the moon, E the earth, represented as covered with water. When the waters at c fig. 42, are under the moon, they will be heaped up at c, and recede from the intermediate points a and b, and being less attracted on the opposite side will be heaped up also at d. The sun tends to raise tides at a and 6, but its only effect is to diminish those of the moon. In fie 26 b 302 APPENDIX. 43, both the moon and sun tend to raise tides at the same places as at a and b. LESSON 49. Eclipses, figures 44, and 45, Engr. VI. Fig. 45, repre- sents an eclipse of the moon. A F and BG are two straigh lines drawn from the opposite parts of the solar disk, touch- ing the surface of the earth at C and D. The moon m is seen passing through the earth's shadow in opposition to the sun. Besides the dark shadow of the earth, C F D G which would terminate in a point if continued far enough, there is another shadow C r s D, distinct from the former and called the penumbra, which is faint at the ed£>;cs towards r and S but becomes darker towards F and G. The instant the moon enters the earth's shadow at x, it is deprived of the sun's light, and is eclipsed to all in the illuminated hemi- sphere of the earth. As the shadow of the earth is but a little darker than the region of the penumbra next it, it is difficult to determine the exact time when the moon passes from the penumbra into the shadow, and from the shadow into the penumbra, that is, when the eclipse begins and ends. Fig. 44, represents an eclipse of the sun. As the sun constantly illuminates half the earth's surface, and as the moon's shadow falls upon but a part of this illuminated hemisphere, the sun therefore appears eclipsed to but a part of those to whom he is visible. Sometimes when the moon is at its gre;ite:-t dis- tance, its shadow o m terminates before it reaches the earth, and then to an inhabitant directly under the point o, the eclipse will appear annular. The other shadow C r s D i< the penumbra. Within the dark shadow, the sun is totally eclipsed, but within the penumbra, only a part of the sun's rays are intercepted, and the sun is partially eclipsed. The beginning and ending of a solar eclipse may be determined instantaneously. The penumbra, under the most favourable circumstances, falls upon but about half of the illuminated hemisphere of the earth. Note. The pupil should be taught to enlarge the above as well as other explanations of the figures. LESSON 60. Caloric. Different kinds of Thermometers. Fahrenheit's thermo- meter is universally used in Great Britain, and for the most APPENDIX. 303 part throughout the United States. In it, the range between the freezing and boiling points of water is divided into 180 degrees ; and as the greatest possible degree of cold was then supposed to be that produced by mixing snow and com- mon salt, it was made the zero, or commencement of the scale, hence the freezing point became 32" and the boiling point 212°. Reaumer's thermometer, which was formerly used in France, divides the space between the freezing and boiling of water into 80-'-, and places the zero at the freezing point. The Centigrade thermometer places the zero at the freezing point, and divides the range between it and the boiling point into 100°. This has long been used in Swe- den under the title of Celsius's thermometer. De Lisle's thermometer is used in Russia. The graduation begins at the boiling point, and increases towards the freezing point. The boiling point is marked 0 and the freezing point 150. LESSON 65. Simple Combustibles. The following is an enumeration and classification of the simple bodies in general. I. Compre- hending the imponderable agents, Heat or Caloric, Light, and Electricity. II. Comprehending agents capable of uniting with inflammable bodies, and in most instances of effecting their combustion,—Oxi/^tn, Chlorine, and Iodine. Many learned chemists have doubted whether Chlorine and Iodine were supporters of combustion, any farther than they contain oxygen. They are classed among the simple bodies because they have not, as yet, been resolved into other ingredients. The name chlorine is simply expressive of its greenish colour, and iodine of its violet colour. III. Comprehending bodies capable of uniting with oxygen, and forming with it various compounds,—1. Hydrogen, forming water. 