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PRACTICAL METHODS
VENTILATING  BUILDINGS,
BEING THE
      ANNUAL ADDRESS
             BEFORE THE
MASSACHUSETTS MEDICAL SOCIETY,

           MAY 31, 1818.
APPENDIX,
HEATING BY STEAM  AND HOT WATER.
     BY LUTHER V. BELL, MP., LL.D.
HONORARY MEMBER OP THE SEW YORK STATE MEDICAL SOCIETY, ETC.; PHYSICIAN AND
  SUPERINTENDENT OF THE M'C I.KAN ASYI.OI FOR THE INSANE, A DEl'AETMl'.Nl.
        OF THE MASSACHUSETTS GENERAL HOSPITAL.   ^**r\"
          BOSTON:
DICKINSON IMU.VI'IM; K*'['Ai;iJl,<IP.IKNT....I)A.MKI'IfJJ & MOORE.
            18 4 8. 
 WAA
3437 p
 l%4«2 
ADVERTISEMENT.
  As stated in the title, the following pages constituted the anniver-
sary address  before  the  Medical Society of the Commonwealth, and
as usual, were printed in  one of the volumes of its " Communications."
I have taken  advantage of the type, to have a small number of copies
arranged and  printed for distribution to  private friends, and to some
public libraries in this vicinity, where the  record of a present condi-
tion of facts in any of the sciences or arts of life, may be  preserved
for  the interest of those who succeed us.
  No person can be more sensible than I am of the incongruity, —
almost the absurdity, — of an oration or address on so homely and  un-
rhetorical a topic as ventilation.  I was moved  to select it  in prefer-
ence  to  the many  more  ornamental and  facile subjects of medical
science, because it appeared to me to be of the  most pressing present
moment, as well as of absolute general  novelty in our country, and
because my attention, from my connection with some public institu-
tions, had been turned for many years to its practical details.
  I have directed a view of this Asylum, engraved for another occa-
sion, to be  placed as a frontispiece, because it  served to illustrate a
condition of the ventilating provisions described in the Appendix (the
point of egress at one of the chimnies  surrounding  the dome),  not
presented in either of the diagrams of the fourth Plate.
                                                      L. V. B.
  McLean Asylum, near Boston,
         July 4, 1848. 
ON THE
         PRACTICAL  METHODS

                      OF

VENTILATING   BUILDINGS,
Mr. President and Gentlemen,
   On this anniversary occasion, when so large a
proportion of the almost thousand associated mem-
bers of the medical profession of this ancient Com-
monwealth, has  come up to this  metropolis,  for
the mingled purposes of fellowship, of festivity,
and  of such instructive  suggestion, as "the  hour
and the man "  may furnish, — upon me has fallen
the honorable duty of providing  some  topic  for
your reflections j  and leading your thoughts in the
direction   of some not  unprofitable, nor useless,
inquiry.
   It is but once in the  reach of a single individ-
ual's whole life, however prolonged, that to him
can  be expected to  fall the high privilege, the
profound responsibility, of having his living voice
touch the  living ear of the assembled profession of
a  great  commonwealth.   I  feel that the highest
             2 
6          ON  THE PRACTICAL METHODS

ambition which fills my mind in this office, as well
as  the  strongest  manifestation  of respect to the
character, attainments, and tastes  of an  audience
like this, is, that every sentence uttered should con-
tain a fact, — a useful, available, practical fact, —
or some just, candid, reasonable deduction  from an
undoubted basis.  Willingly would be foregone all
the honors and applause which the most successful
literary or rhetorical  eflbrt could elicit from a grat-
ified, but unprofited audience, could I but feel that
you, or  that great community of which you are, in
some measure, the representatives, as well  as  the
protectors, may not  be unbenefited  by my well-
intended service.
  In accordance with these impressions of what is
due to  this Society, — to  this  occasion, — I have
selected as  the topic of my  address, the  directly
practical or mechanical applications of the science
of ventilation,  or  rather the division of it which
has  been  termed  by writers internal ventilation,
as contra-distinguished from external,  in the  scope
of which  latter is comprised the  means by which
towns, cities, or even large  territorial districts, are
rendered more  salubrious, as respects  the atmos-
phere, and its contents, appreciable or subtle.
  Under the  term, ventilation,  philologically not
very accurate or  comprehensive,  is intended that
science, with its connected  arts, formed by contri-
butions from almost all the other natural sciences,
physiology, chemistry, pneumatics,  mechanics, and
others, through  the agency of which, adequate, per- 
OF VENTILATING BUILDINGS,
i
feet, and certain  supplies of pure  atmospheric  air
are furnished and continued, under ascertained con-
ditions of heat, moisture, and motion, in edifices or
apartments in which the air would become vitiated
and destroyed, by respiration, combustion, or other
oxygen-removing processes, or made unhealthful or
disagreeable by  admixtures  of  suspended or com-
bined foreign matters.
   Under  recent  advances in this science, a true
ventilation is designed,  also, to comprehend  the
acoustic relations of the  air, as well as  its more
palpable and material admixtures.
   At first thought, it  may appear somewhat  fas-
tidious, or even unphilosophical, to regard merely
unwelcome  sounds, recognized by  the ear alone, in
the  light of offensive impurities, or rather as disa-
greeable additions to the medium in which we  live
and intercommunicate, yet no explanation will be
needed by a body of medical practitioners, residing,
in  part, in large towns and  cities, for considering
the means of averting, or obviating, the annoyances
and injurious irritations of painful sounds, in the
same category with the  disagreeably offensive, or
actually malarious contaminations.
   The  physician in the densely populated and in-
dustrial community, must have often  recognized
the discomforts and serious injury  from the former,
to the patient on the bed of sickness, with  keener
regret, than the noisome or pestilential emanations
of the air, as less susceptible of being counteracted
or nullified by ingenuity and care. 
s
ON THE PRACTICAL METHODS
  It is a gratifying coincidence, which will  most
fully develope itself as the various modifications of
the ventilating system are  brought  forward, that
the improvements which have so fully satisfied the
requirements  of health  and  comfort,  as  respects
respiration and purity to the  senses, also meet the
necessities  of the ear.   We  shall see  that  under
the complete  arrangements  for atmospheric sup-
plies, secured in  modern provisions,  this rather
more remote  requirement is completely fulfilled, —
a necessity of the highest moment, as regards that
somewhat  extensive   class  of  edifices,  assembly
rooms  and halls, in which distinct and easy elocu-
tion, or the  completest  delivery and  reception of
musical sounds and literary compositions, are the
principal desiderata.
  Under the  aids  of forced ventilation, or that in
which an independent  motive power is relied upon,
all  varieties  of system require, as a  condition of
their full effect, the avoidance of any direct com-
munication with the outside air, by the closure of
all  windows  or  openings, which might admit for-
eign,  or confuse designed vibrations.   Hence, the
purest efforts of speech and  music are transmitted
to  the  audience, unmutilated and  unmixed, and
with the least labor and pain on the part of the
vocal performer.   The most refined enjoyments of
the musical art, the  most persuasive and overpow-
ering effects  of eloquence,  and the full weight of
instructive attempts, thus unite  their claims  for
consideration, in this  useful  science, as well as the 
OF VENTILATING BUILDINGS.
9
more immediate and pressing demands of body and
mind, for exemption from  disease, prolongation of
days, and the highest intellectual and moral  ex-
ercises.
   It has been customary  with every writer and
teacher on ventilation, to commence his labors with
a more or less thorough elucidation of the chem-
istry of  respiration, and the  other  physiological
relations  of that all-essential process of  the animal
economy.  That these are immensely consequential,
no one would think  of doubting, and well worth
all the laborious experimenting and research which
they have so long and so faithfully received.   The
very fact, that a half  of  the machinery of the
human body, measured  either by its capacity or its
complexity, is devoted to the function of ventilating
the  blood, by processes  essentially mechanical and
chemical, demonstrates the role which the  air plays
in  the  support of  life, and  can  hardly  be  over-
estimated.  But, believing  with Mr. Brande, and
other distinguished philosophers, that neither chem-
istry nor physiology can afford us much direct aid
in determining  the quantity or conditions of  air
needed  for the uses of men in habitations, — that,
like food or clothing, it is  a practical question, to
be  solved only by experience, I do not propose to
dwell upon these indirect subjects, already so well
understood by the profession, and  upon which the
fullest and most  trustworthy authorities are access-
ible at every hand. 
10         ON THE PRACTICAL  METHODS

  Indeed, it seems to me, that the  experimental in-
vestigations  which are to aid us in  applying results
to useful purposes of existence, are only those  in
which, (to use the words of Dr. Reid,) men in bodies
and aggregations are regarded in the light of matters
for  chemical  examinations and  trials, while their
habitations, from palaces to prisons, are the pieces of
apparatus, in which the analyses of results are to be
wrought out, by patient and oft-repeated tests.
  Nor do I intend to open  to  any considerable ex-
tent, the pathological considerations, — the charac-
ter and causation of the  multiform diseases,  con-
nected with that deterioration of the medium of life,
which it is the object of ventilation to, prevent and
to cure.   This connection has grown into an import-
ance, under  " this new era of sanatory reform," as
it has been so  well called, its bearings  have been
so fully studied, that  to  do adequate justice to its
claims, the original evidences from the experience of
the old world, must be examined by volumes, not in
abstracts.
  An able writer on Military Engineering, observes
in relation  to his art, that facts, which  are  the
deductions  of long and tried usage, hold in many
instances, the place of principles.   This  axiom ap-
pears equally applicable to the  practice of ventil-
ation. An  art made up of the  contributions of so
many departments of knowledge, involving so many
difficulties in these combinations, and subject to so
many modifications, almost as  numerous, in fact, 
             OF VENTILATING  BUILDINGS.         11

 as the individual examples, can be  safely grounded
 only on experience.  Perhaps in  no other instance
 of the application of science to  the  arts of life, has
 it been found so unsafe to act  from pure scientific
 deduction, or where trial would  more annoyingly
 demonstrate, how  widely fluids,  whether gaseous,
 or liquid, act in  practical usage, from what they
 seem bound  to do, in legitimate accordance with
 theory.
   I would not be thought to undervalue an abstract
 knowledge of the sciences, involved  in the theory of
 this art, but only require that the practical applica-
 tion should be studied and determined, rather in the
 light of antecedent successful  and abortive trials,
 than on any a priori reasoning.
   Sir Humphry Davy, in the zenith  of his fame as a
 chemical philosopher, utterly failed  in ventilating a
 single assembly room, under the most favorable cir-
 cumstances.   Men  of infinitely lower  attainments,
 profiting by a long series of examples of all grades
 of perfection, are now able to succeed under the most
 complicated  and embarrassing difficulties.
   The  means  of ventilating buildings have been
 brought to their present advanced  and  successful
 state in Europe, rather  by successive steps — by a
 gradual gain of new points upon old, than by  new
 discoveries or inventions.  In this mode, will the art
go on to a still higher grade  of completeness, and
hence the necessity  of a  thorough understanding of
what has been done, to  avoid  the  repetition  of ex- 
12         ON  THE PRACTICAL METHODS

periments, which may have been tried and have fail-
ed again and  again.  Viewing our object  in this
strictly practical light, and believing from its very
nature, that no marked novelty can ever be expected
to replace all that has already been attained, as it
is not unfrequently the case, in certain mechanical
ends, I propose, as the most practical and available
method to aid a community like  ours, in search of
this  auxiliary to  health  and  comfort, to  bring  for-
ward, and briefly explain the plans which have stood
the test of adequate trial, in various countries,  and
under  various  conditions of climate and occasion.
From these will then  be separated  the points  and
principles which appear to be ever present and essen-
tial.  The way will thus be opened for the means of
judging of the  relative value of the  modes of bring-
ing about satisfactory results,  which are found to be
constant, and the circumstances which determine an
election  of  individual varieties,  among  the many
ways of accomplishing the  same end.
   I am aware  that the suggestion, that there is no
well founded reason to believe that any of the mod-
ern  improvements in ventilating are to be considered
in  the rank of  new  discoveries,  will  strike many
persons, who  have  only read the books  of certain
 claimants of original methods, as indicating an un-
charitable disposition to detract  from the merits or
honors of origination.   A disinterested investigator,
removed from the influences  of national, partisan,
or personal partialities, I cannot but think, on fair
adjudication, will feel full  confidence, that the  ad- 
            OF VENTILATING BUILDINGS.          13

vanced specimens of  modern ventilation  are  due
only  to the unbounded opportunities  of carrying
out  well recognized ideas  of long standing.   Dr.
Reid's plans, which  doubtless have been regarded
as new, by  those deriving their sole  information
from newspaper paragraphs, or critical reviews,
will be  found, when  fairly analyzed,  only the
fruit  of  well understood principles, applied with
very advantage of mechanical skill, and unlimited
expense, occasionally carried  to  an extreme of re-
finement, fastidious and finical.
   Any one who will run  over  the  annals  of sci-
ence, can go back to the very fountains  of medicine
for the earliest recognition  of the importance,  and
indeed, for  some of the practical methods of  this
department  of  hygienic  and  sanatery  protection.
Moses appears to have  comprehended  the nature
and  importance of external ventilation, as shown
in the geometrical and systematically arranged en-
campments  of the children of  Israel.  Two thousand
years ago, Hippocrates treated of the value of a pure
atmosphere,  its influence on life and  disease,  and
laid down rules for securing this object, with a clear-
ness and  truth, which demonstrated that his won-
derful tact and observation, so many centuries before
the constitution of the atmosphere, or the chemistry
of respiration were dreamed of, had  given him  the
most  correct and  practical notions of  its  import-
ance.
   Celsus, in his instructions as to the treatment of
fevers, directs the air of the  patient's room to be pu-
              3 
14         ON THE PRACTICAL METHODS

fined by a fire lighted in a fire-place — involving the'
same principle of rarefaction as Dr. Reid's Parlia-
mentary ventilation.   Agricola, in  the sixteenth
century, appears not only to have recognized the ne-
cessity of introducing pure supplies of  air artificial-
ly, but has suggested, or at least recorded  for our
instruction, the very  means for  producing  an up-
ward current of vitiated air, by fire applied to the ex-
terior of a metallic tube, through which the air was
thus speeded by diminished gravity and  partial vacu-
um,  long after adopted  by  Davy, and, as we  shall
have occasion to observe, forming the basis on which
various commissions in modern times, have  ventilat-
ed the most important public edifices.
  The real constitution of the atmosphere, we know,
was  a mystery, until analyzed and  its action on the
system  developed, by Priestly, Scheele, Black, La-
voisier and Davy, and that brilliant galaxy of  che-
mists and physiologists, which flourished towards the
beginning of the present century.   But its mechani-
cal properties, and its practical relations to health and
life,  were as well understood and as well applied half
a century  before.  In  1727, Dr.  Desaguliers, and
soon after  Dr. Hales applied  pumps, and  in years
subsequent, centrifugal wheels or fans, and flues urged
by fires, directly or collaterally.  In fact, most of the
means, which ingenious  men manipulating with a
fluid, the mechanical properties of  which were  per-
fectly understood by them, would  naturally adopt,
were actually introduced  to accomplish movements
and  results, which were alike manifest to them.  Pris- 
             OF VENTILATING  BUILDINGS.          15

 >ons, shops, and legislative halls, hulks and hospitals
 of all kinds, were provided with  apparatus to give
 them  pure and healthy air, and our  present plans
 are but little more than the ruder schemes of the old,
 and quaint projectors and philosophers, verified un-
 der circumstances  of  more  enlightened society and
 wider means*  Many of these enthusiasts in ventila-
 tion only lived before their day, and it is truly pain-
 ful to read, that men, the correctness of whose ideas
 in science, and the elevation of whose philanthropy
 entitled them to respectful gratitude, were obliged to
 dance a  fruitless attendance, on sneering and igno-
 rant functionaries of government, or even had plans,
 which in principle were equal to those  now in suc-
 cessful use in our best examples, turned into ridicule
 and rejected, by the mischievous interference of the
 mere menials  whose tempers or whose interests were
 not suited.f
   I am prepared to assert,  after a diligent recur-
 rence  to  the original accounts of these men, that the
 essential points of all  modern contrivances, except
 the single one of producing an  exhaustion by the
 admission of a jet of steam, were all anticipated in
 their writings.   No man of  our own  age, in my
 opinion, can sustain any higher claims  to original
 suggestion,  as regards internal  ventilation,   than
 should be accorded to ingenious  and well  matured

  * Fig. 1, PI. 1, represents a method of exhausting air from mines, copied
from a drawing in the Phil. Trans, for  1665. The fire in the grate produces
a current through the box, b, connected with the mine.
  fSee Desagulier's Philosophy, vol. II. p. 561. Fig.  3, of the same plate, re-
presents the  system invented by Mr. Sutton, an eminent brewer in London,
and much employed about the same period.  The foul air flues from the hold,
were admitted under a ship's coppers, or other fire. 
16         ON THE PRACTICAL METHODS
adaptation, more completeness of detail and higher
refinement of results.
  The English, since  1835, in consequence  of the
destruction,  by fire, of their  House of Commons,
and  the  determination  to   construct  a national
palace for the Legislative Representatives  of the
kingdom, on  a scale of magnificence  and  com-
pleteness, unapproached  in  modern architecture,
have  devoted,  under the patronage  of Govern-
ment,  and  the  impulse which a general  turning
of attention  to  a  subject  of  universal  utility
would naturally give,  a great amount  of research
and ingenuity to the  means  of ventilation of  all
kinds of habitations  of  men, on land  and water.
The accounts of many of the most complete of these
undertakings, drawn  up with the utmost  minute-
ness  of detail, and  the record of their operations
verified with mathematical certainty, are before the
world. Their worth as contributions to the cause of
science and  philanthropy, is not to be undervalued,
yet it is not to be concealed that, thus far, there is
no evidence  that the British attempts have  proved
more  advanced  in  science or  success,  than those
reached  by- their  neighbors  across the Channel,
under the guidance of Gay-Lussac, Thenard,  and
others, who have pursued their investigations and
applied their results,  in that  quiet  and unobtru-
sive,  yet thorough research,  which so eminently
characterises the labors of the French savans in
every field of scientific pursuit.
   While the  opinion is thus confidently  offered,
that no great or original discovery can be justly 
           OF  VENTILATING BUILDINGS.         17

asserted  in modern  ventilation,  a denial which
detracts little or nothing from the honorable claims
of those, whose skilful  adaptations are as useful as
if they had the element  of  originality in them, it
is humiliating to be  obliged to  confess that our
own country stands lamentably in the back-ground,
in this important provision.  It would be  difficult,
if not impossible, to point out half a  dozen speci-
mens of buildings, ventilated in accordance with
the full  application of principles, tested elsewhere
successfully for years, although it must be accorded
that in view of our climate, our  habits of life, our
great disposition (beyond example) to  constant and
protracted accumulation  of numbers,  for  purposes
of business, instruction or amusement,  by night and
day, no  community hi the  civilized  world, more
really and urgently requires the  aid  of the venti-
lating art, so far as regards  its  important ends  of
comfort and health.
   Our common school system, in which  minds and
bodies are moulded at the plastic period of life into
forms to be retained, and I may say without trench-
ing on the domain of  new theories or speculations,
perpetuated, offers a more urgent appeal  for atten-
tion, than can be imagined in  any old world insti-
tutions.
   We, too, are becoming rapidly a manufacturing
people, to follow  in  the awful footsteps of our
prototypes, the world  over, unless we can do that
most difficult  of  moral  feats, profit by the unfelt
experience of preceding races.   We are doing what 
18         ON THE PRACTICAL  METHODS

the world has no historical parallel of, in building
towns and cities.  A few men of giant energies, of
boundless faith,  of far-seeing calculation, sit down
in the counting-rooms of this city, with a surveyor's
sketch,  and a few  engineers' levels.  They decide
that a town shall be built — a manufacturing city
erected.   Straightway, and almost like the falling,
opening, raising, changing  scenes of the theatre,
huge brick palaces arise, streets in long perspective
of shops, schools, houses, side-walks, begin to stretch
themselves out  from a  thousand  nuclei, to  meet
the new formed elements in exact  symmetry, like
the points of ossification in  the growing embryo.
Churches point their spires to the skies, in all the
beauty  of Gothic  tracery, or   plant their firm
columns of stone, in all the solidity of Grecian art.
In short, what  the  conquerors of  the world have
been lives and centuries in designing and accom-
plishing, is called into  existence by our  merchant
princes, almost with the wave of Prospero's wand !
  Would that the  same prophetic and  far-seeing
vision, which pierces  so clearly into the distant
future, as to warrant these  unbounded outlays, —
the same forecast, which casts  its bread  upon the
waters  with so  lavish  a  hand, in  the  confident
expectation  of a bountiful return — which  boldly
cuts down hills and fills up  vallies to accommo-
date the hundred thousand inhabitants, presenting
themselves in  the mist}" future, while the grass  is
still green in the projected  avenues, — would  that
it could, at the same time, foresee and prevent, the 
OF VENTILATING BUILDINGS.
19
disease, the death, the  misery, the moral, social, as
well as political ills, which appear, upon the best of
evidence, to go hand in hand with neglect  of  plain
sanatory precautions, — and realize the illustrations
unnumbered from experience  past, which  tell with
demonstrative  certainty, that moral and  social de-
gradation are indissolubly  linked  with disobedience
of nature's laws.
   I blame not these  founders of cities, that they
have paid but little regard to hygienic and sanotary
measures.  It is  glory enough to  build cities, — it
is too much to expect  the same  minds which can
grasp  all  the elements  essential to  these  great
undertakings, in a commercial point of view, should
comprehend  all the mysteries of typhus, struma, or
contagion, and the relation of these to ventilation,
sewerage,  and water  supply.   It is for  our pro-
fession to step in at this point, and to guard  the
rights of  generations yet unborn, in  these  respects,
and the wise  interest, the sagacious foresight, the
honorable ambition for unmixed success, will  guar-
antee  the co-operation of  the builders  of cities,
whenever they are convinced  of the reality of  the
evils, and that  they are susceptible of prevention and
relief.
   The " ghastly  bills of  mortality," as they have
been termed  by an English statistician, (under some
overlooked  or mistaken  modifying  circumstances
perhaps,) of  one of  our new cities, the prevailing
impression of the unhealthfulness already of  our
lately  populated  manufacturing  towns, call  aloud 
20         ON THE PRACTICAL METHODS

to the medical profession to look  at  the growing
evils  of hygienic  neglect, full in the face, and if
they require a plenary and  decided remedy,  how-
ever costly, it will not be long in being found.
  It might not be out  of place, were it of any prob-
able utility, to inquire  into the causes of  this  want
of advance  generally, in an  art so universally ad-
mitted, in language, to be important.   We scarcely
ever read the description of a new  assembly room,
or theatre,  or hospital, or penitentiary,  in which
we  do not  find laudatory and  congratulatory no-
tices of the excellent provision for ventilation.  This
provision, of course, in ninety-nine cases out of a
hundred, is  nothing more  than some small holes
left in the  ceiling, the inefficiency \of which has
been notorious for a hundred years.   Still such a
general recognition  is  sufficient to  prove a general
necessity.
  Our inefficiency cannot be from want of acquaint-
ance with what  has been done in other  countries,
more advanced in the arts of living, since  the books
detailing the necessities and the modes  of meeting
them, in the most authoritative manner of investi-
gation, are known to every scientific  inquirer, and
are  to be found in every considerable library *   We
must rather ascribe  our backwardness to the same
general causes, which  have kept architecture, both
as a useful  and  an ornamental art, at so low an
ebb, throughout our country.   One of these is, that
* Appendix D. 
OF VENTILATING  BUILDINGS.         21
 for the moderate  capital we have to devote to such
 purposes, we have  an undue desire, a morbid am-
 bition to produce more of splendor and show, than
 is compatible with permanence, completeness of in-
 terior arrangements, or regard to hygienic consider-
 ations.  Anything out of sight, like the deep and
 enduring concrete foundation, the inverted  arches
 of support, designed to meet the possible failures
 of succeeding centuries, or the concealed  arrange-
 ments needful for a thorough and universal venti-
 lation, which must commence almost at the  corner
 stone and be kept in  continuous design until the
 last finish, would be struck out, in a vast majority
 of instances,  from the  architect's specification, (if
 he dared to  suggest  them,)  as  an expense which
 might be saved without  being  felt.  On the other
 hand, the dome, the spire, the columns, the pilas-
 ters  and balconies, some of which, as mere  orna-
 mental appendages, could be added at any time,
 now  or a century  hence when funds might be more
 abundant, or never, would be adhered to as essen-
 tials, as indispensable.
   Despite the science and mature experience of a
 thousand European  attempts, fully and exactly de-
 tailed in the unmistakable language of  description
 and  pictorial  representation, our  Building Com-
 mittees would assuredly, after  making  their per-
 sonal inquiries among   the  hundred  interested
patentees or dealers in new furnaces, chimney-tops,
revolving turn-caps, and the like, conclude  that.
amongst  so many practical men.,  promising in their
              4 
22         ON THE PRACTICAL  METHODS

advertisements and  circulars,  so  many  cheap and
effectual methods of doing that which the old world
artists  consider so  difficult and expensive, some
ready measures  would turn  up, when their part of
the duty was finished.
  The  most costly edifice in  the northern states,
just finished with eternal granite, on  foundations
based in the ocean, at a cost of a million of dollars,
is an  illustration, an abundance more of which
could be easily adduced, were  not the  task an in-
vidious one.   Proposals for heating and ventilating
were advertised for, after the building was finished !
  I would not, however, be  understood to  criticise,
with undue severity, an  unacquaintance or neglect,
for which our profession would certainly be obliged
to  assume a  fair  proportion of  the  responsibility.
It is to be considered,  that  ventilation,  however
appreciated by the scientific, is only gradually forc-
ing  itself into the  notice  of ordinary minds, to
whose practical experience a predominating weight
of  deference must naturally be paid in a new coun-
try.  We  have yet scarcely a class of architects,
whose character or  attainments  are  sufficiently ac-
knowledged,  to allow their judgment and taste to
overrule  the  occasionally  absurd  phantasies, or
conceited presumption  of Building Committee ma-
jorities.
   A new country, engaged in  burning up the origi-
nal forest as rapidly as possible,  in laying deep the
basis  of  civil and political institutions, in taking
care of things indispensable  to actual existence, 
OF VENTILATING BUILDINGS.          23
cannot  be  expected to provide  for all present —
much less future and contingent evils.   Had those
who laid out the  three-mountain city, by  taking
the cow-paths, or no more positive indications, as
their guiding lines, seen that in a couple of  centu-
ries it was to be a great metropolis, yielding  all the
moral and social good and evil of a great city, how
widely different would  have been the expanse of
their  views, and the modes of  applying  them in
practice !
   Could those now on the stage, see the hundred
and fifty thousand of the population of it, and its
suburbs, quadrupled in  a hundred years, how much
ought  they to learn by the  present  condition of
analogous cities of the  old world.  What has been
will be ; and we can read no plainer augury of what
we are  to  be  socially, and municipally, than to
apply the lessons presented by our mother country.
Sir Christopher Wren, after the ground was all laid
open in London by the great fire of 1666, matured
and delineated a plan, lately rescued from oblivion
and published, by which that  city was  to be con-
structed, as regards the  great provision  of pure air
to its  inhabitants, so as to secure its healthfulness
to all future time.   Could the citizens  then  on the
stage, have had that faith, which now seems to have
been so obviously irresistible, what myriads of lives,
what a boundless extent of disease, moral wretch-
edness and misery, would have been saved!  Yet in
New England, we see  thousands of  houses con-
structed on the marine marsh, with scarce an inter- 
24
ON THE PRACTICAL METHODS
vening yard of gravel, perhaps not a foot, between
highly finished  and furnished mansions, and  that
awful quagmire  of  decomposing  animal and  vege-
table  remains,  the  emanations of the  pestiferous
gases  from which, penetrate the closest interior, and
leave  the stain  of their  chemical action upon the
valuables contained — still more  is it to be dreaded
upon  the bright faces and active lungs of the youth-
ful inmates,  called into existence,  in  habitations
suspended  over this sea  of corruption !
   Besides  these  natural obstacles to  sanatory pro-
vision in  a new country, we  have undoubtedly in-
dulged the fallacious hope  or impression, that our
peculiar climate, or abundance of space, would save
us from the consequences of those violations of  sana-
tory laws, elsewhere followed by the direst penalties;
and as every new settlement is pronounced salubri-
ous, until disease and death afford undeniable  proof
to the contrary,  so we have waited to have an  over-
powering  weight  of unequivocal evidence  of the
injurious  influences of  neglected ventilation, before
it is  deemed worth while to  act.  These  evidences
have  been slow  and gradual in coming.  Our cities
have  not been much compressed  with living masses,
our penitentiaries,  almshouses, and  hospitals, have
been   too few and on  too  small a scale, to present
the lesson so as to be clearly read.  Manufacturing
establishments, where hundreds are engaged in labor
within reach of each others' inhalations, with their
 crowded boarding  houses, in which the operatives
are almost piled at night, so that only a few feet of 
            OF VENTILATING BUILDINGS.         25

space separates the lungs of each denizen of a large
town, constitute emergencies of but yesterday.   Still
more, the rapid growth of many of our commercial
towns, increasing from  hundreds to thousands, as it
were, in a night, carrying them, with no intervening
space for adaptation and experience, from the rank
of mere villages to great cities, has given  them no
warning, nor led to any protective  measures against
the physical or moral evils, which are incident to
these " great sores  on the body politic,"* whether in
the new or old world.   In short, the call to alleviate
and provide for the consequences, necessary and un-
avoidable, of great accumulations of human beings,
poverty, filth,  disease, and death,  comes at  once,
without premonition.   The imperious necessity, and
the  skill, intellectual  and mechanical, to meet its
pressing  demands, follow  in that slow succession,
which leaves' thousands of victims in the track.
   Our present demand for internal ventilation as a
domestic necessity, has also been strongly influenced
by the change in the modes of heating, within a few
years.  The roaring fire-place, built with an open-
mouthed immensity of voracity, as if the struggle
were to aid in getting rid of the primeval forest, —
in which the  Roman  poet's verse was practically
illustrated in every household,
                  --------ligna super foco,
                  Large reponens ;

