OPINIONS OF THE WORK. Prom JOHN HOMAJNTS, M. D. 129 Tremont Street, Boston, Nov. 5, 1859. DR. Garratt. Dear Sir: I am happy to learn your intention to publish a treatise on Electro-Therapeutics, or the medical and surgical uses of Electricity. Such a work, by an educated physician who has bestowed much time and labor on the subject, both in study and practice, setting forth the value of this often neglected and sometimes misapplied agent in the treatment of a large class of diseases, will supply a want long felt by intelligent medical men, and cannot fail to be well received. The division of the subject into the different chapters, as indicated by you, appears judicious. I am very truly yours, JOHN HOMANS. From "WALTER CHAINING, M. D. " This large octavo volume is illustrated abundantly by descriptions, and drawings of instruments, both original and selected; by anatomical sketches, and by cases in which electricity has been employed, together with the limitation of its uses. What has particu- larly struck and pleased us in our examination of Dr. G.'s work, is the patient minuteness which every where marks his treatment of his subject. Nothing seems to have been over- looked. It is a very valuable work." Prom EDWARD H. CLARKE, M. D., Professor of Harvard University. Boston, June 5, 1860. Alfred C. Garratt, M. D. Dear Sir: It gives me great pleasure to acknowledge the receipt of your work on Electro-Physiology and Electro-Tiierapeutics. I shall read it at my earliest leisure, and hope to derive equal pleasure and profit from its perusal. The subject of the Medical Uses of Electricity is one of great importance, and but little understood. I hope your labors may be the means, not only of enlightening medical men with regard to it, but of awakening the attention of other observers. Please accept my best thanks for your book, and may you long be enabled to pursue the path you have entered on..... Very truly yours, EDWARD H. CLARKE. Prom J. V. C. SMITH, M. D. Boston, June 15, 1860. Dear Sir: Your industry and profound attainments in the domain of that special branch of the medical profession to which your powers have been directed, as exhibited in the beautiful volume presented to me, must result most favorably for your scientific and literary reputation. It is a monument which your descendants, in after times, will contemplate with proud satisfaction. Very truly, I have the honor to be your obliged friend and servant, A. C. Garratt, M. D. j- v- C> smith- Prom the Boston Medical and Surgical Journal. " This volume, dedicated to our friend John Romans, M. D., President of the Massachu- setts Medical Society, is a very full and elaborate contribution to the medicinal powers and uses of Electricity. Dr. Garratt has sought, in the best authorities at home and abroad, and in their original sources, the whole literary history of this important subject, and has 2 OPINIONS OF THE WORK. presented it after a manner which deserves, and we believe will receive, the careful study of the profession. It is in Avorks like this, which come directly out of the deep interest of the authors in their subjects, and from abundant experience concerning them, that a pro- fession gains useful and important light, which enables it to put them to the full test of practical uses. We close with quoting the last paragraph of this very interesting and val- uable work: — " ' Medical Students : Our investigations in this intensely interesting field of medical lore must here draw to a close. Let us now congratulate ourselves and thank God for this day and opportunity of seeing under standingly so much of this new phase of our noble art. I said to you in the Preface, that we were rich in the materials for a systematic Avork of this kind, and now say again, that we feel still burdened Avith the untold matter that so interests ourselves, and Avhich we desire you to know. But the original bounds of this work are already far exceeded ; I therefore only will remind you, with a parting emphasis, of the beautiful aphorism of Dr. Altheus, (who, by the way, has written well on this subject,) that " it is not electricity that cures diseases, but the physician who may cure disease by the means of electricity." In a Avord, it is the method and skill directing' this agent that gives the success.'" Prom the Louisville Medical Journal. " There is no similar work in the English language; therefore this treatise by Dr. Garratt will supply an actual want heretofore felt by the profession." Prom the Chicago Medical Examiner. " From a careful examination of its contents, we are confident that the medical profession Avill be under lasting obligations to Dr. Garratt. The Avork is both scientific andpractical; a book which should be in the hands of every medical student; and no medical library will be complete hereafter without it." Prom the New York Tribune. " The special subject to which this volume is devoted is the medical and surgical uses of Electricity. The author has given many years to the study of the subject, and in prepar- ing this work at the suggestion of many eminent medical men in different parts of the United States, he has combined the results of his own clinical experience with those of the highest practical authorities. The volume abounds in statements of the greatest interest and value to the student of physiology, as well as to the medical practitioner, and is founded on a strictly scientific basis." Prom the New York Independent. "We can commend without hesitation, to professional men, a portly octavo (now lying before us) on the ' Medical Uses of Electricity; by Alfred C. Garratt, M. D. This thorough and learned Avork is designed for'medical students ' — a phrase which designates a very large class, inasmuch as no good physician ceases to be a student in medicine till he retires from the practice of his learned and liberal profession. Dr. Garratt's book, if we mistake not, is the most comprehensive and systematic work on this subject in the English language." Prom the Philadelphia Enquirer. "Beyond all question, there is no work, British or American, on this subject, which, for exhaustiveness and logical acuteness of reasoning, can be compared with this large and valuable treatise. AH our observation of late leads us to the conclusion that there is much importance in the subject Avhich Dr. Garratt so learnedly discusses in this treatise." Prom the Cincinnati Journal of Rational Medicine. " The past month has been somewhat prolific in the productions of publications of interest to the profession ; and among the most novel and important books, no one in likely to command more attention than a work on Electro-Physiology and Electro-Tiiera- peutics, by Alfred C. Garratt, M. D., of Boston. It is an elaborate and comprehensive preu- OPINIONS OP THE WORK. 3 entation of important scientific and therapeutic facts, too seldom even slightly understood by the profession. ^ The publishers have done their part admirably, making this book a model one. The only objection that can be raised is, that they have made the book too good; and that its expensiveness may limit its sale. Price $4.00." Prom the Louisville Medical News. " It is doubtless true that the great majority of specialists are the most consummate quacks, and it is equally true that from the investigations of other honorable specialists the cause of truth has been most illuminated. It is the part of wisdom, therefore, to discriminate between these two elasses. It is very easy to determine to which of these classes the author of the noble work before us belongs. (Garratt on the Medical Uses of Electricity,) and equally easy to perceive that he is a gentleman of learning, and a profound and prac- tical thinker. A careful perusal of the work will convince any one, that judgment formed from the opinions or treatment of travelling or local electropathists may be very unjust, and that there is a veritable potency in the modification of electricity for the treatment of disease, which Ave may not safely ignore. The author's propositions, and the scientific bases claimed for them, are modestly suggested. The work is published by Ticknor & Fields, of Boston. It is beautifully executed and illustrated, and if the profession be true to its own interest, another edition will soon be demanded." From the Georgia Medical and Surgical Encyclopedia. The work before us (Medical Uses of Electricity by Garratt) is one which we can recom- mend to our friends with pleasure, for by its study they will obtain both knoAvledge and profit. He treats this subject calmly, deliberately, and scientifically, — an honor to himself, and a credit to his country. This Avork should be in the hands of every student of medicine, of every practitioner in the land. If the profession is true to themselves, their own interests, and the interests of their patients, several editions will have to be issued to supply the demand. Prom the Medical and Surgical Journal, St. Joseph, Mo. " The author (Dr. Garratt) has produced a very valuable work on the medical and surgi- cal uses of Electricity; the first attempt at a complete and systematic work on this sub- ject, we believe, ever made in America. How striking the coincidence, that Boston, the first home of Dr. Benjamin Franklin, should produce this work! We regard this book as a great boon to the profession, and as furnishing information that a majority of medical men now require, and cannot longer, Avith credit to themselves, fail to possess. Royal 8vo., 700 pages, 100 cuts. Price $3.00." H^° Whoever has an electro-magnetic apparatus, or a magneto-electric ma- chine, or a Galvanic battery, (primary current,) and intends using either of these for Neuralgia, Rheumatism, Paralysis, &c., should have at hand a copy of this work, which gives very plain and practical directions as to how, where, and when to employ electricity as a remedy with safety as well as success. ICf By sending $3.00, by mail or otherwise, to Dr. A. C. Garratt, No. 7 Hamilton Place, Boston, Mass., the book will be forwarded free of expense. It may also be found at the bookstores throughout the country « 'M ELECTRO-PHYSIOLOGY AND ELECTRO-THERAPEUTICS SHOWING THE BEST METHODS 'f^L5 View of Terminal Nerve Fibrils highly magnified............162 View of Elementary Muscle Fibres highly magnified...........163 VieAV of the Electric Fishes,...................183 " " " Motor Nerve Terminal Fibrils magnified...........200 " " " Brain shoAving its Base,................220 " " " Spinal Column,...................223 " " " Cerebro-Spinal Axis..................22! " " " Spinal Cord, Posterior Aspect,..............22o View of a piece of the Spinal Cord, Natural Size,............