,illustration       ,,lectures ,,on     
,,ventilation3    ,,being ,a ,,course   
,,delivered ,,in ,,the ,,franklin       
,,institute1 ,,of ,,philadelphia1       
,,during ,,the ,,winter ,,of #ahff-fg4  
,,by ,,lewis ,w4 ,,leeds1      ,special 
,agent of the ,quartermaster-,general1  
for the ,ventilation     of ,government 
,hospitals during the ,war2 and         
,consulting ,engineer     of            
,ventilation and ,heating for the ,u4   
,s4 ,treasury ,department4   ,man's own 
breath is his greatest enemy4     ,,new 
,,york3   ,,john ,,wiley  ,,son1        
,,publishers1   #b ,clinton ,hall1      
,astor ,place4   #ahfi4      ,entered   
according to ,act of ,congress1 in the  
year #ahfh1 by   ,,lewis ,w4 ,,leeds1   
,in the ,clerk's ,office of the         
,district ,court of the ,united         
,states for the ,southern ,district of  
,new ,york4     ,new ,york ,printing    
,company1   #ha1 #hc1 and #he ,centre   
,street1   ,new ,york4     ,,preface4   
,these ,lectures were not originally    

written with any view to their          
publication2 but as they were afterwards
 requested for publication in the       
,journal of the ,franklin ,institute1   
and there attracted very favorable      
notice1 ,i believed the rapidly         
increasing interest in the subject of   
ventilation would enable the publishers 
to sell a sufficient number to pay the  
expense of their publication2 and1 if   
so1 that this very spirit of inquiry    
which would lead to the perusal of even 
so small a work1 might be one step      
forward towards that much-needed more   
general education on this important     
subject4  ,it was not my desire to give 
an elaborate treatise on the subject of 
ventilation4 ,i believed a few general  
principles1 illustrated in a familiar   
way1 would be much more likely to be    
read2 and1 ,i hoped1 would act as       
seed-grain in commencing the growth of  
an inquiry which1 when once started in  
the right direction1 would soon discover
 the condition of the air we breathe to 

be of so much importance that the       
investigation would be eagerly pursued4 
,l4 ,w4 ,l4     ,,contents4   ,,lecture 
,i4      ,philadelphia a healthy        
city--,owing to the superior ventilation
     of its houses--,but the theory of  
ventilation still imperfectly           
understood--,about forty per cent4 of   
all deaths due to foul     air--,the    
death rate for #ahfe--;,expense of      
unnecessary sickness--,in               
,london--,in ,massachusetts--,in ,new   
,york--,in ,philadelphia--,consumption  
the result of breathing impure          
air--,entirely preventable--,infantile  
mortality--,report on warming and       
ventilating the ,capitol--,copies     of
 various tables therefrom--,carbonic    
acid taken as the     test1 but not     
infallible--,the uniform purity of the  
external     atmosphere--,illustrated by
 the city of ,manchester--,overflowed   
lands unhealthy--,air of ,paris1 ,london
 and other cities--,carbonic     acid in
 houses--,here we find the curse of foul

 air--,our own     breath is our        
greatest enemy--,scavengers more healthy
 than     factory operatives--,wonderful
 cures of consumption by placing     the
 patients in cow stables--,city         
buildings prevent ventilation1          
consequently are unhealthy--,the air    
from the filthiest street     more      
wholesome than close bed-room           
air--,unfortunate prejudice     against 
night air--,dr4 ,franklin's opinion of  
night air--,compared     with the       
instructions of the ,board of ,health1  
#ahff--,sleeping with     open          
windows--,fire not objectionable--,a    
small room ventilated is     better than
 a large room not                       
ventilated--,illustration--,fresh       
air at night prevents                   
cholera--,illustrated by ,new ,york     
workhouse--,dr4 ,hamilton's             
report--,night air just as healthy      
as day air--,candle extinguished by the 
breath--,the breath falls     instead of
 rises--,children near the floor killed 

first--,physicians'     certificates do 
not state killed by foul air--,open     
fire-places     are excellent           
ventilators--,all fire-boards should be 
used for     kindling                   
wood--,illustration showing when ceiling
 ventilation     is necessary4          
,,page #c   ,,lecture ,,ii4      ,the   
effect produced by heat upon the        
movements of air--,air     a real       
substance--,exerts a pressure of fifteen
 tons on an     ordinary sized man--,it 
cannot be moved without the expenditure 
of power--,the sun's rays the great     
moving power--,they pass     through the
 forty-five miles of atmosphere without 
heating it1     and heat the solid      
substances of the earth's               
surface--,experiments     showing the   
effect of radiant heat and reflected    
heat--,the air     of the room not pure 
and dry--,the ordinary moisture absorbs 
from fifty to seventy times as much as  
the air--,many gases     absorb much    
more--,the moisture in the air the great

 regulator of     heat--,air is heated  
by coming in immediate contact with     
hotter     substances--,impossibility of
 any air remaining at rest--,the        
practical application of these          
principles--,the open fire acts like    
the sun1 heating by radiation           
only--,probable electric or ozonic      
change in furnace-heated air--,the stove
 heats both by radiation     and        
circulation--,the stove nor the open    
fire not suitable for     large crowded 
rooms--,circulating warmed air          
best--,erroneous views     in regard to 
ventilation--,experiments with liquids  
of different     densities--,when       
warming and ventilating by circulating  
air1 the     escape for the used air    
should be from the bottom of the        
room--,but     when ventilating with    
cooler air the escape should be from the
     top of the room--,windows should   
lower from the top and flues open     at
 the bottom of the room--,the           
fashionable system of heating by        

direct radiation1 without any fresh air1
 very objectionable4                    
,,page #ah   ,,lecture ,,iii4      ,one 
breath of impure air shortens our       
life--,difficulty of getting     pure   
air to breathe in houses and cars--,foul
 air in steam     cars--,want of the    
proper knowledge regarding ventilation  
among     all classes--,want of         
ventilation in this lecture room--,want 
of ventilation in the ,cooper           
,institute1 and in many other new       
and splendid buildings--,street cars    
very foul--,my own chamber     fully    
ventilated--,i have no new patent idea1 
sufficient for all     time without     
further thought--,constantly varying    
conditions     require separate         
intelligent thought and action--,the air
     moves horizontally in              
summer--,flues are then of no           
account--,we     must depend on open    
doors and windows--,how to ventilate a  
sick     room in the morning--,the same 
in the evening--,windows should         

always lower from the top--,to make air 
move in the summer is     the great     
desideratum--,when in motion the cold   
air falls and     warm air rises2 when  
at rest1 it is arranged in horizontal   
layers1 according to temperature--,a    
flue is simply a passage     for air of 
different temperatures--,experiments    
with flues     of different             
temperatures--,expansion of air by      
heat--,weight     required to keep it   
from expanding--,heating air weakens it 
instead of giving it power--,experiments
 showing draughts by     lighted        
candles--,ventilation of                
churches--,illustrations not            
exaggerated--,examination of church in  
neighborhood--,fresh air     taken from 
foul cellar--,no fresh air supplied to  
churches used as     hospitals in       
,washington--,depending on a sham       
ventilator painted     on the solid     
wall--,foul air in ,philadelphia        
schools--,new ,york     public          
schools--,many of the ventilators       

perfect shams--,covered up     air-tight
 by the capping stones--,importance of  
the evaporation     of water--,a strong 
fire in basement will draw gas out of   
second story stove--,a strong fire up   
stairs will draw foul     gases from    
untrapped sewers--,a very healthy       
location may     thus be made very      
unhealthy--,drs4 ,palmer1 ,ford and     
,earle's     report of epidemic at      
,maple ,wood ,institute--,an arrangement
 for     ventilation that ought to be in
 every house--,flues generally     too  
small1 especially in                    
,philadelphia--,very large ones put in  
government hospitals1 which proved      
thoroughly efficient--,the     leading  
points in regard to heating--,the fresh 
air must be     warmed before entering  
in winter--,a hot water furnace requires
     additional moisture--,heating by   
steam--,steam-pipes ought to be     laid
 through the street the same as gas and 
water--,two-thirds     of heating       
surface should be for heating the fresh 

air and one     third for direct        
radiation--,forty pounds of water       
required to     be evaporated every     
minute for ,u4 ,s4 ,senate              
,chamber--,all stoves     should have   
fresh-air boxes--,dampers in fresh      
air-boxes not     good--,experience has 
fully demonstrated that careful         
attention     to these things will be   
amply rewarded by increased health1     
strength1 happiness and longevity4      
,,page #ca       ,article relating to   
the ,grand ,prize awarded to ,hospital  
,ventilation     and other ,sanitary    
arrangements1 ,paris ,exhibition4       
,,page #ea     ,,lectures ,,on          
,,ventilation4     ,,lecture ,i4        
,philadelphia is one of the healthiest  
cities in the ,united ,states1 and1 in  
proportion to the number of its         
inhabitants1 few more healthy cities    
exist in the world4  ,this is not owing 
especially to its more salubrious       
situation1 but should be attributed1 in 
a great measure1 to the accidental      

superiority of the ventilation of a     
large proportion of its dwelling-houses4
  ,notwithstanding this comparative     
excellence1 the theory of ventilation is
 not so thoroughly understood1 nor is   
the practice so perfect1 even in this   
city1 that no advantage can be gained by
 further knowledge upon the subject4    
,far from it4 ,from the very best       
information we can command1 and with the
 most accurate statistics at our        
disposal1 we are forced to the          
conclusion that about forty per cent4 of
 all the deaths that are constantly     
occurring are due to the influence of   
foul air4  ,the ,registrar of ,records  
of ,new ,york gives nearly half the     
deaths in that city as resulting from   
this cause4  ,the deaths in this city   
for #ahfe1 according to the report of   
the ,board of ,health1 were seventeen   
thousand one hundred and sixty-nine2 the
 average age of those who died was      
between twenty-three and twenty-four    
years4 ,it ought to have been twice     

that1 as shown by some districts in the 
city and also in the country1 where the 
houses are so arranged that they        
frequently have good ventilation4       
,taking the deaths caused by foul air at
 a very low estimate1 say forty per     
cent4 of the whole1 7the per centage    
from that cause is not so great as in   
,new ,york17 we have six thousand eight 
hundred and sixty-eight deaths in this  
city1 caused alone by impure air1 in one
 year4  ,it is estimated by physicians  
that there are from twenty-five to      
thirty days of sickness to every death  
occurring2 there would therefore be     
something like two hundred thousand days
 of sickness annually as an effect of   
foul air4  ,we all know how very        
expensive sickness is1 but few persons  
realize the enormous aggregate expense  
of unnecessary sickness in a city like  
,philadelphia4#a  ,this subject has     
awakened much interest in ,europe of    
late years1 and has led to the          
expenditure of immense sums of money1   

for the purpose of improving the        
sanitary condition of its cities4  ,dr4 
,hutchinson estimated the loss to the   
city of ,london1 growing out of         
preventable deaths and sickness1 at     
twenty millions of dollars annually1 and
 ,mr4 ,mansfield estimates the loss from
 this cause to the ,united ,kingdom at  
two hundred and fifty millions of       
dollars4  ,in the single ,state of      
,massachusetts1 an estimate exhibits an 
annual loss of over sixty millions of   
dollars by the premature death of       
persons over fifteen years of age4  ,it 
is estimated that a few only of the     
principal items of expense incurred by  
preventable sickness in the city of ,new
 ,york amount to over five millions of  
dollars annually4  ,and if it is thought
 that ,philadelphia is exempt from such 
enormous unnecessary expense1 just      
glance at the report of the ,board of   
,health for last year1 and see how the  
deaths from disease of the lungs largely
 exceed those from any other disease4   

,consumption is almost entirely the     
result of breathing impure air1--it is  
as preventable by the exclusive use of  
pure air as maniaa potuor drunkenness is
 by the exclusive use of pure water4    
,and see1 too1 what slaughter among the 
innocents--over twenty-five per cent4 of
 the whole deaths were under one year of
 age4  ,the infantile mortality is by   
many considered the most delicate       
sanitary test4 ,but why does such an    
intelligent community as this so neglect
 its own interest8  ,they have listened 
to and satisfied the first imperative   
demands of nature--shelter from the     
elements and warmth1--and in doing this 
they have not brought into use that much
 higher order of intellect which can    
alone teach them how to supply1 in      
connection with an agreeable warmth1 an 
abundance of pure air in their otherwise
 air-tight houses4  ,i have been much   
interested in examining a large         
collection of tables of the analysis of 
air1 which accompany a report to        

,congress1 on ,warming and ,ventilating 
the ,capitol1 prepared by ,thomas ,u4   
,walter1 ,professor ,henry and ,dr4     
,wetherill4 ,these tables were made by  
men of various nations1 giving the      
results of their analysis of air taken  
from all manner of places1 from great   
elevations on the mountains and in      
balloons1 from the valleys1 from the    
centre of the ocean1 and from the middle
 of the continent1 in cities and in the 
country1 in winter and in summer1 at    
night and in the day1 and also the      
comparative analysis of the air out of  
doors and in houses4 ,believing that    
these would be of much interest and     
assistance to us in the investigation of
 the subject under consideration1 ,i    
have had copies made of some of the most
 interesting4  ,these give the per      
centage of carbonic acid in the air as  
the test of the amount of impurities in 
it4  ,this is not an infallible test by 
any means--there are various other      
causes of deterioration4 ,there is the  

exhaustion of the oxygen constantly     
occurring to support combustion and     
animal life2 there are various other    
deleterious products of combustion and  
respiration besides carbonic acid4 ,but1
 as carbonic acid is always found in    
certain known proportions in pure air1  
and is always formed in certain known   
quantities by respiration or combustion1
 it is considered by many to give a very
 fair indication of the condition of the
 atmosphere with reference to its       
influence on animal life or combustion4 
,i think one of the most valuable       
lessons to be learned by the study of   
these tables is the uniform purity of   
the external atmosphere all over the    
world1 even in large cities4  ,this is  
strikingly illustrated in the case of   
the analysis of the air in the city of  
,manchester4  ,we have nothing in this  
country like that city1 where two       
millions of tons of coal are burned     
annually1 the smoke from which fills the
 air and stretches like a black cloud   

far into the country4  ,thus1 added to  
the five hundred tons of carbonic acid  
thrown from the lungs of its animal life
 every day1 are many times that amount1 
7some two thousand tons17 daily1 pouring
 out from its forest of factory         
chimneys4  ,to this city were the labors
 of the ,health of ,towns ,commission   
first directed1 to see if they could not
 find in the air of its streets that    
mysterious influence that has caused    
such alarm throughout the civilized     
world1 as the thoughtful and intelligent
 sanitarian sees one-half of all his    
fellow-citizens hurried to untimely     
graves4  ,they were disappointed1 and   
well might ,dr4 ,smith exclaim1 after   
the most thorough and careful           
investigations1 ,how insignificant are  
the works of art in contaminating that  
vast ocean of air that is constantly    
sweeping over the surface of the earth6 
,but do not be discouraged3 more recent 
investigations have discovered the      
whereabouts of this pestilential breath4