—has been replaced  by furnaces, stoves, air-tights,
* Jefferson. 
26         ON  THE PRACTICAL  METHODS

of all forms  and shapes which caprice or ingenuity
has invented.   The sweeping flood of  air, which
carried with  it, in its  course,  the most liberal in-
draughts of the pure breath of heaven, compensating
for the abduction so largely of the warmed air itself
by  the  radiated caloric of the  blazing  pile, has
been dammed up, and  that almost entirely.   The
re-respired, roasted, ill-conditioned air of the dwell-
ings even of the rich, is the result of a parsimonious
economy, which strangely  and absurdly exists as to
this, in  a  thousand instances, where  comfort and
luxury make no other sacrifices to saving.  Fuel
saving is one of the cardinal virtues, in the house-
keeper's creed, while provision saving, or pure water
economy, would be scouted as the height of mean-
ness, or uncalled for  self-denial.
  Be  all the circumstances  of defective  sanatory
provision, (of which  ventilation is surely one of the
most pressing,) what  they may, there can be no
question that the results  of impure  air, are upon
us, in all the  malignity and  infection of  the old
world in degree; and even  since we last met, and in
our midst,  amongst  our associates, the  Angel  of
Death has hovered around, sending his fatal shafts
to pierce some of the noblest sentinels of our ranks,
and warning  us, that if we would improve  the sad
experience  of older  countries, we may not longer
delay our defensive preparations  against that most
broad spreading missile of  destruction, poisoned air.
  In that  unfortunate over  self-estimation, which,
happily,  is  now beginning  to  be felt and acknow- 
           OF  VENTILATING  BUILDINGS.         27

ledged as having formed almost  one of the charac-
teristics of our national identity, we are accustomed
to speak of ourselves as a long-lived people, inhab-
iting most salubrious climates, and advanced to that
grade of civilization and general education, in which
the laws of nature were recognised and obeyed, as
well as the laws  of  revelation and  of the social
compact.
   Reposing self-complacently in a presumption of
this kind, (unfounded, it is true, as statisticians am-
ply demonstrate, as  far as health and vitality are
concerned,) we have  felt less  called  upon,  than
communities conscious of  their  own  deficiencies,
to search out  and correct any of those prejudicial
influences in hygiene, which bear upon the proba-
bility of life.
  This is not the occasion to examine the important
question, how far, as New Englanders, we compare
with  other  communities  in  life  and health.  The
simple fact that the tables of life  probabilities, de-
duced from the experience of the crowded, poverty
oppressed nations  of  the  old world, the  victims of
so  many circumstances, moral  and physical, calcu-
lated to influence health and shorten existence, are
practically found not inapplicable to  a New  Eng-
land population, at the present  time, casts  a  most
melancholy foreboding  upon the  prospects of  com-
ing generations, when all  the  health-influencing
concomitants,   whether of penury or  luxury,  of a
dense population, are added  to  our already prolific
life-abridging  influences. 
28           ON  THE PRACTICAL METHODS
   An  associate  of  this  Society,  Dr.  Jarvis,  in  a
report,   as  Chairman  of  the  Committee  of  the
American  Statistical  Association, appealing  to the
Legislature at its last session, for  a sanatory  survey
of  the Commonwealth, demonstrates this important
fact so conclusively that  I  cannot  forbear to leave
the proof on record. *
   How wide spread and active one of these life-short-
ening causes, the daily, hourly inhalation of vitiated
air is, may  be deduced  most  conclusively, though
from its  nature, only generally, from the universal
  * We may be a favored people in many respects ; but, in comparison with
some other nations, we do not enjoy the highest degree of life.
  According to the best calculations, the average longevity of the people of
this state is less than in Sweden, France, and some counties of England; and
it seems to be less here now than it was in the past generation.
  The average age of all who died in Geneva,  Switzerland, from
                         1814 to 1833, was
Massachusetts from          1842 to 1845,  "
            in                 1842,  "
                               1843,  "
                               1844,  "
                               1845,  "
The average age of all whose deaths are recorded in
40 years 8 months
Massachusetts, in

Concord,

Dorchester,

Boston,
1842,
1845,
1779 to 1808,
1809 to 1842,
1817 to 1829,
1830 to 1843,
1811 to 1820,
1831 to 1840,
The average age of the living,            was in
England in               1841,
Massachusetts, in          1840,       was
United States in              "         "
And in  the northern states, including New Eng-
  land, New York, Michigan, Wisconsin, and Iowa,
In the middle states, south of the above, and north
  of North Carolina and Tennessee,  -  - - -  -
In the states south of the middle,.....
33
34
33
33
30
 0
 9
10
34.9 years 9 months
30.9
39.9
36.9
33.9
31.9
27.7
22.7

  26
  25
  22

  23

  22
  19
 3
 7
 0
11
 2
 3
 9

 7
10 
OF VENTILATING' BUILDINGS.          29
experience of men in all places.   Numerical  facts,
collected with cautious observation, and over long
periods of time, justify exact conclusions, as respects
those bodily conditions, which language is precise
enough to specify.  Yet how few, how insignificant
are those  truths on  this subject, capable  of being
exactly recognized and statistically recorded, com-
pared with the infinitely wider spread, more pene-
trating evils,  which can  be conveyed only in  the
words  of  general  impression  and personal convic-
tion.
   When  the .laborer is drawn from  the  well,  the
vat, or the  mine,  asphyxiated  by  immersion  in
carbonic acid gas,  or is  smitten with instantaneous
death,  by the noisome  burst  of phosphureted or
sulphureted hydrogen,  or ammoniacal gases of a
Parisian  sewer, we  see an extreme exhibition of
this causation, in  palpable and undeniable promi-
nence.   In  the deadly  typhus of jails,  emigrant
ships, or  other dwellings of numbers and misery,
we can as little  doubt  the  fatal consequences of
impure air.   When we examine the immense mass
of  sanatory documents,  collected  under  the Par-
liamentary inquiries  of the  British  government,
detailing the connection between  the  damp, unven-
tilated lanes and  cellars of Liverpool  and Man-
chester, and  the  prevalence   of struma,  phthisis,
rachitis,  fevers  of all types  of malignity,  from
simple  ephemera  to deadly typhus; in  fact,   of
almost  every  form  of  acute   or chronic  diseases,
which  constitute the great outlets of human  life, 
30         ON THE  PRACTICAL METHODS
we recognize an equally unbroken link in the chain
of cause and effect, antecedent and consequent.
   The experience  of the  celebrated Black-hole  at
Calcutta, in which one hundred and  forty-six  per-
sons were  confined over night, within a space  of
about five thousand cubic feet, showed the singular
fact, that the deaths of all but twenty-three from
immediate  suffocation, were not  more  directly the
result  of  vitiated  air, than  that  of most of the
survivors within a  few  weeks after, of putrid fever.
   Dr.  Southwood  Smith,  in his  testimony  before
the Commission for inquiry into the state of large
towns and  populous districts, observes, that it is no
exaggerated  statement to say  " that  the  annual
slaughter in England and  Wales, from preventible
causes of typhus fever,  which attacks persons in the
vigor of life, is double  the  amount  of what  was
suffered by the allied armies in the battle of Water-
loo."   Add to  this  the  appalling fact, that each
death  from  typhus  implies from seven  to  twelve
persons dragging out a long and  painful  sickness,
under circumstances  of the greatest privation  and
misery, and we shall realize  the  terrible extent  of
suffering within the power of relief.
   Yet how little do we comprehend of  the  extent
of the evils of the depraved pahidum  vitae, atmos-
pheric air, from these palpable,  tangible illustra-
tions.   Dr. James Johnson,  in  his  striking  and
impressive  manner, remarks, in his Diary of  a  Phi-
losopher, in discoursing of the evils of impure air,
that " ague and fever,  two of the most prominent 
OF VENTILATING  BUILDINGS.             31
 features of  the  malarious  influence, are as a drop of

 water  in the ocean, when  compared with  the  other

 less  obtrusive  but  more  dangerous  maladies,  that

 silently disorganise the vital structure of the human

 fabric,  under the  influence  of  this  deleterious  and

 invisible poison."*

           * {Extract from the Report of the Registrar General.)
  " Out of an equal number of males  living, there were three deaths in Lon-
 don for every two in the healthy counties.  Out of 1,000 boys under five years
 of age in Surrey, and 1,000 in Sussex,  48 and 50 died annually ; out of 1,000
 in London, 93 died annually.  The mortality of  children under five years of
 age, is twice as great in London as in the adjacent counties, including several
 towns.
  " The excess of deaths in London  is not the result of climate, for the
 climate differs  little from that of surrounding counties ;  and some of the
 London districts are not more unhealthy than many country districts.  Take
 Lewisham, for  instance, comprising Blackheath, Sydenham, Eltham,  and
 Lewisham itself.  The annual mortality of females was 16, of males  18, in
 1,000.
 The  actual deaths registered in  London during the seven  years
  1838—44, were..........342,000
 If the mortality during the period had not been greater  than in
  Lewisham, the deaths in London would have been about  -  -  -  244,128

           Excess of deaths in London,    -                    97,872
 Here are 97,000 deaths in seven years, from causes peculiar to London.  Other
 districts may be taken in the place of Lewisham, but the result would be the
 same.
  " A considerable part of the population of  London  is recruited frdm the
 country ;  immigrants entering chiefly at the ages 15 to 35, in a state of good
health.  The sick and weakly probably remain at home ; many of the new
comers too, unmarried, when attacked  in London by slow consumption — the
most fatal disease at the ages 15 to  35 — return to their father's house to
die ;  so that the mortality of the great city is made to appear, in the returns,
lower at those ages than it is.  If we take children under five years of age,
where neither these disturbing  causes  nor occupation interfere, the delete-
rious influence on health, of London in its present state, will  appear undis-
guised in all its magnitude.
The deaths registered in London under 5 years of age were  -  - -  139,593
The deaths, if the  mortality had not been higher than in Lewisham,
  would have been..........80,632
Excess of deaths in London among children,       -    -            58,961 
32         ON  THE  PRACTICAL METHODS

   The British Government has  long  evinced  the
most high-minded and liberal policy,  fully repaid
by the returns  to  human health  and happiness, of
aiding science  in its  researches,  as respects those
great  points  of  inquiry,  which,  however conse-
quential  in their  bearings, can, from their magni-
tude and complexity, only be  elucidated  on  the
largest  scale,  and   by authority.   Among   the
immense mass of facts, bearing  on  man  and  his
diseases,  ever  in the process  of  collection,  and
accessible to proper  examination,  are  the  reports
of  the army and navy  medical officers,  on  the
sickness  and mortality of  troops  stationed  around
the globe.   " These,"  remarks  Mr. Hood,  " prove
most clearly the immense  effect  upon  human life,
produced by small and almost inappreciable differ-
ences  in the quality of the  atmosphere.   For, in
the same class  of  persons, performing  the  same
duties, and placed  as exactly as possible  in  the
same circumstances, the average mortality varies in
different parts of  the  world, from 1.57  per cent, to
66.83 ; or the mortality is nearly forty-nine times as
great in some localities as in others."*

  " Here are more than 58,000 children destroyed in London within seven of
the last ten years."
  Ninety-seven thousand deaths in seven years, from causes peculiar to the
" comparative health" of London ! Fifty-eight thousand children destroyed
in London, within seven years, by removable morbid agencies !  Three deaths
in London, where there might be two !  The chances of infant life in London,
reduced one-half below even that very unsatisfactory standard elsewhere real-
ized by sanatory arrangements!
  * These reports contain the results of twenty years, and present the follow- 
OF  VENTILATING BUILDINGS.          33
   Did the hour or the  scope of my design  permit
the general  consideration of the  effects, immediate
and remote, of the  pulmonary imbibition  of the
gaseous agents into the  human  constitution, under
all their forms and combinations, how could I  so
powerfully illustrate my subject, as by bringing  to
your minds  the great discovery of our age, connect-
ed so intimately with the name of a  distinguished
associate of  our  number, — a discovery  already
world wide, in the glory reflected on the land of its
birth, upon our metropolis, our profession, as it is in
the blessings it has conferred upon our race — a dis-
covery, which, with vaccination, forms  the two great
triumphal columns in the world of  medical science,
— the annihilation of pain  by the inhalation  of the
vapor of ether ?  If in our hasty illustrations  of the
influences of  the gaseous mixtures of the  air we
breathe, upon health and life, we see disease, pain,
death, horror, in the inspiration of the pestilential
vapors of many names—in this we see health, re-
lief, blessing,  extasy!   If  those  bring with  them,

ing per centage of deaths per annum, among white troops only — native troops
being excluded:
                   Per cent.                     Per cent.
British Guiana, -----  8.4  Sierra Leone, -----  48.3
Trinidad,  -------  10.63  Cape Coast Castle,  -  -  -  66.83
Tobago,.......15.28  St. Helena,   .....3.3
Granada,.......6.18  Cape of Good Hope,   -  -   1.37
St. Vincents,.....5.49    do. Frontiers,  -  -  -  -   .98
Barbadoes,......5.85  Mauritius,......2.74
St. Lucia,   ......12.28  Ionian Islands,  -  -  -  -   2.52
Dominica,......13.74  New Brunswick, -  -  -  -   1.47
Antigua,    ------  4.06  United Kingdom,  -  -  -   1.4
St. Kitts,    ------  7.10  Canada,   ......1.61
Jamaica,    ......12.13 
34         ON THE PRACTICAL  METHODS
" blasts from hell," this, this  truly  " breathes airs
from heaven!"
  Proceeding then, in that strictly inductive method
I have  intimated as being essential  to reap  practi-
cal  and applicable advantage in this art, I shall
endeavor  to sketch a brief but  substantially com-
plete account of the modes of ventilating various
kinds of habitations, selected  from the most suc-
cessful  and well  tried  examples.   Having  no
particular  preferences for,  or  convictions  of  the
superiority of any given system by itself—confident
that various considerations  may render,  sometimes
one, sometimes another the  more  eligible, I shall
not confine  myself to a few methods, but endeavor
to point out the prominent features of all the really
tried arrangements.
  I hardly need explain or apologize for the fact, that
only a mere outline, an unclothed skeleton as it were,
of the subject, can be presented within the compass
of an hour, compelling a resort to pages  omitted, to
notes and appendices, for much  of the  exact and
practical details, from which alone  a clear  under-
standing and ready adaptation of the  labors and
experience of others can be secured to our  own
community.   It is fortunate that the precedent  of
so many of my distinguished  predecessors, on this
occasion, warrants a departure from what is written,
which   under other  contingencies,  would  be  so
obnoxious to just  objection.   In this, as in most
mechanical descriptions, knowledge, to be available,
must  be exact,  precise, and specific; and  the aids 
            OF VENTILATING  BUILDINGS.          ."35

perhaps of diagrams, mathematical formulae, tabular
deductions and results, and other matter not capable
of  being  presented orally — addressed  to the eye
rather than  to  the  ear — are essential  to  a full
impartment of the subject.
  With aids like these, it would seem that the art
of  ventilation could be brought intelligibly to the
most moderate mechanical ingenuity, and that a few
hours study would justify that self-reliance,  which
would prevent the professional man from  giving
place to merely artizan ability to  repeat what has
been done   before,  irrespective of  differences of
circumstances, and to protect the community against
a  presumptuous and bold  empiricism,  promising
great results from insignificant means.
  It may not be  out of place to observe, that most
of  the examples  which will be adduced  as illustra-
tions of  the best  results of modern  ventilation,
have been critically investigated by your speaker,
during a recent short visit of exploration to the old
world, devoted to this and some  few other  topics,
connected  with  the  completeness  of our  public
institutions.
  This declaration is  advanced  from no vain  desire
to give authority  to opinions  by  any assumed weight
of credibility as an eye witness, but from the notori-
ous fact, that the accounts of most of these  great
works having been drawn up  by their immediate
friends, supposed inventors or suggesters, some safe-
guard seems  proper  against the undue  partialities
and extravagant eulogiums,  natural enough  to en-
thusiastic men, even when honest  and disinterested. 
36         ON THE PRACTICAL  METHODS

  It is worth while to mention in this connection,
that almost all our accounts in the regular treatises,
of improvements in heating and ventilation, are from
writers, hardly standing  in  that  disinterested posi-
tion, which entire  disconnection with the  successful
result of plans, would enable them to claim.   The
books  on architecture,  have  hardly  a  page in  a
volume devoted to this  subject.   Some of the best
known works make no reference to it whatever; and
others merely sufficient to constitute an entry in the
table of contents.  A judicial  mind  thus becomes
necessary, to separate the claims  of interested par-
tiality from the cool  results of fact and experience.
  The first illustration will be drawn from  the re-
cent arrangements under Dr.  Reid's direction, for
ventilating the English Houses of Parliament.  This
constitutes so marked and prominent  an  instance of
the modern attempts in  many of the  works, that  a
brief history of still anterior trials on the  same field
may not be irrelevant.  We  can, in fact, upon this
spot, trace the progress of the ventilating  art almost
from its first rude and  undigested beginnings — at
which I  humbly conceive, we in this country now
stand — up to that point of luxurious perfection, in
which zephyrs, sifted and washed, cooled in  icy pas-
sages in  summer,  and gently softened by the prox-
imity of steam  in winter,  as  well as impregnated
with the balmy fragrance of " Araby the blest," are
admitted in gentle and imperceptible volumes,—
weighed and gauged, as it were, to fulfil the required
demand. 
OF VENTILATING BUILDINGS.
37
   From the varied ages and temperaments, the often
impaired constitutions, the  luxurious habits, the in-
tellectual activity of so large and important a body,
charged with so high functions, compelled to be to-
gether for many long hours at night, under circum-
stances often of the most  intense attention and ex-
citement, a defective  ventilation  must have been
early recognized, and measures of relief projected.
The illustrious Sir C. Wren, the original architect
of the late edifice, as well as of all  the best  struc-
tures of the English metropolis, introduced nearly
the same rudimentary method, so common with us,
a specimen  of which in  fact ornaments, if it does
not  improve, this  our anniversary assembly  room.
" At  each  corner of the house, in the ceiling, he
made a large square hole, which was the bottom of
a truncated pyramid, that was  carried  six or eight
feet into the room above, and which was opened or
shut with a kind of lid."  " But it often happened,"
continued the describer of this early plan, " that when
the pyramidal funnels were opened, the air above,
being colder and denser than what was in the house,
descended through  the pyramids and annoyed the
persons who sat beneath  them;"  one  of  the fatal
objections to this plan which exists  in undiminished
intensity down to our days.
  To obviate  this difficulty the celebrated philoso-
pher, Dr. Desaguliers, was called upon to devise a
remedy.  He constructed in the attic above the hall,
a fire-place, the back and sides of which were of iron,
forming  a  cavity,  the  upper part of which opened
               6 
38         ON THE PRACTICAL  METHODS

freely into  the  atmosphere through the common
chimney, while tubes  from the truncated pyramids
opened  into  the  bottom  of the box thus heated. *
The obvious rarefaction produced an upward draught
of vitiated air from the ceiling of the assembly-room.
The activity of  this  current  and the consequent
change of foul air for fresh, would depend upon the
amount of fire, and the freedom with which the re-
placing supplies  were admitted below.   From his
description, it does not  appear as  if the  Doctor
appreciated fully the  necessity of this last provi-
sion to a complete working of a  ventilating plan.
The effect of his  arrangements, comprising so much
of the  true  elements, as  to render  the remaining
almost  certain to be discovered on a fair trial, was
defeated by the mischievous interference of an upper
female  domestic or house-keeper, who was deprived
of some apartments by the occupancy of the space by
the philosopher's apparatus.
   In 1736,  Dr.  Desaguliers again introduced into
the same  edifice, the  common centrifugal wheel or
blowing fan, probably using it for  the first time to
propel fresh air into, or exhaust vitiated air from in-
habited apartments. This machine  for giving motion
to air, is now in too common use in the arts of life to
require a description.  As  a cheap and mechanical
contrivance in winnowing grain, in furnishing liber-
al supplies of oxygen to facilitate  the combustion
  * Fig. 2. PI. I. c, c, are the pyramids, now closed at the top, opening
over the hall and connected by the flues e, e, with the cavities x, x, of
the enclosing iron box a : b is the fire grate, fed in the attic r r. 
OF VENTILATING BUILDINGS.         39
of anthracite and other fires in steam engines, in pro-
ducing a copious evaporation where rapid desiccation
is  required, and  other purposes in the arts, it is
widely employed ; its rotary motion being given by
steam, water, horse, or human power.   As  the exte-
rior of the case covering the wheel, or the opening at
the centre, is connected with the apartment, so will be
its effect in throwing in, or sucking out the contained
air.  The  natural practical result of this property is,
that to accomplish the first of these processes, the ap-
paratus is placed below, in the cellar or basement;
for the latter, in the attic, or above the apartment.
   The Doctor's machine  was driven  by the power
of a single laborer.   The  fan is described as being
seven feet in diameter,  and having  twelve floats
or leaves.   The speed was doubtless as great as so
limited a power could  maintain.
   This was the sole apparatus  employed up to the
year 1820, when an  ingenious  French nobleman,
the Marquis de Chabannes, introduced his method,
which had previously attracted  considerable atten-
tion from  its  efficiency at the Theatre Royal, Covent
Garden.   It  consisted, essentially, of  a large trunk
or chimney,  opening at the centre of the ceiling,
into  which various smaller flues carried from  the
galleries, or other neighboring  cavities, were admit-
ted.   A number  of  cylinders were placed high up
in this main foul-air chimney, into which steam was
admitted,  from a boiler below or  above, as might be
convenient.   The air,  rarefied by contact and radi-
ated heat  from these cylinders, would ascend, and its
place be immediately supplied from the vitiated air, 
40         ON  THE PRACTICAL METHODS
provided  fresh  supplies  were  properly admitted
below;  a point of great importance, now specially
regarded, but, as before suggested, much overlooked
in the earlier attempts.
   The House of Lords,  a much  smaller apartment,
does not appear to have been regularly ventilated,
until within quite a  late period.   In 1811, Sir H.
Davy was desired to furnish a plan, which  duty he
discharged.  The following is an outline of  his pro-
ject.  A  grate or fire-place  for the  combustion of
coals, was constructed in the attic, through the midst
of which fire a tube of iron a foot  in  diameter was
carried, so that the  whole exterior of the  cylinder
was surrounded by the burning fuel.  This  cylinder
was continued downward, in a  copper tube of the
same size, so as to open in  the top of the ceiling,
and upwards to the roof*   Sir H.  Davy  did not
overlook the necessity of a free  admission of air to
replace  that withdrawn, nor the importance of its
not being  admitted  in unhealthy  or unpleasant
draughts  or currents.   This  fresh  air,  whether
warmed or of its natural temperature, was admitted
through a multitude of perforations in the  floor.
Two lines of an epigram, written  on the occasion,
have brought down alike the evidence of this plan
 of diffused  admission being no  recent invention, as
 well as  perpetuated the liberal  reward  he  received
 for his scientific skill.
           " For boring twenty thousand holes,
           The Lords gave nothing----d—n their souls ! "
 * In Fig. 4, Plate I, a represents the escape flue with its lower end opening
at the ceiling; c is the grate or stove enveloping the iron part of the tube. 
           OF  VENTILATING BUILDINGS.         41