2. Bodies form- ing acids. Nitrogen, forming nitric acid. Sulphur, forming sulphuric acid. Phosphorus, forming phosphoric acid. Car- bon, forming carbonic acid. Boron, forming boric acid. Fluorine, forming fluoric acid. 3. Metallic bodies, which have been divided into the seven following classes. 1st. The metals which combine with oxygen and form alkalies. These are potassium, sodium, and lithium. The volatile al- kali ammonia has been found bv Sir H. Davy to be a triple 304 APPENDIX. compound of nitrogen, hydrogen, and oxygen. 2d. Those metals which by combining with oxygen form the alkaline earths; viz. calcium, magnesium, barium, and strontium. Calcium is the base of lime, magnesium of magnesia, and so on. These metallic substances are of the colour of silver. 3d. Those metals which by combining with oxygen consti- tute the remainder of the earths. These are silicum, alu- mium, zirconium, glucinum, yitrimn, and thorinum. These are presumed metals, for the earths, of which they are sup- posed to constitute the bases, have been as yet but partially decomposed : respecting some of them little is known. 4th. The metals which absorb oxygen and decompose water at a high temperature. These are iron, tin, zinc, cadmium, and manganese. 5th. Those metals which absorb oxygen at different temperatures, but do not decompose water at any temperature. This class is composed of twelve distinct metals, viz. osmium, cerium, tellurium, titanium, uranium, nickel, cobalt, copper, lead, antimony, bismuth, and mercury. 6th. Those metals which do not decompose water, but ab- sorb oxygen, and are thereby converted into acids. These are arsenic, molybdenum, tungsten, chromium, columbium, and selenium. 7th. The metals which do not decompose water, nor absorb oxygen from the atmosphere at any tempera- ture. These are platina, gold, silver, palladium, rhodium, and iridium. LESSON 66. 1 Retort, fig. 48, Engr. VI. A vessel in the shape of a pear, with its neck bent downwards, used in distillation. The extremity of the neck may be fitted into another glass ves- sel, called a receiver. Fig. 48, represents a common glass retort, an instrument much used in chemical laboratories for various purposes. A tubulated retort is an instrument like the latter, with a tube at the bend T, and with aground glass stopper to fit it. This is the most useful kind of retort, as materials may be put in through the tube during the opera tion. The student may find engravings and descriptions of a chemical apparatus in Parkes' Rudiments of Chemistry. Note. Chlorine may be procured by heating in a glass retort a mixture of equal weights of the black oxyd of man- ganese and common muriatic acid (spirit of salt.) The gas APPENDIX. 305 •s soon liberated, and may be conveniently collected over warm water. The attraction of chlorine for the metals is in most instances extremely energetic : when copper leaf, or antimony, or arsenic in powder, are thrown into the gas, they immediately enter into vivid combustion and form binary compounds. Upon the French theory of combustion, oxy- gen is absolutely necessary to the phenomena, but here are in- stances of brilliant inflammation without the presence of that body (that is if chlorine be a simple substance, containing no oxygen.) Other cases might be adduced, such as the combustion which ensues when copper filings and sulphur are heated together in an exhausted vessel, or when potas- sium and arsenic are made to combine under .similar circum- stances. Combustion therefore is to be regarded as the general result of the exertion of powerful chemical attraction, and not as dependent upon any peculiar substance, or as re- sulting from the decomposition of any distinct form of matter. When phosphorus is introduced into chlorine, it sponta- neously ignites and burns with a pale yellowish flame, pro- ducing a white volatile substance, composed of two propor- tions of chlorine and one of phosphorus. LESSON 67. Electrical Machine, fig. 49. A the glass cylinder.—B the prime conductor.—R the rubber, or cushion.—C the chain. LESSON 68. Leyden Phial, fig. 50. A a round brass ball at the ex- tremity of a wire, which passes through a cork D. R is a discharging rod,—a a two brass knobs or balls attached to w ires which are fastened to the handle at x. LESSON 70. Voltaic pile, fig. 47. The pieces of copper, zinc, and woollen cloth, are supported with three rods of glass, as a b, a b, ab, and pieces of wood x and z. LESSON 71. Fig. 46. A B a trough made of baked wood.