  ,i have placed the table of ,dr4      
,angus ,smith's analysis of the air of  
,manchester at the head of the list1 and
 have copied it complete1 because it is 
the only table that ,i have examined of 
the analysis of the air of towns in     
,europe or ,north ,america1 in which    
there occurs an amount of carbonic acid 
exceeding ten parts in ten thousand4    
,here we see three such cases in the    
twenty-eight experiments1 one ten1 one  
twelve and one fifteen4  ,the average of
 the whole is also greater than in any  
other similar tables1 being about seven 
and a half parts in ten thousand4 ,this 
is certainly quite a perceptible        
contamination1 pure air containing four 
or four and a half parts in ten         
thousand4 ,yet considerable as this     
appears in this view1 the additional    
amount of carbonic acid is only the     
proportion that would be added to the   
air1 if unchanged1 of a room fifteen    
feet square and ten feet high1 by a     
father1 mother and three children1 with 

a gas-light1 in seven minutes4  ,and    
this1 probably1 is the highest average  
contamination that is produced by       
artificial means upon the air of any    
city in the world4  ,there are1 of      
course1 great natural causes which      
affect the air of whole countries1 such 
as the decomposition of great masses of 
vegetable matter similar to that        
occurring on the low flat lands along   
rivers1 especially where they overflow  
their banks1 like the ,ohio and         
,mississippi4 ,the best system of       
ventilation1 as applicable to this kind 
of foul air1 is to keep as far out of   
its reach as possible4  ,the other      
tables giving the analysis of the air of
 ,london1 ,paris1 ,madrid1 ,geneva1     
,bolton1 ,england1 at different         
elevations on the mountains1 on the     
,atlantic ,ocean1 ,washington ,city and 
various other places1 are interesting   
only because they show so great a       
uniformity in the carbonic acid1 seldom 
exceeding six parts to the ten thousand1

 and seldom under four4  ,but now let us
 look upon the other side of the room4  
,here we have tables giving the carbonic
 acid in houses4 ,here we will find very
 different results4 ,but the first is a 
green-house2 in that there is no trace  
of carbonic acid in the evening and     
scarcely a trace in the morning4        
,plants1 you know1 absorb the carbonic  
acid1 and give off oxygen1 while animals
 absorb the oxygen and give off carbonic
 acid1 thus keeping up the equilibrium  
in nature1 as is so beautifully shown in
 the aquarium4 ,plants are generally    
supposed to give off carbonic acid at   
night1 but it must be in very small     
quantities4  ,i consider them very      
conducive to health in a living-room1   
morally and physically4  ,but this want 
of carbonic acid does not last long4    
,the next is ,m4 ,dumas' lecture-room4  
,at commencement of lecture #db4e1 and  
at close of lecture #fg parts in ten    
thousand4  ,now1 ,i think we are on the 
right track for discovering that        

mysterious poison that has carried so   
many of our friends to their graves1    
even in the very prime of life4  ,here  
we have dormitories1 #eb2 do41 #cg2     
asylum1 #ag2 school-room1 #cj2 do41 #ef2
 ,chamber of ,deputies1 #af2 ,opera     
,comique1 parterre1 #ae2 do41 ceiling1  
#bh2 stable1 #g2 do41 #ad2 hospital1    
,madrid1 #cj2 do41 do41 #dc2 air of     
bed-room on rising in the morning1 #dh2 
the same after being ventilated two     
hours1 #af2 railroad car1 #cd2 workshop1
 ,munich1 #ai2 full room1 do41 #bb2     
lecture-room1 #cb2 beer-saloon1 #di2 and
 worst of all is a well-filled          
school-room1 #gb parts of carbonic acid 
in #aj1jjj4  ,that1 ,i think1 is enough4
 ,here we have the solution of the whole
 mystery4  ,it is not in the external   
atmosphere that we must look for the    
greatest impurities1 but it is in our   
own houses that the blighting1 withering
 curse of foul air is to be found4 ,we  
are thus led to the conclusion that our 
own breath is our greatest enemy4  ,the 

,health of ,towns ,commission1 in their 
investigations1 after examining various 
trades1 where the employees were        
confined mostly in houses1 and having   
left the scavengers to the last1        
expecting to find a rich harvest of     
mortality among them1 were much         
surprised to find them more healthy than
 many very clean occupations1 but which 
were conducted in houses instead of in  
the open air4 ,i have not the statistics
 before me1 but ,i should not be        
surprised to learn that that singular   
race of beings that live in the sewers  
of ,paris were as healthy1 if not even  
more so1 than the operatives of some of 
those exquisitely beautiful1 clean1     
air-tight factories of ,new ,england4   
,there was quite an account made a few  
years ago of the wonderful cures of     
consumption that had been performed by  
the patient being removed to the stable 
where he could be in close proximity to 
the cow1 and ,i have no doubt many      
consumptive patients would find great   

benefit by such a course of treatment1  
not that there is any virtue in the     
smell of the cow1 but that the air of   
the cow-stable would be nearer pure than
 that of their own chamber4  ,many go or
 send their families to the country in  
summer to get fresh air4 ,some go to the
 sea-side1 others to the mountains2 but 
there ensues a greater change in a few  
minutes in a close bed-room by being    
occupied by a family than there is      
difference between the external air of  
any city and that of the country4  ,the 
reason why cities are so much more      
unhealthy than the country1 is not      
because the air in the street is so much
 more impure1 but because the houses are
 so built together that this vast ocean 
of air cannot get at and through them to
 purify them as it does in the houses in
 the country1 and the reason why        
,philadelphia is so much more healthy   
than its neighbor1 ,new ,york1 is       
because the houses here are built more  
like those of the country1 so that the  

air can sweep all around them1 and      
sometimes through them4  ,i therefore   
believe1 that a family living in the    
filthiest street in our city1 if they   
were careful to have a constant current 
of air from that street1 filthy as it   
was1 passing through the house at all   
times1 night and day1 would be more     
healthy1 other things being equal1 than 
a family spending their winters in the  
finest house1 if kept air-tight1 in the 
healthiest location in the city1 and    
their summer in the country1 especially 
if they were always careful to exclude  
the night air from their bed-rooms4  ,i 
say night air2--there is1 unfortunately1
 an unnecessary prejudice against what  
is termed night air1 which means1 ,i    
suppose1 fresh external air from the    
dark4  ,to show that this is not a new  
idea1 ,i will read a few lines from the 
writings of a very accurate reasoner and
 an eminently practical mechanic and    
philosopher1 one whom ,i consider even  
now one of the very best authorities    

upon the subject of heating and         
ventilation4 ,i mean the illustrious man
 after whom this ,institute was named1  
,benjamin ,franklin4  ,in his letter to 
,dr4 ,ingenhaus1 physician to the       
,emperor1 at ,vienna1 he says3 99 99 99 
99 for some are as much afraid of fresh 
air as persons in the hydrophobia are of
 fresh water4 ,i myself had formerly    
this prejudice--this aerophobia1 as ,i  
now account it1--and dreading the       
supposed dangerous effects of cool air1 
,i considered it an enemy1 and closed   
with extreme care every crevice in the  
rooms ,i inhabited4 ,experience has     
convinced me of my error4 ,i now look   
upon fresh air as a friend3 ,i even     
sleep with an open window4 ,i am        
persuaded that no common air from       
without is so unwholesome as the air    
within a close room that has been often 
breathed and not changed4 ,moist air1   
too1 which ,i formerly thought          
pernicious1 gives me now no             
apprehensions2 for considering that no  

dampness of air applied to the outside  
of my skin can be equal to what is      
applied to and touches it within1 my    
whole body being full of moisture1 and  
finding ,i can lie two hours in a bath  
twice a week1 covered with water1 which 
certainly is much damper than any air   
can be1 and this for years together1    
without catching cold1 or being in any  
other manner disordered by it1 ,i no    
longer dread mere moisture1 either in   
air1 or in sheets or shirts2 and ,i find
 it of importance to the happiness of   
life1 the being freed from vain terrors1
 especially of objects that we are every
 day exposed inevitably to meet with4   
,you physicians have of late happily    
discovered1 after a contrary opinion had
 prevailed some ages1 that fresh and    
cool air does good to persons in the    
small-pox and other fevers4 ,it is to be
 hoped1 that in another century or two  
we may all find out that it is not bad  
even for people in health4 ,and as to   
moist air1 here ,i am at this present   

writing in a ship with above forty      
persons1 who have had no other but moist
 air to breathe for six weeks past2     
everything we touch is damp1 and nothing
 dries1 yet we are all as healthy as we 
should be on the mountains of           
,switzerland1 whose inhabitants are not 
more so than those of ,bermuda or ,st4  
,helena1 islands on whose rocks the     
waves are dashed into millions of       
particles1 which fill the air with damp1
 but produce no diseases1 the moisture  
being pure1 unmixed with the poisonous  
vapors arising from putrid marshes and  
stagnant pools1 in which many insects   
die and corrupt the water4 ,these places
 only1 in my opinion1 7which1 however1  
,i submit to yours17 afford unwholesome 
air2 and that it is not the mere water  
contained in damp air1 but the volatile 
particles of corrupted animal matter    
mixed with that water1 which renders    
such air pernicious to those who breathe
 it2 and ,i imagine it a cause of the   
same kind that renders the air in close 

rooms1 where the perspirable matter is  
breathed over and over again by a number
 of assembled people1 so hurtful to     
health4  ,after being in such a         
situation many people find themselves   
affected by that febricula1 which the   
,english alone call a cold1 and1        
perhaps1 from that name1 imagine they   
have caught the malady by going out of  
the room1 when it was1 in fact1 by being
 in it4  ,now1 to show that his hopes   
have not yet been fully realized1       
although one century has nearly closed  
since he wrote what ,i have just read1  
and this unnecessary and unfortunate    
prejudice against night air still       
prevails extensively1 ,i will read a few
 lines from the highest public medical  
authority in this city4 ,it is the      
instructions of the ,board of ,health   
for the prevention of cholera for #ahff3
       ,,article--,,ventilation4        
,your premises1 particularly sleeping   
apartments and cellars1     should be   
thoroughly ventilated4 ,ventilation is  

no less a purifier     than water4      
,it cleanses by oxidizing and drying4   
,keep your houses open and     your     
windows hoisted during the day in good  
weather1 and from ten     o'clock until 
four in the afternoon1 that they may    
have the full     benefit of sunlight   
and free circulation of pure air4       
,during     the remaining hours of the  
day1 and through the night1 keep the    
windows closed4 ,when the weather is    
cool or rainy1 be sure to     keep a    
fire in the house1 in order to prevent  
dampness1 or in     sparsely settled    
neighborhoods1 or in the suburbs of the 
city1     have a fire in the house the  
entire season4  ,on page #i we read3 ,be
 careful to dress comfortably for the   
season1 avoid the night air as much as  
possible1 and when thus exposed1 put on 
an extra garment and do not go into the 
night air when in a state of            
perspiration4  ,thus1 while recognizing 
the great value and importance of       
ventilation in a general way1 they give 

the most definite instructions for      
thoroughly and most effectually         
preventing it1 because it is at night1  
especially when we are asleep and cannot
 move from the air1 that the air ought  
to be moved from us4  ,the frequent     
recommendations to avoid night air are  
simply recommendations to smother       
ourselves to death1 because the foul1   
poisonous exhalations from our lungs    
cannot be removed from our chambers     
without being replaced by night air2    
there is no other fresh air at night but
 night air4  ,the recommendation to     
build a fire in the house on cool days1 
and in low marshy districts every day in
 the year1 is an excellent one4  ,the   
recommendations to dress warmly and to  
avoid checking a perspiration suddenly1 
are valuable suggestions and too much   
attention cannot be paid to them4  ,but 
they are of equally great importance in 
reference to day air as to night air4   
,to shelter oneself from the sudden     
change of temperature after sundown is  

an animal instinct1 and a very necessary
 one1 which is strongly implanted in man
 and beast alike4  ,the harm comes from 
the fact of so intelligent and          
intellectual a body as the ,board of    
,health of ,philadelphia encouraging the
 accomplishment of this very desirable  
object1 by thwarting that great         
universal law of our ,creator1 the      
ceaseless agitation of the air by which 
it purifies itself1 7and by which       
perversion of nature's laws millions are
 already being killed unnecessarily     
every year17 instead of their           
encouraging its accomplishment in that  
much more healthy and rational way by   
adding more clothing or more fuel to the
 fire1 and still continuing to breathe  
the pure air at night as well as in the 
day-time4  ,i have practised for many   
years sleeping with my windows open     
every night1 summer and winter1 allowing
 the unobstructed breeze to flow across 
my bed1 to the great improvement of my  
health and strength4  ,there is no      

objection in a well ventilated room to  
having a fire if desired4 ,a small room 
with a hot stove or open fire and the   
windows open1 is much more wholesome    
than a large air-tight room freezing    
cold4  ,let us illustrate this by a     
simple experiment4 ,here we have a very 
small tube1 in which we place a lighted 
candle1 occupying nearly the entire     
space--this burns brightly1 you see4    
,illustration3 ,fig4 #a4  ,here we have 
another glass chamber1 much handsomer   
and twenty times as large2 we also place
 a similar candle in it1 that burns with
 equal brightness1 but watch them both  
for a few moments--see how rapidly this 
light in the large chamber diminishes in
 size4  ,illustration3 ,fig4 #b4  ,that 
represents1 in a beautiful manner1 the  
diminished force of your life in an     
air-tight room4 ,there it goes--entirely
 extinguished by foul air in so short a 
time1 but the other continues to burn   
just as brightly as when first lighted4 
,the smaller one had the window open1 so

 to speak2 we will imagine the candle in
 the large chamber to be a consumptive  
patient who thought the room so large he
 did not need the windows open4         
,remember1 therefore1 that no matter how
 small your room is1 if there is a      
constant circulation of fresh air       
through it1 the lamp of your life will  
burn brightly2 but if ever so large and 
air-tight1 your life will soon be       
extinguished4  ,instead of averting the 
cholera by avoiding fresh air at night1 
the experience of the last summer seems 
to have taught us just the contrary2 for
 whilst most physicians admit that they 
are still unable to explain             
satisfactorily1 the cause or remedy for 
this most mysterious disease1 that has  
within a lifetime carried its fifty     
millions of victims from time to        
eternity1 they almost universally       
believe it is a foul air poison1 and    
they have as yet found no surer         
prevention than pure air4  ,one of the  
most striking illustrations of this1 and

 perhaps one of the most wonderful cures
 of cholera on record1 was that of the  
,new ,york ,workhouse on ,blackwell's   
,island4 ,it lasted only nine days1 but 
in that brief period one hundred and    
twenty-three out of eight hundred       
inmates died4 ,i visited the building   
with ,dr4 ,hamilton1 on the third day   
after its appearance1 but the hospital  
then contained sixty or seventy         
patients1 and some twenty-five or thirty
 had died within twenty-four hours4     
,dr4 ,hamilton attributed the rapid     
propagation and fatality of the disease1
 after it once had gained admission1    
mainly to confinement and crowding4 ,it 
was observed that the cholera was       
confined1 for several days1 among the   
women2 the women had the smallest       
apartments1 were most crowded in their  
cells1 and with few exceptions1 were    
employed within the building1 in close  
contact with each other during the day4 
,the men were employed mostly in the    
quarries and out of doors4  ,the        

doctor's prescription on that occasion  
is worth studying4 ,it is very short and
 simple1 however4  ,a slight change was 
made in the diet2 disinfectants were    
used2 fifteen drops of the tincture of  
capsicum with an ounce of whisky1 as a  
stimulant at night1 was all the medicine
 given to each individual4 ,but the     
great means the doctor relied upon for  
success1 was pure air all the time4     
,they were kept out of doors from       
morning until night1 and all the windows
 were kept open night and day2 and      
although in the hot weather of summer1  
fire was made in the wards1 to insure   
more perfect ventilation4 ,in six days  
after the initiation of these simple    
hygienic measures1 the epidemic entirely
 disappeared4  ,the disorders and       
sickness caused by the too rapid        
chilling of the unprotected body after  
sundown1 have given rise1 ,i have no    
doubt1 to that erroneous popular        
prejudice so common among all classes1  
even those of education and ordinarily  

good common sense1 who imagine there is 
some peculiar poison or source of       
unhealthiness in the air at night1 that 
is not contained in the air in the      
day-time4 ,it will no doubt greatly     
relieve the minds of these from such    
vain terrors1 and prove most            
conclusively the entire fallacy of such 
reasoning1 to examine these tables      
again4 ,in the copies ,i have made1 ,i  
have not classified the results given by
 day and by night1 but a careful        
examination in detail1 fails to show any
 appreciable difference in the          
aggregate1 by day or by night4  ,mene's 
numerous experiments on the air in      
,paris1 gave less carbonic acid at night
 than in the day-time4  ,lewey's        
analysis on the ,atlantic ocean1 one    
thousand miles from the coast1 gave a   
decided excess in the day over that of  
the night4 ,he attributes this to the   
action of the sunlight upon the ocean   
liberating the gases which it holds in  
solution4  ,in cities there is a much   

larger quantity given off from burning  
coals of factories in the day-time than 
at night4  ,it is not improbable1       
however1 that the more rapid evaporation
 of moisture towards evening may carry  
with it the volatile particles of       
corrupted animal and vegetable matter to
 an extent slightly in excess of that   
which occurs in the morning1 but it is  
believed these would not equal the      
greater contamination from burning      
coals1 and the usually greater stillness
 of the air1 producing partial          
stagnation1 so that the air would be a  
little nearer pure at night than in the 
day-time4 ,and how unmistakably do all  
these investigations prove what we ought
 to have known and accepted without a   
moment's hesitation1 that the ,creator1 
who has made such vast and such minute  
provisions for supplying every living   
creature with a constant and copious    
supply of fresh air1 and has made it so 
important for their existence that they 
cannot live a moment without it1 has    