  This apparatus is said not to have been uniformly
efficacious, although it is difficult to see wherein the
principle of it was not sufficient.  A writer suggests
that the management of the windows  and doors in
the hands of careless or idle persons, explains the
occasional reversed action which was complained of.
The architect attempting to remedy this,  removed
the  artificial heating above,  and  with it all the
ventilation of the hall.   Insufficient magnitude of
apparatus was the probable  explanation of Sir Hum-
phrey's failure.  Dr.  Desaguliers' wheel had contin-
ued in use seventy-four years, proving a considerable
degree of efficacy, at least,  when the great fire oc-
curred in 1834.
  At this epoch, the  construction of the new houses
of Parliament was decided upon, on a scale of  mag-
nificence  and cost, quite unequaled in  the modern
history of architecture.   This is still in progress, not
having received  the  finishing touches after a  lapse
of fourteen years. To  render  this national palace
as complete in convenience, acoustic perfection, and
healthful arrangement, as it is in architectural gran-
deur and artistic decorations, the scientific corps of
the United Kingdom were invited to aid  the Com-
mittee charged with  its construction, in the various
points of pure air, proper heating, and acoustic fit-
ness.  In the careful and minute reports  of the
evidence given by these men of science, we undoubt-
edly have all that was valuable, then known in the
scientific  world.   The evidence of Dr. Reid, a lec-
turer on chemistry of some  eminence at Edinburgh, 
42         ON THE PRACTICAL  METHODS

impressed the Parliamentary Committee so favorably
on his examination, that he was instructed to enter
upon an extensive course of experimental trials upon
the edifice temporarily occupied for  the House of
Commons, in order that any important results might
be transferred to, or  incorporated with,  the  new
edifice.
  The building  which has been the seat of  Dr.
Reid's labors, is,  in  fact,  the old  House of Lords,
which was the only portion of the former  structure
preserved from the flames.   His experimental trials
have been diligently continued for a number of years,
and in a  field where no want of means  is allowed.
  Dr. Reid has been subjected to much ridicule and
unkind aspersion, in regard to his  ventilating ar-
rangements ; and a misunderstanding with Mr. Barry,
the architect of the  new  Houses, has not unlikely
prevented the full application of his entire views, in
that location to which all his previous attempts have
been  preliminary.  Although  unable  to perceive
aught in the essential points of his arrangements, so
novel or peculiar as to place Dr. Reid in  the class
of discoverers — nothing, perhaps, which was  not
obviously understood and applied under  more re-
stricted circumstances,  by Desaguliers,  Chabannes,
Sutton, Hales, and Davy — yet  it cannot be denied
that in a full application of the principles of science
in his preferred  adaptation, he has  done all which
any man  could do.   If occasionally, under an  em-
barrassment  of riches,  he has  allowed  himself to
seek a degree of perfection, passing into  over refine- 
            OF  VENTILATING  BUILDINGS.         43

ment and fastidiousness, it is the pardonable error
of aiming too high.
   Under  the  obstacles which have  prevented the
completion of his great work, according to his views,
it is probable we must be compelled to look at the
present application, as the highest specimen of his
success, — subject  as  it is,  of course, to  the  diffi-
culties  of adapting new arrangements to an edifice
long since finished.
   A series of openings through the wall into a court
yard, admits the fresh external air to the basement
of the building.   This being situated in a most im-
pure and insalubrious district, it was necessary to
connect the street sewers with the chimney, hereafter
to be described, in order that their foetid exhalations
should not contaminate the air, at its point of ad-
mission.  A suspended fibrous veil, 42 feet by 18,
hangs before the external openings, the object of
which  is  to  separate the  mechanical impurities,
especially the flakes of soot, of which the London
atmosphere is  full, 200,000  visible portions having
been arrested during a single evening.
   The air  thus screened, is next passed into  a re-
ceiving chamber, constituting about one third of the
basement.  A partition divides this its whole length.
At the middle of this wall,  an opening permits the
air  to  pass through  an apparatus in which, by  a
thousand jets of water crossing  each other in every
direction, it is washed and moistened.   It then passes
amongst iron tubes filled  with hot water, by which
its  temperature is raised  to any required degree. 
 44        ON  THE PRACTICAL METHODS

 It now reaches a  long chamber, parallel  to  the
 receiving  chamber,  from  various parts of  which,
 apertures  are left which allow the air to press up
 into an equalizing  chamber  above, which extends
 under the whole  hall of assembly.   As the current
 passes  up, it impinges against a flat board at each
 aperture, raised a short distance above, called a dis-
perses which throws the air somewhat horizontally,
 breaking its upward current.
   No less than 300,000 of gimlet holes of a  conical
 shape,  with  the smaller orifice upward, to prevent
 clogging by dirt, allow the air to  escape into every
 part of the room above; and to make its diffusion
 more perfect, a hair-cloth carpet, woven porously for
 the purpose, gives it  an extreme and universal sep-
 aration.
   At one  part of the partition, between the first, or
 receiving  chamber, and  that from which the air is
 admitted  after  passing  through the warming appa-
 ratus, is another door,  making a direct passage for
 the  fresh  air without  its  impinging  against the
 heater.  By closing entirely or partially either  of
 these two openings, as  the  case may require, any
 degree of  change in heat can be  obtained with but
 little delay.   This circumstance, valuable in  an edi-
 fice  where  the  persons present  may change from
 fifty to a thousand at  once, or vice versa,  is less
 imperious for  common occasions, where  no such
 contingency exists.
   The escape of the  vitiated air is  provided for at
 the top of the room, where holes  are  left from one 
              OF VENTILATING BUILDINGS.          45

end to the other  into a  horizontal channel above,
which is received into a descending flue  passing to
the ground, and  communicating  with  the lower
extremity of a  brick chimney one hundred and ten
feet in height.  A fire-grate, with a door of supply for
fuel, is placed in the centre of this shaft, a portion of
the air passing under it to supply the combustion, and
the larger remainder at the sides.  A valve, or register,
suspended in the main foul-air channel at the point
above the ceiling where it turns to descend, regulates
the rapidity of movement, and  consequently,  the
quantity of air which is  drawn through  the house.
In bringing the air  downwards from the ceiling to
the foot of the chimney, there is, of course, a lose of
power in reversing the natural tendency of warm air
to ascend.   This, in an original  construction, would
be readily obviated by having the shaft  commence
in  the attic.   It still would be  often a question,
whether  permanence of foundation and convenience
of attendance,  might not render practically eligible
the additional   height of chimney needful to coun-
teract the loss by descent.*
  * Fig. 8, Plate I, is a diagram illustrating the general outlines of Dr.
Reid's celebrated attempt; a represents the place at which the outside air
enters and passes in summer against ice suspended in a netting.  In winter
it is warmed by contact with the pipes represented in section b.  Thence
it follows through the  passage c, and air chamber d. The current  then
ascends through the opening c, where its velocity  is  checked by striking
against the flat board above. From the chamber below the  floor, it enters
through the gimlet holes and hair cloth, a portion being carried up by sepa-
rate flues, /, to the galleries.  Through orifices at g, it escapes into the
foul-air chamber, /*.  From this, the suction of the chimney with the fire at
its base draws down the foul air through the channel, i.
               7 
46            ON  THE  PRACTICAL METHODS
   The  house  is  heated  to  the temperature  of  62°
(F.) before  it  is  opened, and  maintained  at  a tem-
perature between  63°  and  70°  by  regulating  the
velocity of the draught.*
  * Any one desirous of verifying the remarkable uniformity in temperature
maintained in the House of Commons under the peculiar difficulties, will find
the tabular records of the thermometer in Dr. Wyman's Treatise, page 226.
  Dr. Reid states, that after the completion of the  alterations, and when
four hundred of the Guards were seated, in  order to  make some  acoustic
trials, impossible with empty benches, the experiment was made of the power
of the ventilating draught.  Large trains of gunpowder mixed with oils and
perfumes to increase the  fumes and prevent detonation, were fired in the
chambers below. The House was filled at once with so dense a smoke that
few could see each other; but in a few minutes it was clear, the full power of
the ventilation being put on.
  Dr. Reid also states, that the greatest  supplies of air  are required in
autumn, when the air is warm and moist, the wind imperceptible, and the
barometer low.  Fifty thousand cubic feet  are scarcely then sufficient, per
minute, to sustain comfort in a crowded house.
  A very neat and satisfactory adaptation of  Dr. Reid's plan  of ventilation
was described by Dr. E. Rigby, senior physician of the Lying-in Hospital in
the York  Road, Lambeth, a low section  of the British Metropolis.  The
hospital was seldom free, for any length of  time, from puerperal fever, occa-
sionally producing frightful ravages, and requiring the building every now
and then to be closed.  "After the greatest attention had been paid to
cleanliness in every respect, the wards left open night and day for weeks,
fumigated, repaired, and frequently renewed, and the most scrupulous atten-
tion paid to cleanliness, the fever re-appeared, on some occasions, immediately
on the hospital being opened."
  Believing that the cause of disease existed in the malarious emanations of
upwards of 1,500 feet of open  ditches, the Commissioners of Sewers were
induced to clean and arch over a considerable proportion, at a cost of £500, but
without remedying the evil.  It was then deemed advisable, in 1842,  to adopt
Dr. Reid's plan of ventilation; and accordingly, a large sum was expended in
the necessary alterations.   The annexed diagram, (Fig.  11, Plate  II), will
explain the general method. Fresh  air was introduced under the roof, at a,
in order to obtain a purer supply at an elevation.  From a general air cham-
ber, b, it  descended to separate apartments ;  a hot water pipe, c, gave it  a
moderate warmth, double glass windows  being also introduced.  A vitiated
air chamber, d, regulated by valves, received the air from the rooms.  The air
in the basement, contaminated; by  the proximity  of  drains and impurities
below, was prevented from passing into the wards above by the flue i; the
air from it, and from the chamber in the roof, passing  down the shaft /, and
then into the  discharging chimney g,  to which an  upward current  was
obtained by the fire grate at its base ; i i are registers commanding the inlet. 
OF  VENTILATING BUILDINGS.           47
It may be  well  to mention,  that the size of  this
room is 80 feet by 40, and 30 feet in height.
   In   consequence  of  jealousies  and  difficulties
among the men of science  connected with this im-
mense  undertaking,  both painful and unnecessary
to  recapitulate,  an  entirely  different  and  novel
arrangement  for  the  heating  and  ventilation  has
been provided, under  the direction  of  Mr.  Barry,
the  architect, and  Mr.   Bell,  who  seems  to have
devised the air and steam arrangements.
   The air  is  received in the usual method into the
basement, — is  there  compelled  to  pass  through
tubes which are enveloped in  steam, and thus have
the temperature of the passing current raised to the
desired point.   It  then passes under flues  beneath
the  floor,  after  the  method used  in  heating  the
floors of the ancient Roman baths, which,  through
their cast  iron  coverings, part with  a portion of
their heat, and radiate it directly  under foot  to the
room.    It  then   ascends to  a pure-air reservoir,
  After this plan was completed,  much opposition to its fair effect was
experienced from the female attendants, who closed the egress and ingress
apertures.  A recurrence of the disease was directly traced to this unpardon-
able interference. The drainage of the building was also found to be defec-
tive.  After these difficulties were corrected, in February, 1843, to the time
when the testimony was given, June, 1844, not a trace of puerperal fever had
existed.
  Dr. Rigby states, that before this plan was adopted, the air of the wards
was always close, oppressive, and bedroomy, owing to a want of proper venti-
lation.  But as soon as Dr. Reid's plan of ventilation was permitted to have a
fair trial, the air became not only free from effluvia, "but has now a remark-
ably clean, clear, refreshing feel, which I can only compare to the sensation
produced on entering an empty room which has been recently whitewashed."
— Health of Towns Commission, First Report.  Vol. I, p. 119. 
48         ON  THE PRACTICAL METHODS

which delivers  it downwards from openings  in  the
ceiling, through  the  carved  open-work  of  the
beams.
  The  foul  air escapes into  another receptacle
above  the ceiling, which  communicates with  a
chimney  or  flue, into which  a  jet  of steam is
allowed  to  escape,  producing a  most  effective
draught.
  In summer,  the air is drawn in through  the
same orifices,  the  heating  being omitted,  and  a
channel is also  provided, governed by doors, which
allows as much cool air, for tempering, to enter, as
the state of the interior may require.  Indeed, it is
proposed  to  fill the  space ordinarily  occupied by
steam, with cold water, from an Artesian well,  to
reduce the temperature of the air as  it passes. That
the air is well diffused throughout the apartments
is  certain, from no draught  being  perceptible,  as
well as from the fact, that  a hundred large wax
candles are burning in the evenings unprotected by
any glass, with perfectly steady flames,  as well  as
from direct experiments like the following :
  When the  air in the supply chamber is fumigated
with a perfume, the aromatic  odor is perceptible in
four or five minutes, by a person sitting in any part
of the house, and in fifteen  or sixteen minutes, all
trace of the perfume has disappeared.   The figures
will explain  the  detail of this apparently very suc-
cessful arrangement.*

 * Fig. 21, Plate IV, represents a longitudinal section; A is the House of 
OF  VENTILATING  BUILDINGS.             49
   Our next specimen of successful ventilation on a

large  scale, is  the late  Chamber of Peers of France.

   The hall of assembly is in the  Luxembourg Pal-

ace, situated  in the  centre of  a  large  garden,  and

Lords.  D the Victoria Hall or Lobby; E the Peers' Lobby; a a a the cham-
bers under the house, &c. divided from it by a perforated iron floor, rendered
air-tight from the house  by a covering of lead.  These chambers are for hot
or cold air as may be required; C, the fresh air chambers in the roof; c the
vitiated air chambers ; and this  part of the building is  shown for clearness
in double section; one half to represent the fresh air  chamber, the other the
foul or vitiated.  The actual construction cannot be well shown in the longi-
tudinal  section, but  is  seen in the cross section where  the centre division
represents the foul-air channel, and the  lateral spaces b b, are the fresh air re-
ceptacles.  The dotted line d d indicates an iron tube for conveying the foul
air from the Victoria  Hall to the discharge shaft, wherein is the jet,/', for
moving  the air; e is the foul air tube from the Peers' lobby to the same shaft;
g the discharge shaft and chimney to the engine; h is the steam boiler; i the
tubular arrangement by which the air is heated as it passes; k the orifice by
which it passes into  the diffusing chambers a a; I the steam pipe to supply
the heater ; m the room where the temperature is regulated ; n the flues of the
south wall of the Victoria Hall, up which the air passes with great velocity to
the supply chambers, over  the ceiling, two flues  being appropriated to the
Victoria Hall and four to the  House  of Lords; o continuation of flue for
air from basement.   Each flue has an area of six feet, thereby allowing the
passage, with the ordinary velocity, of upwards of 7,000 cubic feet of air per
minute  ; pp passages to supply the heater ; r doors to shut off hot air.
   Fig. 20, Plate IV. is a transverse section of the same; A House of Lords ;
B B  the lower corridors; C C the upper do.; aaa the air chambers under the
House; b b the fresh  air chambers over the ceiling; e the foul-air chamber;
d foul-air  tube from the Victoria Hall.   The flues on each side, from the air
chamber b b, downwards, convey  the air, if required, to the underside of the
covings to the galleries, through  the ornamental work.  The air enters from
the river  side, the edifice  being on  the margin of  the Thames, through a
passage into a small chamber, on the floor of which are five or six inches of
water, and passes through a finely perforated zinc screen, over which water is
constantly trickling, and  is thus freed from impurities. It  then passes
through the pipes, surrounded by steam, and thence to the chamber beneath
the house ; nearly 40,000  cubic feet being thus always ready for admission.
The air  next passes up the flues in the  wall of the Victoria Lobby, into the
upper reservoir over the ceiling.
   The vitiated air is drawn up from the body  of the house through the perfo-
rated enrichments in the beams of the central division.
   The currents from the supply chambers are poured down through multitu-
dinous perforations, in the side  divisions, the two currents meeting in the
centre of the chamber.  The foul-air shaft and the chimney are united above. 
50         ON THE PRACTICAL METHODS

under favorable circumstances for a pure circumam-
bient atmosphere.  It is a semi-circular apartment
of about sixty-five feet diameter, with galleries for
the spectators on  the sides.  The air for warming
and ventilation is brought from the open garden in
an underground  shaft of masonry, about  ten feet
square.   At  about the  point  where  this airduct
enters the cellar, two fan wheels are arranged, each
two metres, (between  six and seven feet,) in diame-
ter, and one  and a half metre,  (about five feet,) in
length, and each with six floats or leaves.   These
are propelled by the  labor of two men at  a crank,
banded to each wheel, and geared, to provide a suit-
able speed  for such a motive power.   These draw
in the air from the outside,  and at the same time
drive it forward, and amongst the hot water heating
pipes.  It pursues its course  thence by various up-
right flues to the  apartment  where it  is to  be used,
and which it  enters through a vast number of small
orifices, dispersed in the risers  of steps, and other
convenient points, so as to produce a proper extent
of diffusion.   The vitiated air  escapes at a large
circular opening in the centre of the ceiling, directly
under which  hangs an immense chandelier, the heat
from the  numerous gas burners of which, occasions
a powerful rarefaction, and consequent upward as-
cent of the air.   The galleries   are connected with
the main trunk, by collateral flues entering it.
   It was determined by various experiments, con-
ducted with  that system, science, and deliberation,
for which  the French  philosophers  are so  distin- 
OF VENTILATING BUILDINGS.         51
guished, that this apparatus in its usual full action,
withdrew each hour 425,700 cubic feet of air.
  The  summer  ventilation  was effected by adding
the action of another pair of centrifugal fan-wheels,
of the same dimensions, and propelled in the same
manner, to supply the  upward force of the heating
apparatus, the use of  which being, of course, then
suspended.   Moved at their ordinary speed, it  was
found that seven cubic feet of fresh  air were  sup-
plied each minute, to each person.
   The  sufficiency of these  arrangements, designed
by M. Talabot in 1840, were tested  and approved
by a  government commission, consisting of M. M.
Thenard, Gay-Lussac,  Poullet,  and Peclet, some of
whom have a world-wide reputation in science.
   Let us pass to another class of institutions — from
palaces to prisons.  The  condition  of  these  was
most early and prominently connected with the his-
tory  of ventilation, as well as of epidemic  disease.
The writings of Howard, the history of the Black
Assizes at Oxford, and other sad memorials of the
fatal ills resulting from prison-air, attest how  fully
the necessity of artificial changes of atmosphere was
required, long before science had lent its aid.   And
in these  very  seats once  of  the  most pestilential
miasmata, we now find the most complete and lux-
urious  examples of the application of our art.
   The Model Prison,  as it is termed, at the suburb
of Pentonville, near London, was in every particular
designed by the most  competent persons, with the
most unrestricted provision of  means, to fulfill the 
 52         ON THE PRACTICAL METHODS

 highest  attainable perfection  in all its material ar-
 rangements, especially in its heating and ventilating.
 Although some respectable observers have supposed
 that they had detected deficiencies in the operation
 of its apparatus, yet it is certain from the Parlia-
 mentary Reports containing the exact tables of Dr.
 Rees, the physician, and others, — presumptively in-
 capable of bending, much less of falsifying records
 of numerical facts, — that the quantity, temperature,
 and hygrometric  condition  of the air, furnished to
 each  convict, are measured with almost as much
 certainty and precision, as his food,  drink, or light.
 The form of prison discipline  there adopted, would
 be considered  with us a mild  and modified form of
 the Philadelphia or separate system.  Each prisoner
 is detained  constantly in his  cell, except during a
 comparatively liberal allowance  of time devoted  to
 religious exercises,  educational  improvement,  and
 out-of-door  exercises.   Each   cell  is thirteen  feet
long,  seven  feet  wide, and nine  feet  high, to the
key-stone of the  arched ceiling above, and conse-
quently contains  about 820  cubic feet of space.   It
is, however, scarcely worth while to adduce a point
so immaterial in any true system of ventilation,  as
the size  of an apartment.  The  windows are sta-
tionary, and each cell is  fitted  up with  water-closet,
washing  apparatus, gas  burner, besides bed, table,
and seat, together with the loom or other implement
of the mechanical art, pursued by the inmate.*
* Fig. 10, Plate II, is a diagram reduced from one of the elaborate and exact 
            OF  VENTILATING  BUILDINGS.          53

  An under-ground flue, commencing at a low tower
to protect the inlet from animals or other accidental
sources of impurity, brings  the pure fresh air into
contact with  the  hot-water circulating apparatus in
the basement of the building.  This apparatus con-
sists  of plates  and tubes of iron, filled with hot
water, which dispenses its heat, by conduction  and
radiation to the air, as it  passes by to  enter a flue
or channel running from the  centre to the ends of
each  corridor, just  in  front  of the ranges of cells.
From this horizontal channel,  upright flues  are
carried into each of the two  stories of cells, and are
made to discharge themselves near the ceiling,  and
are controlled  by registers,  to regulate  the  admis-
sion of warm air.
  The foul-air  or escape flues  open in a grated ori-
fice, about two feet long by six  inches wide, near
the  floor, and  thence  pass up in  flues in the wall,
into the attic, where they enter a common horizontal
channel, the end of which terminates  in the large
chimney shaft,  rising twenty or thirty feet above the
ridge of the roof.
  The smoke flue of the fire which heats the water
for  warming  the  air, opens directly into the foul-air
chimney,  and,  by the rarefaction  produced, consti-

drawings to a scale, published in one of the Reports to Parliament — to which
reference is made, for  any desiring more precise information of the architectu-
ral detail.  The cold-air flues deliver the fresh air under the hot water appa-
ratus at C  It passes up the flues EE, to the top of the cells GG.  The foul
air leaves the cell floors at FFFF, ascends to the attic channel H, where the
smoke flue is turned in, on one side. For summer service, a grate and fire at
I, aids the ascent into the flues  KK, which become one by the partition or
withe at L, having been omitted. 
54         ON THE PRACTICAL  METHODS

tutes, in the winter season, the motive or exhaustive
power, — the warmed air also aiding to some degree
the egress of the vitiated air, as  it enters the cells,
by its vis a tergo.
  In summer, when it is desired that the air should
enter through the same  channels, but without heat,
a fire is  made in a grate  inserted in the chimney,
and  accessible from  the attic,  through and by the
sides of  which  the  foul  air ascends and  escapes.
The peculiar  advantage of  having the warm air
admitted at the ceiling, is, that  the change of di-
rection diffuses  it through  every part of the  cell,
breaking up the draught; and it is also less likely to
be interfered with, polluted, or  blocked up, than if
admitted at the floor.   The  effluvium from  tobacco
or other impure ejections, instead of combining with
the  entering current, to be imbibed in  respiration,
is drawn out forthwith — a circumstance of unusual
importance in all American  attempts at ventilation,
where the personal  habits of the  community,  in
some respects, are so exceptionable.  The  only ob-
jection to this reversed movement of the current, is
the loss of ascensive force, easily supplied by a little
addition to the fire.
  The whole arrangements of the Pentonville prison,
relating to ventilation, contain so  complete an em-
bodiment of one of the most common of the  modern
systems, as to be worth a closer investigation  than
the  discursive character of  an  address will  permit.
A reference to the accompanying plan, will enable
its action and its efficiency to be fully comprehended. 
OF VENTILATING BUILDINGS.         55
   In the continued advances made in a country of
so much capital and science as Great  Britain, we
find the same general  system introduced, in later
constructions, with improvements in those particu-
lars where experience had shown defects.
   In the immense penitentiary, established at Wake-
field, in the Wrest Riding of Yorkshire, the hot water
pipes pass  along a channel, or large flue, which runs
from the central boiler to each end of this corridor.
Each section or joint of this iron pipe is  increased
in diameter in order to compensate  in quantity of
warming fluid, and  extent of radiating surface, for
the diminished heat lost in passing from the  boiler.
In this institution, the foul-air flue, instead of open-
ing at the floor and  then passing upward, descends
from the lower  part of the cell, and  enters a hori-
zontal drain, the common  receptacle of all the foul
air flues, which delivers its contents into the upright
chimney shaft, partly entering through, and  partly
around the fire-grate, as usual.
   Few classes  of  inhabited  buildings demand so
effective, certain, and controlable means of supplying
pure, and removing vitiated air, as hospitals for medi-
cal and surgical diseases, and asylums for the insane.
In these, pure air becomes not merely hygienic, but
sanatory — not  only a preservative, but a curative
appliance.  As respects the first-named institutions,
their history in  all countries demonstrates not only
how important ventilation is as regards those forms
of epidemic and contagious diseases, directly result-
ing from impure air, as typhus, erysipelas, hospital 
56         ON  THE PRACTICAL METHODS

gangrene, and the like, but as respects those general
results  of aggregate experience for years, not less
certain, although less palpable. The statistical results
of simple amputations, in particular hospitals of Paris,
and in the whole, are well known to those interested
in surgery, and most strikingly illustrate the connec-
tion referred to.  In the latter class, those for the
insane,  the peculiar depressive, torpifying influences
upon the mind  and feelings — the intellectual  and
sensitive faculties, are now  universally  acknowl-
edged, and are as susceptible of proof, as any of the
purely physical disorders, dependent on vitiated air.
I have frequently thought and observed, in passing
from one to another of the lunatic receptacles of the
old world, that a glance upon the  countenances of a
group of the inmates, would  at once tell the fact,
whether they habitually dwelt in a habitation, the
purification of  which was abandoned to the chance
changes from doors and  windows, and  the  almost
equally unreliable draughts  of upright  flues, in
which the currents of air were spontaneously deter-
mined only by  the accidental  preponderances of in-
ternal heat and external currents; or whether they
passed  their days and  nights in that pure, elastic,
healthful  medium of equalized temperature, quali-
fied  hygrometric  condition  and  copious  supply,
which some of the modern and improved exhaustive
arrangements so fully command.
   The eminent philanthropist, Dr. Southwood Smith,
in his testimony before the Parliamentary Commis-
sion, is the first writer who appears to have recog- 
OF VENTILATING BUILDINGS.          57
nized fully the connection  between  the intellec-
tual and moral faculties, and the habitual imbibition
of vitiated air.   " The poison," he observes, " gener-
ated in these neglected districts, and to which these
persons are habitually exposed, is a sedative poison,
among the most distinctive  characters of  which are
the depressing effects produced by it, both on mind
and body.  This is one of the main causes, not only
of  the  mental  apathy,  of  which I have already
spoken, but also of that  physical listlessness which
makes them incapable of any great exertion.   I am
satisfied that this feeling of depression, is  one of the
chief inducements to the use of stimulants."
   Let us select an example  of improved insane hos-
pital ventilation, which has  undergone the test of a
dozen or  fifteen years' actual and successful expe-
rience, in the asylum of the county of Kent, at Maid-
stone, in the  southeast part  of England.   This was
arranged for  a complete  exhaustive ventilation from
its commencement, under the direction of Mr. John
Sylvester, who has long maintained an eminent place
in this department of applied science, and the basis of
whose arrangement is that originally suggested  by
Mr. Strutt, of Derby.  I prefer giving the substance
of his own account of what it is, with suggestions
as  to certain  alterations which he would  subse-
quently have recommended, as inferred from his tes-
timony before  the  Parliamentary  Commission so
often referred to, in preference to  using my own
notes of a visit  to, and examination of, the institu-
tion itself.   I need only  say as regards  the example 
 58         ON THE PRACTICAL METHODS

 itself, as I found it, that nothing more satisfactory
 could be conceived.  The distinguishing peculiarity
 is the supply of the whole  edifice with an immense
 volume of air, warmed scarcely above the tempera-
 ture  at which the interior was designed to be main-
 tained.  This system is predicated on the principle,
 that in certain circumstances the unpleasant exhala-
 tions from the diseased human body require a change
 of air, far greater  than the quantity indicated for
 the vitiation produced by the respiration processes.
 The pure air is received by  means of a large revolv-
 ing cap or cowl, kept with its open side to the wind
 by a vane, into a tower of moderate elevation, a few
 hundred feet from the buildings, to prevent any ob-
 struction of wind, or defilement.   An  underground
 channel of masonry, two hundred  yards  long, and
 six feet square, terminates  at  the usual  hot  water
 apparatus, with the exterior of which the  passing
 current is brought in contact,  and thus ascends in
 immense flues, which open  near  the ceiling of  the
 galleries.  These channels are all so large as to allow
 the velocity of the air to be  exceedingly small, mov-
 ing through the underground  channel  only at the
 rate of four feet per  second.  The air, at its  point
 of delivery, by its amount, its gentle current, and its
 moderate  temperature, reminds one of the gentle,
 elastic breeze of the tropics;  and there is in its  large
 volume and slow movement, little necessity of any
 arrangements  for divided admission, or other  diffu-
 sive means, to enable a general and uniform spread-
ing of it to be attained.   An exhaustive apparatus 
           OF  VENTILATING BUILDINGS.          59

of the simplest kind and least force is sufficient to
deflect and  scatter a current  moving at this slow
rate.  Mr. Sylvester thinks that it is desirable that
the rate at which the air should flow into the inte-
rior, should  not exceed  half a foot per second, or
about a third of a mile an hour.
   Mr. Sylvester's plan provides ranges of pipes, filled
with steam,  in  the attic, to raise the temperature,
and by rarefaction  produce the upward  current.
The summer ventilation  is through the  same chan-
nels, omitting  the warming as the air enters.  A
vacuum cap, turning its mouth to leeward, permits
the vitiated  current  to  escape, and when the  air
externally is in motion, is of some auxiliary service
in this way.
   Mr. Sylvester, in explaining the plan he  would
adopt for ventilating the House of Commons, esti-
mates the entire interior contents at 200,000 cubic
feet;  and here he purposed admitting the air over
the whole area of floor,  as far as practicable.  The
combined area of the apertures to this  end he cal-
culated at 665  feet.   The current of air was to flow
in at the rate of  half a foot  per second, at which
velocity it would change the contained air six times
within each hour.  He  would admit the warmed
air at a temperature within 5° of that  at which it
was decided to maintain the house.
   The diagram and explanation will  give a clear
view of his  ideas of ventilation, in the experience
of which, in the largest  and most  complete exam-
ples in Great  Britain, he seems to have had  far 
60          ON  THE PRACTICAL METHODS
more  general opportunities than any  other  indi-
vidual.*
   In  another  example  of  a lunatic  hospital, the
most modern and  complete of the French institu-
tions,  the  Maison  Royale,  at  Charenton, the ex-
haustive  power  to withdraw  the vitiated  air  is
formed  by running  the  small  pipes  filled  with
heated water longitudinally through the foul-air
flues;  the  rarefaction  thus  produced liberates the
foul  air, and  draws in the pure supplies below.
   I will  adduce from  the elaborate  and  scientific
work of M. Peclet, a still further illustration of a
plan of ventilation, which has stood the test of ex-
perience, in a hospital  for common  diseases,  refer-
ring  to the drawing for the  exact  details.f
  * Fig. 9, PI. II. is reduced from the plan offered by Mr. Sylvester to the
Parliamentary House Commission ; m, is the body of the house ;  a, is the
tower, which admits the cold air and allows it to pass through the channel h,
impinge against the hot water or  steam pipes at c, and then is admitted
through the floor d, as the arrows indicate ; i, i, are the escape holes in the
ceiling ; n, the steam pipes which serve as the motive power ; o, is the turn-
cap, moved by the vane so as to present its mouth to the leeward; a:, is a flue
which would allow the warm air, by means of a register, to pass directly into
the attic, aiding  the upward  ascent, and acting as a waste when too great
heat arose from the apparatus ; the aperture, also marked x, near the floor,
enables the foul air to be drawn off at bottom, when the upward orifices are
closed by their registers.