—w w are wires fastened to pieces of copper and put into the outer cells 26* 306 ATPFNDIX. —a a are little glass tubes to hold the wires by,—v is a glass plate on which the ends of the wires are to be brought to- gether. LESSON 76. Mineralogy. Werner divides the external characters of minerals into two kinds, namely, general and particular. The general characters are the following: 1. Colour; 2. Cohesion ; 3. Unctuosity ; 4. Coldness ; 5. Weight; 6. Smell; 7. Taste. The particular characters are the following: 1. Aspect of the surface ; 2. Aspect of the fracture ; 3. Aspect of the distinct concretions; 4. General aspect; 5. Hard- ness ; 6. Tenacity ; 7. Frangibility ; 8. Flexibility; 9. Ad- hesion to the tongue ; 10. The sound. General Characters. I. The colours of minerals are ex- tremely various. Werner conceives eight fundamental co- lours, and describes all the others as compounds of various proportions of these. The fundamental colours are, 1. Snow white. 2. Ash grey. 3. Velvet black. 4. Berlin or Prus- sian blue. 5. Emerald green. 6. Lemon yellow. 7. Car- mine red. 8. Chestnut brown. II. With respect to cohe- sion, minerals are either solid, friable, or fluid. III. With respect to unctuosity, minerals are distinguished into greasy, and meagre; the first have a certain degree of greasiness in the feel; the second not. The other four general charac- ters require no particular description. Particular characters. 1. In the aspect of the surface of a mineral, three things claim attention. 1. The shape of the mineral. 2. The kind of surface. 3. The lustre of the surface, whicii is either splendent, shining, glistening, glim- mering, or dull. II. When a mineral is broken, the new surface exposed is called the fracture. Three things claim attention: 1. The lustre of the fracture. 2. The kind of fracture. 3. The shape of the fragments. III. Distinct concretions are distinct masses, which may be separated from each other, without breaking through the solid part of the mineral, by natural seams. Three particulars with respect to these are, 1. Their shape. 2. Their surface, 3. Their lustre. IV. Under the head of general aspect, three particu- lars are comprehended, 1. The transparency. 2. The streak. 3. The soiling, or the stain left when rubbed. V. Minerals v APPENDIX. 307 arc either, I. Hard. 2. Semihard, or, 3. Soft. VI. With respect to Tenacity, minerals are, 1. Brittle, when on being cut with a knife the particles fly away with noise ; 2. Sectilc, when the particles do not fly off but remain; 3. Ductile, when the mineral can be cut into slices. VII. By Frangi- bility is meant the resistance which minerals make when we attempt to break them. The degrees are five, 1. Very tough; 2. Tough; 3. Moderately tough; 4. Fragile; 5. Very fragile. VIII. With respect to Flexibility, some are, I. Elastic; others, 2. Common; others, 3. Inflexible. IX. Some minerals adhere to the tongue, 1. Very strongly; 2. others moderately ; 3. others slightly ; f 4. and others very slightly. X. Some minerals give a ringing sound ; others a grating sound ; others a creaking sound, as tin. With respect to electricity, some minerals become electric when healed, others when rubbed, others cannot be rendered electric. The electricity of some is positive, of others nega- tive. LESSON 79. Silver and Mercury. Freezing mixtures. Salts dissolved in water, ice, or snow dissolved in nitric and muriatic acids, reduce the temperature of the mixtures a great number of decrees. Mercury has been frozen or rendered solid, even in "summer, though it requires the temperature of 39° below zero at least to congeal that metal. Four parts of caustic potash crystallized, and reduced to a fine powder, mixed with three parts of snow sinks the mercury in a thermometer from '3<>o above to 51° below zero. Two parts muriate of lime mixed with one of snow, sinks it from zero to 66° below zero The cause is, that the mixture has a larger capacity for caloric than would be derived from blending the two ca- pacities of the ingredients, and taking a mean proportional between them. LESSON 91. Roots, Stems, Buds and Leaves. The generality of roots may be arranged under the following heads. 