^'-(> View of the Ear, External and Internal, Anterior View,.........233 VieAV of a piece of the Auditory Nerve magnified, ...........231 View of the Sympathetic System of Nerves, .............247 u << « «Regions" of the Human Body,.............251 " " " Organs of Digestion,.................253 " " " Muscles on the Face and Neck,.............266 " " " Muscles on the Back of the Trunk,............269 " " " Muscles on the Back of the Second Layer,.........273 " " " Muscles on the Front of the Body,............275 " " " Muscles on the Sides of the Body,............276 " " • " Various Muscle Fibres,................277 u « « paciai Nerve, (Portio Dura,)..............432 « « « Tri-Facial Nerve, (Fifth Pair,)..............436 " << « Pneumogastric Nerve,..................443 " " " Nerves of the Throat and Ganglia in Neck,.........445 ii « a Brachial Plexus and Arm Nerves, ............448 u ii u Nerves and Blood-vessels at Bend of ElboAv,.........449 ii u ii Nerves on the Front of the Forearm............450 u u ii Nerves on the Back of the Forearm,............451 « " " Lumbar and Sciatic Plexuses,..............458 ii ii ii Greater Femoral (Crural) Nerve,.............463 u u u Great Sciatic (Ischiatic) Nerve..............465 u it ii Popliteal Nerve and its Branches, ............466 u u ii Posterior Tibial Nerve, ................467 u u u Terminal Branches of the Posterior Tibial Nerve of the Foot, . . . 468 " " " Anterior Tibial Nerve.................469 View of all the Muscles of the Human Body, (anterior aspect,).......473 View of all the Muscles of the Human Body, (posterior aspect,)......475 View of the Muscles on the Front of the Forearm and Hand,.......525 " " " Muscles on the Palm of the Hand.............526 u u u Muscles on the Back of the Forearm,...........540 u ii u Muscles on the Back of the Hand,............542 u u ii Muscles about the Hip-joint,..............544 u u i< Muscles on the Back of the Thigh,............545 " " " Muscles on the Front of the Thigh,............546 u u u Muscles on the Front of the Leg,.............547 ii u u Tjpper and LoAA'er Jaws, Avith Teeth in situ,.........663 View of a Smee's Portable (constant) Battery for Office Use.........667 VieAV of Drake's Apparatus for Spinal Curvature, and his Apparatus for Paralyzed Limbs, as peculiarly adapted to Cases of Spasmo-Faralysis in Children, . . . 552 ELECTRO-TIIERAPEUTICS. CHAPTER I. NATURAL ELECTRICITY. In the physical sciences it is now assumed that all bodies, ani- mate and inanimate, contain a subtile influence which Philoso- phers have from time to time designated as Natural Electricity. This influence has two distinct characters. It is divided into these two parts by natural, as well as by artificial disturbances ; yet is it subtile, invisible, and imponderable. These divisions are now familiarly known as positive and negative electricities, whose tendency is to coalesce, and form that equilibrium which we call natural electricity. The particles or molecules of the one kind, always attract those of the other, or opposite kind. The mole- cules of the same kind, be they positive or negative, always repel their fellows of the same order. Although ever tending to obtain a counterpoise for a rest, yet as easily and perpetually are these two electricities unbalanced, even so sure as our re- volving globe receives her accession, duration, and declination of solar rays. So also, whatever disturbs any molecule of matter, fluid or solid, as heat, friction, or chemical action, as also mag- netism and vitality, liberates active electricity. The relative greatness of quantity and of tension of the given electricity, varies even to the greatest extreme, according to its source ; but its nature is always one and the same. (15) 16 ELECTRO-THERAPEUTICS. It is presumed that every intelligent practitioner of medicine, in these days, understands the fundamental Laws of Electricity; but the author makes here a free but easy rehearsal of so much of those laws and conditions, to which in its respective forms Electricity is obedient while acting upon, or traversing through, the different living tissues of the human organism, as will prove a sufficient vade mecum, in its department, for ready reference to the working practitioner. Certainly no conscientious and high-minded person would be willing to attempt to employ this powerful agent in any form on the human body, actively, as a remedy, and much less as a trifling experiment, without first being familiar at least with the outlines of its sources, its prop- erties, its actions, and its results. Sources of Electricity. There are usually acknowledged three principal sources of appreciable Electricity; namely, heat, mechanical friction, and chemical action. While inanimate bodies are at rest, there is no appreciable electricity to be found. The positive and nega- tive exist in them in such proportions, that, although they do not destroy each other, their effect is counterbalanced, and their very existence is masked. Under the same distance and circum- stance, the attractive power of the one is equal to the repulsive power of the other. This natural rest of electricity must there- fore be disturbed, in order to produce any appreciable existence or action. The earliest mention of electricity is supposed to have been by the Ionian philosopher, Thales of Miletus, who discovered that if a smooth piece of amber was rubbed with a dry cloth it at- tracted various light bodies that were placed near it. Although he was reckoned as one of the seven wise men of Greece it°is also recorded of him, that from this phenomenon he supposed that amber possessed a soul, and was thus nourished by the attracted bodies. This was at an early day, however, for he died in the ninety-sixth year of his age, about five hundred and forty-eight years before the Christian era. Pliny the elder also NATURAL ELECTRICITY. 17 speaks of a hard, violet, or deep-red colored stone, which, when heated in the sun, and then rubbed with the fingers, would attract small light bodies. We now know that when a piece of amber, wax, or glass is rubbed with a dry cloth or fur, it acquires the property of attracting light bodies, as pith balls, or bits of paper, because the friction has decomposed the natural electricity of the amber, or wax, so that it has become " minus,'1'1 as Dr. Franklin would say, or resinous and negative, as it is now more famil- iarly termed ; i. e., the negative electricity is thus accumulated in a state of rest in the rubbed, non-conducting body ; so that if now it is approached by any light body, a law of electricity is observed, and the bit of paper, for instance, is attracted to the amber, and that neutralizes a given portion of its single elec- tricity, but still adheres to it. If the paper were larger, so. as to neutralize all the negative electricity of the amber, it would then instantly leave by repulsion. This kind is therefore termed " frictional electricity'." A quiet and simple elevation of temperature, is also alone suffi- cient to render a body electrical which was not so before. This is termed heat, or thermo-electricity, to distinguish it from pyro- electricity, which was discovered first in the tourmaline and then afterwards in other crystals and precious stones ; also to desig- nate it from hydro-electricity, which was a term early applied to voltaic electricity, and which is the same as galvanism. The third great source of electricity, then, is from chemical action; and this is termed dynamic or voltaic electricity, — so called after its distinguished discoverer, and also because it is in currents or motion. It is, as just said, also termed galvanism. But there are also two other important sources of electricity ; and these are magnetism, and the animal body. These will severally be considered under their respective heads ; but we must observe that there is another phase of electricity which we should notice, and that is, first, electricity at rest, as accumulated in or on a non-conductor, and hence termed " static electricity," and second, electricity in motion, as from chemical decomposition, &c, and hence termed " dynamic electricity." 