made the air at night just as pure and  
wholesome as in the day-time4  ,we have 
thus traced the scourge of foul air to  
our houses1 and much of it to our       
bed-rooms4 ,the next question is1 how to
 get clear of it4  ,we want to know1    
however1 what poisons the air1 so as to 
know in what part of the room it is to  
be found4  ,we will try a very simple   
experiment1 to show you what a deadly   
poison the breath is1--to the flame of a
 candle1 at any rate4  ,here is a simple
 glass tube1 open at both ends--an      
ordinary lamp chimney--a candle burns   
freely as you see1 and would burn so all
 night1 if it did not burn out4 ,i will 
now remove the candle1 and breathe into 
the tube through this pipe1 and now you 
see how suddenly the candle is          
extinguished as ,i drop it in again4    
,illustration3 ,fig4 #c4  ,animals are  
killed suddenly or after a more         
prolonged struggle1 by the exhaled      
breath1 according to the activity or    
sluggishness with which the blood       

circulates--a bird would be killed very 
soon--some partially torpid animals     
would live a long time4 ,man has great  
endurance--struggles long and hard2 but 
if closely confined1 will be poisoned to
 death in one night1 as in the case of  
those confined in the celebrated ,black 
,hole of ,calcutta1 and on board of     
vessels where they have been confined   
below decks in time of a storm4 ,others 
will struggle on longer1 as in the case 
of the two thousand and twenty-six who  
died of consumption last year1 in       
,philadelphia4  ,and now let us see in  
which part of the room this deadly      
poison of our breath is mostly found4   
,it is the popular idea1 that because   
the body1 and consequently the breath1  
is warmer than the ordinary temperature 
of a room1 it rises and accumulates at  
the ceiling4  ,upon this theory most of 
our buildings have been ventilated      
whenever any attention whatever has been
 given to the subject2 but that theory  
is incorrect2 consequently1 all practice

 based thereon is also wrong4  ,this    
subject of the direction taken by the   
breath upon leaving the body1 has been  
warmly discussed within a few years4 ,it
 has been a very difficult matter to    
prove conclusively and satisfactorily1  
but ,i think we have devised some very  
simple experiments that will prove to   
you very clearly what we have stated4   
,i have here a simple glass tube two    
feet long and one and a half inch       
interior diameter2 one end is closed    
with a rubber diaphragm1 through which  
is passed a small rubber tube--the other
 end is all open4 ,we will rest this    
about horizontal1 and taking a little   
smoke in the mouth1 it will be          
discharged with the breath into the     
glass tube2 it is first thrown towards  
the top1 but it soon falls1 and now see 
it flowing along the bottom of the tube 
like water--watch it as it reaches the  
far end--there1 see it fall almost like 
water4  ,illustration  ,now1 by raising 
the closed end of the pipe1 you see we  

can pour it all out1 and by filling it  
again and raising the other end1 it     
falls back4 ,thus you see that1         
notwithstanding the extra warmth in the 
breath1 it is heavier than the          
atmosphere1 and falls to the floor of an
 ordinary room like this1 say1 when the 
temperature is from #fj deg4 to #gj     
deg44 ,this is owing to the carbonic    
acid and moisture contained in it4  ,i  
have varied this experiment in a number 
of ways1 by passing it through smaller  
tubes and discharging it into the air in
 one or two seconds after leaving the   
lungs1 and by passing it through water  
of various temperatures1 and discharging
 it into rooms of different             
temperatures1 with the same general     
results4 ,as the temperature of the air 
diminishes1 the tendency of the         
discharged breath to rise increases4    
,much care is required in conducting    
these experiments1 to avoid as much as  
possible1 the local currents which are  
always present in a room4  ,this is a   

very important fact to be borne in mind2
 yet notwithstanding this1 there are    
times1 under certain circumstances1 in  
which the foul air will be found in     
excess at the top of the room4  ,for the
 further examination of this subject1 we
 have here a little glass-house with    
glass chimneys and fire-place in the    
first and second stories4  ,illustration
  ,as the flame of a candle is such a   
beautiful emblem of human life1 we will 
remove the roof and part of the floor of
 the second story1 and place four       
candles in our house4 ,they are all of  
different heights1 you see4 ,we will    
call them a father1 mother and two      
children4  ,as carbonic acid is that    
much dreaded poison in our breath1 and  
the heavy portion of it which causes it 
to fall to the floor1 we will make a    
little by placing a few scraps of common
 marble in this glass vessel1 and       
pouring over it some sulphuric acid4    
,it is now forming1 and will fall and   
flow across the floor the same as       

carbonic acid does when it pours into a 
basement from the gutters on the street 
or filthy yards where it is formed1 and 
before it is absorbed or diluted by the 
current of pure air sweeping over them4 
,it first kills the smallest child1     
because it is nearest the floor4 ,you   
remember the excessive infantile        
mortality in this city in #ahfe4 ,this  
is partially owing to their breathing   
more of this foul air near the floor1   
and partially owing to the great fear of
 their mothers and nurses1 of letting   
the little innocents get a breath of    
fresh air for fear it will give them    
colic1 and consequently they smother    
them to death4  ,the other child dies   
next1 and then the mother1 and lastly   
the father4  ,thousands are thus        
poisoned to death by their own breath   
every year4 ,but did you ever see a     
physician's certificate that gave you   
any such idea8 ,why do not the doctors  
tell the living1 in such language as    
they can understand1 what killed their  

friends1 so they may avoid it in their  
own case1 instead of giving it in some  
,latin terms which ,i fear many         
interpret to mean some special          
dispensation of ,divine ,providence     
instead of the true cause--their utter  
disregard of the laws their ,creator    
made for the preservation of their      
health8  ,had this family known enough  
about ventilation to have kept the      
fire-place open1 with a little fire in  
it now and then1 they would not have    
been thus killed4  ,let us see--we will 
take out the fire-board which has been  
put in to make the room look a little   
neater1 and with a very small light     
there to create a draft in the chimney4 
,we will again light the candles1 and   
pour in the poisonous breath4 ,ah6 there
 goes the little one--he is hardly high 
enough to keep out of that deadly       
current flowing across the floor4  ,we  
shall have to let it in a little slower1
 or we will set him on a platform1 as   
many persons who have carefully studied 

this subject1 consider it judicious to  
do4 ,now1 by the smoke from this taper1 
you can see the air is flowing across   
the floor and up the chimney4  ,there   
has been a steady current flowing in    
long enough to have filled the house1   
but the lights are all burning brightly1
 and you thus see the value of an open  
fire-place for ventilation4 ,thousands  
of lives are thus saved1 and many more  
would be if all fire-places were kept   
open4 ,i have recommended hundreds of   
fire-boards to be cut up for            
kindling-wood1 as ,i consider this is   
the best use that can be made of all    
fire-boards4  ,never stop up a          
fire-place in winter or summer1 where   
any living being stays night or day4 ,it
 would be about as absurd to take a     
piece of elegantly tinted court-plaster 
and stop up the nose1 trusting to the   
accidental opening and shutting of the  
mouth for fresh air1 because you thought
 it spoiled the looks of your face so to
 have two such great ugly-looking holes 

in it1 as it is to stop your fire-place 
with elegantly tinted paper because you 
think it looks better4  ,if you are so  
fortunate as to have a fire-place in    
your room1 paint it when not in use2 put
 a bouquet of fresh flowers in every    
morning1 if you please1 or do anything  
to make it attractive2 but never close  
it4  ,now1 there are other conditions in
 which a fire-place or an opening near  
the floor1 will not answer for          
ventilation4 ,this occurs in rooms where
 the air is made impure by burning lamps
 or gas1 and where the fresh air        
entering the room is cooler than the    
temperature of the room itself4  ,to    
illustrate this1 we will put the roof on
 and take the entire floor away1 or as  
it will be a little more convenient1 we 
will represent it by this glass-house1  
using this shade for that purpose4      
,illustration  ,this is supported some  
six inches from the floor1 and has no   
bottom4 ,by lighting another candle and 
standing it outside1 you can judge by   

comparison1 of the foulness of the air  
inside4  ,the tallest one is affected   
first1 this time4 ,you see that is a    
perfectly formed light1 but it gives but
 about half the light the one does on   
the outside2 this is the way with many  
of us who are obliged to1 or rather do1 
breathe foul air half the time4  ,we    
often think1 by comparing ourselves with
 others around us1 that we are pretty   
fair specimens of humanity1 while really
 we do not give more than half the light
 in the world that we ought to do1 and  
kill ourselves before our work is half  
done4  ,you see the two tallest are dead
 already1 and the others will soon      
follow--there they go4 ,here is the     
bottom of the house removed1 and yet    
these candles all went out for want of  
fresh air4  ,therefore1 when we see the 
air is made impure by burning candles or
 gas lights1 owing to its exceeding     
heat1 the foul air is mostly at the top 
of the room1 and especially when the    
fresh air enters cooler than the air in 

the room4 ,we will find1 however1 that  
in a very few minutes the candles will  
relight long before the contained air or
 the glass shade cools down to the      
temperature of the room4  ,the products 
of combustion1 like those of            
respiration1 are heavier than the       
ordinary atmosphere1 and consequently   
fall to the floor very soon if not      
removed while very hot1 by special      
openings immediately over them in the   
ceiling2 after it has thus fallen1      
provision must be made for its removal  
from the level of the floor1 in         
connection with the foul air from the   
breath4  ,i hope that by these few      
simple experiments1 and the statistics  
presented here this evening1 we have    
strengthened your previous convictions  
of the importance of fresh air1 because 
we are well aware that you will find1 as
 you proceed in your investigations of  
this subject1 that it is frequently     
surrounded with complications2 yet the  
laws governing the circulation of air of

 different temperatures1 are as fixed   
and immovable as the laws governing the 
rising and setting of the sun1 and with 
a very little careful investigation1 can
 be easily understood4  ,and we believe 
no similar amount of money or thought1  
will produce a greater amount of        
satisfaction than the increased health1 
strength and happiness thus secured4    
,,lecture ,,ii4   ,as ,i stated in our  
last lecture1 much interest is being    
awakened1 in this country and in        
,europe1 by recent investigations       
showing the enormous numbers of untimely
 deaths that are caused throughout all  
classes of society by foul air4  ,it    
would have been a startling             
announcement1 ten years ago1 to have    
stated that impure air caused as many   
deaths1 and as much sickness1 as all    
other causes combined1 and yet the most 
diligent and accurate investigations are
 rapidly approaching that conclusion4   
,few really comprehend the immense      
pecuniary loss1 to say nothing of the   

amount of suffering1 that we endure by  
this extra and easily preventible amount
 of sickness4  ,i propose1 this evening1
 to enter upon the consideration of one 
of the most important parts of our      
subject--the effect produced by ,,heat  
upon the movements of air4  ,i think it 
probable that many of us do not         
comprehend the actual reality of the    
air4  ,we are apt to say of a room that 
has no carpet and furniture in it1 that 
it has nothing in it1 while1 if it is   
full of air1 it has a great deal in it4 
,a room between twenty-seven and        
twenty-eight feet square contains one   
ton of air--a real ton1 just as heavy as
 a ton of coal4 ,now1 there is not only 
twenty-seven feet1 but more than        
twenty-seven miles of air piled on top  
of us4 ,the pressure of the atmosphere  
at the level of the ocean is about      
fifteen pounds to the square inch4 ,an  
ordinary sized man sustains a pressure  
of about fifteen tons1 and were it not  
that this pressure is equal in all      

directions1 we would be crushed thereby4
  ,we must accustom our minds1          
therefore1 to consider air a real       
substance1 and that it is as totally    
unable to move itself1 or to be moved1  
without power1 as water or coal4 ,it    
requires just as much power to move a   
ton of air from the cellar to the second
 story1 as it does a ton of coal4  ,heat
 is the great moving power of air4      
,those whose attention has not been     
especially directed to the subject of   
the amount of power exerted by the sun's
 rays upon the earth1 have little       
conception of its magnitude4  ,the power
 of all the horses in the world1 added  
to the power of all the locomotives1 and
 of all the immense steam engines in all
 the world1 express but a small fraction
 of the power exerted by the sun's rays 
upon the earth4 ,it is estimated to be  
sufficient to boil five cubic miles of  
ice-cold water every minute4  ,his rays 
are the chosen power of the ,creator for
 moving all matter upon the globe4 ,it  

is his rays that lie buried in the vast 
coal fields beneath the earth4 ,his rays
 cause every spear of grass to grow1    
rear the mighty oak1 form the rose1     
burst its beautiful buds1 and send its  
perfume through the air4  ,no bird      
warbles its sweet music in the air1 no  
insect breathes1 save by his power1 and 
all animals love to bask in the genial  
glow of his light and heat4 ,he rolls   
the scorching air of the tropics to     
frozen lands1 and wafts the ships across
 the seas4 ,he forces the heated waters 
of the equator to the poles1 tempering  
all the earth4 ,he lifts the water from 
the sea to sprinkle all the land and cap
 the distant mountains with eternal     
snow4  ,now1 let us examine a little    
more minutely how this influence is     
exerted upon the air1 which is the      
subject we are especially interested in 
at present4  ,does it commence at the   
top1 and heat it1 layer by layer1 until 
it reaches the bottom8 ,not at all2 but 
it passes through the whole forty-five  

miles of air1 heating it very little1 if
 any1 and falls upon the solid          
substances at the earth's surface1      
heating them1 which1 in turn1 heat the  
air by its individual particles coming  
into immediate contact with those solid 
hotter substances4  ,we will endeavor to
 illustrate this in a crude way4        
,illustration3 ,fig4 #g4  ,here we have 
a tin tube1 a1 fifteen feet long and ten
 inches in diameter1 open at both ends2 
two feet from one end we introduce this 
ascending pipe1 b1 the upper end of     
which is merely inserted in a small     
flue1 extending to the top of the       
building4 ,the height of this flue is   
sufficient to make a current of air pass
 through this tube1 as you will see by  
holding this smoking taper at the far   
end4 ,we will now place a large heated  
ball1 c1 at this end1 and outside of    
that we will place this reflector1 d1   
pressing it quite close to the end of   
the tube1 so that no air can enter here4
  ,the rays of heat from this ball1 or  

from any other warm body1 are thrown    
like rays of light1 in every direction  
equally2 there would1 therefore1 be some
 of the rays thrown through this tube to
 the other end without any reflector1   
but the proportion that would reach the 
other end would1 of course1 be small4   
,we therefore collect those going the   
other way1 and change their course1 and 
then send them straight through the tube
 to the far end4  ,we will place another
 reflector1 e1 at the far end1 to       
receive and concentrate those rays1 in  
the focus of which we will place a      
candle1 ,f1 with a little phosphorus on 
it1 to show you that the rays of heat   
are passing through4  ,there you see the
 candle is lighted1 thus proving that   
there is a strong current of radiant    
heat coming from the hot ball1 through  
the tube to this end4 ,and you see by   
this smoke that there is a current of   
air passing the other way4  ,now1 we    
want to know how much that air is heated
 in passing the whole length of this    

tube against that shower of radiant     
heat1 or whether air absorbs radiant    
heat at all2 but1 before going to the   
other end1 where the hot ball is1 we    
will take two thermometers that have    
been lying here1 side by side1 both     
indicating a temperature of #fi deg44   
,one of them1 g1 we will hang at this   
end1 about opposite to the centre of our
 tube1 which1 ,i think1 will give us a  
fair average of the entering air1 first 
removing1 however1 the candle that has  
been lighted1 and the reflector4  ,we   
will hang the other thermometer in the  
ascending tube1 at the end near the     
heated ball4 ,we have had two glasses1  
,h1 inserted here1 so that we might     
observe what was going on within by the 
smoke from this taper4 ,you see there is
 a strong current of air passing up the 
tube1 all of which must come from the   
far end1 flowing against the strong     
current of radiant heat going in the    
opposite direction4 ,now1 leaving this  
thermometer to rise or fall according to