1. A Ftbrous TJot, consisting only of fibres eitherf branched oi^mded Manv grasses and the greater part of annual herbs Havestftis kind'of root 2. A Coping Root, as in Mint. 3. A $»» 308 APPENDIX die-shaped or Tapering Root, as the Carrot, Parsnip, and Red Clover. 4. An Abrupt Root, is naturally inclined to «' the last mentioned form, but from some decay or interruption in its descending point, it becomes abrupt, or as it were bit- i ten off. It is found in many of our native Violets. 5. A • Tuberous or Knobbed Root, is of many different kinds, as in the Potatoe and the Artichoke. Several of the Pea kind are furnished with them on a smaller scale. 6. A Bulbous Root, is either solid, as in the Crocus ; tunicate, composed of concentric layers, as in the onion; or scaly, like that of the Lily. 7. A Jointed or Granulated Root, as in the Wood Sorrel and White Saxifrage. It is evident that fleshy roots, whether of a tuberous or bulbous nature, must at all times powerfully resist the drought. The common herdsgrass, or Timothy, when growing in pastures that are uniformly moist, has a fibrous root, but in dry situations, it acquires a bulbous one. This is an evident provision of nature to guard the plant against too sudden a privation of moisture from the soil. The seven kinds of stems are as follows. 1. Caulis, a stem properly so called, which bears or elevates from the root, the leaves or flowers. The trunks and branches of all trees and shrubs come under this denomination, as well as of a greater proportion of herbaceous plants. 2. Culmus, a straw or cvim, is the peculiar stem of grasses, rushes, and plants near- ly allied to them. 3. Secpus, a stalk, springs from the root, and bears the flowers and fruit, but not the leaves, as in the Primrose and Cowslip. 4. Pedunculus, the Flower-stalk, springs from the stem, and bears the flowers and fruit, but not the leaves. 5. Petiolus, the Foot-stalk, or Leaf-stalk. This term is applied exclusively to the stalk of a leaf. 6. Fruns. A Frond. In this the stem, leaf, flowers, and fruit are produced from the leaf itself as in the Fern tribe. 7. Stipe*, Stipe, is the stem of a frond, which in ferns is com- monly scaly. Botanists enumerate above 100 distinctions of leaves, ac- cording to their position and form. There are several kinds of appendages to a plant which were not mentioned in any of the Lessons on Botany. 1. Stipula, Stipule, a leafy appendage to the proper leaves or to their footstalks. They are usually found in pairs at the base of the petiole. In the common Pea they are round, and in APPENDIX. 309 other plants they assume other figures. In the natural order of Grasses it is solitary, forming a membranous scale, which arises from the summit of the sheath, and like it encloses the culm. 2. Bractca, The Floral Leaf, a leafy appendage to the flower or its stalk. It is of a variety of forms. 3. Spi- na, a thorn, whicii proceeds from the wood itself. 4. Acu- leus, a prickle, arises from the bark only and comes off with it. 5. Cirrus, a tendril. This is intended solely to sustain weak and climbing stems upon more firm and sturdy ones. Tendrils or claspers when young are usually put forth in a straight direction ; but they presently become spiral. 6. Glandula, a gland, a little tumour discharging a fluid. They occur in the substance of the leaves of the Myrtle, Lemon, and common St. John's Wort. 7. Pilus, a hair. This is an excretory duct of a bristle like form. In the Nettle it is tu- bular and pervious, having each a bag of poison at its base, like the fang of a serpent. But the hairs which clothe many plants are merely a protection against cold, heat, or insects. The several kinds of Inflorescence, or modes of flowering are as follows. 1. The Umbel, a number of flower stalks is- suing from a common centre, diverging like the rays of an umbrella, bearing their flowers on the summit, and raising them about the same height. The Carrot, Parsnip, and Hemlock are familiar examples, which, with all others like them in this respect, are called umbelliferous plants. 2. A Ci/me has the general appearance of an umbel, and agrees with it so far that its common stalks all spring from one cen- tre, but differs in having those stalks variously and alternate- ly subdivided, as in the Elder and other species of Viburnum. 3. A Corymb is a spike whose partial flower stalks are gradually longer as they stand lower, so that all the flowers are nearly on a level. The flowers of Yarrow grow m this manner. 