2* 18 ELECTRO-THERAPEUTICS. Nature of Electricity. It is important, before we go further, for us to form an idea of the properties of electricity, or, in other words, of what electricity is; at least, to be reminded of the opinions that have been formed on this subject. The knowledge of these theories, as has been remarked, is absolutely necessary for us, even were it only to make us familiar with the established expressions em- ployed by writers on this subject. But all this will be more fully and naturally explained, in connection with the history of the development of this branch of science. Here then, we will only stop to mention certain prominent opinions. Dr. Benjamin Franklin's theory consisted in admitting but one single imponderable electric fluid, very subtile, and that all the particles of which mutually repel each other; that each body has a determinate capacity for this fluid ; that a body is in a natural electric state when it contains as much as it ought naturally to have. He held that to electrize a body vitreously, is to give it more electricity than it naturally contains; and when so conditioned, the body is in the positive electric state. To electrize a body resinously, is simply to deprive that body of a portion of its natural electricity, and then it is in a negative electric state. So that Franklin's theory gave rise to the terms positive and negative electricity the world over. But his the- ory of simple plus and minus, just as he gave it, cannot, in the present state of the sciences, be admitted. We now regard the two electricities, the vitreous and the resinous, as excessively subtile and imponderable fluids or influences, each of which orders is composed of particles that naturally repel each other, while the particles of the one order as naturally attract those of the other order; that,these differ- ent influences or fluids are able to travel in and through con- ducting bodies ; yet as their fellow-particles of the given order tend to repel each other mutually, they therefore, when on insulating bodies, arrange themselves on the surface of these, and remain, because they meet the dry air, which being to them an insulator, they can go no farther. Why a given article, as amber or glass, NATURAL ELECTRICITY. 19 is a non-conductor, or why these two fluids are so restrained in their movements, until they accumulate to a given degree, we cannot further explain, than to attribute this to their being held by the peculiar particles of these bodies; but that when these two influences — positive and negative — do unite by virtue of their mutual attractions, they then become one natural electricity, which is neutral, the relative action and influence of which is insensible. Such are the more modern and commonly received views, which are indeed based upon the celebrated " Symmer's two-fluid theory." M. De la Rive, however, says, " We may for the present say it is very probable that Electricity, instead of consisting of one, or of two special fluids, sui generis, is nothing more than the result of a particular modification in the state of bodies, which modification probably depends on the mutual action exercised on each other by the ponderable particles of matter, and the subtile fluid that surrounds them on every side." Th e rmo-Ele ctricity. From the earliest times philosophers observed that heat facili- tated the development of electricity, particularly if it was at- tended with friction, and on insulating bodies. M. Becquerel lays down as fundamental, that the propagation of heat, at least in a metal, is always attended with a liberation of electricity, and that the current is from the heated end towards the colder end of the bar. Thermo-electric currents are not instantaneous, like those of induction, and for that reason thermo-electricity is not calculated for the production of electric currents, except in particular cases, as where we are more concerned in studying the effects of dynamic electricity, than in producing effects, or de- termining the laws of its propagation. The thermo-electric pile of Nobili, formed at first of only six dry pairs of bismuth and antimony, has been greatly multiplied and improved, so that it now constitutes one of the most sensitive and delicate means known for appreciating differences of temperature. M. Melloni improved this by composing a pile of some fifty small and slender 20 ELECTRO-THERAPEUTICS. bars of bismuth and antimony of about two inches in length, so soldered together alternately and folded back and forth upon itself, as to form a very small compact cube, or block, by means of insulating wax, or shellac, for filling the vacancies between the bars, which must touch only at their solderings. The two extreme ends of this sort of folded chain, the one of bismuth and the other of antimony, which are the poles of the pile, connect, by two short bits of ordinary insulated copper conducting wire, with the two extremities of a multiplier. The two studs pass through a piece of ivory, or glass, fixed upon a metal ring, which receives the thermo-electric block, and may be furnished with a pivot, or a hinge, by means of a piece attached, and so allow the axis of the pile to be placed hanging in any direction. The face of this instrument, that we now wish to be kept at an ambient temperature, must be covered with a finely-polished metal shield, which so envelops it as not to touch it; while care must be taken to blacken the terminal faces of the pile, which is to be uncovered and turned directly facing the source of the heat, or cold, that is to be tested. The nice sensibility of this apparatus, small and exceedingly simple as it is, we learn from M. De la Rive, is such, that if the uncovered face of this little pile is turned towards a person who stands at a distance of even twenty-five feet, the deviation of the needle of the multiplier detects the emanation of the radiant heat of that person, and shows the evidence to all who behold ! By this marvellously delicate instrument, MM. Nobili and Melloni were enabled to discover the presence of heat even in insects — in phosphorescent bodies, and under many circumstances where it could not be detected by any other known means. M. Becquerel has taught us to make use of thermo-electricity for the measurement of the temperature of the different tissues of the human body, by preparing mixed metallic needles of a diameter of less than a twentieth of an inch, which are used simply by introducing them as we do acu-puncture needles. Then, if we compare thoroughly, yet very carefully, all the phe- nomena in which heat and electricity are concerned together, we NATURAL ELECTRICITY. 21 everywhere discover molecular influence becoming very manifest; the passage of the artificial electric current, by increasing the polarity of the atoms, exalts their velocity of rotation, and this again increases their individual electric polarity. The idea thus put forth by M. De la Rive, and Dr. A. Smee, that atoms have an electric polarity, which they owe to a more or less rapid motion by rotation, leads us to think that if this facility for actual increase of rotation is truly augmented also by moderate heat, and at the same time it exalts their electric polarity, we may, in some measure, and I think in a very satisfactory manner, account for what takes place in living bodies, as electro-calorific phe- nomena, since this applies mostly to moist tissues or fluids. Static Electricity. It is true that natural electricity is at rest, because it is neu- tral ; but this is not what is meant by static electricity, although it also refers to an electricity at rest. But where the natural electricity of bodies has been decomposed, as by friction, heat, or decomposition, then there is a separation of the positive and negative, the one occupying a given locality, and the other another, in a state of accumulation and rest, as on insulated and non-conducting bodies. This state is also called electric tension. Hence, when the electricity that is produced by the friction elec- trical machine is spoken of, in connection with medical practice, we always designate it as static electricity. This form of elec- tricity, above all other forms, exercises the most remarkably attractive and repulsive powers, even at a distance. But the energy of these properties are in proportion to the tension and distance. The neutralization of these two electricities is usually instantaneous and by a spark or shock. The neutralization can take place slowly and imperceptibly, as through imperfect con- ductors. The quantity of frictional or static electricity is always relatively small, but it possesses the highest degree of tension. For this reason it is easy to draw very brilliant sparks from the electrical machine, while large and powerful series of galvanic batteries, which furnish an enormous quantity of electricity, (but .?•"> ELECTRO-THERAPEUTICS. of less relative tension,) will produce only the least spark. Now, if these two kinds of electricities, i. e., positive and nega- tive, be constantly renewed, there will likewise be a continuous neutralization, either through the air as a fine succession of sparks, or through a conductor in contact. The essential dif- ference between a discharge of electricity, and a current of elec- tricity, as they relate to physiology and therapeutics, will be plainly delineated in this work. I will only mention hero, that a discharge or shock, although it produces a number of other powerful effects, has almost no chemical effect and no influence on the magnetic needle, whilst all currents of electricity are able to accomplish both. We find that we can produce electricity instantly and con- stantly ; but the accumulation of electricity is a matter of time. And here 1 must remind you of an electric law that is not so known, or else is more generally forgotten ; and that is, that one of the electricities by friction is never liberated without the other or opposite electricity being equally so, and that in the same proportion. I mention this as a particular reminder, be- cause a provision must for this reason be always made for the escape (as for instance to the earth) of the electricity we do not want, in order to obtain freely and largely that other kind which we do want. This law, first laid down by M. Wilke, ap- plies also to other forms of electricity, but all the more distinc- tively in this, where one only of the electricities is collected, as for instance when highly charging the Leyden jars. True, Faraday caused two bands of flannel to be rubbed against each other crosswise, and thus both were rendered negative. But this is an apparent exception, although it can be explained. Finally, we are taught that the kind of electricity that is de- veloped upon a body does not depend solely upon the nature of this body, but likewise upon that of the substance with which it is acted upon, or rubbed, as one electricity is never developed without its opposite ; and either of these may prefer to accumu- late on the one or other body. There is not, therefore, an iden- tity between the electricity that glass acquires by friction, and which we call vitreous, and that which wax acquires, and which NATURAL ELECTRICITY. 