 the temperature of the air flowing     
through1 we will go to the other end and
 examine another very interesting part  
of this experiment3 it is the manner in 
which the radiant heat is received and  
appropriated by different substances4   
,radiant heat is thrown from a hot body 
in every direction equally1 but no two  
kinds of substances receive those rays  
of heat in the same manner1 nor do they 
make the same use of them after they    
have received them4  ,every substance   
receiving heat1 however1 must give a    
strict account of it4 ,it must give out 
an equal amount of heat1 or1 what is    
taken as an equivalent1 some action or  
power4  ,i have a sheet of ordinary tin1
 and as ,i hold this polished side      
behind this light1 you see it throws a  
belt of light across the room2 and as ,i
 put it in front of the end of our tube1
 and turn it so that the rays of heat   
will be reflected in your faces1 ,i     
think some of you will be able to feel  
the reflected heat4 ,the rays of heat   

are turned from their course1 and thrown
 in a belt of light across the room1    
similar to the rays of light4  ,but you 
cannot give away and keep the same      
thing4 ,this bright polished surface    
appropriates but a very small portion of
 the radiant heat4 ,a thermometer       
hanging for some minutes against the    
back has scarcely risen one degree2 but 
we have given the other side a coating  
of lamp black1 with a little varnish1   
and by turning that side towards the    
pipe1 the result will be quite          
different4 ,by this coat of black       
varnish the whole character of the sheet
 of tin is changed4 ,the black1 however1
 has but little to do with it2 if it    
were white1 or red1 or blue1 the        
formation of the surface being similar  
in every respect1 the result would be   
the same almost precisely4  ,instead of 
acting merely as a guide-post1 to change
 the direction only of the rays of heat1
 as before1 it now becomes a receiving  
depot1 absorbing nearly all the heat    

that comes to it4 ,it must soon become  
filled1 however4 ,the thermometer       
hanging at the back has risen six       
degrees already1 and is going up        
rapidly2 it must soon begin to          
distribute its extra stores4 ,but mark  
the different manner of distributing the
 heat4 ,instead of reflecting the whole 
all in one direction1 as when received  
on the other side1 it now radiates them 
equally in every direction4  ,some solid
 substances allow the rays1 both of heat
 and light1 to pass directly through    
them without either reflecting or       
absorbing them4 ,other substances allow 
the rays of light to pass through them1 
but absorb much of the radiant heat1    
like clear glass4  ,rock salt is one of 
the best non-absorbents of radiant heat1
 allowing nearly the whole of the rays  
of heat to pass through unobstructed4   
,we will now return to our experiment at
 the other end of the tube4 ,i find     
there is something wrong here--the      
mercury in the thermometer has risen    

several degrees4 ,i knew this was rather
 a crude arrangement for illustrating   
this very beautiful and interesting part
 of our subject1 but ,i hoped it would  
assist me a little in conveying to you  
the idea ,i desired to impress upon your
 minds4 ,i find1 however1 that it is    
scarcely delicate enough to illustrate  
perfectly what ,i wanted to show4  ,but 
this increased temperature is not owing 
to the effect of radiant heat on the air
 coming from the far end1 for ,i find by
 the heat at the top of the pipe1       
between the heated ball and this        
ascending pipe1 ,i1 and by the current  
of heated air on the side next the ball1
 that there is a current of circulating 
air that has been heated by coming into 
immediate contact with the hot ball4  ,i
 designed this smaller tube1 k1 to carry
 off the air thus heated1 but it appears
 to be too small4  ,we ought to have had
 a piece of rock-salt to have closed the
 end of this tube1 so that the radiant  
heat would have passed through without  

allowing any circulation of heated air1 
but ,i was unable to find such a piece4 
,but ,professor ,tyndall1 in his        
lectures before the ,royal ,institute of
 ,great ,britain1 gives the results of a
 large number of very accurate and      
beautiful experiments tried for the     
purpose of determining whether the      
forty-five miles of atmosphere          
surrounding the earth absorbed any of   
the sun's rays1 and if so1 how much8    
,these experiments prove1 in the most   
conclusive manner1 that dry pure air is 
almost a perfect non-absorbent of       
radiant heat4 ,thus1 were the air       
entirely dry and pure1 the whole        
forty-five miles through which the sun's
 rays have to pass1 would absorb a very 
small fraction thereof1 so that in the  
length of our tube it would be but an   
exceedingly small fraction of one       
degree1 that is1 for pure dry air4  ,but
 is the air of this room pure and dry8  
,very far from it4  ,professor ,tyndall 
found that the moisture alone in the air

 of an ordinary room1 absorbed from     
fifty to seventy times as much of the   
radiant heat as the air does4 ,air and  
the elementary gases--oxygen1 hydrogen  
and nitrogen--have no power of absorbing
 radiant heat1 but the compound gases   
have a very different effect2 for       
instance1 olifiant gas absorbs #giej    
times as much as air2 ammonia1 #gbfj2   
sulphurous acid1 #hhjj times4 ,perfumes1
 also1 have a wonderful power of        
absorbing radiant heat4  ,the moisture  
in the air1 however1 is of the greatest 
practical importance in various ways4   
,it is the great governor or regulator  
or conservator of heat2 it absorbs it   
and carries it from point to point and  
into places where the direct rays of the
 sun could not get2 it is like a soft   
invisible blanket constantly wrapped    
around us1 which protects us from too   
sudden heating or too sudden cooling4   
,professor ,tyndall1 speaking of the    
moisture in the air1 says3 ,regarding   
the earth as a source of heat1 no doubt 

at least ten per cent4 of its heat is   
intercepted within ten feet of its      
surface4 ,he also says3 ,the removal for
 a single summer's night of the aqueous 
vapor from the atmosphere which covers  
,england1 would be attended by the      
destruction of every plant which a      
freezing temperature could kill4  ,in   
,sahara1 where the soil is fire and the 
wind is flame1 the refrigeration is     
painful to bear4  ,and in many of our   
furnace-heated houses1 we have an       
atmosphere very similar in point of     
dryness to that of ,sahara1 but more    
impure4  ,the foregoing remarks in      
regard to the impossibility of heating  
air1 apply especially to radiant heat4  
,air does become heated1 but in a       
different manner2 it is heated by each  
individual particle or atom coming in   
immediate contact with some hotter      
substance4 ,see what a wonderful        
provision for creating a constant       
circulation of the air4 ,the sun's rays 
pass through it without heating it1 but 

they heat the surface of the earth at   
the very bottom of the ocean of air2    
this1 in its turn1 heats the air by each
 individual atom coming in immediate    
contact with these hotter substances1   
expanding them so that they must rise1  
thus enabling the colder and heavier    
particles to rush in and take their     
places4 ,with this great universal      
moving cause1 in connection with the    
innumerable minor causes resulting from 
the very different absorbing1 radiating 
and reflecting powers of various        
substances1 it becomes almost impossible
 for the air to be entirely and         
absolutely at rest1 even in the most    
minute crack or cranny1 or bottle corked
 air-tight4  ,now1 to apply these       
principles to every-day life1 to the    
heating and ventilation of our houses1  
taking the open fire first1 we find that
 it acts like the sun1 heating          
exclusively by direct radiation4 ,the   
rays of heat fall upon the sides of the 
room1 the floor and ceiling1 and the    

solid substances in the room1 which thus
 become partially heated1 and in their  
turn become secondary radiators4 ,this  
radiant heat from the fire does not heat
 the air in the room at all1 but the air
 becomes partially warmed by coming in  
immediate contact with the sides of the 
room1 the furniture1 c4  ,one great     
reason1 therefore1 why an open fire is  
so much more wholesome than any other   
means of artificial heating1 is because 
it more nearly imitates the action of   
the sun4  ,the rays of heat fall upon   
our bodies1 heating them1 while it      
leaves the air cool1 concentrated and   
invigorating for breathing4 ,the bright 
glow of an open fire has a very cheering
 and animating effect4 ,it produces a   
very agreeable and healthy excitement4  
,it is not improbable that future       
careful investigations may prove that   
there is an important change takes place
 in the electric or ozonic condition of 
air as it passes over1 or in contact    
with1 hot iron1 which does not occur to 

the air of a room heated by the open    
fire4  ,the air in a room heated by an  
open fire can scarcely become stagnant1 
because that fire must necessarily be   
constantly drawing a considerable amount
 of air from the room to support        
combustion1 the place of which will be  
supplied by other air1 and here is where
 one of the greatest inconveniences     
arises in the use of the open fire2 if  
the air entering to supply this         
exhaustion comes in at a crack of the   
door or window1 on the opposite side of 
the room1 and that air is cold1 say #aj 
deg4 or #ae deg4 above zero1 it flows   
across the floor to the fire1 chilling  
the feet and backs of those sitting in  
its track4 ,it is quite possible to     
roast a goose or round of beef in front 
of a fire1 while the air flowing by it  
into the fire is freezing cold4 ,this   
should be remedied by having the air    
flowing in partially warmed before it   
enters1 say to a temperature of #dj deg4
 to #ej deg41 either by having the halls

 overflowed by partially warmed air1 and
 opening a door into it1 or by admitting
 the air to enter around the back of the
 fire-place1 as ,dr4 ,franklin arranged 
it4  ,thus1 while an open fire is the   
healthiest known means of heating a     
small room1 and should be in the family 
sitting-room of every house1 and in     
offices and other places where the      
occupants are at liberty to move closer 
or further from the fire at pleasure1   
yet it is entirely unsuitable for a     
large building1 or for rooms where many 
persons are assembled1 and have fixed   
seats1 similar to a school1             
lecture-room1 factory1 c4  ,a stove in a
 room heats both by direct radiation and
 by heating the air that comes in       
immediate contact with it4  ,but our    
latest styles of elegant new patent     
gas-consuming air-tight stoves1 require 
so small an amount of air to support    
combustion1 that there is a strong      
probability of the occupants of a room  
thus heated smothering to death for want

 of fresh air1 sooner or later1 and     
generally the former4  ,but a stove1 if 
properly used1 creates a comfortable and
 wholesome atmosphere1 and is one of the
 most economical means of heating now   
known4 ,there should always be a        
separate pipe for introducing the fresh 
air from the external atmosphere1 which 
fresh and cold air should be discharged 
on or near the top of the stove4 ,and if
 this supply of fresh air is abundant1  
with a constant evaporation of moisture 
sufficient to compensate for the        
increased capacity therefor due to the  
additional heat given it1 and an opening
 into a heated flue near the ceiling1 to
 be opened in the evening when the      
gas-lights are burning1 or when the room
 is too hot1 and kept shut at all other 
times1 with another opening into a      
heated flue on a level with the floor1  
which should be kept always open to     
carry off the cold1 heavy foul air from 
the floor--a stove thus arranged for    
many small isolated rooms1 makes one of 

the most economical as well as most     
comfortable and wholesome means of      
heating at our command4 ,it combines the
 three great essentials necessary for   
comfort and health--warmth1 partially by
 direct radiation1 fresh air and        
moisture4 ,but neither the open fire nor
 the stove1 as desirable as they may be 
in many small rooms1 are suitable for   
large rooms1 especially where many      
persons are assembled4 ,heating         
principally by circulating warmed air1  
or in combination with direct radiation 
from exposed pipes filled with steam or 
hot water1 is in such cases more        
convenient4  ,it is in connection with  
this system of heating by circulating   
warm air1 that the erroneous views in   
relation to ventilation generally       
entertained by the public1 produce the  
most injurious effects4  ,the special   
points to be borne in mind in           
considering this subject are that1 when 
in motion1 warmer air rises and colder  
air falls2 but when at rest1 the        

stratums of air of different            
temperatures arrange themselves         
horizontally4  ,one other thing3 we must
 remember temperature has nothing to do 
with the purity or impurity of the air4 
,the pure air entering a room is        
sometimes colder than the average       
temperature of the room1 and falls to   
the floor1 forcing the warmer1 and1 in  
that case1 fouler air to the upper part 
of the room4  ,but frequently1 in       
winter1 the fresh air enters warmer than
 the average temperature of the room1   
and rises to the ceiling1 and flows     
across the room above the colder and    
fouler air that has been longer in the  
room4 ,you must not forget the          
experiments in our first lecture1       
showing that the breath in an ordinary  
room1 of a temperature of #gj deg41 fell
 to the floor instead of rising to the  
ceiling4 ,i propose illustrating this   
part of our subject1 by using a little  
glass room to show the movements of air 
of different temperatures4 ,we can      

either use air of different             
temperatures1 showing the motion of the 
various currents by a little smoke2 or1 
as the laws governing the circulation of
 liquids of different densities are so  
similar1 and by the use of a little     
coloring matter will express to an      
audience of this kind more promptly and 
clearly the ideas which we wish to      
convey1 we therefore propose using the  
different colored liquids this evening4 
,the colors1 of course1 have nothing to 
do with the densities1 but are merely   
used as a convenient method of          
designation2 the red representing heat  
or rarity1 and blue1 coldness or        
density4  ,the room is now filled with  
clear water1 slightly blue1 to represent
 cold1 and a little salt1 which makes it
 a little more dense than fresh water4  
,now1 ,i will let in at the top a little
 fresh water1 colored red by cochineal1 
to represent heat1 and by making a      
similar opening on the opposite side for
 its escape1 you will be able readily to

 see in what direction it moves4 ,there1
 see it entering--see how it flows      
directly across the top of the room1 and
 escapes at the opening on the opposite 
side4 ,you see it disturbs the lower and
 colder parts of the room but very      
little4 ,thus a large flow of pure fresh
 warm air might be going through a room 
all day1 and be entirely wasted1 neither
 warming nor ventilating it4            
,fortunately1 there are but few         
buildings arranged in quite so absurd a 
manner as this4 ,i believe it was tried 
in the ,house of ,lords1 on the erection
 of the new ,houses of ,parliament1 but1
 of course1 failed4 ,i think they still 
adhere to it in some of the wards of    
some ,insane ,asylums1 where they       
depend1 ,i suppose1 upon the excitement 
of the patients to keep themselves warm 
and the air stirred up4 ,i also noticed 
this arrangement in a new building just 
being finished1 a few years since1 at   
,yale ,college4 ,the architects of that 
building had probably been impressed    

with the dreadful effects upon the      
health of students of the air from our  
ordinary hot air furnaces1 and thought  
they would avoid all such danger4 ,i    
think1 however1 it would have answered  
their purpose just as well1 and been    
much more economical1 to have placed the
 furnaces at the coal mines1 and saved  
the trouble and expense of carrying the 
coal so far4 ,i expect they have made   
other arrangements1 probably1 by this   
time4  ,illustration3 ,fig4 #a          
,illustration3 ,fig4 #b  ,illustration3 
,fig4 #c  ,we will now close the opening
 at the top for the inlet of the fresh  
warmed air1 and open a valve1 so as to  
allow it to flow in at the bottom4 ,we  
will allow the opening at the top for   
the outlet of the foul787 air to remain 
as before1 7see ,fig4 #a1 ,lithograph   
plates47 ,this is quite an improvement2 
it agitates the air much more than the  
other1 and by going and standing        
directly over the register1 you can     
always get in the current of fresh warm 

air4 ,but you see to what a very small  
portion of the room the heated air is   
confined1 rising in one perpendicular   
column directly to the ceiling1 and then
 flowing horizontally along the ceiling 
to the outlet4 ,how little it disturbs  
the main portions of the room1          
especially the lower and occupied part4 
,i hope you will notice that this       
illustrates the popular notions of      
ventilation4 ,i suppose three-fourths of
 all the buildings in this country1 or  
in ,europe1 where any attempts at       
artificial ventilation have been made1  
are thus arranged4 ,dr4 ,franklin knew  
better1 and made a much more perfect    
arrangement than this4 ,but we are      
probably mostly indebted to that very   
able and enthusiastic advocate of       
ventilation1 ,dr4 ,reid1 for this       
popular opinion4 ,the whole of the plan 
that he advocated is but little         
understood by the public4 ,he assumed   
that the natural warmth of the body     
created an ascending current around us1 

and caused the breath to rise towards   
the ceiling1 and consequently1 in all   
artificial arrangements1 it was best to 
endeavor to imitate this natural        
movement of the air4 ,and to overcome   
the great practical difficulty we see   
here exhibited1 of the fresh warm air   
flowing through the room1 and disturbing
 so small a portion of it1 he proposed  
making the whole floor one register1 and
 thus have an ascending column over the 
entire room4 ,for this purpose1 the     
floors in the ,houses of ,parliament    
were perforated by hundreds of thousands
 of gimlet holes1 and the whole cellar  
made a hot air chamber4 ,this was a     
magnificent idea1 and1 ,i believe1 in   
some few instances1 where fully carried 
out1 has given a good degree of         
satisfaction2 but it is always difficult
 to adjust the opening and the pressure 
so as to cause an even flow over so     
large a surface1 and at the same time to
 be so gentle as not to be offensive to 
those with whom it comes in contact4    