4. A Fascicle is an assemblage of flowers more densely arranged than in the Corymb, as in the Sweet-Wdl- iam 5. A Soike is an assemblage of flowers arising from the sides of a common stem, as in the herdsgrass. The flowers are commonly all crowded close together but some- times they form separate groups, as in some Mints, b. A Raceme, or cluster, as in the Currant. /. A Head, or luit, (capitulum) is an assemblage of flowers upon the extremity of the branch or stem, and arranged in a globular, oval or cylindrical form, as in the Globe Amaranth, and in several 310 APPENDIX. species of Clover. 8. A Whorl ( Verticilhts) is an assem- blage of flowers surrounding the stem or its branches, as in the Dead Nettle and Mint. 9. A Panicle bears the flowers in a sort of loose subdivided bunch or cluster, without any order, as in the Oat. 10. A Thyrse is a dense or close pani- cle, more or less of an ovate figure, of which the Lilac is an example. LESSON 92. Flower and Fruit. The Calyx, Flower-cup, or Empale- ment, as it is sometimes called, is divided into seven kinds. 1. A Cup, (Perianthurn) properly so called, as in the five green leaves which encompass a Rose. 2. A Fence, (Involucrum) as in the Hemlock or Carrot. 3. A Catkin (Amentum) as in the Willow or Hazel. 4. A Sheath, (Spatha) as in the Snow-drop or Narcissus. The Spatha sometimes en- closes a Spadix, or elongated receptacle, as in Dragon-root. In Indian corn, the spadix is enclosed by leaves or husks; in the Sweet Flag, it is naked. 5. A Husk, (Gluma) as in oats, wheat, or grasses. 6. A Veil, or scaly sheath, (Peri- chaetium) as in some mosses. 7. A Cap, or Wrapper, ( Volva) as in mushrooms. The seed-vessel (Pericarpium) is also divided into seven 'kinds. 1. A Capsule, as in the poppy. 2. A Pod, (Siliqua) as in wall-flower and honesty. 3. A Legume, or Shell, as in pea and broom. 4. Drupe, as in cherry and peach. 5. A Berry, (Bacca) as in elder and gooseberry. 6. A Pome, as in apple and pear. 7. A Cone, (Strobilus) as in fir and pine. A Seed is composed of several parts. Embryo, or germ called by Linnaeus Corcvlum, or little heart. The Cotyle- dons or seed-lobes, immediately attached to the embryo. Albumen, or the White, a farinaceous substance to nourish the germinating embryo. The Yolk, ( Vitellus) less general than the other parts already mentioned, but absorbed, like the albumen, for the nourishment of the embryo. The Skin ( Testa) contains all the parts of a seed above described, giving them their due shape. The Scar, (W'um) the point by which the seed is attached to the seed-vessel, or recepta- cle. The Pellicle, closely adhering to the outside of some seeds, so as to conceal the proper colour and surface of their ^ APPENDIX. 311 j skin. The Tunic, (arillus), a complete or partial covering of | a seed, fixed to its base only, and mare or less loosely, or close- j ly enveloping its other parts. The Seed-down, (Pappus,) the i chaffy, feathery, or bristly crown of many seeds that have no Pericarp. Its use is to transport seeds from their native spot, as in the Thistle, and Dandelion. The Tail, (Cauda,) formed from the permanent style, and generally of a feathery, hairy appearance. Beak, (Rostrum,) an elongation of the seed-vessel, though applied to some naked seeds. A Wing (Ala) is a membranous appendage to seeds, or their cap- sules. The Awn is usually an appendage to the flower and seeds of grass-'s Seeds are occasionally furnished with spines, hooks, scales, &c., designed for their security while living, and for their subsequent dispersion. LESSON 93. Table of the 24 Classes. 1 Monandria... . 1 St *nen. Pigeon's foot and Star wort. 2. Diandria.... 2 stamens Pennyroyal, Lilac. 3. Triundria .. . . 3 do. Blue flag, Hcrdsgrass. 4. Tetrandria.. . 4 do. Chequer berry, Witch hazel. 5. Pentandria .. . 5 do. Swamp Pink, Mullein, Violet. 6. Hexandria. . 6 do. Barberry, Lily, Sweet Flag. 7. Heptandria . 7 do. Horse chestnut. 8. Octandria . . 8 do. Blue berry, Crane berry. 9. Enneandna. 9 do. Sassafras, Fever bush. 10. Decandria. . 10 do. Ground Laurel, Chickweed, Pink. 11. Dodecandria .12 do. Purslane, Wild Ginger. 12. Icosandria.. . 20 do. or more, inserted into the Calyx. Rose. ens, inserted into the recepta- 13. Polyandria. . . Many Stam cle. Buttercups. 14. Didynamia.. .4 Stamens ; 2 long and 2 short. Spear-mint, Catmint. 