23 is termed resinous, since on each of these bodies, although electrized in the same manner as exactly as possible, the effect of the former is repulsive, and that of the latter is attractive. As experiments teach us that all bodies in nature upon being rubbed acquire one or the other of these two electricities, the following law is deduced : — 1. That there is an attraction between two bodies electrized, the one as by glass, the other as by wax. 2. That there is attraction between an electrized body and a body that is not so. 3. That there is a repulsion between two bodies that are elec- trized by the same source of electricity, and consequently if pos- sessed of the same kind of electricity, whether that be positive or negative. Dynamic Electricity. While the naturalization of an appreciable electricity is being brought about, either through the air as a spark, or invisibly through a conductor, it is said to be in a dynamic condition, for it is moving. This term is therefore applied to all electricity in motion, as where the positive and the negative are supposed to be travelling towards each other through a conductor, and consti- tuting a current, and at the same time neutralizing each other. This denomination includes therefore all electricities that are not included in the denomination of static, as before mentioned; but we must here except natural electricity. The dynamic state of a given electricity may be only instan- taneous, or it may be more or less continuous. It is instantaneous when there is an electric discharge, and consequent neutraliza- tion of the accumulation; or it is continuous where there is a source of constantly renewing supply, as through a closed con- ductor of a battery, and this is termed the continuous dynamic condition, or electric current; and hence we say that the con ductors, and whatever body is included between the poles of those conductors of a battery, are traversed by a current. And here lies the gist of the whole matter: the works that can be accomplished between these two tips of wires, called poles, 24 ELECTRO-THERAPEUTICS. already telegraphing nations with a harmony of intelligence, besides performing every day a thousand other useful works, must also be brought to the aid of our enfeebled bodies, or de- ranged nervo-telegraph systems, to vivify, to restore communi- cation, to clear them of their debris, and enable them again to regulate their more normal and constantly-renewing supplies. We find also the general principle, that every disturbance im- pressed upon a body — and this peculiarly applies to the living human body — from which arises any change, or even the slight- est disturbance in the state of its molecular equilibrium in any department, is strictly accompanied by a like production of elec- tricity, which is manifested more or less according to the phys- ical and chemical condition of the body so disturbed. To sum up, then, we are able to show a rigorous principle that is now fairly demonstrated, viz., that not only friction and heat, but also every sort of mechanical and chemical action which disturbs the minutest particles of the human organism, becomes the producer of electricity in that body ; which, in the living body, we see manifested through the nervous media — first, for healthy function; second, for diseased action. In health, and within certain bounds, electricity does not accumulate in the body, nor yet does it greatly diminish, as occurs in disease, because the two electricities for the most part tend to recompose to a balance, and so become quiet; yet at the same time the same process is continually succeeding. Indeed, we are enabled to prove by direct and conclusive test, as by the aid of a sensitive galvanom- eter multiplier, that every minutest chemical action gives rise to an electric current. This action may be that of a liquid upon a solid, or upon two solids, or of two liquids upon each other, or of a gas in connection with any of these, under certain condi- tions, or it may be that peculiar action which characterizes all the phenomena of slow or rapid combustion. But all this will be more clearly illustrated in Electro-physiology. ATMOSPHERIC ELECTRICITY. 25 ATMOSPHERIC ELECTRICITY. A little over one hundred years ago Dr. Benjamin Frank- lin, the illustrious native of Boston, Massachusetts, first of all obtained the proof that the lightning and thunder of the clouds, are due to electricity alone, and are indeed the same as electricity artificially produced by means of friction accumu- lated and discharged by the Leyden jar. True, this was strongly conjectured in all those years, as indeed it had been by the Romans for centuries before, but no one could prove it. In physics, it is experiment and demonstration, first and alone, that can decide. Therefore our Franklin resolved to send into that region of thunder, and bring to earth a spark of evidence, which he actually accomplished in 1752, by means of his famous kite. And this proved a satisfactory answer. By it the learned world was truly electrified. New interest every where burst forth in this field of natural science. At once, from the city of Mexico to Moscow and St. Petersburg, kites were flying in the service of philosophy. Other effective means were also soon devised to witness this then new and extremely interesting phe- nomenon. M. de Romas, in June, 1753, raised his kite for this purpose, with a very fine copper wire inlaid through the whole length of the kite-string; and thus he obtained most wonderful effects. It is said that he drew from the kite, which was thrust high into the midst of the shower clouds, sparks or streaks of lightning from eight to ten feet long, and one inch in diam- eter. Notwithstanding his precaution, in using large glass insu- lators, with which to hold the kite-string while experimenting, he was knocked down by a shock, but was not killed. Professor Richmann, of St. Petersburg, however, erected a tall iron rod for the same purpose, and during a thunder storm it led a bolt of lightning into his house. The rod not being well connected with the ground, or perhaps not at all, as he stooped down to watch the experiment at the bottom of the rod, and near the 3 26 ELECTRO-THERAPEUTICS. floor, he was struck in his head and killed instantly. Lightning and thunder, then, is but a simple discharge of electricity, only on a large and magnificent scale. Clouds. We may notice, without the weather being decidedly stormy, that the very presence, in the otherwise serene atmosphere, of a small or thin, fine cloud, or of the fall of a few drops of rain, or a few flakes of snow, is sufficient to modify the normal state of electricity in the air. But this is far from possessing the im- portance that results from the existence of a storm, a dense fog, or thunder and lightning, with wind, rain, hail, or snow. The mere formation of a single cloud, or of the slightest fog, is accompanied with a sensible disturbance of the electric state of that stratum of air in which this formation takes place. The aqueous vapor with which the atmosphere is always more or less saturated, being usually invisible, becomes in the clouds and fogs visible ; and wc know that their globules are so many small spherical balloons, in which a small capsule or pellicle of water serves as an envelope to the interior air, which is polarized. We have only to place an electroscope in the middle of a cloud, or fog, when driven by the wind, and we see how greatly the di- vergence of the needle varies with the passage of the successive flakes of denser portions of the fog or cloud. Now, to understand in some degree those wonderful electric phenomena of clouds over and about us, and which are so full of meaning, it is well, and indeed necessary, to be more familiar with the individualities of each of the globules of which they are composed. But this must not be entered upon here. I will only remind you, that the globules themselves are grouped by small flakes, which have their limits and their spheres of action, much like the globules themselves ; the small flakes, by grouping, con- stitute the large flakes ; the latter group and form Mamillce; a certain number of these again, by their reunion, form a Cloudlet; and the cloudlets marshal by a law into given definite clouds ; and these again, grouping as so many individual and definite ATMOSPHERIC ELECTRICITY. 