  f Figs.  15 and  17, PI. III. represent the middle section of a hospital of
three stories.  In the cellar is the air-chamber, containing the hot water ap-
paratus, and channels communicating with the external air. A, is the boiler;
E, a double spiral coil of iron pipe, to give ascent  and some warmth to the
air of ventilation, which then ascends  in the flue F, which distributes it on
each story. It passes along the corner of the walls, at G G, H H.  The foul
air escapes into the attic, from which it escapes by the chimney I, aided  by a
grate for summer use.  The hot water is carried into each story and radiated
from the hot water stoves, D, D, D, &c.  Fig. 17, is a ground plan of a  part
of one of the stories, showing sections of the ventilating flues H, H, H, and
the horizontal branches g, g, g, opening under the beds. 
OF VENTILATING BUILDINGS.
61
   In the middle of the  cellar is a large air cham-
ber, receiving its fresh supplies from  the outside.
A boiler of water having a concave bottom to  re-
ceive the full force of the fire, is placed within the
air cell, from which radiate the tubes designed to
warm the house.  One of these tubes proceeds from
the bottom of this boiler, passes to the lower end
of a fresh-air flue, which leads from the air cham-
ber  communicating with the exterior, and  is  then
twisted into a double spiral nearly filling the width
of the flue.   A certain degree of ascensive  force is
thus given to the air of ventilation.   This air chan-
nel sends off branches as it reaches the different sto-
ries, in wooden boxes which deliver the fresh supplies
at various  openings.  A horizontal branch passes
out under each bed, where it delivers its pure air,
slightly raised in temperature, through  three free
openings, a valuable point of the operation of which
is understood to be, that a sheet or curtain of  pure
air, rising around the patient on every side, protects
him against the approach of  odors or exhalations
from  those  in adjacent  beds, as it does them  from
his.
  The vitiated air is conducted through a set of es-
cape-flues, which terminate in the attic.  A chimney
proceeds from the attic upwards, a fire-grate at the
inferior orifice of which gives activity to its draught.
The interior is heated, in  addition to  the small
amount of heat contained in the air warmed for ven-
tilating purposes, by one of the varieties of the  mild
              9 
62          ON THE PRACTICAL METHODS
hot water apparatus *;  the tubes from the boiler in
the cellar, passing to what  are termed hot-water
stoves, which are merely ornamental iron reservoirs
of hot water, having a pipe  for  its admission and
return, and  the  large  radiating surface of  which
raises  the interior atmosphere to the requisite tem-
perature.  The peculiarity of this arrangement is,
that the heating  and ventilation are  combined  in
a certain way calculated to  save any waste  which
would occur from heating more of the external air
than  is  necessary for  the due  restoration of the
atmosphere.
  An example of the every-day application of some
of the true principles of heating  and ventilation in a
cheap and simple form, will be found in a common
Parisian  school-house.   The specific   example  is
taken, with  the  annexed sketch,f from the work
of Peclet, although the general principle has long
been  in common use, under very  many modifica-
tions.   The apartment is of a rectangular form, and
about of the dimensions of one of our larger forms
of grammar school-houses.   The teacher's desk is
placed within  a few  feet of one end, and in the mid-
dle.   On each side of this, and midway between the
 * Those forms of hot water apparatus, in which the fluid is raised to a
temperature not exceeding 212° F. are designated under the term mild, in
contradistinction to Perkins's intensely heated water tubes.
 t Fig. 13, PI. Ill, is a diagram of a room of the school-house, shortened
in length for convenience.  B, B, are the seats ; C, the stove covered by its
case ; D, is the funnel entering the chimney, E ; i, is the damper in the cold-
air flue ; f, is a grate inserted in the chimney. Fig. 14, is an end view to show
the mode in which the foul-air flues enter the chimney ; b, is the door to the
ventilating grate ; F, F, revolving registers ; E, the chimney. 
           OF  VENTILATING BUILDINGS.         63

sides of the house, arc placed two coal stoves, very
similar to the common cylindrical anthracite stoves,
in so common use among us.  This is covered over
with a case of iron, copper, or other metal, leaving
a space of three to six inches between.   The case
extends to the level of the floor, where it rests upon
a groove in a cast iron plate, which  is  set over a
flue extending  horizontally under the floor to  the
external air.  Various holes are left in this plate,
so as to allow the fresh air to pass up in  the inter-
space between  the stove and the exterior case.   It
is warmed by this contact, and escapes freely either
by large openings, or small perforations around a
few  inches of the top  of the  case.   The top is
usually flat; and the impulse of the air, striking
against.it as it rises, naturally diffuses  and spreads it
much better than if the apertures of exit were more
direct in the top itself;  the  lower  surface of this
cover has been made in the form of a blunt cone,
or segment of a sphere, to produce this  effect more
freely.   A valve or damper in the cold-air flue, com-
manded  by a handle,  permits the amount of air ad-
mitted to be  controlled.
   The funnel is carried in the usual way, perpendic-
ularly, high enough to prevent any undesired radia-
tion upon the  heads of those seated beneath,  and
then horizontally to the middle of the opposite  end-
of the school-room.   Here  it enters a smoke chim-
ney  which commences  at  the ground  level.   At
three or four feet from the floor are openings, com-
manded  by  revolving registers or  other valvular 
64
ON THE PRACTICAL METHODS
arrangements, which admit the foul air into the
chimney by the suction produced by the  rarefaction
resulting from the stove pipe which enters  above.
At the same level, or a little  above, a fire grate  is
inserted in the  chimney, with a door for feeding.
This of course is designed for the summer ventilation
only, when the  heating  fire is omitted;  and the
pure air supplies are drawn from the outside through
the winter channels,  with  perhaps  additional and
more direct orifices of admission, but without open-
ing the windows.
  I am aware that this form of air stove or furnace
has been  pretty widely used in this neighborhood
for  a  good many years;  but  the  long  previous
experience in  France is  corroborative of its excel-
lence. It has been a common mode to place anthra-
cite  stoves in  the basement vestries of  churches,
with an air flue running  from between the  coal
vessel and the external case, often of tinned iron,
kept bright to prevent radiation at a point where it
is  undesirable.  The hot-air flue is carried directly
into the church or hall above.   An opening  is also
left in the external case  in the vestry or basement
below;  and the dampers commanding these  respec-
tive places of exit of warmed air are connected by a
wire, so that when one is  opened, the other is nec-
essarily closed.  A damper in the external air-duct
should never  be omitted, as otherwise  the varying
direction and strength of the winds will produce an
irregularity in the supply.   If the cold-air duct can
also  be extended out to the open air on both sides, 
OF VENTILATING BUILDINGS.
65
a great improvement in its  regulation will  result.
The connection  of the  dampers admitting air into
the respective rooms where it is to be used, is quite
indispensable  to obviate the danger from careless
or  ignorant persons closing  both  at once, an acci-
dent which terminates in a destructive accumulation
of heat, pernicious to the purity of the atmosphere,
and melting and warping the tin  coverings, and
even the fire surfaces.
   The  plan  of heating,  and consequent  partial
provision for ventilation, recently recommended and
introduced into  some  of the Boston school-houses,
is, essentially, that described above.   A stove is used
in its position, construction, and receipt of fresh air,
precisely similar to those long employed in France
and elsewhere, except that the warmed air, instead
of being allowed to escape through large openings,
or small perforations around  the top, passes directly
out at the upper point of the interspace between the
case and the stove;  while  an obtuse, conical  top
with its hollow  downward is suspended, or slips on
a rod or on the  funnel of the  stove, as if designed
to  act as a register, which has received the name of
a distributor.  If this is allowed to be  closed down
to  a certain point  only, wide enough to give  full
egress to the warm air, it does not differ much from
the common French cover, in which the oval open-
ings  are  large,  and separate'd by columns or wires
of  metal sufficient  to give  firmness  to  the  top.
If it is allowed to slip down, so as to act as a valve,
and interfere with or prevent the  escape of heated 
66        ON THE  PRACTICAL METHODS
air, the apparatus is brought back at once to a species
of old box stove with double walls.  The attempt to
regulate the quantity of heat admitted to  a  room
in any form of calorifer or hot-air furnace, should
be made any where else rather than  at its  point of
escape.  The heat is only  accumulated  by such
attempts to  be  expended upon the stove itself, and
then  to  roast the  air.  Indeed, with a  command
over the admission of the air of  combustion, over
the register of the ingress  flue,  and  for extraordi-
nary emergencies, with a waste opening to the out-
side from the air chamber  itself, no  necessity need
exist for checking the heated air at its outlet.
  The Boston school-houses appear to have their
exhaustive power furnished in a much less  reliable
method than in our French specimen, that is, by a
chimney cap.  The attempt to  obtain an  upward
current, by  the  action of the wind upon  any form
of cap, is for obvious reasons perfectly inadmissi-
ble in  any  true ventilation.  That  employed  in
the instance adduced, was  invented  by St.  Martin,
in 1788 ;  and, when made at a proper angle —
which is  found by Dr. Wyman's  investigation,  to
differ some degrees from that most frequently used
by our manufacturers — is as effective, perhaps,  as
any apparatus of this  kind  when the wind blows.*
  The absence of any apparatus for fire at the foot,
or any other point of  the foul air or smoke chim-
neys, would  seem to imply that the summer  ventila-

 * See Report to American Academy of Arts and Sciences, on Ventilators
and Chimney Tops, p. 14. 
OF VENTILATING BUILDINGS.         67
tion is to be principally dependent on the  opening
of windows.   This, it is  hardly necessary to  say,
must be considered as a great defect in any complete
modern ventilation for school-houses in large  and
noisy cities and populous towns.
   A form of this,  which  is in fact a  kind of air
furnace in  the  room  itself,  much  used in some
parts of Europe, is selected from among a great
variety given by  Peclet, and a  copy of  it  annexed
will explain  itself at  a glance.*  The  cylinder
stove is  covered with a case of metal,  crockery, or
even  stone,  more  or  less ornamental,  receiving
its air from the outside, warming  it as it  passes
the interspace, and delivering  it around the  up-
per few inches of the top.   The funnel is carried
directly through the  fire-board or masonry filling
the  original  fire-place.  Here  also is inserted a
revolving register,  or other  movable valve.   The
heat of the smoke produces a lively upward current.
This sucks off the lower stratum of air of the room,
draws down the warm portions, and thus  equalizes
the temperature throughout, while it is renovating
the whole by degrees.
   Three registers, one in the  cold-air  flue, one in
the exit  or foul-air flue, and one in the smoke-flue
to command the rapidity of combustion, enable the
management of it to be controlled with  the smallest
amount of intelligence and observation.

  * Fig. 16, Plate III.  In these two examples, the air stove stands before
the closed fire place ; A  admits cold air from without, into the interspace ;
B is the smoke-flue; C the foul-air duct. 
68         ON THE PRACTICAL METHODS
  After all, however, these are merely forms of hot-
air  furnaces  placed in the apartments, instead of
the basement or cellar  beneath ;  and it is question-
able whether the comparison of conveniences and
disadvantages will often justify this location.  The
fact that in all  combustion of fuel, especially of the
carbonaceous varieties,  there will be some escape of
ashes, or of gases, into the room where it is used;
the inconvenience  of feeding the grate in the room
itself;  the care  of preserving an exterior of metal
in a clean condition ; the greater inconvenience of
establishing an evaporation of water  into  the air
heated, and some  other objections, may sometimes
be  overbalanced  by  convenience  of  attendance.
Usually, however, in  public buildings where the
extent of operations will justify the  attention of
some person to the business of heating and venti-
lating, the true point of location  for the hot-air
apparatus is in the cellar or basement.
  The character of any variety  of the  hot-air fur-
nace i« measured, in my judgment, by the simplicity
of its construction, its  non-liability to be brought
to an  undue degree of heat  in any part,  and its
ready receipt and  emission of air.  That made and
sold by  Mr.  Gardner  Chilson, of Boston, with an
air chamber of brick and an interspace of two or
three feet in width, appears to  me  to  combine  all
the  essentials attainable of this mode of  heating
air  more fully  than  any  other which  has fallen
under  my observation.   In  proportion as  they
approach the old Wakefield furnace,— in which the 
           OF VENTILATING BUILDINGS.         69

sides  of the  air  chamber are removed from  the
cockle  or fire-vessel  by  an interspace  of a  few
inches only, and  the passing air is held in contact
with the overheated surface as long  as practicable
by various turns  of direction at right angles or
those forms of the  French calorifer, in which the
cast  iron tubes  are  heated to a red  heat, while
the air to be  respired is passing through them, —
so far do all the various hot-air furnaces deteriorate
in healthfulness and comfort.
   A single other  illustration of successfully arrang-
ed ventilation on  a scale and after an experience
sufficient to give  it a character, will close this part
of our subject, and enable us to pass to the general-
ization  deducible  from the mass  of  individual in-
stances, each one of which is of course merely a
type of more or less numbers.   The National Bank
of England and also of Ireland, have been ventilated
under the direction of the bank engineer Mr. Old-
ham, by the revival of a method,— the employment
of bellows,  or the blowing  cylinder,  introduced
more than a century since (1741), by  Dr. Hales,
into   many  of  the  prisons, hospitals,  and other
buildings of the British metropolis, and into nearly
all the  ships  of the Royal  Navy,  and in many
instances, when under  adequate supervision, with
the greatest success.  At  that period when steam
power was unheard of, instead of being as it has
almost become in our days an appliance of domestic
use,  the apparatus was dependent on human labor,
              10 
70
ON THE PRACTICAL METHODS
which must have rendered its employment inconve-
nient and uncertain.
  Mr. Oldham availed himself of the steam engine
in use for printing and other processes of the estab-
lishment, to give motion to a large  blowing cylin-
der of the double-acting kind, drawing  its supplies
from the  outside, and forcing the air amongst the
steam heating tubes, until it enters by many orifices
the  large room in which the many officers and persons
having business are congregated.   The temperature
is of course easily regulated by the extent of radi-
ating surfaces employed and the activity of the air-
propelling movement.
  Having now recapitulated  in  a  brief manner,
but still, it is hoped, with  all the characteristic and
distinguishing features, the principal examples on
a large  scale  of modern ventilation,  it  remains for
us  to attempt  to generalize the various points and
peculiarities, to  select the  essential from the acci-
dental, and deduce principles of universal applica-
tion from instances in which they may be more or
less distinctly combined.
  The first peculiarity which strikes  us,  is of a
negative character — the  omission of all reliance
on,  or provision for the  admission of the  pure
element, or  the discharge  of it when vitiated,
through direct lateral openings, doors, or win-
dows,— methods  so primitive  and  so  universal,
that at first  glance we  almost  deem  them the
natural  modes.  In  fact, these  ready  substitutes
have been proved  by all experience to  be wholly 
OF VENTILATING BUILDINGS.          71
 unequal to the duty; and also so incompatible with
 the systems involving other indispensable points, as
 to  render their entire  omission a first principle.
 Every modern system, as shown in  our illustrations,
 recognizes the closure of all  orifices not connected
 with,  and forming part of the  ventilating system,
 as  a matter of course ;  the windows  in  fact, gener-
 ally being made double, either by duplicating the
 sash, or what is better, having a  second  range of
 lights set in  the same fixed  sash, with a confined
 stratum of air  between half an inch thick.  The
 doors  also  are  duplicated at  the  extremities of a
 short passage or entry,  so that the one in front is
 not opened until that in rear has  thrown itself to.
 In  fact, the cross-draughts,  supplies  from sources
 and emissions of air at points not determined by
 the motive power, would be utterly inconsistent
 with  any uniformly arranged  plan.  As Dr.  Reid
 well remarks, in any scientific plan, the apartment
 to be ventilated  is  to be deemed  and treated as  a
 piece of philosophical apparatus, the  results of the
 operations of  which are to be interfered with by no
 fortuitous influences.
  The second point of agreement in our examples is
 also of the negative or  omissive character.  This is
 the abandonment of all attempts  to rely upon the
 slight differences of  temperature and  the resulting
 ascensive power, derived from the presence of num-
 bers of occupants,  or from the  ordinary  artificial
 warming.   Though under certain favorable circum-
 stances of aerial currents, external and internal states
of the  thermometer or other contingencies, flues for 
72         ON THE PRACTICAL METHODS

permitting vitiated air to escape and its place to be
supplied by fresh quantities, may operate with some
energy, yet experience shows that it is a system too
capricious, too wholly devoid of that  certainty and
controllability, radically essential to a perfect venti-
lation, to be thought of at this  day.   This is  the
mode which  has obtained  so generally in  our
American prisons, hospitals, and public  assembly
rooms,  and from its unfortunate universality  its
consideration deserves more detail than the present
limits permit.  In the Appendix, a practical view
of the circumstances affecting the delivery of  air
through various forms and conditions of flues will
be given.*
  The third circumstance of uniformity in our suc-
cessful examples adduced, as well as in a  wider
spread series  of  cases, (were it of moment to  inves-
tigate them,) is also one of absence:  viz., the omis-
sion of dependence upon all kinds of apparatus or
contrivances  operated upon by the passing current
of external wind.  This, of course,  comprehends
all kinds of turncaps, cowls, louvres,  and the like.
In some instances, the plenum and vacuum cowls,
as they  are  respectively termed when their open
mouths are turned to or  from the  wind, giving
them a filling or exhausting action, are advant-
ageously  employed  as  a  collateral  or  auxiliary
measure, saving a certain amount of  motive power
when in action, but never trusted to as  the effec-
tive and constant power.
* Appendix A. 
           OF VENTILATING BUILDINGS.         73

  With respect to all the hundred varieties of con-
trivances  of the  turn-cap or cowl order, most of
which have been  invented and reinvented every few
years, their whole consideration may be briefly de-
spatched in  simply observing that their utility is
wholly dependent on a movement which frequently,
at uncertain times and sometimes for long intervals,
ceases to  exist.   Consequently  the  ventilation of
buildings depending on the winds, must be just as
uncertain  as the wind itself, and  the occupants of
a crowded  habitation might as  reasonably trust to
the prevalence of calms  and breezes in a certain
sequence for their food and  drink, as for their air.
  During brisk and  active winds, any varieties of
them  will  produce a  considerable fluctuating, up-
ward  draught.  At such times, however, the natural
ingress  and  escape of fresh air unassisted, is the
most ready, and of course the necessity of artificial
aids the least urgent.   In the  stagnant, heavy at-
mosphere,  prevailing not unfrequently week  after
week  at certain seasons of our climate, the necessity
of certainty of change becomes the most imperious.
The effect, at these important times, of any or all of
these  multiform contrivances is only that of imped-
ing whatever disposition the internal air has to escape
arising from augmented  temperature, by more or
less obstruction at the orifice of the tube, amounting
in the least unfavorable specimens of  the  revolving
kind,  to one turn at right angles and the friction of
more  or less  uneven surfaces.
  The experiment of two distinguished practical me-
chanics in New York, Messrs. Ewbank  and  Mott, 
74         ON  THE PRACTICAL METHODS

demonstrated that there is a considerable difference
in the exhaustion of  these variously shaped  con-
trivances ;  that is, when  they do act at all.   The
exact, certain, elaborate experiments on certain va-
rieties of these things, made by a committee of the
American Academy of Arts and Sciences before re-
ferred to, the detail of which  was directed by Dr.
Wyman, forever settle all controversy as to the
respective merits of  the different specimens tested,
as well  as  the  want of originality in any modern
modifications.
  In reverting  to the points  of positive accord in
our examples, we find that they all present a com-
mon feature in  the following essentials.
  I. The obtaining the fresh air from pure external
sources, by distinct, appropriate, ample avenues.  It
is never taken  from  the cellar or basement of the
building, nor from the accidental crevices, or  pas-
sages provided for other  uses.   Most frequently a
channel of masonry is constructed  under ground,
and carried to such a distance  from the house as to
make sure  of a pure admission.  A  tower, or chest
with openings, prevents the orifice  being blocked
by snow, or the accidental admission of living ani-
mals or other impurities.   Local sources of impure
air, which cannot be better avoided by the selection
of a spot for the outer opening, are connected with
the exhaustive  arrangements.    Sewers which may
be crossed, are  covered with air-tight cement work.
In fact,  no pains  are  spared to obtain  the air in a
perfectly pure condition.
  In cities where carbonaceous flakes are common, 
OF VENTILATING BUILDINGS.         75
a fine wire netting  is thrown across the flue to ar-
rest the palpable defilements.  Even  veils of fine
gauze  cloth  are  used by Dr. Reid, and the finest
perforated sheets of zinc by Mr. Bell, to  stop the
impalpable, dust-like particles;  and the air is also
washed by jets of water, crossing each other in every
direction, or  by water dribbling over  the perfora-
tions.
   Mr.  Sylvester found in his  trials, that there was
still another  advantage in bringing the air through
long underground  channels.  They had the effect
to equalize its temperature.   In one hundred yards,
for instance, it received in winter about 15° of heat,
and lost the same amount in summer.  In the in-
tense heat of our northern summers, this last advan-
tage, combined with the hygrometric addition of jets
of water, would be no small consideration.
   In Dr. Reid's  plans for  the  new parliamentary
edifice, he proposed taking his  fresh air at the top
of a tower some two hundred feet from the ground,
from the difficulty of finding a pure source at the
level, in the impure and crowded district in which
it  happens to be  located.   This  arrangement  of
course  is  attended  with  the  sacrifice  of motive
power  necessary to reverse  the admitted  column of
air.
   In various foreign instances, of which one exam-
ple is presented in Dr. Rigby's evidence,* the air is
admitted under the roof, and carried directly down-
wards to pass through the heating  apparatus, from
• Fig. 11, PI. II, described in note, page 46. 
76         ON THE PRACTICAL  METHODS

which  it is then delivered  into  the rooms  above.
The air  describes three  sides of  a square in its
course.
  In various  instances, to prevent the irregular
draughts through the ingress channels, the air is re-
ceived into a chamber of considerable size, which acts
as a reservoir, destroying the motion of the air.  It is
then subject to the equable  indraught of the motive
power.   Our examples refer to the  placing of ice
suspended in a netting, to reduce  the temperature
in the heats of summer, or filling the steam or hot
water heaters with cold water in circulation  for the
same end.
  II. Raising the air admitted to produce warming
and ventilating, only to a very moderate tempera-
ture.
  The subjects  of heating and  ventilating  are  so
intimately connected  in  practice,'  that  they can
hardly be treated of separately.  In our  examples,
the summer ventilation is  often carried on by an
arrangement independent of the heating.   In win-
ter, the two processes  appear  to be rarely entirely
disjoined.
  It seems to be admitted universally, that the true
principle of heating the air is never to have its tem-
perature raised above what  results from the  contact
and radiation  of metallic plates or  pipes, filled with
hot water or steam.   A peculiarly  unhealthful
change appears to be occasioned by raising air, even
apparently free from appreciable accidental  impuri-
ties, to any higher heat than about the boiling point. 
           OF  VENTILATING  BUILDINGS.         77