15. Tetradynamia 6 do. 4 long and 2 short. Mustard. 16. Monadelphia . Filaments united at bottom, but separate at top. Mallow. 17. Diadelphia . Filaments in two sets. Fumitory, Lupine.. 18. Polyadelphia . Fil aments in many sets. St. John s Wort. 312 APPENDIX. y 19. Syngenesia.. Anthers united into a cylinder; flowers compound. ^ 20. Gynandria. .. Stamens and pistils together. Ladies i Slipper. A, 21. Monoecia.... Stamens and pistils in separate flowers, upon the same plant. Nettle, i 22. Dioecia......Stamens and pistils in separate flowers, upon different plants. Hop. 23. Polygamia .. Variously situated. 24. Cryptogamia. Flowers inconspicuous. The names of the classes, which at finA sight appear dif- ficult, are formed of Greek words, expressive of the charac- ters of each class; and those of the first ten classes may be easily remembered, by considering the word andria, as meaning the same as stamens, and annexing it to the Greek numerals. The names of the orders, like those of the classes, are formed from the Greek numerals, but with the addition of . the word gynia, instead of andria; so that when there is but one pistil, the plant is said to be in the order monogy- nia ; if there arc two, digynia, &c. Names of the Orders of first 13 Classes. Trigynia .... . . . 3 do. Tetragynia . . . . . . 4 do. Pentagynia. . . . . . 5 do. . . 6 do. . . 7 do. . . 8 do. Enneagynia . . . . . 9 do. . . 10 do. . . . 12 do. The 14th class has only two orders; gymnospermia, in which the seeds are naked at the bottom of the calyx; and angiospermia, in which they are enclosed in a seed vessel. Examples of the first are spearmint, motherwort, and catmint, and of the second, cow-wheat, toad-flax, and beech-drops, APPENDIX. 313 The two orders of the 15th class are distinguished by the form of the fruit; the first, called siliculosa, has broad short pods, as in pepper-grass or wild-crtss ; and the second, called siliquosa, is known by its long pods, as in wild radish and common mustard. The orders of the 16th, 17th, and 18th classes, are characterized by the number of stamens in each flower, and the names of some of the classes, therefore, are used to distinguish them, as Triandria, Decandria, Polyan- dria, &c. The 19th class has five orders, 1st, aqualis, all the florets with stamens and pistils, and all fertile ; as dan- delion, burdock, and cotton thistle : 2d, superflua, florets of the disk, or surface with stamens and pistils, those of the margin with pistils only, all fertile, as common life-everlast- ing, white weed, and elecampane : 3d, frustanea, florets of the centre with stamens and pistils, fertile; those of the margin with pistils only, barren, as the sunflower: 4th, ne- cessaria, florets of the centre with stamens and pistils, bar- ren ; those of the margin with pistils only, fertile, as what is called high water shrub, growing about the borders of salt marshes : 5th, segregata, comprehends such flowers as have tubular florets, all perfect, each floret having its own sepa- rate calyx, in addition to the general calyx, which includes all the florets, as the globe-thistle. The orders of the 20th, 21st, and 22d classes are distinguished by the number of sta- mens. The 23d class has three orders, 1 st, moncecia, barren, fertile, and perfect flowers, found in one plant, as poke root, or American hellebore: 2d, dicecia, barren, fertile, and per- fect flowers on different plants, as ginseng, swamp maple, rock maple, and white ash : 3d, tricecidf'the same on three sepa- rate plants; of this, the figtree is supposed to be a solitary, though doubtful example. The 24th class has 5 orders, Filiees, Ferns ; Musci, Mosses; Hepatica, Liverwort; AlgeB, Flags; Fungi, Mushrooms. The term, Alga;, was original- ly applied to marine plants, as sea-weeds, but it has been employed in a more extensive sense, and, among others, em- braces the Lichens which cling to rocks. Note. The 21st, 22d, and 23d classes have been abolished by some writers. . The instructor should read and explain to his pupils the names of the classes and orders, ana! point out the circum- stances on which their distinctions are founded, by the help of engravings, or real specimens.