27 clouds, thus result in a Cumulus; and several cumuli organize into a Nimbus. Then, again, the clouds themselves, if we except the invisible clouds, are distinguished as three grand species or kinds : the Cirri, which have the appearance of loose filaments, and fly the highest; the Cumuli, which are less elevated, have a rounded appearance, and form the large clouds which we see usually accumulated or formed at the horizon, and which we fancy so resemble the gorgeous sight of distant mountains when covered with snow and sunshine ; or as if the looming and ap- proximating of the very land of Beulah. The next are the Stratose clouds, which are horizontal and parallel stripes, or bands, form- ing at sunset, and disappearing again between break of day and sunrise. We observe that when the Cumuli are piled up, and become quite dense, they then pass into the compound state of Cumulo-stratus, which themselves shortly after pass into the state of Nimbi, or true rain clouds.. These latter are distinguished by their uniform gray tint, with fine fringe edges ; this, how- ever, soon passes into the uniform, undefinable, and extensive Storm Clouds, which are peculiar for being without visible edges. Thunder clouds are usually formed during the heat of sum- mer days, from the occurrence of a rapid condensation of the vapor with which the atmosphere is then saturated. When this watery vapor, or evaporation from the earth's surface, reaches an elevation where the condensing power of cold (magnetism ?) is sufficient to overcome the repulsive force of the electricity that attends the vapor, then thunder clouds are speedily formed, and the electricity, like latent heat, becomes sensible in the con- densed vapor of that cloud. As the earth is the great reservoir of electricity, so is evaporation the principal and perpetual agent in conveying off the earth's surface electricity so abundantly to and throughout the upper strata of the atmosphere. The evap- oration of the earth's moistures is too extensive to be computed and comprehended, and yet it is this mighty force, that, particle by particle, carries off and up to the sky such prodigious quan- tities of electricity, which particles themselves are rendered all the more volatile by the self-repellent effects of the minute po- 28 ELECTRO-THERAPEUTICS. larized electricity which they severally contain. As these minute globular particles increase in density and extent, the tension of their free electricity becomes greater, until this speedily reaches such a degree as to overcome the resistance of the non-conduct- ing air, when a discharge of lightning takes place, either to the earth or to some other cloud less charged. Thunder clouds are often negative in regard to each other, as also in regard to the earth; in that case the lightning is seen to leap from one to the other, until the equilibrium is nearly or quite restored between them. But it is the new and isolated thunder clouds, those which form so rapidly from vapor con- densed by the violent meeting of very warm and very cold cur- rents of air, that present the highest degree of electric excite- ment, and exhibit the most terrific electric phenomena. As the thunder storm and shower clouds now approach, the flaky portions of these clouds are observed to be in the greatest com- motion by a whirling and flying of various detached portions, and a scudding of other fragments to other denser portions, as if to find an adjustment— the whole having a dismal, dark, or black and threatening aspect, which are instantly and fearfully augmenting ; and then comes the blazing of frequent discharges of lightning, followed by, or almost simultaneous with, crash- ing peals of terrific thunder, and that with torrents of rain. These thunder clouds, then, may be regarded as a huge pano- rama of electric batteries suspended in the sky and insulated merely by the surrounding air. Thus prodigious quantities of electricity are restored to the earth's surface again by the lightning and the falling snow or rain. But M. De la Rive believes that a still greater quantity of electricity from the higher regions of atmosphere returns to the earth at the magnetic poles. Thus the quantities of elec- tricity which pass into the air in all the equatorial and temperate regions, flow through the air in currents towards the north and south poles, and are there discharged into the earth at and about the magnetic axes ; and from thence flow through the earth back again towards the equator, for reestablishing the equilibrium. This philosopher believes that such a process accounts for the beautiful, but often pain-attending phenomena of the aurora bo- ATMOSPHERIC ELECTRICITY. 29 realis. The gentle flashes and streamers of auroral light, he thinks, are caused by the passage of unusual quantities of elec- tricity from the regions above, to the negative pole of the earth. But that this is also connected with the magnetism of the earth, is quite as evident from the fact that the magnetic needle is found to be more or less affected by the north, or perhaps the south currents,during these gorgeous dissolving views of auroral exhi- bition. The irregular and augmented action of the electro-mag- netic telegraph during some days, causes registers to operate as if in contact with a powerful battery, and thus gives the signal of this as yet unseen, but/eft, atmospheric phenomenon, which is usually verified in the evening by the appearance of the halo and streamers of an aurora borealis. This is admirably demonstrated by causing one of the poles of a straight magnet, that connects with the moist earth, to enter the glass globe of an air-pump. Above and around the upper end of this magnet is placed a metallic circle. Now, upon removing the air from the globe, and charging the circle with the electric machine, there appear the halo of dim light and the streamers of a miniature aurora. Meteorology. It is profitable and interesting to know in this connection, that Meteorological observations have now become multitudinous. These, conducted by so many scientific persons, and in so great a number of countries, as well as under so great a variety of circumstances, and that for so many successive years, appear to us calculated to inspire the greatest confidence, so far as the facts are agreed upon. The following table, formed by the dis- tinguished De la Rive in 1858, has made manifest the following concise results: — 1. Whatever the state of the sky may be, the electricity of the air presents a maximum or greatest tension in January, and a minimum or least tension towards the summer solstice. 2. The difference between the maximum and the minimum is much more sensible during serene weather, than it is during cloudy weather. 30 ELECTRO-THERAPEUTICS. 3. During the different months, generally, the electricity of the air is more powerful when the sky is serene than when it is cloudy, excepting towards the months of June and July, when the electricity attains its maximum ; the value of which is nearly the same, whatever be the state of the sky. Thus, setting out with these views, the electricity of the at- mosphere during a serene sky exceeds the electricity observed during a cloudy sky, and so much the more as we approach neajer to January. In this latter month the ratio is more than four to one. Now, this powerful atmospheric electric intensity, during the serene sky of winter, is a very remarkable circum- stance. This has been again and again proved by philosophers, who have been especially engaged in observing the phenomenon of atmospheric electricity, but who appear to give it a less rela- tive value. Storms. Mr. Quitman has collected tables of observation made during extraordinary circumstances, such as in times of snows, rains, and fogs. He finds that under certain conditions, a powerful electric atmosphere obtains at the approach of a rain storm, and after a rain storm, which is sometimes positive and sometimes negative. The electric intensity observed during fogs has a mean, the same as that obtained during snows, and is not much influenced by the time of season. The value of electricity observed during a tranquil rain, differs very little from the mean taken in the course of the whole year. The electricity of the air estimated at an elevation always the same, suffers a diurnal variation, which generally shows two maxima and two minima; and these are displaced according to the different epochs of the year. The first happens before 8 o'clock in the morning in the summer, and at about 10 A. M. in the winter. The second maximum is after 9 P. M. in the summer, and about 6 P. M. in winter. The day minimum is found to be about 3 P. M. in summer, but near to 1 P. M. in winter. The night minimum is as yet not so exactly obtained. Observations accurately taken at all even hours Greenwich ATMOSPHERIC ELECTRICITY. 