Whatever  may be the chemical changes in air so
heated or the pathological effects  of its respiration,
the actual annoyance arising from roasted or scorched
air is too  notorious to be doubted.   Its probable
explanation is the decomposition of floating, impal-
pable particles of vegetable  and  animal nature —
certainly not, as is often  suggested, and  even  pro-
vided for by stone or earthen radiating surfaces, any
deoxygenation from the combination with the iron,
since this is chemically impossible, and equally ob-
servable when no oxide is formed.
   So impressed was that eminently practical philoso-
pher Mr. Tredgold, with the exceptionable character
of any air introduced heated above the temperature
of boiling water, that he declined taking into view
any of the varieties of apparatus  in which such a
result is practicable.   All kinds  of stove  heat he
regards as wholly inadmissible.;
   It is probable that some few of the hot  air fur-
naces composed of a very extended dome or cockle,
air chambers sufficiently large and arranged for so
low a  temperature as to allow a person to enter
and remain, and with perfectly free avenues of ad-
mission and egress of air, may not fall  within the
purview of his  unrestricted and  generally correct
dismissal  of this class of  apparatus.
   Public experience has settled down into the  con-
viction that this moderate elevation  of temperature
can be best secured by the use of steam, or the mild
hot water apparatus.  This latter name is, as before
intimated, applied in contra-distinction to the system
              11 
78         ON THE PRACTICAL METHODS

of hot water pipes invented by our countryman Jacob
Perkins, a few years since, in which water was heated
in small strong pipes to a temperature of several hun-
dred degrees, and radiated heat proportionably.  The
facts that the air was vitiated  by these, as much  as if
heated by blazing fuel inside,  and that the apparatus
was complicated and hazardous, have occasioned so
general an abandonment of his  method, as to re-
quire for  it merely a simple recognition of its ex-
istence.  It certainly ought never  to be used where
the highest perfection is sought.
  The heating  apparatus, whether hot air furnace,
hot  water of either class, or steam,  may be em-
ployed by being placed below, and the air delivered
from the air  chamber which encloses the  tubes or
other radiating cavities into the apartment in which
it is  to be used;  or secondly, by  the air  supplies
being admitted to  the air chamber of  the apparatus
in the room itself; or thirdly, a part of the air may
be partially warmed and admitted for ventilating,
while  the remainder of the needed  supply is fur-
nished by some disconnected  heating means, as open
fires, water'  stoves,  steam pipes,  or  otherwise; or
fourthly,  the apartment itself may constitute the
air chamber to the furnace, and the  air of ventila-
tion be admitted  in a natural state  from  outside,
to mingle with  that artificially  warmed.   The ob-
jection to all  arrangements  involving this latter
peculiarity is, that cold and warm air do  not mix
readily; and in this direct plan of admission, cold
draughts  can hardly be obviated. 
OF VENTILATING BUILDINGS.
79
   The modes of managing the heating by mild hot
 water and steam, the most salubrious and agreeable
 of all methods, comprise a most extended variety.
   The advantages of steam  are  the  less extent of
 radiating surface required, the surface being always
 kept up  to  212° F., while  hot water cannot be
 maintained in practice above from 180°  to  200°.
 Steam can also be more rapidly brought into action,
 the elastic vapor pressing the moment it is generated
 into the most remote part of the apparatus, while the
 circulation of hot water is gradual.  By increasing
 the pressure of steam its temperature is increased,
 so that in very cold and urgent weather, a boiler
 capable  of sustaining the usual pressure may be
 depended upon  to furnish  steam of a temperature
 and  consequent power of radiating heat, consider-
 ably above the boiling point; for example, under a
 pressure of one and  a  half  atmospheres, or 22 1-2
 pounds to the inch, the  temperature of steam is
 240° F., under two atmospheres  or 30 pounds,  the
 temperature will be  about 250°, still  short of any
 scorching liability.
  The advantages of warm water are, that its cir-
 culation  goes on long after it  is  below the  boiling
 point, which accommodates its action to the mod-
 erate demands of certain seasons.
  It is again necessary to refer to our Appendix for
 a recapitulation of  many of the practical details
connected with these forms of heating and result-
ing ventilation, as well as  for tables indicating the
extent of  the respective  apparatus to  produce a
given result. 
80
ON THE PRACTICAL METHODS
  III. We find as the next common  characteristic
of modern ventilating arrangements, some method of
diffusing the air,  or  spreading  and  breaking the
entering  current  into  divided streams, instead of
permitting its ingress at a single point or in few
openings, which when it is cold form  unwholesome
draughts, and when heated are equally uncomfort-
able and  deficient in  uniformity of condition, fail-
ing to  give an equalized, homogeneous  atmosphere
of the proper character;  nor  does the column of
air mingle with that present in the apartment.
  Dr.  Reid  introduces what  he  terms a mixing
chamber, under  the apartment  into which the air is
to be admitted as it enters the reservoir;  the current
from the heating apparatus impinges against a flat
surface placed a short distance above the orifices of
admission, which he terms  a  deflector,  and  which
throws it horizontally.  This destroys its tendency
to enter unequally at different points and  aids its
admixture with cool  air, admitted to temper the
medium  as  required.   From  this  reservoir  it is
admitted by a vast number of small orifices, as we
have  seen, and is  still further divided by a porous
hair-cloth carpet.  This method of making a hot-
air reservoir under the whole room or by channels
in various parts of it, and small openings through
the risers of steps, beneath  the  seats, and similar
unoccupied places, is quite general in  these edifices,
where  sudden  changes in the  numbers of  those
present demand a  rapid adaptation of temperature.
The diffusion,  as we have also seen, is occasion- 
OF VENTILATING BUILDINGS.          81
ally effected by reversing the current of air  as  it
enters  at the  ceiling,  by the action of  a lively
draught  from near the floor, and  thence  proceeds
upward  into the attic, or descends perpendicularly
to a common flue in the cellar.
   Several simple experiments demonstrate how lit-
tle the passing currents can be relied on for an ad-
mixture  of the fresh air and warmed supplies.   The
stream  of air  admitted at an opening in  the wall,
can be clearly traced by a lighted candle at both its
upper and under margins, till it strikes the top  of
the  room  and thence to its  place  of escape.  Or
we may  notice how slightly the  motion of persons
passing  about a room, or dancing with considerable
activity, occasions any waving motion of  the can-
dles.  Still more is this exemplified in the  imperfect
method  in use in our hospitals for the insane, where
a current of hot air enters and escapes without re-
moving  that lowest test of impurity, recognition by
the  olfactories.
   IV. Another, and  by  far  the  most  important
essential, which we find  in our  various  adduced
illustrations of scientific and successful ventilation,
consists in the invariable provision  for some active,
continuous, controllable, motive  power, by which a
current  of air  is maintained through the occupied
 space.   This power may be arranged to exhaust the
vitiated stratum, and thus have  the partial vacuum
 filled with pure supplies through atmospheric press-
 ure, or  its action may be  to propel in the fresh air,
 driving  it before that already respired and depraved.
   This  mechanical provision we have found to con- 
82          ON THE PRACTICAL METHODS
sist  of various contrivances, acting in  both these
modes and on different principles.
   The motive force is derived from the rarefaction of
air by a fire in some portion of a tall shaft or chim-
ney, under a variety of modifications all involving the
same principle, the ascent of rarefied air and its con-
sequent tendency to produce a vacuum, and all effect-
ing the same result but adopted as economy, conveni-
ence, or caprice may have dictated.* We have seen
the fire sometimes at the lower extremity of the shaft
for the final escape of foul  air, the flues turning
their draughts received from all quarters under  and
around a fire-grate; sometimes the fire is arranged
towards the middle so as to  be fed from the very
apartment ventilated,  and more frequently still in
the attic.  The fire employed as a motive power  is
at times expressly for  this  end; at others it is that
used for heating and other purposes;  or the first of
these methods may be relied on in summer,  the
latter in winter.   The foul air  may be turned  di-
rectly into the chimney  or smoke shaft,  or into a
flue  contiguous  to it, or a succession  of foul-air
flues communicating with different apartments may
surround the chimney flue  as a centre.
   We find in many of the  recent applications, that
the  foul-air  flue  is  carried up in  contact with
 * For some illustrations of ventilating shafts, as respects the position of the
fire grate, see Fig. 12, Pi. II. which explains itself.  B represents the chim-
ney shaft, C the fire, A the main foul-air flue from the inhabited apartments,
D the door to feed the fire, E the ash pit. In the right hand diagram, the
smoke passes up in  an interior funnel or cast-iron pipe, and the air of com-
bustion is admitted from the outside, instead of being taken as in the other
examples, from the foul-air drain. 
OF  VENTILATING  BUILDINGS.          83
the  smoke chimney  until  a  point is reached at
which  no  more  collateral  flues  enter, when the
withe or partition is  left out.   The expansion  and
ascent  of the smoke and  vapors  aid  in increasing
the rarefaction below.
   Occasionally a large mass of chimney flues, built
to serve many fireplaces in the  same house, has been
replaced by a foul-air  flue, and a central  cast  iron
smoke  flue, with lateral elbows  to supply the  fire-
places, has been introduced.  The ventilating  con-
nections  are made from each  room in the vicinity,
from top or bottom as  preferred.*
   In constructing  chimnies for  receiving foul air
with the fire within  them, it is hardly necessary to
observe, that  a greater power  will  be  obtained by
having  them  of circular area and  of  a conical
shape or gradual  taper, as  the  ascending current
as it rises,  diminishes in density, and  eddies natur-
ally diminishing its exhaustive  power  are produced.
The amount of rarefaction and consequent draught
will depend of  course upon  the  size  and  length
of the  chimney and  the  amount of fire which may
be  in  combustion.f   These are  susceptible  of a

  * Appendix C
  f The use of chimnies already in operation for other purposes is frequently
adapted to valuable ends in ventilating.  A few years since, a long building
in Glasgow, divided into tenements for five hundred workmen, was from its
dirty and ill-ventilated condition, frequently visited by fever in its most fatal
types.  The superintendent of the mill to which these dwellings were attach-
ed, placed a large iron tube along the whole range of these houses, one end of
which was closed while the other was built directly into the  chimney shaft
of the engine.  At proper places in each house,  tin tubes, an inch and a
quarter in diameter, extended horizontally and were made to present an
open extremity over the bed of each room. The register, closing the  chim- 
84            ON  THE  PRACTICAL  METHODS
certain  approximate  calculation,   the  elements   of
which have been often  theoretically demonstrated.*
ney of the engine, was so connected to the fire damper, that on stopping the
work, the valve was opened, and of  course an active  current  of air was
drawn from each room, to be replaced with presumptively purer supplies.
  Since this powerful ventilating arrangement (considering its size of pipes)
was provided, — which is described inUre's Philosophy of Manufactures, p.
394, — these factory houses have been free from fever.
  It is stated in the report of the Health of Towns Commission, that the Glas-
gow Fever Hospital is ventilated by a similar arrangement of pipes of a small
calibre opening over each bed.  While such arrangements are worth recording,
as illustrating a principle, or even an ingenious adaptation where more propor-
tionate aids are impracticable, it is hardly necessary to suggest that so small
an egress pipe, and the absence of any provision for  a proper renewal of the
air withdrawn, are incompatible with  the idea of any scientific'ventilation.
  There are also many instructive examples, arranged by ingenious persons,
of connecting the seats of water closets with unemployed flues in the chim-
ney stack  producing  a lively  current downwards and totally nullifying any
offensive exhalations.
  I have been gratified  to observe in a popular and wide-spread agricultural
periodical some time since, plans for  cheap farmhouses, embracing a costless,
simple, and efficacious provision for  removing the  foul air and dampness of
cellars.  It is well known to every practitioner in farming districts, that the
cellar is usually the store house of many of the animal and vegetable products
of the farm, and becomes, from their slow decomposition, the source of endemic
fever, as well as of unpleasant effluvium.  In the diagrams referred to, a
single flue is carried up between the  smoke flues and opening with these at
top, while below it opens into  the  cellar.  The constant heat  of culinary
operations and other purposes  communicated to  the air  flue produces a
current easily controllable by a lid or valve hung on hinges.  To prevent the
freezing which would result from the cellar being supplied with the external
air in certain extremely cold periods,  an opening into  the kitchen might be
necessary.  The principal call for an  active purification is, however, towards
spring, when the danger of frost is least pressing.
  * The  principle and methods of calculation of the  draughts of chimnies
heated directly or by contact with  smoke flues, in producing a ventilating or
exhaustive suction of vitiated air, are plainly shown in Dr. Wyman's Treatise
and Mr. Hood's work.
  The primary force is the difference in weight of air, occasioned by the heat.
Air as well as other gaseous bodies is subject to the law, that each degree of
heat added from 32° to 212° F., increases the volume l-480th.
  "If this column of air [in a ventilating chimney] be  ten feet high, and
have its temperature raised 20°, then it will expand 20-480ths, or l-24th of
its bulk;  so  that  its specific gravity would be diminished, and it would
require a column of air ten feet five inches high, to  balance a column  of the 
OF  VENTILATING  BUILDINGS.  "
No
    2.  Another  mode  of  obtaining   an  exhaustive
power  consists  in  a rarefaction  of the  air  in  the
  external air ten  feet high, when the temperature of the  latter is 2)° lower
  than that of the former.  But as the height of the heated  column is limited
  by the height of the tube or chimney, which we suppose to be only ten feet
  high, the colder column presses it upwards with a force proportionate to this
  difference in weight, and with a velocity equal to that acquired by a  body
  falling through a space equal to  the difference in height, that two columns of
  equal toeight would  occupy, which in this case is  five inches.  Now, the law
  of gravitation is this : — that the velocity  of descent is  relatively as the
  square root of the distance through which the body falls ; and as a body falls
  16£ feet in a second (or sixteen feet neglecting the fraction), the velocity will
  be, agreeable to  the well known law of gravitation, equal  to eight times the
  square root of the height of descent,  in decimals of a foot;  or 2 \/ g h, when
 g is  the  distance through which a  falling  body descends in one second of
  time, namely, 16.09  feet, and h the height of the descent.
   In the case we have supposed five inches is the  height of the  effective
  descent of the heavy column of air.  This fall  of  five inches is equal to .416
 of a foot; therefore, by the rule, 2 \/  1G.09 x .416 = 5.174 feet  per second
 or 310 feet per minute, will be the velocity with which the heated column of air
 would be forced through the tube or chimney under the  circumstances we
 have supposed.  If therefore the tube were one foot square, there would pass
 out three hundred and ten cubic feet of air  per  minute."   This  rule, how-
 ever, would be subject to the modifications of friction, curvature, chemical
 changes, &c.
   In practice, after all, the height and dimensions of a chimney for producing
 a ventilating current, must be  reached experimentally ; for  the many qualifi-
 cations and  modifying circumstances would prevent any  calculation  from
 being of direct utility.
  The ventilating chimney  of the houses of parliament with which Dr.
 Reid's experimental trials have been made, and which was equal to a supply
 of thirty or forty cubic feet of air per  minute to its thousand persons, is one
 example.  This chimney was one hundred and ten feet high, twelve  feet
 diameter at base, and eight at top.  In the ventilation of the Butler Hospital
 for the Insane,  calculated for about  one hundred and fifty persons,  with  a
 downward ventilation in all  three stories  and to an exceedingly thorough
 extent, it was expected that the smoke flues of the kitchen, bakery, steam
 engine for pumping, and in winter  that of th# boilers for generating the
 steam for  heating — the whole carried up in a flue ^occupying  twenty feet area,
 to a height of about seventy feet — would have, by contact with flues of about
 the same area and of the same elevation connected with the  vitiated air flues,
produced a perfectly certain and adequate effect.  At least this was the judg-
ment  of some of  the most competent English engineers with whom I con-
versed on  the plan.
                    12 
86           •ON  THE  PRACTICAL  METHODS
eduction  or  foul-air flues,  by  means  of  heat  from
radiating  surfaces of pipes  or  plates within  them,
  Precisely this original arrangement is to be carried out in the new Asylum
for the Insane at St. John, New Brunswick.
  As a general rule  in modern styles  of architecture, it will rarely be found
that a central chimney need be carried higher than good taste would permit,
in order to effect a thorough ventilation.  For in the event of  its  proving on
any occasion or at any season not equal to its expected duty, a little additional
force, in  the shape of an anthracite coal fire at the  base of the  ventilating
chimney would meet the emergency.
  Where many rooms are to be ventilated, as in a hotel, of various sizes, it
would be found best to arrange the main stacks of chimneys so that several
flues for ventilating should surround that into  which  the smoke  of the con-
stant and large fires for cooking and similar  purposes is received.  Then at
the base of those connected with apartments which might be  called into use
under occasional exigencies,  as halls, large reception rooms,  &c, should
be  an opening  to permit more  exhaustive force to be added.  Or even the
steam  of the boilers, now in almost universal use in large establishments,
could be directed  into a  principal foul-air flue,  according  to  Mr. Bell's
system.  At the McLean Asylum  the waste  steam  of the small engine is
turned into the foul-air flue of  two of the  least ventilated galleries.  The
noise which was feared as  a serious objection  proved  quite inconsiderable,
and the amount of  upward current was probably increased tenfold when the
engine was in operation.
  In another instance at that institution, an underground horizontal flue was
run from beneath the seat of a water closet, from which it was impossible to
effect a removal of foul air by other methods, to an unused flue in the kitchen
chimney stack, a distance of twenty-five or thirty feet.  The effect was most
decided ; even the smoke of the most foetid substances burnt in the pan of the
closet, never ascended above the level of the  seat.  As a general rule, it is
undoubtedly best to make a ventilating chimney as high and as large  as is
consistent with economy of space, cost, and symmetry of exterior.  In school
rooms, counting houses, lecture rooms,  and   the like, double  the  extent
of the smoke flues may be expected to accomplish the ventilation.
  It would seem to be proper to make some reference to one objection to the
use of exhausting chimneys in ventilation which has attracted sufficient atten-
tion to be at least thoroughly refuted, — an attention not so much due to the
soundness of the objection, as  to  the scientific character of the objector.
Dr. Ure, the chemical philosopher, in his Dictionary as  well as in his parlia-
mentary evidence, and in announcing his views  in other places, has asserted
the opinion very confidently, that the exhaustive methods  in  ventilation
produce a rarefaction of air most deleterious to health.  In his  impatience
at  Dr. Reid's experiments, he observes :  " These  curious  effects clearly
illustrate and strongly enforce the propriety  of ventilating apartments by
means  of condensed air, and not by air rarefied by large chimney draughts, 
OF  VENTILATING  BUILDINGS.          87
 containing  steam  or hot water.  We  have  found
 these  as long since  as  Dr. Desaguliers'  trials in
 England in the  last  century, and  we  still  notice
 them in some of Mr. Sylvester's latest improvements,
 and recommended by him in the great  Parliament-
 House undertaking.
    The forms of  calorifers  or hot-air furnaces, in
 which the tubes admitting the air below and  allow-
 ing it  to escape  above at a high  temperature are
 enveloped in  the burning coals and attain a  red or
 white heat, would be exceedingly convenient to effect
 this  object, especially where no fear existed of fire
 being accidentally produced by the dropping of coals
 below, as might  occur when wooden flues entered
 the ventilating chimney.   Here the air furnace or
 calorifer, placed within the shaft and fed from with-
 out, would allow the air to pass through its heating
 pipes with great velocity.   It is, in fact, all the use
 that  such  unhealthful and  overheating appliances
 should  receive.   In one of our figures an early ap-
 plication of  this plan is delineated.*
   In the costly Maison   Royale for  Lunatics,  at
 Charenton, we have seen  that the hot-water  pipes

 as has hitherto been most injudiciously, wastefully, and filthily done in too
 many cases."
 The simple fact that the diminution of atmospheric pressure through any
 of the exhaustive methods, is stated by Mr. Hood seldom to exceed l-100th
 of an inch of the barometer, and generally does not reach l-200th of an inch,
while the  ordinary meteorological changes of this instrument, still unfelt
upon the  animal economy,  run through more than two and a  half inches,
demonstrates the exceedingly "thin air" of Dr. Ure's hypercriticism.
 * Fig. 5 and 6, PI. I. are representations in elevation and cross section, of
a. calorifer long since employed to produce eduction, n is the reservoir for 
88         ON  THE PRACTICAL METHODS
are carried longitudinally through the escape flues, to
induce the escape of foul air, in their way towards
the points where they are  expanded into suitable
radiating surfaces.   One of the applications of Per-
kins's high-heated pipes of  water accomplished this
result.  The direct pipe which connected the radiat-
ing coils in different stories was carried through an
upright flue, which had openings made to allow the
air to be drawn in at suitable  points near the floor
to the ceiling as  preferred.  A stop-cock was placed
near  the point where  the  horizontal pipe left the
perpendicular  which cut  off  the  circulation  de-
signed for heating, but still left it free in the pipes
within the  flue.   This of course secured a ventila-
tion in the season when it was too  warm for arti-
ficial heat.
   In the  New  Jersey  State  Lunatic Hospital, a
discharge  current is to be promoted by a  steam
pipe  between one and two inches in diameter run-
ning the whole  length of the  foul-air flue perpen-
dicularly.   It will  probably be found expedient to
fit a jet  apparatus to the  upper end  of  this pipe
and secure an upward draught on this recent appli-
cation.
   The rarefaction in the eduction flues is produced
also  by chandeliers suspended just below  the in-
ferior openings, as in the French Chamber of Peers,
 and  in  most  modern  theatres where  a  systematic
feeding ; k, the fire grate ; a a, the tubes, surrounded by the flames ; e, c, c, c,
tubes which bring the foul air from various places into the common box, d,
through which it ascends into the chimnoy, o. 
            OF  VENTILATING BUILDINGS.         89

ventilation  is provided.   Single lamps or  Argand
burners have also been  hung within flues  to meet
particular emergencies, but would be too  expensive
a method for any extensive employment.*
   3.  The provision of a chamber, or an expansion
of the foul-air  flue just over the apartments  to  be
relieved of their vitiated contents,  which shall  be
supplied  with  a  portion of the hot air  generated
for heating purposes in  the  basement  below, is
characterized by Mr. Brande in his  Parliamentary
testimony in  1835,  " as  the most  generally and
conveniently applicable  method."  Its modus oper-
andi  is obvious;  the air below  rushes up to fill the
space above, in which the air is of less density.
   4.  Centrifugal  or  fan  wheels acting  either  as
exhausters  to  suck  out vitiated or propellers  to
force in pure air, — which conditions of their  action
are respectively determined as before indicated  by the
circumstance of their  centre  or their periphery be-
ing connected with the entering or exit channels,—
have been  used from an early period and with  sat-
isfaction  in some of the  greatest  examples, as is
still  the  case in the French Chamber of Deputies.
The  formula? by which  the efficiency of  these val-
uable machines  may be  calculated  will be  found
below.|
  * Fig. 7, PI. I- represents the chandelier a, surrounded by  the metallic
cone b, which is inserted into the shaft c, into which the foul air from various
points  is turned through the  boxes o and n, and into the open air by the
cap u.
  + The method of determining the efficiency of the rotary fan is thus given
by Mr. Hood: —
  " The mean veloeitv of the portion  of the vnnee of the fan by which the 
90             ON  THE  PRACTICAL  METHODS

   5.  The  employment  of exhausting  and propel-
ling  pumps and  bellows   is  still  maintained  very
efficiently  in  certain  large  establishments, an   ex-
ample of which we  have introduced.
 air is discharged, is about J of the velocity of the extremities of the leaves;
 but owing to the inertia of the air, there will be a further loss in the velocity
 of the issuing current, increasing with the greater velocity of the vanes ; so
 that, under ordinary  circumstances, the current will be discharged with a
 velocity equal to about § of the velocity of the extremity of the leaves.  This
 velocity in feet per second, multiplied by the  area of the discharge pipe in
 square feet, will give the number of cubic feet of air discharged per second.
  To estimate the force necessary to cause the rotation of the fan, the follow-
 ing method of calculation, founded on the ordinary mode of estimating steam
 power, will be found sufficiently accurate: —
  Suppose the effective velocity of the vanes  of the fan to be 70 feet per
 second, and the sectional  area of the eduction  tube to be 3 square feet, then
 70 x  3 = 210 cubic feet will be the quantity of air discharged per second;
 and this number, multiplied by 60, will give the quantity per minute.  As a
 cubic foot of air weighs 527 grains, there will be about 13 cubic feet of air to
 a pound; therefore —j^—  = 969 lbs. is the weight of air put in motion per
 minute, with a velocity of 70 feet per second.  The height  from  which a
 gravitating body must fall, in order to acquire a velocity of 70 feet per second,
 is -p- = 76..5 feet; which, multiplied by the number of pounds weight moved
 per minute, will give  the power necessary to be expended, in order to  dis-
 charge this quantity of air at  the stated velocity.  And this product divided
 by 33,000 (the number of pounds weight that one horse will raise one foot
 high per minute), will give the amount of  steam power required.  Therefore
 3^   = 2.24, or nearly 1\ horse power, will be necessary to  discharge  the
 given quantity of  air at the velocity stated."
  Fig. 22, PI. II., represents  an improved  form  of the fanner, as compared
 with the construction of  Dr. Desaguliers and  others.  The case  and  the
 interior wheel are not concentric : o, o, is the case; a, the axis ;  and c, c, c,
 c, the vanes; d is  the channel through which the air is forced in the direction
 of the arrows ; x marks the central openings in the ends of the case, for  the
 induction of the air.
  In the application of fan wheels for ventilation, it must not be forgotten
 that the quantity of air, not its velocity and pressure, is the object sought;
 the  reverse of what is required in blowers for facilitating combustion.   A
 speed of  3  to 500 revolutions  per minute, is as much as can be maintained
 without an unpleasant noise ; and, in view of all the loss of power in gearing,
 &c, the diameter of the fan should be calculated for a speed, certainly within
 that naniad.
  The curvilinear  blades of some modern varieties have no superiority suffi-
cient to counterbalance the mechanical disadvantages. 
OF  VENTILATING BUILDINGS.          91
   The reciprocating action  and  friction of packing,
as well as the loss of power resulting in most forms
from wire drawing the  air, as it is called, that is,
forcing it  through  a diminished aperture, prevent
this from being as  economical  a method of using
power, as the  centrifugal wheel.   There may, how-
ever, be  situations in which it may form the most
desirable apparatus.*
   Dr.  Arnott, in his testimony before the Health of
Towns Commission, observes   that when he visited
Glasgow in  company with  Mr. Chadwick,  there
was described to them a vast lodging house in con-
nection  with  a  manufactory, in which  fever was
formerly very  prevalent,  and  which was in  conse-
quence ventilated by making  an  opening from each
room into a duct which terminated in an  air  pump.
The  supply of pure air, he  says, obtained by that
method  of  ventilation, was sufficient to dilute the
cause of disease, so  that it became powerless.
   6. The use of the steam  jet, the latest  and prob-
ably the least troublesome  and most certain of the