* . . It may be proper to give an example of the division ot 27 614 APPENDIX. classes, orders, genera, and species. The geranium, from its having ten stamens united in one set, is in the class . Monadelphia, and order Decandria : the whole family of the 1 plant geranium constitutes a genus of the order above men- « tioned; and the different kinds, as ivy-leaved, rose-scented, , spotted (or Cranesbill,) wood geranium, &c. are the different species of the genus. To distinguish the species of a plant, botanists employ two words ; the first which is called the generic name, is common to all the species of the same genus; and the second, termed the specific name, is confined to a single species. For ex- ample, rosa damascena, which is the botanic name for the damask rose, rosa is the generic name applicable to the whole genus or family of roses, and damascena is the specific name, used to distinguish the particular kind or species of rose. Rosa alba, or white rose, is another species. Sweet Briar is a species of rose, called Rosa rubiginosa. The genus Rosa is in the class Icosandria, having 20 or more stamens, in- serted on the Calyx, and in the order Polygynia, having many pistils. The Lily is represented in the upper part of Engr. VII. It belongs to the class Hexandria, order monogynia, having six stamens as c c c c cc, and one pistil as d. Its corolla is composed of six petals, as bbbbbb. The Lily has no calyx. Fig. 7 is an enlarged view of the pistil; g its receptacle or base, and d its style. Fig. 5 e, is the seed vessel or pericar- pium, with its pistil represented as withered. There is an enlarged view also of a stamen with its filament, anther, and pollen. Figures 1, 2, 3, 4, represent a Geranium with several of its parts separately sketched :—a, calyx five leaved, and 1, the same separated from the stem :—b b b b, the corolla, com- posed of five regular obcordate petals: the petals are called obcordate, because they are heart-shaped with the point in- ward or downward, as may be seen in b 2, which represents one of the petals apart from the rest.—The nectary in the spotted geranium consists of five glands, as i i i i on the base of the longer filaments, c c cc, four which only are repre« sented in fig. 3.—d 4, a*pistil, and/ its seed or fruit. The bottom fig. h h represents the base, or receptacle of the cotton thistle; it is cellalar like a honeycomb, APPENDIX. 316 LESSON 95. Animal Kingdom. I. Vertebral Animals. 1. Mammalia, viviparous, and nourish their young with milk. 2. Birds, oviparous. 3. Reptiles, as frogs and serpents. 4. FisUes. The two first of the above classes are warm blooded, and the two last cold blooded. II. Invertebral Animals. 5. Insects.* 6. Crustacea, as the lobster and crab. 7. Mollusca, as the oyster, clam, and cuttle fish. 8. Vermes, or worms, as the leech, earth worm, and hair worm. 9. Zoophytes, as the star fish, sponges, corals, and madre- pores. Note. According to the Linnaean arrangement, which will be found in most works that treat systematically of na- tural history, all animals are divided into six classes, 1. Mam- malia, 2. Birds, 3. Amphibia, 4. Fishes, 5. Insects, 6. Worms. LESSON 96. Orders of Mammalia. 1. The Bimana or two handed animals. Man is the only example. He has hands upon his superior extremities alone. He has nails of a thin and delicate texture, which give to his thumb and fingers a wonderful delicacy of touch. 2. The Quadrumana or four handed animals, comprising apes, monkeys, and baboons. They have hands upon all four of their extremities, but less perfect than those of man. 3. The Carnivora or carnivorous animals. These have no hands, but their feet are furnished with claws. Note. These three orders have all the three kinds of teeth, which differ however in shape and strength, according to the habits and food of the different species. .... ., ,,.. „,, ._, .. „ ----------....... '"■"■ -------V V" V* 316 APPENDIX. 4. The Rodentia or gnawers. They have no canine teeth; and their claws are similar to those of the carnivora. 5. The Edentata or toothless animals; so called because they are deficient always in thev incisive teeth, and some- times have no teeth at all. 6. The Ruminantia or ruminating animals are those which chew the cud. They are cloven footed, and have more- over no incisive teeth in the upper jaw. 7. The Pachydermata or thick skinned animals. This order includes a considerable variety of other animals with hoofs, but which do not ruminate. 8. The Cetacea, or animals of the whale kind, distinguished by having no posterior extremities, and their anterior so con- structed as to answer the purpose of fins, as whales, porpoises, and dolphins. 