,but this thorough diffusion cannot be  
conveniently applied in one case in a   
thousand4 ,it must necessarily be always
 very extravagant1 as it will constantly
 require a great amount of air to insure
 a thorough circulation through all     
parts of the room4 ,i wish1 therefore1  
most emphatically1 to condemn all       
systems relying upon openings in the    
ceiling for the escape of the foul air1 
while depending upon the circulation of 
warmed air for obtaining the necessary  
additional warmth4 ,in practice they are
 universally closed in winter1 for the  
purpose of keeping warm1 and as such    
openings have been so generally         
considered the only ones necessary for  
the proper ventilation of a room1 and as
 they had to be shut in winter1 just    
when artificial ventilation was most    
necessary1 it has created a very strong 
prejudice in the popular mind against   
all ventilation4  ,the result of the    
advocacy of these impracticable theories
 by so many able and learned men1 7most 

physicians writing upon this subject    
have adopted them17 has been the        
shutting up of many thousands and tens  
of thousands1 till they have smothered  
to death4  ,the ravages of consumption  
and the excessive infantile mortality1  
and the many diseases resulting from    
foul air poisons1 are in a great measure
 due to the general advocacy of these   
false theories4 ,as ,i have before said1
 ,dr4 ,franklin knew better than this1  
and had we been contented to have       
followed his simple practical advice1   
instead of being dazzled by the splendid
 theories of others1 thousands of our   
friends would now be with us who died   
long since for the want of fresh air4   
,now1 let us see how ,dr4 ,franklin says
 a room ought to be ventilated4 ,he     
says1 the fresh air entering1 becoming  
warmed and specifically lighter1 is     
forced out into the rooms1 rises by the 
mantel-piece to the ceiling1 and spreads
 all over the top of the room1 whence1  
being crowded down gradually by the     

stream of newly warmed air that follows 
and rises above it1 the whole room      
becomes in a short time equally warmed4 
,this is the principle upon which his   
celebrated ,franklin stove was arranged4
 ,now1 let us see if we can arrange our 
little glass house so as to illustrate  
this4 ,we will first fill it with what  
we call our cold air1 and will close the
 outlet at the top1 and take out the    
fire-board4 ,now1 as ,i let in the warm 
fresh air1 it rises immediately to the  
top1 as before1 and flows across the    
ceiling1 but as it cannot escape there1 
it forces the cold air down1 and causes 
it to flow out at the fire-place4 ,see  
how quickly the whole room is filled    
with the fresh warmed air4 ,ah6 ,i see  
,i am a little too fast--there appears  
to be a stratum of a foot or two1 lying 
on the floor1 that is not disturbed yet4
 ,it flows out at the top of the        
fire-place1 and therefore does not reach
 to the floor4 ,this is frequently the  
cause of cold feet and much discomfort4 

,we will make the opening directly at   
the floor1 7see ,fig4 #b1 ,lithograph   
plate17 and that forces all the cold air
 out1 warming and ventilating the whole 
room4 ,here is the whole problem solved 
in the most beautiful and simple manner4
 ,and you may exclaim1 as you see the   
simplicity and perfect working of this1 
how came any one ever to think of       
anything else4  ,here1 again1 you see   
the value of that most excellent and    
valuable of household arrangements1 the 
open fire-place2 even without the fire  
it serves a most important purpose4     
,illustration3 ,fig4 #d  ,illustration3 
,fig4 #e  ,illustration3 ,fig4 #f  ,we  
must not forget1 however1 that there are
 other circumstances in which it will   
not do to depend on the fire-place alone
 for ventilation4 ,now1 by leaving the  
fire-place open1 just as it is1 and the 
room full of warm air1 we will simply   
change the condition of the air         
supplied1 and allow cold air to flow in 
at the bottom instead of the top4 7,see 

,fig4 #c47 ,there1 you see the fresh    
cold air simply falls to the bottom and 
flows across the floor1 without         
disturbing the upper part of the room at
 all4 ,it acts just the reverse of the  
hot air let in and taken out at the top 
of the room4 ,when you are ventilating a
 room by opening a window1 therefore1 it
 is often necessary to open it at the   
top2 but remember when you are          
ventilating by doors and windows1 7which
 are the great natural ventilators17    
they are an entire substitute for       
flues--flues are then of no account4    
,all windows1 therefore1 ought to be    
made to lower from the top1 and all     
ventilating flues ought to be made to   
open at the bottom of the room4  ,i have
 noticed another very interesting       
feature in regard to the circulation of 
liquids of different densities2 for     
instance1 suppose we fill our little    
room half full with salt water1 and the 
remainder with fresh water1 we will now 
apply a spirit lamp to the bottom of the

 room4 ,as the salt water becomes heated
 it rises rapidly1 yet not to the top of
 the room1 but only half-way1 or to the 
top of the denser liquid1 and then      
spreads across the room horizontally4   
,thus the salt water will keep up a     
rapid circulation1 and may be heated    
almost to a boiling temperature         
underneath1 and without heating or      
disturbing1 the cold fresh water above4 
,i have tried some very beautiful       
experiments of this kind with a number  
of liquids of different densities in the
 same vessel4 ,gases of different       
densities are probably influenced in a  
similar manner by the application of    
heat4 ,and here we see the value of that
 beautiful law of the diffusion of      
gases1 by which each gas1 no matter what
 its density1 is equally diffused in all
 directions through the other gases1    
independent of temperature4  ,i desire  
to call your attention this evening to  
one other distinct system of heating--,i
 mean that very convenient1 economical1 

cleanly and ,,fashionable system of     
heating by direct radiation from        
steam-pipes4  ,as steam has become such 
a common article in all large buildings1
 both for power and as a convenient     
means of distributing heat1 most large  
buildings are thus heated2 and as a     
perfectly air-tight building can be very
 easily heated thus1 and as most persons
 are too ignorant or too careless to    
provide a separate and distinct supply  
of fresh air simply for ventilation     
alone1 the consequence is1 that this    
system1 thus so shamefully abused1 is   
probably drying up more talent and      
killing more business men in our cities 
than any other system in existence4     
,this applies especially to the         
editorial rooms of nearly every one of  
our leading newspapers and publishing   
houses4 ,they use steam for driving     
their beautiful printing presses1 and   
the heating and ventilation1 or rather1 
the entire want of ventilation1 in their
 offices1 would indicate that they think

 that the same power that drives their  
presses1 to do the printing so nicely1  
is entirely sufficient to drive them to 
write the original articles for the     
printer1 and that they have no more need
 of fresh air than their presses4  ,you 
may think that ,i am certainly mistaken 
that so intelligent a class of the      
community1 who are building such        
splendid fire-proof buildings1 such     
perfect palaces of iron and stone and   
marble1 as our newspaper establishments 
are building in ,new ,york1             
,philadelphia and other large cities1   
would never make such a blunder as to   
omit providing the most abundant supply 
of pure1 fresh air to every employe in  
their establishments1 and at all times1 
both in summer and winter4  ,should     
there be any one present thus doubtful1 
,i wish he would undertake to get any   
one of our enterprising newspaper       
establishments to publish in their paper
 an accurate intelligible account of    
their system of ventilation1            

illustrating clearly the known quantity 
of pure1 fresh air delivered within     
using distance of each one of the       
editors and employes4  ,i think he would
 soon come to the same conclusion ,i    
have1 that the advice of the minister to
 his congregation would be very         
applicable to them--,always do as ,i    
say1 but never do as ,i do4             
,,lecture ,,iii4   ,in my first lecture1
 ,i endeavored to show how much we were 
suffering from the effects of foul air1 
and the advantages to be gained by      
supplying ourselves all the time with   
pure air4 ,because we must first feel   
that there is something to be gained    
before we will make any great effort    
towards obtaining a given result4  ,in  
my second lecture we considered the     
general principles governing the        
circulation of air1 the courses of its  
movements1 the manner of the action of  
heat upon different kinds of substances1
 which creates a constant1 ceaseless    
motion of the air1 in all places1 from  

the minutest corked bottle to the vast  
currents that sweep over the face of the
 earth4  ,now1 having learned the       
necessity for pure1 fresh air1 and      
studied the general laws governing its  
circulation1 let us apply these         
principles to every-day life4 ,to       
every-day life8 ,i should say every-hour
 life--nay1 every moment of our lives2  
for twenty times every minute of our    
entire life1 from the cradle to the     
grave1 do we breathe what ought to be   
pure air4 ,is it always pure8  ,if we   
breathe one single breath1 in the entire
 day1 of impure air1 it will weaken us1 
deduct from our capacity to attend to   
our daily duties1 and shorten our lives1
 in exact mathematical proportion to the
 amount of impurity in that one single  
breath4 ,now1 we breathe twenty times   
every minute1 twelve hundred times every
 hour1 twenty-eight thousand times every
 day1 and nothing but absolute and      
perfectly pure air answers the exact    
requirements of perfect health4  ,well1 

you may ask1 at first thought1 if fresh 
air is such a panacea for all evils1 and
 there is such an abundance of it out of
 doors1 why not breathe it1 and always  
enjoy perfect health8  ,think one       
moment4 ,i eat my breakfast in the      
morning1 generally refreshed by a night 
of good sound sleep1 7for ,i sleep with 
my windows open47 ,immediately after    
breakfast1 ,i enter the cars to come to 
the city4 ,what a smell comes from the  
car as the door is opened6 and unless ,i
 wish to incur the displeasure1 or      
provoke the indignation1 of almost every
 passenger1 by opening a window1 ,i am  
obliged to sit in that foul1 offensive  
atmosphere1 and breathe the poisonous   
exhalations from my own lungs1 and that 
from dozens of others1 some of them1 it 
may be1 badly diseased1 7most persons'  
lungs are diseased in this country1 from
 breathing foul air1 and many other     
diseases besides consumption are        
produced thereby47  ,thus1 in one half  
hour1 ,i have inhaled six hundred times 

of this foul and poisonous air1 and the 
blood has carried it to every portion of
 my body1 so that my entire system is   
completely saturated1 poisoned1 yes1    
thoroughly poisoned by it1 from the     
crown of my head to the soles of my     
feet4  ,and thus is the day commenced4  
,your blood is thoroughly poisoned      
before your breakfast is digested2 for  
your breakfast will no more digest      
without pure air than the coal in your  
stove will burn without it4 ,you are    
subjected to headache1 dyspepsia1 and a 
half dozen other aches and pains1 and   
are tired out long before night4 ,and   
thus you are killed long before you     
would die if you breathed pure air only4
  ,and am ,i relieved from the          
difficulty when ,i arrive in the city8  
,start to-morrow morning at the         
,delaware ,river1 on ,arch or ,walnut   
,streets1 or any other street1 and go to
 the ,schuylkill4 ,inquire of every     
individual1 in office1 store1 dwelling  
or factory1 if he knows whether he had  

pure air to breathe all day1 or whether 
he can tell you1 with any degree of     
accuracy1 how pure the air was in the   
room he occupied for any hour of that   
day4  ,i fully believe there is not one 
in ten--no1 not one in a hundred--of the
 most intelligent men in that entire    
street1 doctor1 lawyer1 architect1 or   
any other1 that can give you an accurate
 account of the condition of the air    
breathed during any one hour of the day4
 ,that is not all4 ,there is scarcely   
one in a hundred that can satisfy you1  
by an intelligent description1 of the   
means used for providing it3            
,first--,assuming the air outside to be 
pure1 that there was a constant1        
positive and sufficient supply of that  
outside air introduced4                 
,secondly--,that that pure air was not  
deteriorated by overheating1 or         
contaminated by being mixed with the    
poisonous gases of the burning coal4    
,thirdly--,that there was sufficient    
moisture added to it to compensate for  

its increased capacity for moisture1 due
 to its expansion by the additional heat
 given to it1 7which is a very important
 thing47  ,fourthly--,that there was any
 accurate1 positive means provided for  
insuring the fresh air to be brought    
within reach of the lungs of those for  
whom it was intended4  ,and1            
lastly--,that there was a positive means
 provided for the removal of all the    
poisoned air thrown from the lungs1 so  
that none could possibly be re-breathed4
  ,no2 you will find them in close1     
unventilated offices1 in close          
factories1 in almost air-tight          
dwellings4 ,in the large stores they do 
better4  ,the air is very commonly      
overheated1 it is often mixed with      
impurities1 and very seldom supplied    
with a proper amount of additional      
moisture4  ,the air is often so dry1    
that in a few minutes' conversation the 
linings of the air-passages to your     
lungs become parched and husky1         
producing irritation and a feverish     

condition of the system4 ,and even in   
this room1 to-night1 do you see any     
opening at your feet1 connected with a  
heated flue1 for drawing the foul air   
from the floor as fast as thrown from   
your lungs8 ,i believe there is not a   
square inch provided for that purpose4  
,or1 do you see any escape immediately  
above the gas-lights1 for carrying off  
the burned air while hot enough to      
escape8 ,not one4 ,there are two or     
three openings1 ,i think1 in the back   
part of the room1 just at the ceiling1  
but for your breath to get there1 it    
must rise and pass by the zone of       
respiration1 and much of it be again    
re-breathed2 and the products of        
combustion1 as we have seen1 would cool 
sufficiently to fall to the floor long  
before they reached that point4  ,i take
 the liberty of calling your attention  
to this with more freedom1 because it   
does not indicate any special           
inattention on the part of the          
,managers4 ,it is not an exceptional    

case1 but it is the rule4 ,it is the    
popular opinion of the proper means of  
ventilation4  ,go with me1 if you       
please1 to that magnificent building1   
completed but a few years since1 at a   
cost of half a million of dollars1 and  
given by its noble and generous founder 
to the city of ,new ,york4 ,you will    
notice1 inscribed above the entrance1   
cut in the solid stone1 ,to the ,arts   
and ,sciences4 ,look in this            
reading-room--perhaps the most useful   
and most appreciated of any public      
reading-room in the ,united ,states4    
,see the large numbers of honest1       
industrious mechanics1 snatching an hour
 from their labors1 to look over the    
current literature of the day4 ,here1   
certainly1 we shall find the most       
perfect arrangement for heating and     
ventilation that our knowledge of the   
arts and sciences could suggest4 ,let us
 see the arrangements for bringing in   
the fresh air1 for warming it in cold   
weather1 and for removing the foul air4 