31 mean time, and that unceasingly for three years in succession, — during the nights as well as days, — shows that the tension of atmospheric electricity is at its minimum at 2 A. M. Setting out, then, from this hour, and we find the tension increases more. rapidly, so that its value at 8 A. M. becomes almost double of that at 6 A. M.; but from this hour the increase becomes more gradual again until 10 A. M., the period of the first or morning maximum. Now, again setting out from this last-named hour, the tension declines gradually until 4 P. M., a period at which its value is only slightly superior to that of 8 A. M. This second minimum is called by the French philosopher De la Rive the diurnal minimum, to distinguish it from the nocturnal mini- mum, which takes place at 2 o'clock in the morning. After that hour (4 P. M.) the tension increases rapidly until 8 P. M., and after a slight further rise until 10 P. M., — the period of the principal or evening maximum, — when the ascending march of the electric tension is terminated. The evening maximum is very notably superior to that of the morning, or say at about 10 o'clock. Between 10 in the evening and midnight, the ten- sion of atmospheric electricity is decreased almost to the value of the diurnal minimum. It is occasionally observed on the same day that where the instruments mark 150° to 200° at the morning maximum, it runs down during the day so as to show only 3° to 4° at the afternoon minimum ; but it usually happens that variations so great are immediately followed by storms. We find that the air under a perfectly clear and serene sky, and when there is no storm within two or three hundred miles of us, is constantly, but moderately, positive ; but this is not always uniformly distributed through all the strata of the at- mosphere. It is found more nearly of the same intensity in a given horizontal stratum, but uniformly stronger in the upper strata, and stronger still in the ratio as we rise through the suc- cessive strata. But at the lowest stratum, i. e., at the surface of the ground where the air and earth unite, the electricity of the air is null. In the open country it does not commence to be sensible to most delicate instruments until about a yard or two above the ground. Where there are large trees, buildings, or 32 ELECTRO-THERAPEUTICS. other elevated bodies, the evidence of its lowest positive pres- sure is to be sought still higher; i. e., more elevated from the ground. The air and the earth are believed to be, as a whole, charged with different electricities, which are continually tending to re- combine, and are perpetually doing so, by varied degrees, in the lower strata of the air, some directly by the dry land, but much more through good conducting bodies that are upon the surface of the earth. This is because our globe is magnetic, and charged with negative electricity (magnetic ?), although constantly unit- ing with the positive of the air; so that over all the surface of our earth, for a very few feet deep, the air is found at a near balance, i. e., neither positive nor negative, and the needle of the electrometer is here almost constantly at zero. Now, avc see that if each drop of rain, or each flake of snow, is of the same kind of electricity with which the globules of the clouds were charged, and of which they had indeed served to form a part, — the whole even, by their agglomeration, — it is easy to conceive how there is an electric change brought about with every fall of rain, hail, or snow, since this is carried onward with them in their fall. Each drop of rain, and each flake of snow, is doing a work that not only causes the electrom- eter and the barometer to fluctuate, but also causes joints, nerves, and bones to feel and confess their united power. Says De la Rive, wherever it rains there is a region of country, or sea, that for the time is charged with positive electricity; that this region is completely surrounded by a zone on all its border, but entirely outside the rain and storm, that is, charged with the negative electricity. Suppose there is rain falling at a very great distance from the place of observation, but which is approaching, and then soon arrives there under the action of the wind, and then passes onward and over without ceasing to fall, until all is passed. In that case, the following is the order in which it occurs, i. e., as the storm clouds approach and pass away: — 1. When the rain is very distant, the instruments indicate positive electricity in the air, as they do almost always, and even this with some considerable degree of tension. ATMOSPHERIC ELECTRICITY. 33 2. When the rain has approached within a certain distance, we find a strong negative electricity; and this not unfrequently produces sparks to the fixed conductor. 3. When the rain has reached the place of observation, a great quantity of positive electricity has rapidly come, as found again indicated. 4. When the rain has passed over and gone, we now have again a strong negative tension ; but this for a very short time. 5. Finally, when the rain is sufficiently distant, so that the zone also has passed off with it, the atmosphere returns to its habitual equilibrium or mean ; i. e., for the time of clear weather ; of moderately positive electric tension. Therefore we can rec- ognize in this a law of three marked electric changes. First, that at the approach of the storm, which is negative. Second, that which prevails during the storm and fall of the rain or snow, which \s positive. Third, that which follows close on its departure, which is again negative; but that this latter is not so marked, or of so long duration; and this is again succeeded, as we have said, by that clear, serene sky that we call a pure atmos- phere, possessing its full quantum of natural electricity, and no more. It is believed that negative or neutral rains do not come ; that negative clouds do not exist. When the air is perfectly pure, the upper stratum of it is electrized positively in respect to the lower strata, while at the same time the surface of the earth is nearly neutral, and hence the electricity of the atmos- phere must increase as we rise. To test or prove this, M. Bec- querel ingeniously employed arrows shot from a cross-bow. To the arrow, when shot, was attached a fine silk thread neatly cov- ered with tinsel, the other end of which communicated with an electroscope. He thus fairly and beautifully demonstrated the increased ratio of positive electricity in the atmosphere to be in ,direct proportion to the height in the air. He made this experiment at the Great St. Bernard, in Switzerland, and upon the top of one of those elevated plateaus near the Hospice. But our space allows us merely to allude to all these highly interesting and instructive observations, made by the aid of the telling Electrometer for testing atmospheric electricity, as to 34 ELECTRO-THERAPEUTICS. quantity and intensity; by the Barometer and other instruments, for ascertaining the atmospheric density, humidity, ozone, &c.; or by the Thermometer, for its heat and cold. Such like meteorological observations made with much care, and that by all these present helps for testing and comparing the normal and abnormal electricities, and other states of the atmosphere, together with another class of observations for de- termining the magnetic variation in the earth, — simultaneously made on the land and on the sea, on different continents, in the extreme north and extreme south, as well as at the equator, — are to any philo- sophic, or logical mind, full of significance, as relating to health and disease, life and death, in the great human family. We will only remark very briefly, that with regard to the real electric state of the atmosphere, and of the terrestrial globe, philosophers have long differed. But of late, Arago and De la Rive have concluded and do now assume, that our globe possesses, at least on its solid surface, an excess of accumulated negative electricity, and that this is the same with bodies on its surface ; that the atmosphere itself, on the whole, is positively electrized, and arises from the same source as the negative of the globe. They noticed that when the most highly charged storm clouds approach mountains, the clouds go towards them with a rush, and with that quickness in proportion as the summit of the mountains have the more marked negative tension. They arc then observed to linger, and adhere as it were to the mountain, as if indifferent or slow conductors, yielding successively either electricity. This, we notice, is observed only in respect to static, electricity. If, now, we consult the galvanometer, we find phe- nomena for study in dynamic electricity. For when the cloud approaches the mountain, and as it commences to pass, the in- strument gives indications of ascending currents, because the electricity of the ground is found to be attracted towards the ATMOSPHERIC ELECTRICITY. 35 clouds; and very frequently have we witnessed the clouds of dust and trash violently raised, not by the wind only, but by this force. And all this is reversed, as soon as the rain pours down, for it brings with it the superabundance of positive electricity from the clouds. At each clap of thunder, or rather at each flash of lightning, the needle of the galvanometer is agitated, and even driven back with force against its stops. At other times the magnetic state of the needle is found to be per- manently altered. Difference between Electricity and Magnetism. Dr. J. C. Atkinson, of England, thinks that magnetism and electricity are not identical, and differ in the effects which they produce upon the weather and climate. Efe says,— Magnetism of the earth is a state of continual and restless fluctuation, and that its changes from moment to moment are strictly simultaneous at every point where observations of this nature have been made. It is my impression that cold is an effect of magnetic influence, as solar heat in the atmosphere is an effect of electric action; and I conclude that the vital prin- ciple of temperature is the result of the combined agency of these two forces, variously modified, according to seasons and latitudes of the several places. The range of the barometer gradually increases towards the north pole. The rise of the barometer mercury may be observed in this country during the prevalence of northern winds, conveying as they do magnetic currents, till at last it reaches to two or three inches. On the contrary, between the tropics the variations of the barometer are exceedingly small, whilst winds from the southward, in tem- perate latitudes, if the electric current or wind is continued for any length of time, will cause a tendency in the mercury of the barometer to fall. The winds are more powerful in the production of weather than would appear at first sight; and although the moon was always supposed to exercise great control over the weather, yet it is strange that both Drs. Herschel and Clarke, great observers 36 ELECTRO-THERAPEUTICS. of the heavens, state in the weather tables, as a set-off, I con- jecture, to her influence, — "If the particular change of the moon, full or new, takes place when the wind is so and so, it will be fine for the ensuing week ; and the reverse if it is not." I ask, Does this prove the dominion of the moon over the winds, or the contrarv ? Magnetism. 