9. The Marsupial animals are distinguished from all others by the possession, in the female, of a bag or pouch (marsupium) on the outside of the abdomen, for the purpose of holding their young after birth. Note. Linnaeus divided the class mammalia into seven orders; 1. Primates, of this order man was placed at the head, and next him, the ape, monkey, Oran-outang, and bat. 2. Bruta, as the elephant, sloth, and ant-eater. 3. Fera, as the seal, dog, cat, and hedge-hog. 4. Glires, as beavers, mice, and hares. 5. Pe- cora, as oxen, sheep, goats, and others. 6. Bellua, as the horse, hog, and the tapir. 7. Cetce, as the whale tribes. LESSON 97. Birds. The orders of Birds according to Linnaeus are, 1. Acci- pitres. 2. Pica, or the pie kind, as parrots, ravens, crows, &c. 3. Anseres, or the duck kind. 4. Gralla, or the crane kind. 5. Gallina, or the poultry kind. 6. Passerest or the sparrow kind. LESSON 98. Linnaeus divided his class Amphibia into four orders 1. Reptiles, as the crocodile, tortoise, lizard, frog, &c. 2. Ser- pents, as the rattle-snake, viper, &c. 3. Meanies, as the si- ren. 4. Nantes, as torpedoes, sharks, &c. APPENDIX. 317 LESSON 102. Vermes. Linnaeus divided Vermes or worms into five orders, 1. In* testinal worms, as tape worms, leeches, &,c. 2. Molluscous worms, chiefly inhabiting the sea. 3. Testaceous worms, as muscles, oysters, snail9, &c 4. Zoophytes. 5. Infusoria, or animalcules. Note. In treating of any particular animal, naturalists are accustomed to designate it by a name derived from its genus and species. This name is comprised of two words; the first being the name of its genus; and the second being altogether arbitrary, or else expressing some circumstance relating to the colour, size, or residence of the animal, which serves in a degree to distinguish it from others. The first is called its generic, the second its trivial or specific name. For example: in the class Mammalia, order carnivora, the genus Felis includes all those of the cat kind (Felis being the Latin word for cat) and these animals, although differing one from another very much in size and colour, have yet a very close resemblance in their general form, figure, charac- ter, and habits of life. The different species of the genus Felis are distinguished from one another in the following manner:—The Lion is called Felis leo; the Tiger, Felis tigris; the Leopard, Felis leopardus ; the Lynx, Felis lynx, &c. In the genus Canis, the dog is called Canis domesti- cus ; the wolf Canis lupus ; the fox, Canis vulpes, &c. In the class of Birds, order accipitres, the genus Falco includes those of the eagle or hawk kind:—The fierce eagle is called Falco ferox, the common falcon, Falco communis, the Ameri- can brown hawk, Falco fuscus, &c The Lessons on Zoology, in this Class Book, have been abstracted from Dr. John Ware's edition of Smellie's Phi- losophy of Natural History ; chiefly from the Introduction, which was wholly prepared by Dr. W., whose system of clas- sification is principally derived from Cuvier, a celebrated French naturalist. The class of insects, however, is ar- ranged in orders according to the system of Linnaeus. Be- sides the above, the following works have been consulted, and from many of them extracts made. Conversations on Natural Philosophy ; Webster's Elements of Natural Phi- losophy : Blair's Grammar of Natural and Experimental 27* 318 APPENDIX. Philosophy; Blair's Universal Preceptor; Blair's Class Book; Joyce's Scientific Dialogues, 3 vols. I2mo. Wil- kins' Elements of Astronomy; Parkes' Rudiments of Chemistry; Conversations on Chemistry ; Thomson's Sys- tem of Chemistry, 4 vols. 8vo.; Wakefield's Introduction to Botany ; Smith's Introduction to Physiological and Syste- matical Botany ; Sumner's Compendium of Physiological and Systematic Botany; Bigelow's Collection of Plants of Boston and its Vicinity ; Conversations on Political Econo- my ; Kett's Elements of General Knowledge; Paley's Natural Theology; Paley's Moral Philosophy; Brown's Lectures on the Philosophy of the Human Mind ; Rees' Cyclopaedia; Nicholson's Encyclopaedia; North American Review; United States Literary Gazette. THE END. 41 11. r^> 17 }>. �5918713 o 2MV0JV jICBmtzzcrJ&&x*mz&aiart V VI. -SST /^HTWiar.....Ill y; ^ J fa____ /■•■■ - ❖ ■ ■* • 7. ' ? P