,what6 no provision for a regular supply
 of fresh air8 ,not one foot1 not one   
inch--neither are there any regular     
flues for the removal of the foul air4  
,and this most remarkable condition of  
things is but repeated in the           
magnificent hotels1 marble palaces used 
as offices1 and in many of the new and  
splendid colleges2 and1 we might almost 
say1 in all other buildings throughout  
the length and breadth of our land4     
,thus you see how difficult it is for   
one to mingle freely in the society of  
his fellow-men1 under existing          
circumstances1 without being subjected  
to being poisoned by foul air4 ,in going
 from here to my home1 to-night1 ,i     
shall have to ride in those cars1 the   
air of which ,i dread more than ,i ever 
dreaded the small-pox or cholera4 ,i    
have been in hospitals where ,i have    
seen much of both4 ,they may slay their 
thousands1 but foul air its tens of     
thousands4 ,and it is only when ,i get  
to my room1 where ,i shall probably     

sleep to-night with two windows well    
open1 allowing the unobstructed breezes 
of half a mile of open country to sweep 
through my chamber1 that ,i shall feel  
entirely secure from the contaminating  
influences of foul air1 and enjoy to its
 full extent the greatest of ,god's     
temporal blessings to man--pure air4  ,i
 have no new patent idea to present to  
you1 which shall secure to you at all   
times perfectly pure air1 without any   
further trouble on your part4 ,there are
 no two constitutions precisely alike1  
any more than there are two human faces1
 or two handwritings1 and there are no  
two hours in our entire life in which   
all the physical conditions of our body 
are precisely the same4 ,it would be    
just as absurd1 therefore1 to go to a   
ventilating establishment1 and tell the 
proprietor to ventilate your house or   
office1 and pay the bill when it came   
in1 and content yourself by saying3     
,well1 ,i am glad this ventilating      
business is done with4 ,i have got my   

house ventilated1 and the bills paid1   
and ,i am glad ,i am through with that  
vexatious business4 ,i say this would be
 just as absurd as it would be1 in case 
you had some pain or ache1 to go to your
 doctor and get some medicine1 and      
therewith content yourself1 and say3    
,well1 ,i am glad this doctoring        
business is over with2 ,i have been     
dreading it all my life4 ,i have been to
 the doctor's at last1 have been        
doctored1 and got my medicine and paid  
my bill1 and so ,i am through with that 
vexatious business4  ,no--you must first
 feel that fresh air is worth taking    
some trouble to obtain4 ,you must then  
make it a study how to obtain it without
 chilling or overheating your body1 in  
winter and in summer1 at night and in   
the day time1 when you are lying down   
and when you are sitting up1 before     
eating and after eating1 before         
exercising1 while exercising1 and after 
exercising--when you are well and when  
you are sick1 when you are alone and    

when you are in the crowded cars1 or in 
a crowded room1 in wet weather and in   
dry1 and for the ever varying changes of
 the external atmosphere--all these     
conditions require separate and         
intelligent thought4  ,in summer we     
depend almost exclusively on the natural
 movements of the air4 ,to cause the air
 to move is then the great matter4 ,we  
must then remember that the great masses
 of air move horizontally1 not          
perpendicularly4 ,of course1 there are  
many little disturbing influences1 but  
,i mean the great mass of the air moves 
over the surface of the earth in        
horizontal strata4 ,you can see this by 
the smoke of the locomotive on the      
prairie1 which can be seen sometimes for
 twenty or thirty miles1 stretching     
along just above the horizon4 ,all      
flues1 therefore1 are of little account 
in summer4 ,we must depend on open doors
 and windows4 ,suppose you wish to      
ventilate your room in the morning1 the 
air outside having become a little      

warmer than the air inside1 and the     
upper parts of the window only lowered3 
the warmer air would flow across the top
 of the room1 leaving the air           
undisturbed in the lower and colder     
part4 ,in this case1 the window should  
be raised from the bottom1 or a door    
opened that would afford an escape for  
the air4  ,but again1 suppose this same 
room to want ventilating in the evening4
 ,the room has become warm through the  
day1 and the outside evening air is     
cooler than the room1 and then1 if you  
raise the windows from the bottom only1 
the cooler air will flow across the     
bottom of the room1 leaving the upper   
part undisturbed and foul4  ,no doubt   
you have all noticed1 frequently1 that  
in going into a room in the evening1    
when your heads were above the window   
opening1 it would be quite hot1 but if  
you stooped down below the line of the  
open window1 it would be cool and       
pleasant4 ,all windows should be made to
 lower from the top1 to meet this       

special case4 ,if you are boarding1 or  
are so unfortunate as to be put in a    
room where the great blunder has been   
made of not having the windows to lower1
 go to the nearest carpenter shop next  
morning1 before breakfast1 and get a    
chisel1 and cut six or eight inches off 
the little strip which supports the     
sash1 and1 with a gimlet1 bore a hole   
directly through the sash1 on both      
sides1 and with a nail you can keep the 
sash up in its place1 when necessary4 ,i
 have had hundreds1 yes1 ,i suppose1    
thousands1 made to lower this way in the
 hospitals4  ,motion1 motion is the     
great desideratum in summer4 ,you have  
all noticed1 no doubt1 how pleasant it  
is to go into a cool room1 like a       
parlor1 that has been kept shut up on a 
hot summer's day2 but in a short time it
 begins to feel oppressive1 and it is   
more comfortable to have the windows    
open1 and a circulation of air1 even if 
it should be a little hotter than the   
stagnant cool air4  ,never sleep with   

closed windows in summer4 ,it is in     
winter1 however1 that the greatest care 
is required in providing a constant     
supply of pure air4 ,if we would but    
accustom our minds to comprehend1       
readily and quickly1 that cold air falls
 and warm air rises1 it would assist us 
in our conclusions4 ,we all know that1  
of course1 but we do not practice       
applying it readily and quickly on all  
occasions4  ,in summer1 as ,i have said1
 the air moves horizontally1 and then   
windows and doors are the great means of
 ventilation2 but as cold weather       
approaches1 we must keep the windows    
shut1 excepting when in bed4 ,in winter1
 therefore1 we must resort to flues for 
the means of creating a circulation1 and
 for conveying the air from one part to 
another4 ,a flue is simply a passage--a 
communication--for air of different     
temperatures4 ,a flue has no power to   
create a draught4 ,if the air within is 
colder1 it will have the power to fall2 
if warmer1 it will be driven up4        

,illustration3 ,fig4 #h4  ,for          
illustrating this1 ,i have here some    
glass tubes about two feet long and two 
inches diameter4 ,this one 7,fig4 #h7   
has been lying on the table some time1  
and ,i suppose is very nearly the       
temperature of the air in the room4 ,i  
have here a little tin box1 which       
answers for a connecting tube1 and over 
one of the openings ,i stand this tube1 
and by the smoke from this taper1 first 
held at the top1 you see there is no    
current down the tube4 ,and again1 by   
holding the taper at the lower opening1 
you see there is no current passing up  
the flue4 ,but ,i will remove that1 and 
place one 7,fig4 #i7 over the same      
opening that is warmer1 and now you can 
see how strongly the smoke is drawn down
 through this lower opening1 and see it 
flowing up this warm flue1 and out at   
the top4  ,we will now substitute a cold
 flue 7,fig4 #aj74 ,this condenses the  
air1 and it falls rapidly4 ,this action 
often occurs in the spring and early    

part of summer1 especially in the       
morning1 as the external air becomes    
heated1 and the solid mason-work of the 
chimney remains cold1 causing a         
descending current1 which is often      
noticeable by the smell of soot in the  
room4 ,we will now add this tube1 of the
 same temperature as the room 7,fig4    
#aa71 to see if the additional height   
will not make an ascending current4 ,but
 you see the smoke is still drawn down1 
the height of the flue adds a little to 
its power1 but the difference in its    
temperature is the controlling force4   
,illustration3 ,fig4 #i4  ,illustration3
 ,fig4 #aj4  ,illustration3 ,fig4 #aa4  
,illustration3 ,fig4 #ab4  ,we will now 
place another tube over the lower       
opening 7,fig4 #ab74 ,just see what a   
wonderful effect that has6 ,here is the 
air rushing down this short flue and up 
the two cold ones4 ,we called those two 
first pipes cold1 but our ideas of heat 
and cold are simply comparative2        
everything is warm1 or has heat in it4  

,perhaps some of us think there is not  
much heat in the air when it comes      
whistling around our ears #ae deg4 or   
#bj deg4 below zero2 but the cold rigid 
chemist will still extract many degrees 
of heat from that4  ,we must1 therefore1
 remember that absolute temperature has 
nothing to do with the air passing up or
 down a flue--it is simply comparative  
temperature4  ,illustration3 ,fig4 #ac4 
,let me show you one more experiment4   
,here are two tubes we have had heated2 
as you see1 the smoke rushes up them    
rapidly4 ,but now we will add this third
 one 7,fig4 #ac71 which reverses the    
current at once4 ,the two first are hot1
 taking the temperature of the room as  
the standard1 but the third one is still
 hotter4  ,illustration3 ,fig4 #ad4     
,the form of a flue has but little to do
 with the draught2 the height has a     
slight influence1 but bear in mind      
constantly that the great moving power  
in all flues is the variation of        
temperature4  ,now1 let us make a       

practical application of this principle4
  ,wait a moment3 just let us lay this  
one aside1 but not forget it1 as we     
shall want to refer to it in a few      
moments1 and try another experiment     
which has some bearing upon the subject4
  ,i have here a tube just one foot     
square and two feet long1 and one foot  
from the bottom there is what we will   
suppose to be an air-tight piston that  
can be moved without friction4 ,now1    
suppose we heat that air #dij deg4 7for 
the sake of easy remembering1 say #ejj  
deg472 this would just double its       
volume--it would then be two cubic feet 
in size instead of one4  ,now1 suppose  
that1 instead of letting this air       
expand1 we should put a weight on it1 so
 as to keep it in its place1 how much do
 you think we should have to place on8  
,two thousand one hundred and sixty     
pounds1 or about one ton4 ,now1 what do 
we find these #bafj pounds to represent8
 ,it is the weight of a column of       
atmosphere with a base of one foot      

square1 or fifteen pounds multiplied by 
#add square inches--it is the weight    
that would rest upon the piston if all  
the air was taken out from under it4    
,therefore1 if you add about #ejj deg4  
of heat to a cubic foot of air1 it makes
 it two cubic feet of air2 or1 if you   
attempt to keep it from expanding1 you  
must put a ton weight upon it4  ,mark   
one thing1 however1 if it takes ten     
ounces of coal to heat that air to #dij 
deg41 which we do by piling our ton     
weight upon it1 it will take fourteen   
ounces of coal if we allow it to expand 
to two feet4  ,in the former case1 where
 the air remains stationary1 it had done
 no work4 ,it was ready to go to work1  
but it had not commenced4 ,but in the   
case of its expansion1 it had done a    
great work4 ,what was it8 ,why it had   
lifted that ton of atmospheric air one  
foot in height1 and that work was what  
used up the difference between ten parts
 and fourteen parts of coal 7,i don't   
trouble you with fractions74  ,you see1 

therefore1 to make the air quit the     
earth and ascend into the upper regions1
 requires a positive power1 the same as 
it does to drive some poor simple people
 away from the fire on a cold day4  ,we 
often say that1 by heating air1 we give 
it power to ascend2 instead of which    
heating it destroys its power to        
maintain its position4 ,it              
weakens--enervates it--so that its      
neighbors easily drive it out and take  
its place4  ,one cubic foot of air1     
diluted to two feet1 would be driven    
about two miles and a half high before  
it found any body as weak as itself1 for
 every #cej feet in height1 in round    
numbers1 the pressure diminishes by an  
amount equal to one degree1 or forced   
under water thirty-four feet reduces it 
to one-half its bulk4  ,now1 let us go  
back and finish our syphon1 or flue     
experiment4  ,here we have our little   
glass house again4 ,we will take the    
roof off and put a pretty large family  
in it--,i mean large in numbers1 if not 

in size4 ,you may call it a school1 or  
public meeting1 or church1 or whatever  
you please4 ,suppose1 for illustration1 
we call it a church1 and we will call   
this larger light in this end the       
minister speaking to the congregation4  
,you see1 the lights are a good deal    
agitated1 and flare around a good deal4 
,there is a rush of air down at this    
end1 and1 as it becomes heated1 it rises
 at the other4 ,let us cover about      
one-half of this up4 ,now see what a    
rush of air there is down these flues1  
instead of up them1 as there ought to   
be4 ,here1 you see1 the main body of the
 building1 though much shorter than the 
flues1 forms the heated leg of the      
syphon2 and you may thus recognize why  
many of the ventilating flues1 put in   
the cold outside walls of many of our   
large buildings1 persist in working the 
wrong way1 and cold air blows down      
there1 instead of the foul air going up4
  ,but there seems to be too much       
draught4 ,let us put the roof on4 ,ah1  

that is better2 but1 then1 what a       
draught there is down this chimney-flue4
 ,call the sexton1 and have that stopped
 up quickly1 or those sitting near there
 will soon catch their death of cold1   
and will never come here again4  ,you   
see1 however1 they shine very brightly1 
notwithstanding all the draught1 but    
there1 now1 it is all closed up as      
snugly as the most fashionable church in
 town4 ,see how quiet and peacefully    
they burn now4  ,ah1 there is one just  
gone to sleep4 ,you must excuse him1 he 
probably was up most of the night with a
 sick child4 ,and there goes another4 ,i
 think he must have been very busy for  
the last week settling up his last      
year's accounts4 ,just see1 they are    
going to sleep so fast1 ,i don't think  
we can pretend to give excuses for them 
all4  ,and1 now1 is not that a brilliant
 congregation to be preaching to8       
,everyone dead asleep excepting the     
preacher himself1 and ,i suspect he     
feels stupid enough to go to sleep1 but 

it would not look well2 and he has to   
tax his energies so severely he will    
hardly get over it1 so as to be good for
 anything for the balance of the week4  
,you may think this an exaggerated      
representation of the real facts4 ,do   
not deceive yourselves4 ,a few months   
since ,i was requested by one of the    
congregation to visit a building within 
a few minutes' walk of this place1 and  
see if there was not some defect in the 
ventilation4 ,the gentleman stated to me
 that he sometimes attended the         
class-meeting1 and would be glad to go  
oftener1 but it was held in the basement
 story1 and it was quite impossible for 
him to keep awake1 as he had to get up  
and go out two or three times during the
 evening1 to get a little fresh air1 or 
he could not keep awake4  ,i examined   
it4 ,the ceilings were low-only nine or 
ten feet2--then there were two old leaky
 portable furnaces1 which were used as  
occasion required for heating the large 
room above1 or the basement room when   

the class-meeting was held4  ,the only  
ventilation they had was to let off the 
surplus heat 7if they had any1 which was
 seldom7 into the room above4  ,now for 
fresh air4 ,by a very careful and minute
 examination1 ,i discovered a little    
pipe 7,i think it was about six inches  
in diameter7 to each stove 7both of     
which would not be over half as large as
 what ,i have to supply my own bedroom71
 for the supply of the fresh air for    
that whole congregation4 ,fresh air1 did
 ,i say8 ,well1 let us see where this   
fresh air comes from4 ,the janitor1     
after taking us down and showing where  
he kept the ashes1 wood1 old benches1   
and all sorts of rubbish1 was about     
going up1 but said ,i1 ,where is the    
part where you get the fresh air to the 
furnaces8 ,oh1 he said1 he could not get
 to that1 it was such a rough place1 and
 there was a sewer or gutter 7from the  
adjoining graveyard ,i suppose7 running 
right across it4 ,and from that place1  
too rough to be got at1 with an open    

sewer running through1 and too foul to  
go into1 was where they got the fresh   
air 767 from for the whole of that      
congregation to breathe4  ,and do you   
suppose this is an exception8 ,let me   
tell you4 ,during the first year of the 
late war ,i was called upon by the      
,sanitary ,commission to examine the    
hospitals in ,washington ,city with     
reference to their ventilation4 ,a large
 number of the churches in that city    
were used for hospital purposes1 and    
many of them were heated by hot-air     
furnaces1 and in not one single instance
 had they fresh air boxes to them1      
neither had they any means for carrying 
off the foul air4 ,the furnaces were    
generally placed in a hole excavated    
under the main part of the building1 and
 all the ground around them left        
exposed1 and the air was sucked in from 
the fermenting1 decaying vegetable mould
 under the building4 ,and this place    
around the furnace was the place where  
all the filth and old rubbish was thrown

 to get it out of the way1 and it was   
thoroughly out of the way too1 for the  
surgeon in charge or any inspector never
 got there to see it4 ,in some cases ,i 
found this space around the furnace used
 as the dead house6  ,did ,i say there  
was no attempt in any of those buildings
 for systematic ventilation8 ,i ought to
 have made one exception4  ,i called one
 morning about ten o'clock at one of the
 finest new churches1 which was then    
being occupied as a hospital1 and asked 
for the surgeon in charge4 ,he had not  
arrived4 7,they did not often venture in
 before eleven o'clock1 the wards became
 so foul during the night it took till  
that time1 with the windows up1 to get  
them fit for the surgeon in charge to   
venture in47 ,i inquired of the         
wardmaster how the building was         
ventilated4 ,oh1 very well--very well1  
indeed--they had good ventilation1      
pointing up to a large1 splendid        
ventilator in the ceiling4 ,do you keep 
that always open8 ,i asked4 ,oh1        

certainly1 he replied4 ,but ,i always   
have a great suspicion of those ceiling 
ventilators1 as they are generally shut4
 ,so ,i walked around the ward1 and when
 under it asked him again if he thought 
that was open4 ,a smile came over his   
face as he discovered1 for the first    
time1 it was a handsome fresco painting 
on the solid wall4 ,and this was the    
only practical systematic attempt at any
 ventilation in any of the church       
buildings used as hospitals in all      
,washington4  ,i have not been in any of
 the public schools in this city for    
many years1 but a gentleman told me the 
other day that he called at one of the  
fashionable schools up town to get his  
son and take him home under his         
umbrella1 as it had commenced raining   
since morning1 and as he opened the     
school room door he was perfectly       
shocked1 as he staggered back from the  
gust of horrible foul air that came     
rushing out of that room4  ,i have      
examined most of the public schools in  