1. The intensity of the mag- netic force in different parts of the earth is according to the distance from the poles. 2. The frigid zone, where magnetism is in the greatest intensity, enjoys an atmospheric calm which is unknown in tem- perate regions; it has no storms, no hail, and scarcely a tempest. 3. The splendor of the au- rora borealis, reflected by the snow, dispels the darkness of the polar night, but is not ac- companied with danger. 4. Magnetism suspends the decomposition of vegetable and animal matter. 5. In northern latitudes the mercury of the barometer al- ways stands high; in the tem- perate latitudes it is liable to frequent variations. 6. Magnetism has been known to produce sedative action on the human frame, when applied under certain conditions, causing repose, if not sleep. Electricity. 1. The intensity of electric force is greatest at the tropics, and diminishes as it approaches the poles. 2. The most vivid lightning and the loudest thunder are peculiar to the tropics; here vegetation is vigorous, and ac- tive at all seasons. '3. Igneous and fiery mete- ors, fire balls, and lightning are the peculiar electrical phe- nomena of the tropics. 4. Electricity assists decom- position in all vegetable and animal substances. 5. The mercury of the ba- rometer is always low in the torrid zone, and varies but little during the changes of weather. 6. Electricity is of an ex- citing character, increasing the circulation of the blood, and rousing paralytic functions of the nervous centres. ATMOSPHERIC ELECTRICITY. 37 7. The northern currents of atmosphere, accompanied as they are with magnetism, have the power of expansive action on the mercurial column of the barometer, wherever it may be placed, either in a warm room, or in the open air. 8. Snow from the north-west wind has been found to con- tain more oxygen than rain or river water, and more carbon. 9. The magnetic intensity of the earth is indicated by nee- dles suspended vertically; and in sailing from England towards the north pole, it is seen that the needle dips, or inclines more and more, with the increase of latitude, till at a certain point it remains exactly perpendicular, with its south pole downwards. The above are some of the reasons which have induced me to think that magnetism and electricity are not strictly iden- tical, their operations being as distinct as heat and cold ; and I have therefore come to an analysis of the influence of the winds, and a theory to establish something of a definite character. Winds are not decisive as to their influence on health, when continually changing ; that is, not remaining in any fixed quar- ter for two or three hours at least. Winds have been known to blow from different currents, as spoken of before. Mr. Green, the aeronaut, in his celebrated aerial trip from Vauxhall Gar- dens to Nassau, in Germany, frequently availed himself of the different currents of air at different altitudes, by raising and lowering his balloon ; and in this way he regulated his passage across the Channel, opposite Dover. The highest elevation 4 7. The southern currents of the atmosphere, accompanied with free electricity, cause a fall of the mercurial column under any circumstance of po- sition of the barometer. 8. Electricity causes the rain to descend with less oxygen than snow water ; and less car- bon also. 9. In sailing towards the equator, with a magnetic nee- dle suspended in the like man- ner, the inclination or dip gradually decreases, until the needle rests in a perfectly hor- izontal position. 38 ELECTRO-THERAPEUTICS. attained by him, during his voyage of nearly five hundred miles, (British,) was twelve thousand feet above the level of the sea. At the highest point of elevation, it appears from the account that there was less circulation of air than at any point below it. On the earth's surface, then, we have frequent changes of wind, and this more particularly in temperate latitudes, or cli- mates ; and hence there are frequent alterations in the atmos- phere as regards both temperature and electro-magnetism. Sometimes a wind, well known for its peculiarly mild character, assumes so different a nature as to be mistaken for a wind from altogether another quarter of the globe. This arises from va- rious winds supplying one current of air. For instance, we have a south-west wind of sonic velocity, of a stormy nature, and highly charged Avith electricity. Suppose, then, this wind to have a parallel breadth of any number of miles, and then to be supplied by north-east and north-west winds ; of course, under such an influence, we shall have a great reduction of the tem- perature, and other qualities somewhat reversed, for a time, at least. A north-east wind, on the other hand, will frequently have its real nature or character altered, owing to rapid changes of aerial currents during stormy or thundery weather; and this happens more particularly when the observer is situated on the external edge, as it were, of a parallel but contrary current of wind, which varies in diameter, at various seasons, from ten to one hundred miles; and hence an unusual temperature is given to it. In the centre, however, of the said parallel current you have the true quality unmodified. We now come to the question of health and disease, under the operation of the several winds. The north wind (I here refer to the magnetic north) has a different influence on differ- ent constitutions and ages. The temperature of this wind of course varies, as has been before intimated, according to the seasons ; but its general characteristics are always alike. This wind is usually unattended by hail, or even snow, although if a few points to the eastward it will often be followed, in the win- ter season, by the above phenomena. ATMOSPHERIC ELECTRICITY. 39 Electric Relations of the Earth to its Atmosphere. Professor Faraday introduced and expounded, at a lecture before the Royal Institute, the hypothesis of M. Pelletier re- specting the electrical relations of the earth and its atmosphere to the "planetary space "in which it moves. The method by which the electricity of the atmosphere was determined by MM. Pelletier and Quitelet was shown to correspond very nearly with those of Becquerel and De la Rive. The instrument employed by these investigators was a brass globe, placed on a thin metallic stem, to which is affixed a delicate galvanometer needle, which indicates by a minute measurement in degrees, the amount of electricity obtained.* This instrument was used on the summits of high buildings, where it was above every surrounding object. The method formerly adopted was to employ for this purpose a long metallic rod, furnished with points which projected into the air, to be examined. M. Pelletier's mode gives the quantity, and the kind, with great certainty; while the old method furnishes un- certain and often contradictory results. Dr. Faraday illustrated, by enlarged models, the influence of various degrees of elevation on M. Pelletier's electrometer; at the same time showing that no changes take place from variation of position, when the in- strument is moved horizontally, and that thus, throughout each stratum, the electricity of the air is the same. It is the vertical elevation, or depression, which produces, a marked difference. The results obtained by M. Pelletier are, — 1. That the electricity of the air increases directly with the distance from the surface of the earth — a fact of great im- portance, as it influences the determination of the question whether the electricity of the earth be derived from planetary space, as Pelletier affirms, or whether, as Professor Faraday thinks, it be the result of various processes taking place on the surface of the earth. 2. The measure of divergence of the electrometer being * Med. Gazette, February, 1850, p. 255. 40 ELECTRO-THERAPEUTICS. the measure of force, it was found from a series of daily obser- vations, extending over a period of five years, (1S44-S,) that the quantity of electricity at the same place, undergoes a regu- lar increase and decrease in certain months of the year; that, contrary to general belief, the quantity of electricity is at its maximum in winter, and undergoes a decrease until it finds its minimum in June, and then again rises to its maximum in the succeeding January. The subjoined table represents the numerical results; and from this it will be seen that at the same level the quantity of electricity in the atmosphere is twelve, times as great in the cold month of January as in the hot month of June. Average of Five Years —1844 to 1849. Months. Quantity of Electricity. January, maximum,........605 February, " ........378 March, " ........200 April, « ........141 May, « ........84 June, minimum,........47 July, " ........49 August, " ........62 September, " ........70 October, " ........131 November, " ........209 December, " ........507 3. The Influence of the State of the Sky. — From the results under this head, it is made evident that the highest degree of electricity is not found in cloudy weather, but rather in the clear, serene sky; i. e., at a time when the atmosphere is free from clouds. Thus, for the whole year, the proportioned quantity maybe represented —cloudy 186, clear 273. In reference to the monthly variations, as influenced by the state of the sky, it was found that in January, the maximum month of the year, the proportionate quantities are, cloudy 268, clear 1133. Only ATMOSPHERIC ELECTRICITY. 