  * The effective performance of blowing cylinders for this purpose, under a
given amount of moving power, is readily calculated.
  " Suppose a ventilating pump three  feet square  and five feet high, and
that the piston makes twenty-five double strokes per minute, each four and a
half feet  long.  In this case, 2025 cubic feet of air  per  minute will be dis-
charged ; and if a valve for  its discharge be ten inches square, the velocity
of its discharge will be equal  to 48.6 feet per second. This quantity of air,
reduced into weight, will be ~ = 155 lbs. put into motion every minute,
at the rate of 48.6 feet per second ; and therefore, we shall have -^— = 36.9
feet as the  height from which a gravitating body must fall, to obtain the
velocity of 48.6 feet per sec, and ^^ = .17, or one-sixth of a horse power,
as the necessary force to discharge this quantity of air, at the stated velocity."
  It will  be recollected, that a horse power in dynamics is  33,000 pounds,
raised a foot per minute. 
92          ON THE PRACTICAL METHODS
 methods of inducing  an exhaustive  current,  has
 been described  in  the account of the new Houses
 of Parliament.
   Steam has  been before used in locomotive en-
 gines, to produce the prodigious draught needful in
 their rapid combustion of fuel, by the escape pipe
 entering the chimney.
   The only exact statement of its efficiency I have
 seen, is  the calculation of Mr. Faraday, that with
 the steam at thirty-two pounds pressure to the inch,
 or about two  atmospheres, a point  not unusual in
 what are deemed low pressure boilers, air is removed
 to the amount of two hundred and seventeen times
 the cubic feet of steam escaping.
   The jet is arranged in the simple and economical
 circular cap,  such  as  constitutes  a very  common
 form  of gas burner.*   No particular length of shaft
 is required into  which  the steam  is to be liberated,
 and the foul air  is received below.
   7.  The use of revolving screws  of various forms,
 to  exhaust and  propel air as  they may  be turned
 one way or the other, requires to be mentioned only
 to put those disposed to invent new things on their
 guard and  lead  them  to examine what  has been
 hitherto done.f

  * Fig. 24, PI. II.
  f Dr. Reid observes  that the Archimedean screw has been extensively
used in Belgium and elsewhere, as a substitute for the fanner or centrifugal
wheel.  Several years since, two gentlemen of nearly the same name, — Mr.
 Combe of Leeds, and M. Combes of Belgium, — made an improvement in
the screw simultaneously, to which Dr. R. is inclined to give the preference
over the preceding varieties.  Fig. 23, PI. II. represents one of the varieties
 of this form.  The double screw is convoluted spirally around the axis c, 
OF VENTILATING  BUILDINGS.         93
   V.   Our last  common  essential  is in the power
 of controlling and regulating the operation  of the
 apparatus,  producing the ventilating change.   It is
 obvious that the various circumstances of numbers,
 character, and detention of the occupants, and the
 state of the external air, must require a command
 over any apparatus or method, to fit it for proportion-
 ate action.   An extent of warming and ventilating
 adapted to  a full  Parliament of eight hundred or a
 thousand persons, during  an interesting and excit-
 ing debate, would be  widely unfit for  the faithful
 few who might remain after it was over to plod
 over the dull  details  of private bills  or financial
 statistics.
   So the amount of air which would be fully  ade-
 quate to the ordinary wants of a hospital, would be
 wholly unequal to  a  pure and salubrious atmos-
 phere in  the parts devoted to fever,  small pox,
 gangrene, and the like.  The galleries of the  con-
 valescent or  cleanly patients of a  lunatic asylum
 require an  insignificant quantity of fresh air, com-
 pared with those occupied with the demented or
 maniacal, lost to  personal propriety.  Apartments
 occupied for a few  hours or a single hour,  like
 lecture-rooms, churches, and the like, would permit
 a much  less energetic provision of machinery than
 if the  sessions were protracted, as in courts of
justice,  schools,  and  legislative halls, while  the
 which is turned by any motive power at hand.  A shifting of the gearing so
 as to reverse the  direction will  change its action from propelling to suction,
 at will.  The arrows show the respective directions of the screw and air
 currents.
               13 
94         ON THE  PRACTICAL METHODS

latter have intervals of repose unknown to prisons,
hospitals, and other places of detention, where the
inmates are present through the day and night.
  All these adaptations are to be provided for, and
in most of our examples we see the most abundant
means of meeting every emergency.   The tables of
the temperature of  the House of Commons and the
prisons on the Model Plan, (and this element perhaps
expresses the renewal of air in those instances where
the  only  heating  is  in  the air of  ventilation,)
demonstrate  the accuracy to which the adaptation
is brought,   It is  hardly  too  much to say, that in
them the  quantity, the hygrometric condition and
temperature of the air are susceptible of as much
exactness, as  the provision of food and drink.
  In the recent ventilations of the principal  Pari-
sian edifices,  a contract providing  for all the requi-
sites of a  perfect system  is entered into, and even
the  precise sum for  the  annual  support  of  these
arrangements is agreed upon.  In Peeler's complete
treatise,  various specimens of  the  accuracy to
which this part of the detail has arrived  are pre-
sented.  A practical  tradesman  agrees to  furnish
without fail,  a certain number of cubic feet of pure
air, per minute, at a given temperature,  at a speci-
fied sum.
  A maximum  supply  may be contracted for,
while the  power of reducing this to  a less degree
required by the circumstances of  the case, is placed
within the ready control  of a moderate degree of
intelligence.   It is of course not within the com- 
OF VENTILATING BUILDINGS.         95
 pass  of  possibility,  that there can  be any self-
 regulating means of  supplying heat or air, where
 the  demand  is  continually varying.   Hence all
 systems  on any considerable scale, must require a
 constant  supervision,  and  management on  fixed
 principles, and  not as  suggested by the capricious
 and uncertain calls of  individuals  of peculiar con-
 stitutions and habits.  Much  of the  obloquy and
 ridicule which have  fallen upon Dr. Reid and his
 ventilating  trials, has been owing  to the impossi-
 bility  of  satisfying men,  whose requirements  are
 widely variant or even diametrically opposite.   The
 rubicund four-bottle country  squire  and the  ex-
 sanguined and aged ecclesiastic, cannot be measured
 by the same  scale without one or  the other suffer-
 ing.   An approximation to the  average necessities
 is all that can be hoped for.
   In most of the provisions of  motive  power, the
 controlling means are  obvious.  Valvular contriv-
 ances,  known as registers or  dampers, are  equal to
 the smaller adaptations or temporary emergencies.
 The amount  of fire or  steam,  or other heating
 means, when these constitute the moving force, the
 velocity of the fan-wheel or other apparatus involv-
 ing the same principle,  are all  readily adapted to a
 very low minimum.   If  in the original arrangement,
 a plan is carefully calculated for a  high maximum,
 as measured  by the  number of  cubic  feet of  air
thrown in or drawn out, there  is little difficulty
and usually but little wasted expenditure, in work-
ing the apparatus at a much diminished activity, 
96         ON THE PRACTICAL  METHODS

  The various modes of effecting the  same results
in ventilation, are by no means to be considered  as
antagonistic or even competitory to each  other. An
abstract preference cannot  be properly  yielded  to
one  at  the expense of the  others, as an  inferior
machine in the arts yields  place to one of an im-
proved  design.   The selection of a  system  or  of
peculiar features  of several systems,  will  depend
entirely upon circumstances.   The degree of per-
fection  sought in some cases, as  in  the  plans  of
Parliamentary  Halls  and   certain hospitals,  de-
manding  the  utmost of hygienic  completeness  or
even  luxurious provision  within  reach,  may  be
allowed to overrule all considerations in  the points
of cost of construction  or  of maintaining in due
performance.
  The  occasion  as determined  by the extent  of
numbers  to be provided for,  their character, and
their continuance  in  the  same place,  is  also  an
important element  in  deciding  the  question.   A
library, a church, a hall  of  assembly for concerts or
lectures of an hour, a school where a  small portion
of  day-time only  is  spent,  a legislative  hall  of
uncertain numbers  and length of sessions, manu-
factories  of. high temperature, offensive  processes
and crowded population, hospitals for numbers of
the sick or insane, equally  pressing at night as at
day, all constitute in an increasing ratio instances
of the inequality of the extent  of provision required.
   The presence or absence  of an available power of
 steam or  water to  give  motion to  ventilating ma- 
OF VENTILATING BUILDINGS.
97
chinery, may give a preference  to  certain arrange-
ments,  entirely out of the  question under other
circumstances.
   To  illustrate  these  modifying  conditions, by
particular instances :   Were it determined  to ven-
tilate a large  already finished hall for lectures,
concerts, or other evening occasions of an hour or
two duration,  the  simple rotary fan, propelled by
the labor of a  man, arranged in the garret or cellar
as it might  be  preferred  to  inject fresh  or exhaust
foul air, would involve least  expense,  least  com-
plexity, least  disturbance  of  work  already  com-
pleted,  with a  sufficiently complete  performance of
its office.
  If,  again, we were required to provide  perpetual,
certain, and copious  changes  of  air for a large
hospital for medical or surgical  diseases or for the
insane,  or  for  a cellular prison, where  no  power
would ordinarily be at hand, little  doubt can exist
that the lofty chimney shaft, urged  by a coal fire or
the late adaptation of  the steam jet, would  be the
most reliable as well as the most economical.   Here
again, circumstances   would decide which  modifi-
cation of the many plans having the tall shaft for
their motive power should be selected.
  Whether the flues for foul air should surround
the central  smoke flue or enter at its foot  under
and around its grate, whether  the  foul air flues
should proceed upwards or descend to  their hori-
zontal main channel, whether the common fires for
culinary and heating purposes should be relied upon, 
98         ON  THE PRACTICAL METHODS

or a separate fire be  provided,  and many inferior
points would all be decided by the position of each
case.   For some  hospitals, hotels, or  prisons, the
kitchen fires might prove adequate; for the larger
class of hospital edifices,  an independent shaft of
lofty height would be demanded.
  Again, to purify the populous halls of a factory
or other building for the purposes of the arts, where
from the aggregation of the employed or the nature
of the processes, a lively and energetic ventilation
would   be  requisite and  where  abundant  motive
power is at hand ready to  be used  as  long  as the
necessity obtains — that  is, by daylight only — the
fan wheel or wind cylinder  in some of their varieties,
might be more expedient.*
  "Where the steam engine or  merely the steam
boiler for heating is found, as is  the case in  most
of the  immense  modern cotton factories of  New
England, the jet of steam  thrown into the eduction
channels might be the most useful mode.
  A downward ventilation, that is, from or near the
floor of the room, requires more power  and con-
sequently is  at some  economical disadvantage, by
the reversing of the naturally ascending movement.
But  in halls where  the  dust raised by the  feet of
an excited  auditory may better  be kept from  their
lungs, — in insane  hospitals,  where  the inlets  if
accessible may be polluted, and indeed  are  con-

  * The ventilating fan is said by Mr. Bernan to be much used in the manu-
facturing  districts of England,  for drawing off the heat,  moisture, and
filamentary dust of the rooms. 
OF VENTILATING BUILDINGS.         99
 stantly liable to annoying depravations from the use
 of tobacco  or  other filthy practices, these become
 harmless from the  current  of air being  drawn
 outwards, not inwards over the offensive matters ; —
 in legislative halls and court houses, where accor-
 ding to the custom of our country an  infusion of
 the same vile  weed  is scattered over the floor so
 profusely that as its vapor  rises in  universal solu-
 tion, no  man with clean interior can hope to escape
 imbibing an equal  share  of the offensive fumes, a
 draught downwards  with  a pure admission of air
 from  a point overhead, is certainly a great desider-
 atum.   Indeed, the  plan  of a united upward and
 downward ventilation  at  the same time, to meet
 some exigencies in the arts, is recommended in some
 modern treatises. So refined and nicely equilibriated
 an adjustment  as this would seem to require, could
 scarcely be maintainable in practical application.
  It is thus obvious, that in  deciding  upon  the
 details of any  plan,  the general principles  of  the
 art must be well understood  and applied in view
 of all the circumstances of the given case.
  For a  numerous  proportion of  the exigencies
which present themselves in every day life, such as
 school-houses, poor-houses, lyceums, and other halls,
vestries,  court-houses and small county prisons,
 my impressions are in favor of  main foul-air flues,
passing up in contact with smoke flues  in constant
use; or in case of hot air furnaces being employed,
the foul-air  duct should  be between  both these
warming sources, the withe or dividing partition 
 100       ON  THE PRACTICAL  METHODS

between the smoke and foul-air flues being removed
at the attic floor to augment the draught.
   For summer use, in case  the kitchen or  other
fires are diminished or discontinued, an  opening for
a fire with a grate should be  made  at some  con-
venient point in the foul-air flue.  The  point  for a
moderate fire of some slowly  burning fuel for this
purpose ordinarily the most convenient,  is in the
cellar where the furnace is, but may be in the attic
as figured in the plan of the  Pentonville Prison, or
even in the apartment itself as  delineated in the
French school-house.
   The main foul-air  flue,  placed either within or
just outside of the apartment, may be  pierced for
the  admission  of vitiated air  at such part  as is
deemed most expedient, in accordance with the sys-
tem of upward or downward  ventilation determined
upon.
   If the supplies of warm  or  fresh air  are  from
below and admitted at the floor, the foul air would
properly be drawn off at  the  ceiling, either  by a
single opening  as large in  area as  the  tube would
permit,  or by  lateral  flues  running horizontally
across, around, or just above the ceiling, (a  box-
like cornice for example,) and  apertures  to equal
the flue-area made in these at convenient distances.
   If the heating is provided by flues  opening  high
or by radiating pipes or stoves,  the foul  air  may be
drawn off at a similar opening  at the floor of the
room into  the foul-air duct.
   Or if it is decided to protect  the  lungs  from the 
            OF  VENTILATING BUILDINGS.        101

dust and vapors by a downward current, horizontal
flues beneath the  floor should extend from many
parts of the room, with perforations  into them at
every point  protected from closure,  arranged as
respects size and frequency with a constant regard
to the comparative indraught, at different distances
from the upward flues.
   In  a climate where so much wind  exists as in
ours at certain  seasons,  I  would  not wholly  dis-
card the use of turn-caps, for  aiding  in admitting
and discharging air.   These, of course, are  merely
auxiliary measures, calculated to save some expense
in motive  power; as no one  acquainted Avith  the
demands or completeness of modern ventilating ar-
rangements, would even think of relying exclusively
or mainly,  upon any contrivance depending  on so
proverbially inconstant a power as the wind.  For,
as before intimated, there are occasionally weeks of
most imperious  demand, when the  cowls or caps
are actually worse than merely  useless.
   The cast-iron plenum and  vacuum revolving cowls
constructed by Mr. Mott of  New York and used in
the public  schools  of that city, and the fixed  cap
with a conical border, originally constructed in 1788
by St. Martin (the best form of which is that recom-
mended by the  American Academy of  Arts, in  the
Report heretofore referred to), appear to me to com-
prise most  that  is attainable in that multitudinous
class of contrivances, in the cheapest and most dur-
able form.
              14 
102        ON THE PRACTICAL METHODS
  Our last subject for consideration is the quantity
of change of air which is necessary or expedient.
  In arranging the ventilation of any given habita-
tion, how many cubic feet of air should be thrown
in and taken out, in order to secure  the full advan-
tages of health and comfort, dependent on purity of
the respiratory medium 1
   In estimating  the  quantity of air required for
each pair of lungs in a given time, neither chemistry
nor physiology, as before intimated, affords us any
aid.   Were the question — how much air is needful
to save from suffocation'? the researches of the chem-
ist as to the  decomposition  of ascertained averages
of the amount of air in the lungs, would be  suffi-
ciently precise and reliable.   But when we consider
that the comparatively minute taint or imperfection
from the  effect  of respiration, is  capable, under
most extended dilutions, of  producing an undoubted
deterioration upon the hygienic and sanatory quali-
ties of the atmosphere, we shall see how little any
chemical alterations  bear upon the  infinitely more
delicate, and as it were, spiritual depreciations.   If
analytic chemistry is still too coarse in its  investiga-
tions to be able to detect any difference in the pure
mountain  breeze, and the   stifled  contents of the
small-pox or fever  hospital, — if  the mere  senses
can detect repulsive  additions which tests  do not
recognize or verify, it ought  not  to be blamed for
failing to throw light upon so  infinitesimally  small
 dilutions of respiration. We know by the abundant
 proofs  suggested heretofore, amounting  almost  to 
            Or  VENTILATING BUILDINGS.        103

demonstration,  how momentous  the inappreciable
additions are, as respects disease and death.  If no
scientific acquisitions  enable  us to find out these
important relations, neither do our  senses give us
warning or defence.  A single respiration from the
lungs will produce a medium in which a candle will
not burn ;  yet within my own personal observation,
Irish  laborers have continued at their work at the
bottom of a well, hours after a light had been extin-
guished.
  A depraved taste as to the quality of air can be
acquired and  maintained as well  as in regard to
food or water, of which so many examples will occur
to almost every one.   One  of the  oldest and most
honored of our Supreme Judges, who has been seated
days and years in court-houses filled with the most
polluted and irrespirable atmosphere  to all unac-
customed lungs, avers that he recognizes no defects
in it, and  regards  all call  for ventilating measures
as quite superfluous, on his account!
  We  are  then driven for the  solution  of the
important  question  of quantity, to the result of
experience, a test in a single  case  being quite too
uncertain  and intangible, but when reduced to the
formulae derived from  the  conclusions of many in-
vestigations, must form our standard, because it is
the highest evidence the case admits.
  Commencing with the lowest minimum proposed
by  the  leading authorities, we shall  find  as  we
reach the  highest maximum  a wide  range.   Dr.
Arnott considers two or three  cubic feet a minute,
as all that need be charged to each person.   Mr. 
104         ON THE PRACTICAL  METHODS
Tredgold fixes  his average at four.  Mr.  Hood, a
recent very accurate  and  practical writer, observes,
" that in all public buildings and rooms of dwelling-
houses, a quantity of air equal to from three and a
half to five cubic feet, for  each individual the room
contains, must  be changed per minute, in order to
preserve the wholesomeness and purity of the atmos-
phere."   Mr. Toynbee, F.R.S., an English surgeon,
in a lecture  recently delivered before the Institution
of British Architects, fixes upon ten cubic feet  per
minute, or, what he proposes as  a unit  of measure-
ment,  double  the contents  of  a  man's body, as
required to meet the demands  of respiration.
   Dr. Reid  declares that the provision of ten  cubic
feet to  each person,  per  minute, in  the House of
Commons,  proved to be  a  minimum which  was
generally recognized  as  below  the natural wants
of the  system,  and declares it as his determination,
to adapt his ventilating power to the work of intro-
ducing not  less than from  twenty to  sixty  cubic
feet per minute.  In the French Chamber of Peers,
twelve  cubic feet are furnished.   At the Pentonville
Model  Prison,  the  arrangements are fitted to turn
in from thirty  to forty-five cubic feet.*
   With  data like these, it would not perhaps be an
 * The velocity of air in currents and in flues is measured, and its quantity in
cubic feet determined, in various ways. Anemometers or wind-gauges, indicat-
ing the strength of the current by number of revolutions, or raising weights, or
contracting a spring, have been constructed.  The floating of flocculent parti-
cles or dense smoke, enables the speed  to be noted by a stop-watch, through
a given length of pipe or flue.  Paper covered with a paste of starch, receiv-
ing a current of the vapor of iodine liberated at the other end of the channel,
is struck instantaneously with a deep blue tinge.  The interval is measured
by any time-keeping instrument. 
           OF  VENTILATING  BUILDINGS.        105

unsafe estimate to  consider the quantity of supply
demanded to maintain a due fitness  of  the air for
respiration,  at  from  ten to  twenty cubic feet per
minute, to each person.   Circumstances  may  con-
siderably influence  any general conclusion like  this.
For example: in large rooms to be  occupied  only
for short periods, like churches, it must not be over-
looked  that  there  is at commencement  a reservoir
of pure air  in  the  space above, which is to be sub-
tracted from  the amount to be obtained  artificially.
Mr. Peclet calculates that each person fills ~  of a
metre, or about a foot of area on the floor.  To con-
tain a supply of air for a session of one hour, a room
must then be fifty-four feet high, and  in this ratio.
   Again,  in some cases  of exceedingly uncleanly
inmates or offensive diseases, the quantity of change
demanded to maintain an atmosphere pure to the
olfactories, must  be  more than  the amount  for
merely respiratory purposes.  Generally the contrary
will be the case, and it will be found that the adequate
supply for the  lungs  will prove sufficient to main-
tain a fresh, elastic, and unrecognizable condition.
   On bringing to a close this brief consideration of
a most important art, I would hope not to transcend
the bounds of a respectful deference, in urging upon
the members of this association the  claims which
the various  branches of  sanatory  and hygienic
reform  and  especially that  of  ventilation  have
upon their attention and investigation, particularly
in their relations  to  the population  of  New Eng-
land, at our day and in futuro.   Have  not these 
106       ON  THE PRACTICAL  METHODS

been  emphatically  the  omitted of the  great  ques-
tions  of  professional   culture,  the  world  over X
Pathology, therapeutics, the  profoundest  secrets of
healthy  structure  and  of diseased  change,  have
been pursued with a zeal, perseverance, and success
so  extraordinary as to mark  our age as  that of
critical  exactness and  refined  observation.   The
causation of disease, the prevention of the morbid
influences in operation  prior  to either functional or
organic response, the recognition  and  counter action
of the subtle causes of commotions  set up in  the
animal  economy to expel or to  contest with  some
morbific source of  mischief,  have necessarily been
deficient in that element of numerical and  specific
exactitude, which commends itself to  the accumula-
tor of truths, and may therefore perhaps have been
somewhat  ungracious  to the  tastes  of  our  time.
These have consequently been rather allowed to  fall
into the category of loose speculations, and have been
regarded as topics of a  light  and popular literature
scarcely of the profession,—as presenting proper fea-
tures for the magazine or the  lyceum, rather than for
the strict persevering research, accorded to other
topics of medical investigation.  Let it be thus no
longer — let  the physician claim as his own, these
matters primarily bearing  on life and  disease, and
save them from the unhallowed hands  of merely
popular  sciolists, by a profundity and precision of
knowledge respecting them, which shall overwhelm
all merely superficial acquisitions.
   The old world is roused  to the consideration of 
OF VENTILATING BUILDINGS.        10
sanatory reform, by the  pressing necessities of the
case so urgent as  to allow no further procrastina-
tion.   Its governments have been awakened to the
dire consequences  in  disease, deterioration of the
species,  and frightful mortality,  of a  neglect for
ages of the laws of health and life, and are prepar-
ing to expend with an unstinted hand the stores of
accumulated  treasure, to redeem themselves  and
their posterity from the  consequences of long  per-
petuated ignorance and error.
   Be it  ours  to guide a new people, by the lights
of past experience, and the world's  present science,
so as to  avoid the same errors and omissions, and by
consequence,  the same disastrous results.
   We are so  fortunate as to live at  an era, and in a
country where, despite the forebodings expressed by
the impatient and  the desponding that  the inroads
of empiricism of a  thousand names  are endangering
our profession and  the society of our time, the char-
acter and judgment  of  the scientific, the wise, the
practical physician  are of greater weight than at any
former period of the world's history.   The throwing
off the mere  trappings and  artificial distinctions  of
society now in  progress in the other  hemisphere,
long since achieved with us,  is only one of the re-
sulting manifestations that mind, cultivated reason,
and enlightened conscience,  are destined to  hold
their just influence over the civilized world.   Mea-
sured by such claims  to first rank,  by devotion  to
others'  welfare, by abnegation of self,  by persever-
ance  inter  labores et  tedia,  the  followers  of the 
108        ON  VENTILATING  BUILDINGS.
medical art have no  reason to  dread diminished
consideration, as the world proceeds under its new
system.

Gentlemen of the Society :
  Happy should I  regard myself, if I could close my
short hour's communion with you, in these words of
encouragement, congratulation, and hope.  But alas,
he that stands in this place, as year succeeds year,
must have  the melancholy, yet  not wholly painful
duty, of recalling  to the living, the memories, the
services, and the merits of the dead.  I say that the
duty of commemorating those who  have passed on
before  us, is not  unmixedly painful; for in the long
years of useful labor of some, and  in  the abundant
proofs  in the  shorter career of  so  many  others
more early removed, that
        That life is long, which answers life's great end,
— in the exulting  consciousness  we feel, that there
are still spared so many of the fathers of our calling,
who have so long  filled the  highest places  in the
public  estimation as they have in our hearts, whose
influence upon the elevation of the medical profes-
sion in Massachusetts, in New England, can be fully
appreciated only in after times, — towards each one
of whom, as year after year we greet their venerated
forms  on  this   floor, the  spontaneous ejaculation
bursts from our inmost soul, sero in coelum redeas !—
we cannot  feel that we  grieve for the fallen  of out-
ranks,  as  those without  many circumstances of
mitigation  and of mercy. 
APPENDIX.
15 
APPENDIX.
                                  A.