,new ,york since ,i have those of       
,philadelphia4  ,they have a way of     
their own of doing public business over 
there4 ,there has been a good deal said 
about ventilating public schools of late
 years1 and as it was such a scientific 
and fashionable matter they must have   
their schools ventilated of course4  ,i 
was very unfortunate in my intercourse  
with the ,directors of the ,public      
,schools4 ,i did not happen to meet with
 many of those high toned1 liberal1     
scientific gentlemen that are on many of
 the committees1 of course4  ,those     
beautiful and ornamental gratings called
 registers are accepted as the external 
proof of good ventilation1 suggesting as
 they do the flow of an abundance of    
pure fresh air4 ,so registers were      
bought freely and put in all the rooms1 
top and bottom1 with splendid red and   
green and blue tassels1 altogether      
making a handsome show and doing the    
very able and scientific gentlemen on   
the ,school ,boards great credit for    

their enterprise and great care for the 
welfare and interest of the pupils under
 their charge4  ,now1 let us examine the
 operation of these registers4 ,holding 
a handkerchief in front of them1 there  
it remained perfectly motionless4 ,it   
neither blew hot nor cold--it was       
perfectly lukewarm1 motionless4 ,go to  
another--the same4 ,and to another--the 
same4 ,well that is singular4 ,let us go
 on the roof and see what can be the    
matter4 ,a careful search fails to      
discover any flues at all1 but a        
mechanical examination shows that the   
coping-stone has been put on them1      
making all the flues as thoroughly      
air-tight as the solid wall--more       
perfectly capped than that chimney4     
,there had been no attention paid to    
having the holes for the ventilating    
flues cut through the coping-stone4     
,yes1 ,i believe that to-day a large    
proportion of all those flues with the  
elegant ventilating registers at the top
 and bottom of the room1 are capped and 

made as thoroughly air-tight as the     
solid wall1 and are as perfect shams and
 as useless as the elegant frescoed     
ventilator on the solid wall of the     
church hospital in ,washington4  ,i do  
not believe that ,philadelphians have   
gone quite thus far in satisfying the   
public demand for ventilation in the    
public schools4 ,they may not have done 
any more1 but ,i believe they have not  
pretended to do quite as much4  ,excuse 
me a few minutes2 ,i must illustrate    
another very great deficiency4 ,the     
simple illustration ,i will give you    
represents almost the universal         
condition of our hot-air furnaces4      
,much complaint was made of the         
uncomfortable feeling in one of the     
large public schools1 where they had    
some #abjj or #aejj scholars4 ,i was    
called to examine it4 ,i asked1 as is my
 usual habit1 if they evaporated plenty 
of water4 ,oh1 yes2 they had given the  
janitor full directions about keeping   
the evaporating pans always full4 ,i    

found the evaporating pans full1 sure   
enough1 rather to my surprise1 but what 
do you think they were filled with8     
,several old brooms1 half charred1 and  
some old water buckets all fallen to    
pieces1 and other rubbish thrown in     
there out of the way4  ,and now those of
 you who have been trusting to your     
servants to keep water in your furnaces1
 if you will take a candle when you go  
home and go down and examine your own   
furnaces1 you will most likely find them
 dry1 and if you go to the public       
schools in the morning you will see that
 they too are not an exception4  ,i wish
 ,i had time to explain the dreadful    
effect of this want of moisture in all  
our artificially heated rooms4 ,the air 
in winter is very dry1 the moisture is  
squeezed out as the water is squeezed   
out of this sponge4 ,but as you heat it 
you enlarge its volume again1 and it    
sucks up the moisture just as this      
sponge does1 and if you do not supply   
this moisture in other ways it will suck

 the natural moisture from your skin and
 your lungs1 creating that dry1 parched1
 feverish condition so noticeable in our
 furnace and other stove-heated rooms4  
,few persons realize the great amount of
 water necessary to be evaporated to    
produce the natural condition of        
moisture corresponding with the         
increased temperature given the air in  
many of our rooms in winter4  ,i have   
copied a table expressing in grains troy
 the moisture contained in one cubic    
foot of air when saturated3             
,degrees     ,grains of vapor           
,fahrenheit4   in cubic foot4           
#aj             #j4h            #bj     
#a4c            #cj             #b4j    
#dj             #b4i            #ej     
#d4j            #fj             #f4j    
#gj             #h4j            #hj     
#aj4j            #ij            #ae4j   
#ajj            #ai4j  ,thus you see1   
taking the air at #aj deg4 and heating  
up to #gj deg41 the ordinary temperature
 of our rooms1 requires about nine times

 the moisture contained in the original 
external atmosphere1 and if heated to   
#ajj deg41 as most of our hot-air       
furnaces heat the air1 it would require 
about twenty-three times the amount in  
the external atmosphere4  ,this is a    
very interesting and important subject1 
but ,i am sorry ,i have not time for    
further explanation4  ,i see some kind  
friend has been around and opened the   
doors of our meeting-house and awakened 
the sleepers4 ,and now you see the      
lights shine1 and the cheeks glow as    
brightly as would those of our young    
ladies could they be persuaded to go    
skating1 or take a five mile walk every 
day1 rain or shine1 and sleep with the  
windows open1 and never ride in any of  
our cars1 or go to parties or any other 
public gatherings unless the buildings  
where they are held are well ventilated4
  ,but those dreadful drafts6 ,people   
will not bear them4 ,let us see if we   
can accommodate them4 ,put on the roof1 
and here comes this dreadful current    

again down the ventilating flue4 ,well1 
ventilating flues have the name of being
 great humbugs4 ,let us shut them up4   
,there are your poor consumptive        
patients--there they go1 you see4       
,one-half dead already1 and the rest    
will soon follow if we cannot rescue    
them4 ,let us open the flue again4 ,see 
how they brighten up as the fresh air   
comes in4 ,there is no use of disputing 
about it1 you must have a current of    
fresh air coming into the house or you  
will surely die4  ,now let us change the
 programme4 ,let us build a fire in this
 fire-place in the lower story--that    
burns up brightly4 ,where does it get   
fresh air from now8 ,there can be no    
current down the chimney4 ,let us search
 it out with this smoking taper4 ,ah1   
here it is coming down through the      
ventilator from the very top of the     
house4 ,we will soon stop that by this  
cap4 ,but see1 it still burns as        
brightly as ever4 ,let us try again4    
,ah1 do you see the smoke rushing down  

the second story chimney and across to  
the stairway1 and down the stairs1 and  
across the room again to this fire8     
,there is a valuable hint4 ,have you not
 noticed frequently gas in the room from
 the fire-place or stove1 and especially
 at night8 ,and do you see how easily it
 would be to account for it if the house
 were shut up tight at night1 with a    
large fire in the kitchen or furnace in 
the cellar1 and but a small fire in the 
second story8 ,don't you see how the    
whole products of combustion1 all the   
poisonous gases1 may be drawn out into  
the room8 ,you often notice accounts of 
whole families being smothered to death 
in one night1 but many seem to think if 
they are not smothered to death the     
first night1 that it is not so very     
dangerous after all1 and not knowing how
 to remedy it easily go on from day to  
day and sometimes escape the whole      
winter with a little of their lives     
left4  ,now1 let us put out the fire in 
the first story and make one in the     

second4  ,you must remember that this is
 not a fashionable double ceiled and    
plastered air-tight house4 ,it is much  
more open1 in proportion to its size1   
than any ordinary house4 ,and now1 as   
this lower flue has been so highly      
heated1 it may take some time for the   
fire in the second story fire-place to  
become heated sufficiently in excess to 
cause the air to draw down the longest  
flue to the bottom of the house and up  
the stairs to the second story          
fire-place1 but it will soon do it4  ,i 
wish you to notice one thing here       
particularly1 and each one apply it to  
your own particular case4 ,you know the 
lower part of the house is closed up    
tight to keep out the robbers1 and if   
great care is not taken to give an      
abundant supply of fresh air to your    
chambers otherwise1 it will be drawn up 
through the hall out of your kitchen and
 cellar1 and as the cook has left the   
range lid off and shut the dampers1 you 
will have a suffocating smell of gas all

 over the house4 ,but the worst danger  
of all is the air that may be drawn in  
from an untrapped sewer or cesspool4    
,this is a very common but great source 
of ill-health4  ,sanitarians have given 
much attention to this subject lately1  
and have been astonished at the         
magnitude of the evil4 ,i have long     
maintained that a family might go to the
 highest and most healthy location in   
the world1 and by a little carelessness 
might accumulate sufficient filth around
 them1 and by closing up the house at   
night and allowing the foul gases from  
untrapped sewers and cesspools to enter 
through the halls to their sleeping     
rooms1 to thus make what would otherwise
 be a healthy place a very unhealthy    
one4  ,as a case in point1 ,i would     
refer to a very interesting report of   
,doctors ,palmer1 ,ford1 and ,earle1    
giving an account of their              
investigations of the causes of a severe
 epidemic that occurred in the summer of
 #ahfd in a young ladies' seminary in   

,massachusetts4 ,the ,maplewood         
,institute is situated in ,pittsfield1  
one of the most beautiful of those      
charming ,new ,england villages1 which1 
to external appearances1 are the very   
emblem of all that is pure and healthy4 
,yet even in this lovely place1 from an 
ignorant or careless arrangement of the 
drains and cess-pools1 much of the foul 
gas generated there found its way into  
the building1#b making sixty-six out of 
seventy-four young ladies sick1         
fifty-seven of whom had the typhoid     
fever and thirteen died4 ,many similar  
cases are frequently occurring1 some few
 of which1 like this1 are carefully     
investigated1 and the causes removed4   
,many more1 however1 go unnoticed1 and  
are accepted as special dispensations of
 ,providence1 when it is all due to our 
own negligence4  ,i want to show you an 
arrangement that ought to be in every   
house4 ,we have seen the power of a fire
 to create a draft1 and if you will     
think a little you will notice that the 

kitchen fire is the most considerable   
and most permanent power in ordinary    
dwellings1 and this ought to be made use
 of to ventilate the kitchen1           
water-closet and bath-room in every     
house4 ,but you must not make an opening
 directly into the kitchen flue2 if you 
do you will interfere with the draft of 
the kitchen fire1 and if you interfere  
with the kitchen fire you will soon wish
 yourself at anything but keeping house4
  ,but we can easily get over that      
trouble4 ,we will use this square glass 
box again to represent a flue4 ,i don't 
mean this to represent the size--it     
ought to be twice that size4 ,in the    
centre we will put a cold pipe1 to show 
you that a pipe without any heat in it  
would only cause the foul air to tumble 
down into the room4 ,thus you see the   
smoke descending4 ,we will substitute a 
pipe with a gas light to heat it4 ,now  
you see what a rapid current there is   
out of this large flue4 ,see what a     
splendid arrangement this is for        

ventilating1 and it may be extended so  
as to ventilate the whole house4 ,it is 
not necessary that the room to be       
ventilated should be adjoining1 but a   
pipe can be carried between the floors  
#ej or #ajj feet4  ,i had an            
opportunity1 during the late war1 of    
thoroughly testing this system of       
ventilation in the government hospitals4
  ,let me say here that a very common   
mistake in making ventilating flues is1 
that they are entirely too small to be  
of any value4 ,one of these little      
,philadelphia flues1 four by nine       
inches1 made with rough bricks1 and     
nearly or entirely choked up with       
mortar1 as many of them are frequently  
found1 is of no account4 ,they are      
simply a deception1 and a perfect       
provocation to a sensible man4          
,illustration3 ,fig4 #ae4  ,i commenced 
by making some in ,washington1 for      
single wards1 thirty inches square1 but 
in ,st4 ,louis1 and ,louisville1 and    
,nashville1 where buildings four or five

 stories high were used for hospitals1  
,i made them much larger1 some three    
feet square and some four feet by six   
feet4 ,some buildings1 where the        
ventilation was so bad and the          
water-closets were so offensive that the
 government had to abandon them1 ,i had 
ventilated by these immense shafts1     
heated by the kitchen and laundry fires1
 which proved thoroughly efficient and  
entirely satisfactory4  ,i had hoped to 
have time to discuss the subject of     
heating more fully in connection with   
ventilation1 but cannot2 but ,i will    
state1 in the simplest manner1 a few of 
the leading points first4  ,you must    
have fresh air all the time4 ,in summer 
you can get it by opening the doors and 
windows4 ,in winter it must be warmed   
before entering the room4 ,it must not  
enter the room cold and flow across the 
floor to the other side before it       
reaches the heating apparatus4 ,you can 
bear a large amount of fresh air if it  
strikes you in the face and evenly over 

the whole body1 but never let a jet of  
cold air blow upon any small portion of 
your body4  ,to avoid these local       
currents sucking in at cracks1 you must 
make provision for the introduction of  
an amount of air larger than the sum of 
all these cracks1 and your exhaust flue 
besides4 ,this air must be partially    
warmed before entering4 ,if this is done
 by a hot-air furnace1 it must have a   
large fresh air box1 which should be    
from eighteen inches to two feet for a  
large house4 ,it should have a large    
evaporating vessel1 with a ball-cock to 
supply it4 ,you cannot get the servants 
to attend to it1 and you must never     
allow the air from your cellar to enter 
your furnace to be driven up stairs4    
,never allow the furnace to get red-hot4
  ,a hot water furnace disturbs the     
natural conditions of the air the least1
 and1 on that account1 is a very healthy
 means of artificially heating air4 ,but
 they are necessarily expensive1 and so 
few persons really appreciate the value 

of pure air1 that but few will go to the
 expense of introducing them4 ,it is a  
mistake to suppose that they do not dry 
the air1 so to speak4 ,you cannot       
elevate the temperature without         
increasing the capacity for moisture4 ,a
 hot water furnace1 therefore1 requires 
the artificial evaporation of water to  
give the warmed air its true hygrometric
 condition4  ,heating the air by steam  
is the next most healthy means2 as the  
surfaces used are heated a little       
hotter1 less of it answers the same     
purpose4 ,the first cost is therefore   
less4 ,it is the most rapid and         
convenient means of conveying heat to   
any distant point of anything now in    
use4 ,under the pressure of an ordinary 
boiler it will travel seven miles in one
 minute4 ,the time ,i hope is not far   
distant when the subject of heating and 
ventilation will receive an amount of   
attention due to its importance4 ,i     
believe then we shall have steam pipes  
laid through our streets1 the same as   

gas and water now are4 ,the present     
system of each man keeping up separate  
fires all over his house is as crude1   
and extravagant1 and unnecessary as it  
would be for every man to make his own  
gas or have his own well for water4     
,where a steam furnace is used1         
two-thirds of the heating surface should
 be put below the floor and fresh air   
brought into it1 and from there         
conducted to the rooms through large    
pipes4 ,this warmed air should be let   
into the room at the floor1 and an      
opening into an exhaust flue1 two-thirds
 the size of the inlet1 should be       
provided at the floor for the escape of 
the foul air4 ,the remaining one-third  
of the heating surface should be exposed
 in the halls and some in the other     
parts of the house1 to heat by direct   
radiation1 but under no circumstances   
should a room or office be occupied     
heated exclusively by direct radiation  
from exposed steam pipes4 ,it is one of 
the worst1 most unhealthy1 killing      

systems in existence4  ,steam furnaces  
require the evaporation of an additional
 amount of moisture as well as any other
 system of heating4 ,according to ,dr4  
,wetheral's investigation1 it would     
require the evaporation on some days of 
nearly forty pounds of water every      
minute in the ,senate ,chamber to       
maintain the proper hygrometric         
condition4 ,probably one of the very    
best arrangements is to have a good     
steam furnace1 with a large fresh air   
box letting in an abundance of air      
moderately warmed1 and overflowing the  
house with this1 and some direct        
radiation in the halls1 and a good1     
bright1 cheerful open fire in the family
 sitting-room4  ,but if you cannot have 
a steam or hot water furnace1 you can   
make a room very comfortable indeed with
 a stove1 if you will but introduce all 
the fresh air required for the room     
directly against or on top of the stove4
 ,no stove ought to be put up without   
having a supply of fresh air from the   

outside1 and a large evaporating vessel1
 kept constantly filled with water1 with
 an opening in the heated flue near the 
floor for the escape of the foul air4   
,in conclusion1 allow me to urge upon   
you to examine your furnace this evening
 or to-morrow morning1 and if there is  
no fresh air box communicating with the 
external atmosphere1 go to the nearest  
carpenter's shop before going to your   
business1 and get him to come at the    
earliest possible moment and put in a   
good large one1 and if he asks you where
 you want the damper in the cold air    
box1 tell him you don't want any4       
,dampers in cold air boxes are handy    
things to have in the house1 when used  
properly1 but1 like fire-arms1 are very 
dangerous if you do not understand them4
 ,yes1 dampers in cold air boxes and    
other contrivances for keeping the fresh
 air out of houses1 have killed more    
persons than all the fire-arms ever made
 in this country or any other4  ,if you 
have no evaporating vessel in the       

furnace1 stop at your furnace man's1 and
 tell him to put in two good large      
evaporating vessels in such a position  
that they will evaporate two or three   
buckets of water a day in cold weather4 
,and if you have a stove at your office1
 stop on your way down and buy a good   
large earthen pan to set on the top of  
the stove1 and keep it always full of   
water4 ,make a pipe for the inlet of    
fresh air to every stove over which you 
have any control1 and never remain in a 
room one day without a good opening at  
the floor for the escape of foul air4   
,and from my own experience1 and that of
 many others whom ,i know to have given 
much attention to this subject1 ,i can  
assure you1 with the fullest confidence1
 that you will be most amply rewarded   
for your care in this respect by        
increased health1 strength and          
happiness1 and by the reasonable        
prospect of a long life4                
,,ventilation4  ,,the ,,grand ,,prize   
,,awarded ,,at ,,the ,,paris            