41 one exception, for an equal number of cloudy and clear days, was met with to this rule, viz., in July; the electricity on the cloudy days was 41, on the clear days 35. 4. As regards fog, snow, and rain, it was observed that the amount of electricity was the same during the two former states of weather, and was double that observed during rainy weather __the latter corresponding to the minimum of the annual elec- tricity, the former to the maximum of the year. 5. As to the Kind of Electricity in the Air.— It was noted that during a period of five years, only twenty-five observations gave evidence of resinous or negative electricity; the rest con- sisting of eighteen hundred observations, which indicated vit- reous or positive electricity. The negative observations were all recorded after storm or rain, or some other great meteoro- logical change. The normally electrical state of the atmosphere may therefore be considered as positive. 6, Wind. —It was observed that when the wind was E. S. E., or S. E., two maxima were regularly formed, and two minima when at W. S. W., and that these corresponded with the other variations which have been mentioned. 7. The diurnal variations were recorded during the same period of five years, from six o'clock in the morning until nine at night. The degrees of divergence showed that there were two maxima and two minima daily. The maxima were at 8 A. M., and from 8 to 9 P. M., in opposite periods to the magnetic maxima. One minimum was from 2 to 4 P. M.; the other, prob- ably, during the early morning hours. All these great and regular phenomena of the atmospheric electricity, Dr. Faraday observed, are phenomena of static elec- tricity, while the thunder storm, the St. Elmo light, &c, &c, are exceptional instances of current or dynamic electricity; not necessarily, however, requiring clouds for its concentration or evolution. The professor concluded by expressing his dissent from the theory of M. Quetelet, that the electricity of the earth was neg- ative, and that of planetary space was positive. According to this theory, the only true electricity is what we call negative; 4* 42 ELECTRO-THERAPEUTICS. i. e., that kind produced by the friction of resinous substances, while the positive electricity is merely the absence or negation of electricity. It thus reverses all our common notions of elec- trical science. Dr. Faraday observed, that while admitting to the very fullest extent the value of the observations and investigations of MM. Pelletier and Quetelet, which he had brought before his audi- ence, he nevertheless could not receive the hypothesis they had framed thereon. These researches on the electricity of the air, are not only interesting in a meteorological respect, but intensely so in a physiological and pathological point of view. While they account for storms in cloudless skies, and for the occur- rence of severe storms during the winter, or in very cold lati- tudes, as at Capo Horn, for instance, (the Cape of Storms,) they tend to throw light upon the exacerbations of disease at different hours of the day, as well as on the increase and decrease of epidemic and other diseases in different months of the year. Such remarkable changes in the electricity of the atmosphere cannot go on without affecting the static electricity of the human frame. According to the researches of Casper, of Berlin, the greater number of deaths from disease take place at the early hours in the morning, when the quantity of electricity in the air is reaching its minimum. Is this merely a coincidence, or is there some yet undiscovered connection between the cessation of life and the electrical state of the medium in which the human body is placed ? Weather Observations. The British Board of Trade has seen fit to publish, for the use of seafaring men, general maxims of weather, because the color of the sky at particular times affords, wTith the barometer, good collateral weather prognosis. Not only docs the " rosy sunset" presage fair weather, and " a ruddy sunrise" bad weather, but there are other tints which bespeak with equal clearness and accuracy. A bright-yellow sky in the evening indicates wind ; a pale-yellow, wet; a neutral gray color constitutes a favorable ATMOSPHERIC ELECTRICITY. 43 sign in the evening, but an unfavorable sign if in the morning. The form and appearance of the clouds themselves are full of significance. If their forms are generally soft, undefined, and feathery, then will the weather be fine. If their edges appear hard, sharp, and well defined, it will be foul. Besides, gener- ally speaking, any unusual hues, as the deep, dark, or very gay, betoken wind, or some falling weather, (rain, snow, hail, &c.;) while the more moderate and delicate tints bespeak fair weather. Lightning. M. Arago says there are three kinds of lightnings —the forked, the sheet, and the spherical. The forked lightnings are in slen- der white or bluish streaks, that are zigzag or crinkled, and sometimes divided or forked. This is the most common kind. The sheet lightning, he says, is uniformly of a dull red appear- ance. The spherical are the same as thunderbolts, which de- scend more seldom and slowly to the earth, according to a law of their own, rendering lightning rods, as for them, useless. But there are also recognized two kinds of electricity in the atmosphere, so that the one or the other is always prevailing and affecting the health of mankind according to the weather; or, rather, according to the prevalence of this or that kind of electricity, so is the weather. The one is vitreous or positive, the other is called resinous or negative. These two forms of electricity are produced in the atmosphere itself from various cauSes__chiefly from evaporation, more also from conden- sation and separation of its moisture; from vegetation, from combustion, and from friction. This latter arises from large masses of air, moving in contrary directions, and thus encoun- tering or chafing one another. The friction on the edges of such currents develops free electricity, which is more especially active when these moving masses of air, arising from different quarters and at different altitudes, differ also in their respective degrees of moisture and temperature. The cold develops neg- ative electricity, the warm the positive electricity. Thunder storms, then, are the result of the approximation of vast quan- 44 ELECTRO-THERA PEUTICS. tities of opposite electricities, positive and negative, or plus in one and minus in the other, according to Franklin. There is usually thunder with the lightning, but there are lightnings without thunder, and so are there thunders without lightning. There are actual thunderbolts found in several parts of our own country, and in other parts of the globe — ponderable, tangible bodies ; one of the most marvellous specimens of which, I think, is to be seen in the cabinet of Yale College in New Haven. Safety from Lightning. It is often asked of us how to avoid the danger by lightning. We usually advise on general principles, rather than give specific directions. Persons who are perspiring copiously, or are wet, arc, on the whole, more exposed to danger by light- ning than others whose skin and clothing are generally dry. The dress is truly important; but the casting away from one's person, and every way avoiding the locality of metals, as coin, scissors, pocket knife, or the proximity to the butt of a tree, or chimney, or iron, is also important. It is best not to stand in the doorway, nor yet by a window, particularly if it is open, as the warm air of the house acts as a conductor, and in that case attracts the lightning. Ladies dressed in silk, if with no jew- elry, having a dry skin and clothing, are the least exposed of all persons. After having divested one's self of coin, jewelry, etc., then the next best thing to be done is to seek a position in the middle of the room, on a bed, or any where away from con- ductors ; also avoiding the range between two conductors. Dr. Franklin's advice was to avoid the fireplace. 1 say avoid, also, the proximity to stove or gas pipes, water pipes, and lightning rods. Such are prudent precautions, under Providence, and it is but wise and important to observe them; yet we must bear in mind, that there is no absolute safety, as lightning will not always respect silk and glass, nor human wisdom. A person may be struck with lightning and yet not be killed; they may receive only wounds or laceration, or these with death. The victim may bear the traces of dreadful burns, or singed hair, ATMOSPHERIC ELECTRICITY. 45 but these are the indirect effects of lightning. Its direct action on the human body is a shock, more or less great, and this by exhausting the human nerve-batteries more or less; when complete, it leaves the body a mass of disorganized matter, and instantaneous death is the consequence. When wounds are produced they are usually in some internal vascular portion, and from which there is an instantaneous and frightful effusion of blood,