   The  failures of the ordinary modes of endeavoring to introduce  a  pure
 atmosphere into  buildings  and to sustain it under  all circumstances, are
 quite numerous. Although any others than systems with an exhaustive power
 are considered so obsolete as not properly to come within a treatise on prac-
 tical ventilation, and have scarcely been alluded to in the body of this work,
 yet as many persons are yet to go through the trial from necessity or igno-
 rance, a recapitulation of the sources of failure may serve to obviate a portion
 of an evil, if it cannot be wholly averted.
   I. Relying upon the opening of lateral  windows.  In all temperate and
 cold climates, glass windows are made to open either by the raising the lower
 sash, raising the lower  and dropping the upper at  the same time, or  by
 dividing the entire sash  in  the middle while it opens from bottom  to top
 on both sides.  This  last  arrangement is known as the French window,
 and has become quite common in the most expensive class of houses in the
 Atlantic cities.
   It has doubtless been noticed, that in all the  superior examples of ven-
 tilation introduced, the windows  have had no  share  in the process.  They
 have been considered, as in fact they are made in practice, as fixed immova-
 bly.  Experience has ever demonstrated that buildings in which open  win-
 dows are relied upon, are never ventilated at all.  In climates like ours, the
 cold gush of fresh air into a heated room cools, but does not materially change
 the vitiated atmosphere,  while the effect of the  draught upon  the health is
 too well admitted to require a moment's consideration. The windows open-
 ing at  top  and bottom,  by  the sliding of both sashes, may in some cases,
 as in  theory they are intended, permit the air  to  enter at bottom and the
 heated  surplus  to escape at the upper opening.  The slightest moving current
 towards these windows annihilates all hopes of  this, and the  cold air beats
 directly upon the heads of the audience or inmates.
   Again, during several weeks in spring and autumn in the northern parts of
 the United States, the weather is in that state in which it is too warm for
 artificial fires, and too cold or damp, or both, for open windows.  Here, of
 course,  is no ventilation.  It also often happens in cities, that  in public and
 private  buildings, the open window admits  odors, sounds, and  even insects,
 to a degree  rendering  defective ventilation the lesser evil.  Our  courts of
justice are striking illustrations of the difficulty of hearing, from the noise in
streets, except at the expense of an atmosphere  corrupt enough to hebetate
the faculties of judges, counsel, and jury.
   The importance of double sashes in economy of fuel and equality of temper- 
112
APPENDIX  A.
ature, renders some method necessary in houses of the better class to avoid
any  reliance upon windows which, of course, cannot be opened  for ventil-
ation when so duplicated.
  Pleasant as the open window certainly is  in our dwelling houses at times
in the summer months of our climate, yet it may well be  doubted, in these
days when the manufacture of glass has become so perfect as to impede no
vision and so cheap, in view of all the maladies produced by this the most fruit-
ful of causes, whether that will not be a step of the highest value in " sanatory
reform," which renders the window sash a fixture.   Certainly the noisome
odors, the pestilential vapors, and annoying sounds of large cities, must ren-
der supplies of pure air from some  other source exceedingly desirable.  And
in country residences the chilling draughts of windows accidentally or heed-
lessly left open, inducing a long catalogue of  diseases dependent on checked
perspiration, and the crowds of disgusting or irritating winged  insects ready
to approach the evening's light, overbalance the  few opportunities  of that
peculiar enjoyment which the passing current of genial air affords.
  It  is hardly necessary to advert to the  universally admitted  fact that the
draughts of air, impinging upon part of the person as they do in entering an
opened window, are much more pernicious than a complete exposure without
the draught.  Open flagged and dry walks, open verandas, or even projecting
balconies, are accessories to dwellings more than compensating for the opening
or sliding sashes, without destroying, as these must do, all hopes of a regular,
reliable system of ventilation.
  For some important experiments showing the cooling  power of windows,
and  the  consequent  value  of  the double sash, the reader is referred  to  Dr.
Wyman's Treatise on Ventilation, p. 389.
  II. The uncertainty and  insufficiency of flues or passages with no other
aids, leading from the apartment to be  ventilated.   Experience the most
extended, of this  the most common of all modes of  effecting this object, —
indeed the almost exclusive mode of attempting it in the public institutions of
this country,— abundantly demonstrates that it is entirely unworthy of being
considered as a true ventilation.  Still there is some degree of efficacy in it,
and there are various circumstances which influence its value, from its most
considerable action down to the point of utter nullity.
  Where flues are used to allow the  escape of vitiated and foul air, the usual
expectation is that the fresh supplies are  to be received from furnaces below,
from stoves or fires within the room supplied from the outer air into an inter-
space surrounding the fire, or  from  steam or water pipes  also within it in
winter or cold weather; and through other  avenues during the rest  of  the
year.  The circumstances modifying and influencing the efficiency of foul-air
escape or eduction flues, as they have been called, are:
  1.  That tlie fiues are of insufficient size.   Almost  all  persons  who make
their first experiment in ventilation overrate the  effect which  the flue will
produce,  and consequently make it of inadequate dimensions.  Sir H. Davy,
as mentioned in the text, was invited with a carte blanche as to the arrange-
ments and the expenditures, to design a  system of ventilating the English
House of Peers (the present House of Commons).  In  his plan the area of dis-
charge was only one foot. In  the recent method this was augmented to fifty 
APPENDIX   A.
113
feet.  Nor was the difference explained by there being a greater motive power
in the first case, for the reverse was the fact.
  In most of the prisons of this country, both on  the Auburn and Philadel-
phia plan, without now referring to other weakening circumstances, the dis-
charging flues are made of an area of sixteen to forty-eight inches only.
  In the insane hospitals, the uniform  system, when any has been provided
in the original building, has been to make  the  flues for the bed-rooms, &c.
within the brick partition walls, which are a foot or three courses in thickness.
The size,  then, is consequently one brick or four inches wide, by a length once
and a half or twice as great, or from forty-eight to sixty-four inches area, the
orifice being perhaps expanded to twice those dimensions.  Occasionally flues
eight inches square are found in the McLean Asylum; in some hospitals the
orifice is covered, for some unknown reason, with a perforated cover of iron,
reducing  its area to a very few inches, and in other cases a couple of inch
holes only are left.
   Our court-houses, school-houses, lecture-rooms, and other places of con-
tinuous congregation, have been fitted with  outlets in this proportion, most
commonly occupying the vacant portions of the ornamental centre-piece  in
the ceiling.  This contractedness of dimension also existed with the openings
for the admission of fresh air — warm and cold, when any such happened  tn
be provided.
  It is not uncommon under more improved methods to see the orifice of the
warm air-flue (when the air does not enter  in many places or in diffusion),
from two  to three  feet square, and the underground  passage  for fresh air
sufficiently large to allow a man to pass nearly upright to examine and re-
move any impurity, such as  leakage of sewers, rats, cats, and the like, which
might contaminate the air.
  The discharge-flues are also made larger or more numerous.  The principle
now seems to be, that as all flues are so readily commanded and  diminished
by a simple flap or valve register hung on a central point, or by hinges  at the
edges, and turned by a handle passing through the wall, it is better to con-
struct them of the fullest possible size.   If originally made in brick walls  or
under ground of too limited dimensions, it becomes exceedingly difficult  to
enlarge them.  In designing a plan for the Butler Hospital for the Insane,—
one of a class of institutions requiring the greatest amount of ventilation,— it
was calculated that the flues would fill the whole central walls, wherein they
could be carried perpendicularly or nearly so.
  In brick edifices the external wall may constitute flues for some purposes,
and their presence increases the dryness of  the interior without diminishing
the strength of the masonry.  In  public buildings, unless the exact size  is
beyond prospect of change, and the internal divisions are as certainly perma-
nent, and the system of heating and ventilation has been unchangeably de-
termined  upon,  no loss and probably great ultimate convenience would be
found in carrying  the flues  in every point where space will  permit.    If
needed they could be pierced and used as induction or discharge-flues ;  if not
called for, they would constitute a modification of the ordinary vaulting or
air-space left in many first class constructions.
  2. Want of directness of ascent.  When a motive power is intended, this
objection is of diminished  importance, but reference is now rather had to the 
114                      APPENDIX  A.
-pontaneous  movement  induced by  mere diminished  gravitation.   So in
passages where very highly-heated air is admitted or discharged, the great
rarefaction may overcome this obstacle to a greater or less degree.  In the
mere power derived from the animal heat or common warming of apartments,
a change of direction only a few degrees from the perpendicular seems to
produce a series of eddies against the upper side of the pipe, which impedes
the ascent.
  If a flue has more or  less oblique angles,  as occasionally is necessary to
clear doors or other openings in the wall, the same eddy acting like a posi-
tive impediment occurs.  The higher up and  less frequently repeated, the
less will be its injury.
  If the flue turn  at right angles  or pass horizontally, or with  a second
upward run, the draught will be proportionally impeded as the angles are more
frequent and the horizontal portions longer.  In most cases a bend twice at
right angles, at ordinary temperatures, without enlargement of the horizontal
section, and without exhaustive power, is nearly as fatal to  the discharge as
an actual closing of the flue.
  3. The flues are not of a figure  and finish calculated to favor the upward
ascent of a fluid like air.  A tube with oblong  area, or even a square made
with rough bricks, and without pargeting or interior plastering, gives rise to so
much friction, that its actual performance falls far short of its theoretical
power.
  The most effective shape is the circular cylinder, next the ellipitical, then
the square with bevelled corners, and  so on, down to  the narrow  parallelo-
gram.  Air in its ascent is disposed  in obedience to obstacles which affect it,
to take a spiral motion.  The more  regular and smooth  its tube the less
broken will be the spiral motion;  the  friction will be less, and of course the
discharge the more increased.   The  effect of rough surfaces or of air com-
pressed into the angles of the flue, is  not only to retard its speed and quan-
tity directly, but, what  is an important loss when feeble ascensive  power
exists, by this delay to give time for the current to cool, which also acts still
more disadvantageously by increasing the gravity.
  In forming air-flues of metal, they are naturally made round.  A little in-
creased pains and cost more than repaid in augmented efficiency, would  also
furnish them in wood or brick-work of the best form and surface.
  4. Flues are made in exterior walls, and the air which is intended to be dis-
charged in consequence of its  elevated temperature and diminished gravity
is so cooled down by exposure to the exterior cold, as to cease  to ascend; or
even a reversed action may occur in certain conditions of the weather.  The
absurdity of this arrangement of  small square flues in outer walls, was strik-
ingly exemplified in the ventilation of the sleeping rooms of the South Boston
Lunatic Hospital.   As has been before observed, if an active motive power is
employed, the objection to foul-air flues in outer walls becomes of little or no
consequence.
  5. Foul-air flues, in the spoyitaneous mode (i. e. with  no  power to produce
motion), opening directly into the open  air, are not  to be depended upon for an
upward action.  The usual  custom resulting from this difficulty, is to have
them terminate in the attic or garret, from which the communication to the
open air is made through some form of cowl, Chinese cap, or louvre. 
APPENDIX   A.
115
  A simple valvular arrangement to prevent regurgitations in sudden shifts
of the wind, or  when if turncaps are used they are  caught " on the cen-
tre " so as to face windward, is often introduced with great  advantage.  A
mode long used in the McLean Asylum is found free from objection.  Just
below the escape opening in the ridge of the roof, a broad platform a few feet
long is laid so as to cut off four or five feet of the apex.  At each end this
is  boarded up, leaving an oblong  space about four feet  by two.  Wires are
placed horizontally and vertically across this space, making squares of eight
or ten inches, to sustain the valve.   The valve consists of common cotton
cloth, suspended by tacks from its upper edge, while the lower or free edge is
stiffened by a thin strip of wood.   It is placed within the wires.  The ordinary
upward movement keeps this thin  curtain raised before it, scarcely imped
ing the current.   Any retrograde action at once closes  the flap  against the
wire, and prevents any backward flow.
  When the roof is slated,  and indeed, though less  urgently, in other cases,
the attic should be plastered to prevent the sudden cooling down of its air to
a point below that in the house, when, of course, the air descends.
  6. Any flues depending wholly upon the action of cowls or turn-caps in any
of their numerous forms, are totally  unequal  to the demands of a constant, re-
liable ventilation.  Many of these are re-invented every few years, and there is
not perhaps a single form of them which may not find its prototype, or exact
example, in the patent repertories and philosophical transactions. The reader
who has the slightest faith in these machines  will find a great number of
sketches of them in Peclet's complete treatise, in Dr. Wyman's work, and  his
Report to the American Academy of Arts, &c, or in the curious researches of
Ewbank. This latter practical mechanic demonstrated by actual experiment,
as respects the revolving varieties, so far as trials by models are demonstration,
that of all the known forms, the most effective was the simple bent  funnel a
little swelled at its mouth with a vane.  If it has a curved line at the  back, it
must also least impede the  natural  ascent of air, when no current exists, —
a serious objection to all the  others, that of diminishing the  upward move-
ment  in calms by at least one right  angle, and usually by the friction of the
interior.
  The simple fact in regard to those auxiliaries is, that  during  certain con-
stantly recurring and occasionally lengthened periods of entire stillness, when
ventilation is most imperious, they are wholly useless.  Employed with some
other reliable motive power, the plenum and  vacuum cowls, that is, one facing
to the current and throwing the air into the underground flue or other sup-
ply channel — the other drawing off the air  from the ceiling, are aid's which
may be collaterally employed at times quite economically, but are never to
be trusted to alone.
  Mr. Sylvester  the ablest and most practised ventilating engineer of Eng-
land, generally adds a simple form of these at each end of his ventilating cur-
rent.   The New York Public schools have one of each kind ;  pure air being
admitted diffusedly as it enters.
  7. Flues opening for the egress of vitiated air at any point near the floor.
This  method  of constructing escape-flues,  in  the expectation that when
the apartment is crowded full of warm air the lower stratum will be forced 
116
APPENDIX  B.
outward and into them, has often been tried and  always results in failure.
In the earlier attempts at ventilating the McLean Asylum, this arrangement
was well tested.  The hot air was admitted near the ceiling, but no intensity
of heat would drive it into the  rooms to the extent of forcing out the lower,
and of course if this action were maintained, vitiated stratum.   Our text ex-
hibits the occasional  expediency and practicability, especially for the lower
classes of insane patients, of opening exit flues  at the floor, thence carrying
them upwards to the main flue  connected with the  motive power, or directly
down into a common flue passing into the shaft in the cellar.
  7,  Discharge flues fail from  the absence  or insufficiency of the  means
of supply of fresh  air below.  For example, the lately built hospitals  for the
insane usually have no other means of ventilation, than upward  flues  in the
wall.   All the air admitted into  the halls and rooms in the season when
fires are used, is that from the registers of one or two furnaces to  supply
twenty to forty rooms.  In that period often of considerable duration of too
high external heat for artificial warming, while it is  yet too low and damp for
open windows, the same channel and the cracks and openings of doors, con-
stitute all the places of admission of fresh air !  It is singular that the first
principle of pneumatics should have been  thus often violated.  To  expect
vitiated air to depart when no fresh air can take its place, or, on the contrary,
that pure air should enter when the escape is not free and of adequate dimen-
sions, is alike absurd.
  When a high chimney or lengthened flue  in a lofty building may be relied
upon, the constant current may often be produced  spontaneously through a
small room, by opening a channel from its floor to the cellar. A series of very
offensive water closets were rendered quite tolerable by this arrangement.  A
separate flue to each passed from the floor to the cellar, and another from the
ceiling to the attic. The walls having originally been filled with  flues, as re-
commended above, this arrangement was made many years after the erection
of the buildings,  by piercing and stopping them, as  the case required.
                                B.

  The extent of apparatus required in warming by steam and hot water, has
been the subject of experiment, and experience of many years in practice, in
fact since 1745; the results of which are given by various scientific writers, —
Buchanan, Tredgold, Scott Russell,  Arnott, Hood, Bernan, &c.  Their ex-
perience is confined to the climate of Great Britain, and they differ consider-
ably from each other. Yet keeping an eye to the occasional extremely intense
cold of  New England winters, the approximation may have some value as a
basis for any practical undertakings here.

                         I.   Of Steam Heating.
  The following items of the more useful kind, taken from the table of  Mr.
Bernan, deduced by him from Buchanan  and others, exhibit  the practical
effect of a given surface of steam pipe or other form of enclosing surface, in 
APPENDIX  B.
117
maintaining certain areas of interior at a raised temperature, when the exter-
nal air was below the freezing point of water.
   A square foot of steam-warmed surface kept —
       400 cubic feet of space of a chapel,  (cast iron pipes,) at 60°.
       370  "   "  meeting house,             "              "
       180  "   "  dining  room,               "           " 64°.
       209  "   ••  dining room, containing 8,400 cubic ft. 15
                      feet high,                           " 62°.
       306  "   •*  public room, (cast iron pipe,)           " 54°.
       175  "   "  6 cotton mills each containing on an aver-
                      age 205,000 cub. ft. of space (c. i. pipe) " 80°.
       256  '    "  counting house, lighted from ceiling,     " 61°.
       243  "   "  average of three do. lighted from side,   " 64°.
       140  "   "  average of  seven rooms in a public build-
                      ing heated by an ornamental cast iron
                      vase in ea. | in. thick ; greatest effect, " 50°.
                    one of  the rooms fitted with double win-
                      dows could be kept at                " 640,
      266^  "   "  printing office; 4 floors, average,        " 68°.
  For  uses requiring a much higher temperature, as for forcing in green-
houses, drying rooms, the quantity of surface is, of course, much augmented;
for example, in a forcing house, 30 cubic feet  of space were kept at 80°, by
each foot of steam surface;  in drying houses requiring from 90° to 100°, that
amount of radiating surface  supplied from 40 to 80 cubic feet.  As these pur-
poses are not within  the scope of the present inquiry, it is not necessary to
pursue them.
  The application  of these elements is obvious.  For example, if  it be required
to ascertain the amount of iron surface for  a factory containing 100,000 feet
of space, divide this quantity by 175 : the quotient 574.2  will be the number
of feet of steam surface which will  secure a temperature  of 80°, while the
external air is below 32°.  Or if  of a dining room of 5,000 feet space, this di-
vided by 140 will give 35.7 square feet of steam surface to maintain a summer
heat. Mr. Bernan remarks that these though  rough, are safe practical esti-
mates, which may be applied and depended upon in numerous analogous
cases.
  Mr. Tredgold's formula for determining  the extent of steam pipe, is this:
If, for  example, 200 cubic feet of air is to be  supplied per minute, to a room
to be kept at 60°,  (external air at 32°,) he considers the average surface heat
of the steam pipe as 200° —not 212°, the steam point. Then, if  the difference
between the required  temperature and the external air be multiplied  by the
number of cubic feet of air required per minute,  and the  product be divided
by 2.1 times the difference between 200 and the temperature of the room, the
quotient will be the number  of square feet  of surface required.   Thus (60 —
32) X 200 = 5600 -=-2.1 (200 — 60°) = 19  square feet of iron  pipe or other
surface of metal.
  The first of these methods omits any consideration of the heat removed by
ventilating processes. Mr. Tredgold's omits any reference to the space to be
heated. Dr. Arnott takes into view the heat lost by glass windows, by crevices
                     16 
118
APPENDIX  K.
and by openings for change of air.  He estimates that in the winter day, thf
thermometer at 10° below 32°, to maintain a temperature of 60°, there must
be of surface in contact with steam, (which surface in actual average practice
he also considers  as at 200°), one foot square for every 6 feet of common
window glass ; as much more for every 120 feet of wall and ceiling of ordina-
ry materials, and the same for every 6 cubic feet of hot air escaping per minute
as ventilation, and replaced by fresh air.  A window of usual tightness allows
8 feet of air  to pass per minute, and there  should be allowed at least 3 feet of
air a minute, for each person in  the room.  Thus,  suppose  a room  16 feet
square by 12 feet high with two windows, each 7 feet by 3, and with ventila-
tion by them or otherwise, at the rate of 16 cubic feet per minute.
  42 sq. feet of glass requires 1 foot of steam surface for every 6 ft.=7  feet,
  1238 feet wall, ceiling, &c.    "      "      "       "    120  ft.=10J feet,
  16 feet per minute,            "      "      "       "      6 ft.=2§ feet,

                                                                20  feet,
that is,  20 feet of pipe 4 inches in diameter, or other equivalent of metallic
vessel.
  Let us apply the elements  of  Dr.  Arnott to a  common  Massachusetts
school-house for 100 pupils.  The common dimensions of such a school-room
would be, say 40 feet long, 22 feet wide, and 12 feet high, containing of super-
ficial square feet of surface, 40 x  22 x 12  =
                         3248 f. at 120 ft. for 1 ft. of steam surface, is 27 ft.
        Windows, 7 X 3 X 6 = 84 f. at 6 ft.    "     "   "       "    14"
Ventilation 100 persons x 3 f. = 300 f. at 6 ft.    "     "    "       "    50"

                                                                   91 ft.
Or ninety-one feet running  of 4 inch pipe, a length which would be a little
short of passing around at the angle of the floor on three sides of the room.
If larger or  smaller pipe  or  if enclosing vessels of other shapes be used, the
running length or area will be readily calculated.
  The size of the boilers will be fixed by the capacity of  the pipes. As much
space for steam should be left in the boiler, as is equal to all the steam in the
pipes.   The  space for the water should be somewhat,  say one  eighth less.
In the illustration just cited, to find the size of boilers :
    Circum. of pipe.                           in a gallon.
12 X  2 -*- 2 = 12 X 12 = 144 x 91 = 13,104 ~ 231 = 56 gallons for steam,
Less one-eighth, for water,       ...      44

Size of boiler,      .....     100 gallons.

                     II.  Of Heating by Hot Water.
   The cause of the circulation of hot  water  in tubes leaving  and returning
to a boiler  is undoubtedly  owing  to the  diminished  gravity  of the fluid
when rarefied by heat.  The moving power will depend,  therefore, on the dif-
ference of distance at which the upper or warm, and  lower or cooler pipes are
placed  from each other, the directness of  the  current and  the heat with-
drawn.   Mr. Hood says he has known as  small a difference as three  inches
where the pipe was very small, (two inches in diameter,) and free from turns
and angles.   He however regards a foot as rh« minimum height which will 
APPENDIX  U.
119
 obtain a good circulation, where the pipes  do not dip below  the horizontal
 level, as in passing doors.
   The pipes may be carried over  every story of a  house.   In this  case, the
 boiler must be closed, and made capable of  standing the great pressure repre-
 sented by the widest base at the boiler, and the highest line of the column —
 a pressure apt to occasion leakage, unless the mechanism of the joints is ex-
 tremely perfect.
   In case the pipes are carried horizontally in flues, or convoluted in air cham-
 bers, where no  point of  the circulation is higher than the level of the boiler,
 no considerable strength of boiler or of joinings is required.   It is not un-
 usual, under these circumstances, to allow  the  boiler to be covered only with
 a loose cover, the evaporation from it passing directly into the air flues.
   It is by no means necessary that  the pipe  connecting the radiating tubes
 with  the boiler, should be of full size.  Mr. Hood prefers in using four-inch
 pipes of cast  iron (which is his favorite size), that the connections should be
 only  two inches in diameter.
   Masses of pipes may be thrown into air-chambers, located at points in the
 cellar determined by the position of  the apartments above to be warmed.  In
 such  cases, the  difficulty of distributing hot air horizontally in channels, is
 provided for, and the great advantage of a direct perpendicular supply-flue is
 secured.   The connections between  these receptacles of pipes,  each of which
 has its fresh-air channel, may be kept up with the boiler and with each other
 by much smaller pipes, wound with cloth, or other non-conducting material.
   It is common to make  the difference of level of the pipes several feet.  The
 height of the  basement  or cellar, and  the form of vertical boilers, with tubu-
 lar flues, much used of late for this purpose, allow as much variation as the
 case requires, where no attempt  is made to send pipes above.
   The quantity of heat removed in the air-chambers or channels containing
 the pipes, by conduction, is four-fifths of the whole.   The remaining one-fifth,
 distributed to  the walls  of  the  containing cavity by radiation, is not wholly
 lost, since it is again given out to the air when the temperature is lowered.
   Where there are various series  of pipes leaving the boiler, a regulating cock,
 or the simple and much  superior valve used for such purposes of late, should
 be added, to regulate the flow as circumstances may require.  As the current
 depends not only on the difference of level, freedom from turns and angles,
horizontal  or vertical, but also on the rapidity of reduction  of temperature,
 some  care  is required to  regulate the various distributing  coils or aggrega-
tions, by shutting off a portion of  the flow to  those where an undue propor-
 tion of heat is received.
   It is obvious,  that the impinging  of a full current of  extremely cold air
upon one series, would reduce the temperature, and consequently the gravity
and the activity of motion, much beyond the  rate common under other cir-
cumstances.
  In using the  mild hot water apparatus, or  that  in which  the circulating
fluid does not rise above  212°, so termed in  contradistinction to the  method
invented by Mr. Perkins  in which water may even be heated to a degree suf-
ficient to inflame wood  in  small strong pipes,  the quantity of pipe used is
about the same as that employed with  steam, and of  course  the methods of
calculation just given may be applied.   Mr.  Hood, the latest and best writer 
120
APPENDIX   B.
on this subject, gives  the  following rule as  more accurate than any means
hitherto found for calculating the radiating surface of simple hot water tubes.
"Multiply 125 by the difference between the temperature to be produced in
the room and that of the external air ; divide this product by the difference
between the temperature of the pipes and that of the room ; then multiply
the quotient by the number of cubic feet of air to be warmed per minute ; this
product divided by 222, will give the number of feet in length of pipe 4 inches
in diameter.  If 200 cubic  feet of air is  to be warmed in  a minute,  and the
external air is at 32°, the room at 60°, and pipe at 200°, then 125  X 28 -h 140
X 200 -f- 222 = 225 feet of 4 inch pipe required.   This multiplied by 1.38 will
give the length of 3 inch pipe ; by 2 of 2 inch pipe, or four times the length
of one inch pipe."
  The table following gives by inspection, the amount of radiating  surface to
produce a given result.
Table showing the  quantity of pipe, four inches in diameter, which will heat
  1,000 cubic feet of air per minute, any required number of degrees;  the tem-
  perature of the pipe being 200° Fahrenheit*
Temp. of ext. air.	Temperature required for the Room.									
	45°	50°	55°	60°	65°	70°	75°	80°	85°	90°
10°	12b	150	174	200	229	259	292	328	367"	409
12°	119	142	166	192	220	251	283	318	357	399
14°	112	135	159	184	212	242	274	309	347	388
16°	105	127	151	176	214	233	265	300	337	378
18°	98	120	143	168	195	225	256	290	328	368 1
20°	91	112	135	160	187	216	247	281	318	358
22°	83	105	128	152	179	207	238	271	308	347
24°	76	97	120	144	170	199	229	262	298	337
26°	69	90	112	136	162	190	220	253	288	327
28°	61	82	104	128	154	181	211	243	279	317
30°	54	75	97	120	145	173	202	234	269	307
Freezing 32°	47	67	89	112	137	164	193	225	259	296
34°	40	60	81	104	129	155	184	215	249	286
36°	32	52	73	96	120	147	175	206	239	276
38°	25	45	66	88	112	138	166	196	230	266
40°	18	37	58	80	104	129	157	187	220	255
42°	10	30	50	72	95	121	148	178	210	245
44°	3	22	42	64	87	112	139	168	200	235
46°		15	34	56	79	103	130	159	190	225
48°		7 i 27		48	70	95	121	150	181	214
50°		i 19		40	62	86	112	140	171	204
52°		1 11		32	54	77	103	131	161	194
   Find  the  external temperature  in  the first column,  and  the required
temperature of the room  at  top ; the  number at the intersection of these
columns will represent the number of feet of four inch pipe.
  The principle which fixes the size  of  boilers in the hot water apparatus has
no analogy to that in steam boilers.  The size of boilers is based upon the
(quantity of fire surface which may be thought necessary to keep  the  water
heated; — the greater this surface in reference to the capacity of the pipes
and the less the quantity of water, the sooner it is heated.  Of course the
* Hood on Warming Buildings, page 97 
APPENDIX  15.
121
boilers are best, made of a shape in which the under side is concave or rever-
beratory, and the top and bottom  distant only a few inches from each other.
The nature of the fuel will influence the extent of boilers. Mr. Hood says, that
one square foot of boiler surface exposed to the direct  action of the fire, will
be sufficient to supply the necessary heat to forty superficial feet of pipe, or
other radiating surface.  This, he observes, is a very good proportion, suita-
ble for nearly every purpose.  This is a considerable reduction from the max-
imum, which is about 50 feet of pipe to the foot.  This however makes an
apparatus much easier managed, and more  effective and  certain than where
only the extreme is calculated upon.  He gives  the  following table as de-
duced from the allowance  of one foot of direct boiler surface to 50 feet of
radiating surface.
                          Feet 4 in. pipe.     Feet 3 in. pipe.     Feet 2 in. pipe.
    4 square feet,     .    .     200             266              400
    6                           300  .     .      400 ..     .  600
    8                           400             533    .    .    800
    10    "     "     .    .     .   500  .     .    .  666  .    .      1,000
    14    "            .    .     700    .    .    933            1,400
    20    "     "     .    .      1,000  .     .     1,333 .    .      2,000
   In modern practice,  the forms of boilers filled with small tubular flues, like
those of the locomotive engines, are much employed for steam and hot water
warming.
   While I have thus adduced the latest and most practical foreign authorities
as  to the quantity of steam-warmed, or hot-water-warmed metallic surface
adequate to produce a satisfactory temperature, under different circumstances,
I cannot conceal my conviction that the great element  of calculation is so es-
sentially changed in the climate of New  England, that our knowledge of  the
extent of  apparatus to heat  adequately private  or public  houses must be
reached in  an entirely different  method.   This element is the  prodigious
reduction  of temperature during our winters, not infrequently reaching an
extreme, for days, so much below the experience of Great Britain, as certainly
to render nugatory any calculations based on the results of experience in that
eountry.  It must not be forgotten, that  any provision for heating must be
capable of meeting these extraordinary cold seasons.   However well all aver-
age conditions might be fulfilled, no apparatus not fitted for the ultimatum
of New England winter cold could be tolerated, except provision were made
in other forms of heating,  to aid in the extreme emergencies.
   In advising the extent of apparatus of these kinds, I have been disposed to
throw aside the experience of other climates, and proceed tentatively until an
experience, precise and definite, of our own shall  be attained.   It is easy to
contrive arrangements by which  pipe, whether for steam  or hot water, shall
be added successively in the air-chambers, until the exact point  is reached.
The furnaces for anthracite, especially, and for any fuel, can be made so as to
admit of a  very  considerable increase of the usual amount  of consumption,
 both by increasing the draught and by enlarging the grate.
   If  the heating is by steam, a second boiler can be added, if the additional
quantity of pipe required  in the air chambers  cannot be supplied by the first.
   The only objection to these  successive additions is, provided the probability
or possibility of future additions is kept in view from the first, the difficulty of 
122
APPENDIX  B.
making estimates or contracts for the proposed heating.  As, however, the most
common uses on a large scale will for some time, at least  in  this country,
be for hospitals and institutions, where, if well  done, the question  of cost is
quite secondary to  that of hygienic perfection, the method of providing by
contract will not be likely to be selected, until a  greater amount of experience
is aggregated, it is not much to be regretted that we must reach our end in
this way, by trials.
  In our climate, I should prefer to form a judgment of the quantity of ap-
paratus, by a comparison drawn from the amount of fuel used in the common
way, rather  than from the  best data now accessible.  The same quantity of
fuel containing (if its  combustion is equally perfect), as much  caloric when
used through one medium as in another, it would not be difficult to  adapt the
fire surface to meet the estimated quantity of fuel to produce a certain result,
if consumed directly.
  For example, if a hospital was known to use a given quantity of anthracite
or bituminous coal  or wood per annum in hot  air furnaces,  it would be safe
to have the  boiler or heater grates made on a scale to consume the like quan-
tity.  This  estimate would  be controlled by any influencing circumstances,
such as a more extensive waste in ventilation, a less escape  at  the  point of
combustion, &c, which might seem to demand a greater or less quantity of
warming material.  It is  of course not pretended  that the methods recom-
mended of steam or hot  water warming, are the most economical.   It is the
quality, rather than the quantity of the heat which  constitutes their supe-
riority.  Still, however, there can be, from the nature of things, no waste in
fuel, circumstances of waste being the same.
  It fortunately is true in practice, that the size of the hot  air chambers in
which the radiating surfaces are enclosed, is quite an immaterial considera-
tion.  It maybe made sufficiently large to admit twice or three times as much
tube as may at first  be thought adequate, without any loss of advantage, in
case increased quantities are added.
  In practice, the shape in which the radiating surface is arranged is a matter
of considerable moment.  Pipes are much more  conveniently connected than
plates or more solid forms, and those of 3 and 4 inches are more,convenient
than larger sizes, so that it is preferred to use a double small pipe, (which also
allows one set to be disconnected by cocks), rather than a larger single one.
  Of late years, welded iron tube of §  to  2 inches is much  used for steam
and hot-water warming, as well as for many purposes for which lead pipe was
formerly used.   It is  much cheaper than lead, for pumps, aqueducts, &c,
where any considerable amount of pressure is to be provided  for, and has as
regards  the  conveyance of water for household  uses the decisive advantage
of involving no unpleasant or injurious consequences to those using it.  The
frequent poisonings  from  water conveyed in lead pipes, although doubtless to
be explained chemically as ascribable to peculiar circumstances not  touching
all waters, cast a distrust  and a sickening suspicion over its employment, en-
tirely forbidding its adoption while this better method is at hand. The join-
ings are by screws, a jacket with a female screw  uniting two  lengths, a little
white and red lead in oil being used. These pipes cost from 12 to 15 cents per
foot for inch diameter.  The cost of large cast iron pipes  of  3, 4, or 6 inches
diameter, will be  found per foot of outside or radiating surface, to be considers- 
APPENDIX  B.
123
bly less.   The pipes cast  for heavy heads of water can often be obtained, in
consequence  of their thinness, for their value as raw  material.   As  the
pressure  of  steam or hot-water  heating is  never more than  one or  two
atmospheres, these fully meet every requisite.
  Steam  and hot-water pipes are  connected  in  the same  way.  This is don?
by flanges brought together by  screws, with  some suitable  substance, a a
pasteboard, rope-yarn, or felt, covered with white or red lead in oil.  This is a
usual joint for steam under great pressure.   The  socket joint in which  the
end of one tube is enlarged for a length  about equal to its diameter, and the
next one inserted therein  and the intervening  space filled up with iron-ce-
ment is a much neater and equally strong process.  After the iron cement is
thoroughly dried, it becomes as strong as the iron itself.
  The iron-cement for these junctions, as well as other purposes in steam  and
hot-water apparatus, is compounded in various ways — the main  ingredients
being sal ammoniac, iron filings or turnings, and sulphur.
  Mr. Buchanan's recipe consists  of 40 parts by weight of iron borings,  to 1
part of sal ammoniac, and half a part of sulphur, well beaten together.  As
much sulphur renders the  composition brittle, a smaller proportion is advisa-
ble, when no  haste is required to admit the steam.
  Mr. Peckstone  gives the following directions.   Take 1 lb.  of iron borings,
pound in an iron  mortar until they will  pass  through a fine sieve ; mix  two
ounces of powdered sal ammoniac, and one ounce of flowers of sulphur.  Mix
by rubbing in a mortar, and add water to a  proper consistency, to be set up
with a blunt caulking iron into  the space between the pieces.
  The French prescription for this important material, as given by Peclet,
is  one hundred parts iron turnings, two of sal  ammoniac, one of flower3 of
sulphur, and  half a part of sulphuret of antimony, to be mixed with urine
enough to cover it.  It will not attain its hardness for some days.
  A packing  of hempen rope smeared with a mixture of red and white lead in
oil, and driven in with a caulking iron, also  makes a secure and permanent
joining for steam and hot water tubes.
  In arranging pipes for heating  by steam or hot water, it must not be over-
looked to make an allowance for expansion of J  of an inch for every ten  feet
of pipe.  A drip pipe to carry off  the condensed steam is  also necessary, un-
less the tubes are so raised at their farther extremity as to allow this to  run
back to the boiler.
  Nor in  hot-water pipes  must be overlooked the  tendency which air has to
become impacted  at some point of the circulation and thus prevent the whole
current.   It  is safe on this account to  have every elevated point, and every
alteration of  level of the pipe fitted with an air pipe rising as high as the
level in the boiler, and provided with valves or cocks to permit the tubes to
be freed from this embarrassing obstruction.
   There  are practical difficulties in carrying  hot-water pipes to several
stories in height,  arising from the pressure of long columns of water strain-
ing the joinings  and endangering leakage, which, in most cases, renders
it usually more advisable to place the pipes in ranges in  an air chamber in
the cellar below  to  which the  air is admitted by a flue from without,  and
drawn out in upright flues.  The air chambers may be elongated in order
to carry the air horizontally to any distance, or made at convenient points as
respects delivery above, and the connection with the boiler kept up by simple 
124
APPENDIX  B.
 smaller pipes, protected  from waste  of heat by  non-conducting coverings
 In the new Penitentiaries at Wakefield, the upright flues withdraw hot air
 successively for some hundreds of feet.  The only loss is from the conduc-
 tion of the sides of the air flue, in which the hot-water pipes are suspended.
   In the warming of the Massachusetts General  Hospital, the water pipes
 are made of thin  copper  tube, about one thousand feet in length for each
 wing, and four inches in diameter, placed in air chambers.
   I have been induced to go somewhat minutely into the detail of the methods
 of heating by steam and hot water, from several considerations.  I know of
 no American work or reprint which contains any information on the subject.
 This mode of heating for  health and  luxury is  vastly superior to  any other,
 whether in public  or private buildings, occupied by persons for any length of
 time.   The fire-proof character it gives to buildings is important, and in pub-
 lic buildings for libraries, the fine arts, and the like, can scarcely be over-
 estimated.  The methods are  simple, and  were  the mechanical fittings as
 well understood with us as they are in Europe and ere long will be here, a
 true economy would permit  a very wide  use of this elegant,  convenient, and
 healthful addition to the comforts of civilized and refined life.  So far as
 consumption of fuel is concerned, it is obvious that there  can  be no loss as
 compared with other modes, beyond the trifling expenditure of radiated heat
 at  points, as the cellar, where  it is not available.  By the use  of non-
 conductors around the steam and water boilers and pipes, this is reduced to
 a trifle.  The waste  of fuel  by the chimney is better  prevented than in most
 furnaces ; and that  serious  drawback upon  all modifications of hot-air fur-
 naces, calorifers, or stoves furnished with fresh air from the outside, or even
 open grates and fire places — the escape of occasional or constant quantities
 of smoke, gases, and impalpable powders — is unknown.
  The mechanical knowledge of steam power, of cast iron  and other branches
 of  metals, has become  so general in this Commonwealth, that but little
 difficulty can be experienced in appropriating the delightful and hygienic
 advantages of the unequalled atmosphere thus produced, if a directing mind
 can be found to assume the responsibility and oversight of the needful fittings.
 Feeling much hope that this healthful mode of warming  school-houses and
 other inhabited buildings by  pure air warmed by contact  with  hot-water
 and steam tubes,  may  become general, as the facility  and cheapness  of
 providing  the necessary apparatus are augmented — as they cannot but be
 with the advance of the community in the mechanical arts—another circum-
 stance of  detail may be of importance, especially to those  who may have
 apprehensions of the safety of such measures under all circumstances, which
 persons of no practical acquaintance with the management of steam and
 heated water may  naturally  enough be  presumed to feel. A closed  boiler,
 although intended to be subjected to no strain or to the most moderate pres-
 sure only, may by carelessness or accident be subjected to a much greater or
 a dangerous force.  The safety-valve, that simple and efficacious protection,
may from  neglect cease to act, or it  may be secured by  ignorance or mis-
chief,  so as to be  a protection no longer.   Again, the supply of water, so
essential to safety,  may be omitted.
 With the possibility of a contingency like this occurring,  few persons would
feel safe in trusting a boiler large enough to warm  a common school-housp, 
APPENDIX  B.
125
tor instance, in the inexperienced hands which alone can be expected to
manage such an apparatus in such a position.
  It may be satisfactory to any  who might, with this source of anxiety-
removed, be willing to introduce this beautiful method, to be assured that
there is an additional mode of guarantying the safety of boilers from explo-
sion, exceedingly cheap and simple;  which we  have the high authority of
the most eminent writer on  this class of subjects, Mr. Peclet, for saying, of-
fers a complete efficacy against dangerous pressure.
  This consists in the application of a plate of fusible metal to a hole in the
upper part of the boiler, to which the steam has  direct access.  As the pres-
sure of the steam  increases, its heat augments in a  certain well known
proportion.  The readiness with which the metal melts depends on the pro-
portion of the ingredients, lead, tin, and bismuth, of which the  plate is
composed. A plate prepared so as to fuse at  a  point considerably below
the proved strength of the boiler, would promptly become melted, giving
free escape to the steam and preventing all hazard.
  A royal ordinance in France prescribes the various points to be regarded
in these safety plates,  two of which must be  placed to  fuse at different
temperatures on every steam boiler.
  The plates should be of the same size as the area of the  safety valve,  and
as they are liable to be swelled out at a lower point than that of fusion,  and
might be ruptured, they are  covered on the outside by a perforated plate of
iron, which of course gives no obstruction to the issue of steam, when the
fusible metal has yielded to its expected heat.  The arrangement is this : —
A hole as large as the area covered by the safety valve, is bored into the top
of the boiler; the fusible plate, one half to one inch thick, is placed over it with
the usual cement to make a tight joint; the perforated iron plate or grating,
is placed above and screwed at its outer edge  to the boiler, thus confining
the plate.
  The  following table gives the proportion of the metals  to  be alloyed
together to resist the heat produced by steam  at various pressures, of from
one to eight atmospheres, or from fifteen to one hundred and twenty pounds
to the inch.  The last pressure is  of course as  much as  will ordinarily be
employed as a maximum in steam boilers.
Number of	Corresponding	Actual	Proportions of the fusible		
Atmospheres,	temperature	temperature	alloy in parts.		
each 15 lbs. to sq. inch.	of the Steam. 100.	at which the alloy melts.			
			Bismuth	Lead.	Tin.
1		100.	8	5	3—
1*	112.2	113.3	8	8	•1
2	121.4	123.3	8	8	8
24	128.8	130.	8	10	8
3	135.1	132.4	8 12		8
H	140.6	143.3	8 16		14
4	145.4	145.4	8 | 16		12
5	153.8	153.8	8	22	24
6	160.2	160.2	8	■12	36
i	166.5	160.5	8	32	28
8	172.	172.	8	30	24
17 
126
APPENDIX  C.
  The temperatures are here given by the Centigrade  standard, the propor-
tions of which to Fahrenheit's, are as one hundred  to one  hundred  and
eighty, or as five to nine.
  As a means of saving calculation, the following table of the contents of
tubes of various diameters is given.

        Diameter of pipe.             Contents of 100 running feet.
            Inches.                            Gallons.
               h................................84
               1...............................  3.39
              li...............................  7.64
               2............................... 13.58
              2i............................... 21.22
               3............................... 30.56
               4............................... 54.33
               5............................... 84.90
               6...............................122.26

  The question whether large cast iron or small welded tubes should be used
for steam or hot-water circulation,  is readily determined  by the relative
economy of providing a given amount of radiating surface in each.
  Where a steam pipe  over four inches in diameter is used, it is said,  that
the difference of temperature  in the upper and  under portions, and, the
consequent  irregularity in  expansion, gradually produces an upward curv-
ature endangering the soundness of the joints.
  In all steam or hot-water pipes, provision for the expansion and contrac-
tion is readily made.  If the pipe is  of large diameter it is  suspended by
chains or on rollers.  If small, slipping joints with a screw  collar, like the
ordinary stuffing joints, are used.   Or a bend in the pipe  at one or more
places, like  the letter U,  enables  the  two  upper  portions to  be  closed
together or drawn asunder without disturbing  the connections of the tubes.
                                  ('.

  The plan recently proposed, and now in process of completion, for the heat-
ing and ventilation of the male side of the McLean Asylum for the insane at
Somerville, Mass., is predicated on the experience of the English examples, and
is arranged on Dr. Reid's general principles.  It is considered as worth de-
scription, from its having some distinguishing peculiarities in its arrangements.
  The building is in the form of a T, with the perpendicular line at an oblique
angle (see Fig. 18, PI. IV.)  The two portions having been built at different
periods, were unfortunately connected by the end of the earliest being insert-
ed into the new portion, making a  dark and unventilated interior, which  it
has been the object of recent designs to  remove.  The horizontal part  is
90 f. x 40, and the diverging or  old portion 80 f. x 40,  each of three stories,
and consisting of a gallery running the whole  length  with  the  day rooms, 
APPENDIX  ( .
127
 dormitories, water-closets, &c. opening  upon this  central corridor.  About
 ninety patients and twelve or fifteen assistants are accommodated in it, with
 the aid of some attic rooms and a separate lodge building.
   The heating in former years' has been accomplished with various forms of
 hot-air furnace, and the ventilation in the spontaneous method of late years,
 that is, by flues opening from the rooms and running up to the garret, whence
 the foul air escaped by chimney cowls turning to leeward.   The earlier at-
 tempts referred to in  a different part of this Appendix proving wholly nuga-
 tory, without a motive force which could not be readily devised, had  been
 converted as far as possible into the simple escape flue from  the  ceiling ;  in
 more pressing cases, as in water-closets and lodge-rooms, these were aided by
 induction flues, running from the floor directly down into  the  cellar.  It is
 hardly necessary to say, that under all the unfavorable circumstances of con-
 struction, size of flues, use of hot-air furnaces and absence of moving power
 to exhaust the foul air, the condition  of the building as respects an abundant
 supply of pure, gently  warmed air, was like that of all the other insane hos-
 pitals  of New England, which are all  furnished in the same manner, exceed-
 ingly imperfect and behind the age.
  Years of consideration have  elapsed without there appearing to  be anv
 way of overcoming the difficulties presented by the original omissions in the
 construction.   The lighting was imperfect, and the heavy brick walls forming
 the partitions and  resting in part on heavy groined arches below, could not
 be perforated with new flues of proper number and size.   The interior walls
 supporting the attic story of the center and the dome, forbad the idea of any
 upward ventilation with motive power, as it would require the power to be in
 four distinct sections under the roofs, which could not be connected without
 sacrificing a considerable number of rooms and passages necessary for the
 accommodation of the  patients and their due classification.
  Under  these complicated and embarrassing difficulties, the following ar-
 rangement was suggested, as that which would best meet the necessities of
 the case ; — that about fifty feet  of the centre of the front building should be
 eviscerated, and gallery walls be built  up continuously so as  to extend  the
 corridor at a uniform width from end to end, and in these by a proper thickness
 of walls to furnish  as many hot-air and foul-air flues as were required.
  A large space, which in consequence of  the peculiar twist and insertion of
 the wing,  could not be  lighted or otherwise made of value, and which was at
 the most central point  of the two sections, was devoted to the use of a ven-
 tilating shaft.  The ventilating shaft commences with a circular interior of
 about six  feet diameter, and gradually tapers  to about one half the bottom
 area.  The entire  height of the  shaft is over seventy-five feet.   The boiler
 for the hot water for heating  was placed near this, and the smoke  chim-
 ney  of cast iron pipe, runs up until within about  ten or  a dozen feet of
 the top, when the foul-air shaft begins to be contracted to  give impetus  to the
 current at its exit.   Here the smoke and gases of the chimney are to be de-
livered into the shaft.
  The pure air is admitted through a long under-ground flue of about twenty
 feet  area,  terminating in a short tower, which was originally used to supply
 the hot-air furnaces.   From the cellar, openings are made  every few feet
 to permit  the air  (the  current of which,  often troublesome when the  winds 
128
APPENDIX  C.
are strong, is checked by being admitted into the open space or reservoir, as
it were) to enter the  long  horizontal box or air channel divided into three
divisions,  each of which supplies a story of the house, and each has a couple
of hot-water pipes, of large size, connected with the perpendicular boiler by
small tubes.  These circulate the water the whole length of the cellar, under
the central corridor on the one side, and bring it back to a lower point in the
boiler on  the other, a distance of about  one hundred and twenty feet.  The
partition into three channels was considered indispensable to make an inde-
pendent heating and ventilation for each story, as it ever has been found
impossible so to regulate air flues  leaving the same chamber  and opening
at different  heights,  that  there shall be a reliable uniformity in different
stories.
  The pure air enters  all these channels in the  cellar at orifices  commanded
by lids or registers, and  each one of them delivers its  heated air through the
flues opening from its superior surface into the story for which it is designed,
uninfluenced by its neighbor.
  The warmed air is  delivered near the ceiling, at quite a number of orifices
in each corridor, and in those rooms where it was thought it would be required,
and in as free openings  as  the  space would allow.   The foul-air flues com-
mence near the floor of each room or gallery, and descend to the cellar floor in
the wall.  At a point  opposite the ventilating shaft, the joint flues are turned
by the shortest course so as to open beneath the foot of the shaft.
  One of these foul-air flues is to be turned beneath the heating boiler so as
to supply its air of combustion.
  A little  reflection will  show that the objects of this apparently complex, but
really perfectly simple arrangement  are,
  1.  To destroy the effects  of currents connected with the direction and force
of the wind,  by receiving the air into a reservoir.
  2.  To admit it in various  places to the hot-water tube, and discharge it in
each story at openings a few feet distant from each other, so as to produce a
general diffusion.
  3.  To make the heating and ventilation of each  story entirely independent
of each other from the point where the air enters to  its discharge.
  4.  To admit the heated air  at the ceiling, and draw it off at the floor, to
obviate the peculiar difficulties  in insane hospitals  from a reverse of this
movement.
  Precisely the same arrangement connected with the same ventilating shaft
and the same boiler, will be necessary for the projecting wing.
  Fig. 18 represents a plan  of the male side, but the heating and escape flues
are necessarily to avoid confusion, represented rather as a diagram, than
as an actual  plan.  Fig.  19 is a cross section at the point noted in the ground
plan by the  dotted line.  The warmed air is here  figured by the solid lines
and arrows entering the  tri-partite wooden channels, a a; after impinging on
the hot-water tubes running within, it passes in the corridor wall, and is deliv-
ered at the ceiling  ; — the foul air, represented  by the dotted line, descends at
the floor, passes down in the wall, crosses into  the drain at the bottom of the
cellar, passes along that until near the shaft  into which it  ascends.  The
ground plan represents the  course of the foul air from the rooms to the shaft.
  The great number of Warm and foul air flues, on each side of  the corridor, 
APPENDIX  C.
129
and each pair fulfilling the purpose just described, could not be represented
on  so small a scale.
  Dampers  are  inserted at such places as  are convenient to control the in-
gress and egress of the air.  It has been within the purview of this  adapta-
tion, to carry an additional hot-water circulation into such portions of the
wing, as from their occupation by cleanly and convalescent patients, do not
require to have all the heated air used, and which is wasted, if not so requir-
ed by passing off in unneeded ventilation.
  The escape steam from the steam pump used to elevate the water used, will
be turned into the centre of the shaft, to add to the motive power.
  Fig. 19, PI. iv. represents a section of the male wing at the point  denoted
by the dotted line b, of fig. 18; a a, are the  longitudinal hot-air chambers in
the basement, divided into three sections, one for each  story, and enclosing
the four inch cast iron water tubes; b, is the upright tubular boiler in which
the extremities of the tubes  enter at top and bottom, a difference of  level of
five or six feet; c is the exhausting shaft represented in plan at a, in Fig. 18 ;
d is the foul-air drain, opening beneath the shaft, represented in plan by c, of
fig. 18.  d and e, of fig. 18, indicate the position of the hot-air chambers and
water pipes, at the foot of the partition containing the ascending and de-
scending air flues.  For perspicuity, only a single pair  of induction and educ-
tion flues to each room are figured. It is obvious that in view of the several
stories, a horizontal section would show a great number of flues.  The dotted
lines show the course of the foul  air, the solid lines  that of fresh air, each
room of course having a flue of either kind.
  The actual arrangement of the channels in the cellar for the hot-air and foul-
air  flues to terminate in, is not represented as it actually is, in the plate, for
fear of obscuring the illustration of the principle.   Fig. 25, pi. iv. is a  cross  or
end section of the actual construction;  a a is  the partition wall separating
the corridor from the side dormitories, as it appears in the cellar; H H H are
the hot-air channels supplying the three stories respectively; v v v, the ven-
tilating flues coming from the stories.  The lower arrows show the course of
the foul air as it enters the channels terminating under the shaft.
  The upper arrows represent the fresh air entering from the reservoir im-
pinging against the hot-water tubes, and then ascending by the perpendicular
flues.
  The  registers slide before these openings, and are readily commanded
through shutters left at convenient places  in front.
  The same arrangement is provided on the other side of the corridor.
  The water-closets, bathing-rooms, &c, have the same downward ventilation
as the  galleries and dormitories.  The shaft terminates in one of four chim-
ney stacks, standing on the  corners of the foundation of the dome. 
130
APPENDIX  D.
                                 n.

             BIBLIOGRAPHY OF THE  LEADING AUTHORITIES.

  1.  A Treatise on the Economy of Fuel and Management of Heat, especially
as it relates  to Heating and Drying by means of Steam, &c.   By Robertson
Buchanan, Civil Engineer.                            Glasgow, 1815.

  2.  The Theory  and Practice of Warming and Ventilating Public Build-
ings, Dwelling Houses, and Conservatories, &c, See.  By a Civil Engineer.
                                                     London, 1825.
  3.  Reports of the  Select Committee on Ventilation of New Houses of
Parliament,  with the Minutes of Evidence, 1835, et seq.   [These contain the
elaborate and matured opinions of Dr. George Birkbeck* Mr. John Sylvester,
M. Faraday, F. R. S., W. T. Brande, F. R. S.,  Dr. D. B. Reid* Sir Robert
Smirke, and Charles Barry, Architects, Goldsworthy Gurney,  Esq., Dr. Ure,
Dr. Arnott, and others^]

  4.  A New Mode of Ventilating Hospitals, Ships, Prisons, &c. By George
Hawthorn, M. D.                                      Belfast, 1830.

  5.  Report  of the Committee of the House of Commons on Ventilation,
Warming, and the Transmission  of Sound. Abbreviated, with Notes.  By
W. S. Inman, Fellow of the Institute of British Architects.   London, 1836.

  6.  The Principles of Warming and Ventilating Public Buildings, Dwelling
Houses, Manufactories, Hospitals, Hot Houses, Conservatories; &c,  and of
constructing Fire-places, Boilers, Steam Apparatus, Grates, and Drying
Rooms; with Remarks on the Nature of Light and Heat, &c.  By Thomas
Tredgold,  Civil Engineer, &c.  Third Edition, to  which is  now added  an
Appendix, by T. Bramah, Civil Engineer; comprising Observations on Heating
by means of Hot Water,  with Description of various Apparatus in use.
                                                      London, 1836.
  7.  On Warming  and Ventilating, with Directions for making and using the
Thermometer Stove, or Self-regulating Fire, and other new Apparatus.  By
Neil  Arnott, M. D., F. R. S., &c.                        London, 1838.

  8.  A  Popular Treatise on the Warming and Ventilation of Buildings,
shewing the  Advantages  of the Improved System [Mr. Perkins's] of Heated
Water Circulation, &c, &c, &c.   By Charles James  Richardson, Fellow of
the Royal Institution of British Architects. 2nd Ed.    London, 1839.

  9.  Traite de la  Chaleur, consideree dans ses Applications, &c.  Par  E.
Peclet, 2 vols.                                          Paris, 1843.

  10. A Practical Treatise on Warming Buildings  by Hot Water, on Vcnti- 
APPENDIX  D.
131
lation  and the various  Methods of Distributing Artificial  Heat,  &c.   Bv
Charles Hood, F. R. S. &c.                            London, 1844.

  11. First Report of the Commissioners for Inquiring into the State of Large
Towns and Populous Districts, 2 vols.                   London, 1844.

  12. Illustrations  of  the Theory and Practice of  Ventilation.  By David
Boswell Reid, M. D., F. R. S. Ed. &c.                  London, 1844.

  13. On the History and Art of Warming and Ventilating Rooms  and
Buildings, &c. By Walter Bernan, Civil Engineer. 2 vols.  London, 1845.

  14. A Practical Treatise on Ventilation.  By Morrill Wyman.
                                                     Boston, 1846.
  15. Report of a Committee of the American Academy of Arts and Sciences
en Ventilators and Chimney-tops, pp. 20.             Cambridge, 1848.
 
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