,,exhibition4   ,added to the many other
 gratifying signs of a rapidly          
increasing interest in the all-important
 subject of the proper supply of pure   
air to our houses1 is the awarding of   
the grand prize of the ,paris           
,exhibition to ,dr4 ,evans1 for an      
,american sanitary collection4  ,the    
,sanitary ,commission1 during our late  
war1 acted upon the principle since     
expressed by the report of the ,board of
 ,health of ,new ,york4 ,they say3 ,and 
viewing only the causes of preventable  
diseases and their fatal results1 we    
unhesitatingly state that the very first
 sanitary want in ,new ,york and        
,brooklyn is ,,ventilation--ventilation 
supplied in all existing tenant-houses1 
work-rooms1 school-rooms and places of  
assemblage--and in all that shall       
hereafter be constructed4  ,the early   
recognition during the late war1 both by
 the ,sanitary ,commission and the      
government officials1 of the important  
fact that many more men are killed by   

breathing foul air than are killed by   
the enemies' bullets1 led them to use   
very active exertions to secure good    
ventilation in hospitals and camps1 and 
to teach the men themselves the value   
thereof4 ,the result has been highly    
satisfactory4 ,the fact that we must    
make some positive provision for a      
constant supply of fresh air to every   
occupied room1 and not rely on          
accidental cracks and openings1 is now  
very generally felt4 ,the simple1       
practical and efficient means used by   
the government has done much towards    
creating this wholesome public opinion4 
,the annexed plan 7excepting a stove and
 twelve beds1 omitted from centre of    
plan1 indicated by the space7 is a copy 
of one ,i furnished the ,committee2 and 
which was faithfully executed in        
preparing one of the models of          
hospitals1 the arrangements of which    
have been so highly appreciated1 and has
 shared one of the grand prizes at the  
,paris ,exhibition4  ,it is a           

representative plan1 showing the general
 arrangements of wards in a large number
 of the hospitals4  ,illustration3 ,fig4
 #a4  ,the special arrangements of      
flues1 ,v1 for winter ventilation1 and  
the introduction of the fresh air around
 the stove1 were not introduced into the
 hospitals in ,philadelphia1 built at   
the commencement of the war4 ,and the   
subsequent orders of the ,surgeon       
,general and ,quarter ,master ,general  
for the introduction thereof were       
protested against by the ,surgeons of   
,philadelphia1 owing probably partially 
to their proverbial objection to changes
 of any kind1 and partially to that     
dread of ventilation made but too       
popular by the many erroneous theories  
which propose to introduce the fresh air
 directly into the room1 and at times1  
too1 when it is even below the freezing 
point1 without first warming it4 ,these 
arrangements1 shown in the accompanying 
plan and section1 were thoroughly       
tested1 however1 in many of the         

hospitals subsequently built in many of 
the ,western cities4  ,the plan of ridge
 ventilation1 shown in the accompanying 
section1 ,i applied first in ,st4       
,louis1 in the summer of #ahfc4 ,it is  
the principle of the ,emerson ventilator
 applied to ridge ventilation4 ,much    
trouble had been experienced with other 
forms on account of their allowing the  
storms to beat in1 and the difficulty of
 opening and closing them with the      
various changes of wind2 this form fully
 remedies those objections1 and can be  
left open without inconvenience at all  
times while snowing or raining4 ,it uses
 the force of the wind1 whenever there  
is a current passing over the top of the
 building1 for sucking the air out of   
the ward1 because the air in passing    
across the top of the building is       
deflected from the straight line by the 
angle of the roof-board1 which creates a
 partial vacuum in the space below1     
which1 with the friction of the passing 
current with that coming out of the     

ward1 makes an outward draught1 varying 
in proportion to the velocity of the    
external current4 ,this is often very   
useful1 especially in summer1 when there
 is not sufficient difference between   
the external air and that in the ward to
 create a current4 ,there is often a    
considerable force in the passing       
current at the top of the building when 
there is much less below4               
,illustration3 ,fig4 #b4  ,but of course
 these openings had to be closed in     
winter to prevent all the heat from     
escaping4 ,it then became necessary in  
wards that had no fireplaces1 to make   
something as substitutes therefor4      
,wooden shafts or flues were made to    
answer this purpose4  ,i at first made  
large wooden boxes1 placing them in the 
centre of the wards1 and allowing them  
to extend down to within twelve or      
eighteen inches of the floor4 ,this was 
of great advantage1 but as the true     
principle of ventilation is to have an  
opening for the exit of the contaminated

 air at the feet of each occupant of a  
room1 or at the head of the bed of each 
patient in a hospital1 it was soon      
observed that these shafts were too few 
and far between to make a very perfect  
arrangement4  ,the necessity for        
providing for the escape of the foul air
 from the level of the floor in winter1 
so as to utilize the heat1 was1 after   
much opposition1 finally established and
 officially acknowledged by the         
government officers4 ,then arrangements 
were made for its introduction into the 
government hospitals in a more perfect  
manner4  ,i believe in no case1 however1
 was it so fully carried out as to place
 a ventilating flue between each bed1   
but in some they were arranged1 as shown
 7marked ,v7 in the accompanying plans  
between every other two beds4  ,these   
flues were carried together and extended
 through the ridge of the roof and      
capped as an ,emerson ventilator2 the   
opening into the large flue1 extending  
to just below the ceiling1 was closed in

 winter at all times1 excepting when the
 room was too warm4 ,this was for the   
exhaust1 but of no less importance was  
the supply4  ,the popular dread of      
ventilation arises in a great measure   
from the supposition that good          
ventilation implies a strong draught of 
cold air upon your back or feet or some 
other unfortunately exposed place4 ,such
 an unfortunate occurrence must be fully
 remedied in any system of ventilation  
before it can become popular4  ,as the  
simplest way of getting at this1 all the
 fresh air required to supply the       
partial vacuum created by the exhausting
 shafts was brought in around the       
stoves1 and partially warmed before     
entering4 ,at the first the stoves were 
entirely encased1 and the fresh air     
allowed to encircle them completely1 but
 experience soon demonstrated the       
desirableness of having a portion of the
 hot stove exposed for direct radiation1
 so that the feeble and chilly ones     
might come near to it and warm          

themselves4 ,there should always be a   
considerable amount of direct radiation 
in every hospital2 that from an open    
fire is the best1 but that from a stove 
or steam-pipe is very good4             
,arrangements were also made for the    
evaporation of a large amount of water4 
,as the first winter approached after   
the commencement of the war1 the idea   
seemed almost shocking to me of putting 
the sick and wounded men in such open   
barracks1 generally without plastering1 
and made1 as many of them were1 with    
rough boards and very open4  ,but       
experience soon taught me the very great
 superiority of these light and airy    
buildings over many of the elaborately  
finished1 dark1 air-tight structures1   
such as hotels1 colleges1 new-fashioned 
asylums1 c41 which the government was   
compelled to take for hospital purposes4
  ,in fact1 when completed with the     
ventilation as above described1 with the
 abundant sunlight on both sides1       
without any obstructing partitions and  

abundantly warmed in winter1 and with   
the proper supply of moisture1 they made
 undoubtedly the most comfortable and   
wholesome class of buildings1 as a      
whole1 that have ever been erected for  
hospital purposes1 not excepting even   
many of the recent elaborately finished 
buildings1 where not unfrequently too   
much dependence has been placed on the  
very meagre and insufficient effect     
produced by attempts at artificial      
ventilation1 instead of relying more    
upon the great natural means of         
ventilation--an abundance of large open 
windows1 open fires and good ventilating
 stoves4  ,the ventilation of the       
latrines or water-closets of a hospital1
 as well as any other place1 is a matter
 of great importance4  ,in the spring of
 #ahfc1 ,i had put up in a hospital in  
,washington a ventilating shaft for the 
latrine room1 similar to the one shown  
on the plans4 ,this was an experiment1  
but it proved so satisfactory that it   
was subsequently ordered to be applied  

in all the principal hospitals4  ,the   
difficulty in the isolated wards was1   
that it required a separate fire in each
 shaft in the summer4 ,where it is      
possible to get it near the kitchen or  
bake-oven fire1 that answers a splendid 
purpose2 but in the single wards it is  
not necessary to keep up a constant     
fire2 a few sticks of wood every morning
 answer the purpose of keeping the air  
in the shaft warmer than the surrounding
 atmosphere1 which1 of course1 creates  
the proper draught4  ,these shafts were 
made very large--never less than thirty 
inches square and sometimes three feet  
by six feet4 ,the popular plan of       
opening the water-closet windows and    
allowing much of the fresh air to enter 
the building that way was strenuously   
avoided2 the windows in the closet were 
fastened shut1 and then the air to      
supply this large exhaust shaft was     
drawn from the adjoining ward or room1  
which ventilated that ward and prevented
 any unpleasant odor from the closets   

returning into the ward4  ,wherever it  
was possible1 a sheet iron or cast iron 
pipe was carried up into the centre of  
this shaft from the kitchen1 laundry1   
bakery or any other constant fire1 and  
where no heat from a permanent fire or  
from a steam coil could be obtained1 a  
small stove for the purpose was         
provided4                               
,,lewis ,w4 ,,leeds1                    
,germantown1 ,pa4  #gth mo4 #bfth1      
#ahfg4     ,the subjoined are a few of  
the ,letters received from prominent    
,sanitarians and others4                
,office of the ,superintendent of       
,health1                                
,providence1 ,august #e1 #ahfg4         
,friend ,leeds4      ,your ,lectures on 
,ventilation have been received4 ,i am  
much     interested in them1 and think  
the views given are correct4 ,i     hope
 they will be widely circulated4 ,too   
much cannot be said to     the people   
upon the subject4      ,ventilation is  
all-important4 ,indeed1 ,i think that if

 the air     could be constantly kept in
 motion1 the worst sources of impure    
air in our cities would be rendered     
almost free from danger4      ,in       
seasons of epidemic cholera1 the most   
oppressive feature of     danger is the 
stagnation which exists in the          
atmosphere4 ,there     was good sense   
and true philosophy in the old custom of
 burning     bonfires to keep off       
disease4 ,i must close1 wishing you much
     success in your efforts to awaken  
the people to the importance     of this
 subject4      ,truly yours1            
,,edwin ,m4 ,,snow1 ,m4 ,d41            
,superintendent of ,health4         99  
99       99       99       99           
,bangor1 ,maine1 ,august #bc1 #ahfg4    
,my ,dear ,leeds4       ,your pamphlet  
was duly received4 ,i have read it with 
much interest1     and believe it to be 
worthy of extended circulation4 ,it is  
the     clearest paper on the subject ,i
 have yet read4                         
,yours1 in haste1 ,a4 ,c4 ,,hamlin1 ,m4 

,d4         99       99       99        
99       99                             
#fd ,madison ,avenue1 ,new ,york1 ,aug4 
#bc1 #ahfg4      ,my ,dear ,friend4     
,i have just read your ,lectures on     
,ventilation1 and ,i am very     much   
obliged to you for the entertainment and
 instruction they     have given me4    
,you have very happily hit upon a style 
which is     neither flippant nor dry4  
,i am sure the lectures will be read1   
and if read1 they will do a great deal  
of good4      ,i have all my life been  
talking and writing in this direction1  
imploring the people to take less       
medicine and more pure air2     and ,i  
feel truly grateful for the help your   
strong shoulders have     given me in   
what has thus far proved to be a labor  
of ,hercules4      ,your particular     
method of ventilating buildings ,i had  
many     opportunities of proving while 
,i was ,medical ,inspector     ,u4 ,s4  
,a41 and ,i assure you that no plan was 
ever more simple     and                

inexpensive--none could have been more  
effective4 ,indeed1     ,i may say that 
,i never knew it to fail4      ,to you1 
therefore1 ,i fully believe the country 
is indebted for     the lives of many   
thousands of men4      ,with sentiments 
of esteem1                        ,i    
remain yours truly1                     
,,frank ,h4 ,,hamilton1 ,m4 ,d41        
,prof4 ,principles of ,surgery1         
,military ,surgery1 ,hygiene1 c41       
,bellevue ,hospital ,medical ,college1  
,n4 ,y4               ,author of ,work  
on ,fractures and ,dislocations1        
,treatise on                            
,military ,surgery1 c4      ,l4 ,w4     
,,leeds1 ,esq4         99       99      
99       99       99                    
,office of the ,metropolitan ,board of  
,health1                                
,no4 #cja ,mott ,street1                
,new ,york1 ,august #bfth1 #ahfg4       
,friend ,leeds4      ,your ,lectures on 
,ventilation have given me much         
pleasure1 and     have renewed my       

confidence in the utility of popular    
instruction     upon the subject4 ,i    
heartily thank you for the thoughtful   
care     with which you have set forth  
all the essential principles of         
ventilation1 in language so free from   
technical words1 and so full     of     
plain and homely illustration1 that even
 an uneducated reader     can fully     
understand all you have written4 ,the   
good ,dr4 ,d4 ,boswell     ,reid1 ,dr4  
,wyman and myself had each attempted to 
use such a style     of explanation and 
instruction2 but you have far excelled  
us all4      ,the first want of every   
living being is fresh air1 and unless   
the     human lungs are supplied with   
such air constantly at the rate of      
from ten to thirty cubic feet every     
minute1 by night as well as     by day1 
perfect health and vigor cannot be      
preserved4 ,then1 too1     there are    
exhaled from the surface of the body and
 from the lungs1     such quantities of 
waste organic matter1 which tend to     

immediate     putridity1 that it1       
together with the carbonic acid1 would  
keep     the human body immersed in a   
deadly vapor of these exhalations1      
were not fresh air supplied4 ,the       
illustrations by which you have     made
 these truths easily understood1 are    
admirably given in your     lectures1   
and the method1 by which you would best 
insure success     in removing the foul 
and supplying the pure fresh air in     
every     place where persons live or   
sleep1 are1 as ,i believe1 from my own  
careful studies of this subject1 most   
correct and trustworthy4     ,indeed1 ,i
 am able to say that1 in my examinations
 of the vast     number of hospitals and
 buildings which you ventilated during  
the late war1 under authority from the  
intelligent and humane                  
,quartermaster-,general of the army1 the
 proof of entire success     in your    
work was everywhere witnessed4          
,simplicity1 invariable     certainty   
and a liberal sufficiency characterizes 

these admirable     methods of yours4   
,i wish every family in the land had a  
copy of these lectures4      ,sincerely 
yours1                                  
,,elisha ,,harris1 ,m4 ,d41             
,corresponding ,secretary ,metropolitan 
,board of ,health4      ,to ,,lewis ,w4 
,,leeds1 ,esq4         99       99      
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,,vaux1 ,,withers  ,co41 ,architects1   
,no4 #aaj ,broadway1 ,new ,york1 ,august
 #bgth1 #ahfg4      ,dear ,mr4 ,leeds4  
,i am glad to receive your ,lectures in 
printed form1 and trust     that they   
may be widely read throughout the       
community4      ,having been in the     
habit for several years past1 of        
consulting     with you professionally  
in regard to the arrangements to be made
     for heating and ventilation in     
plans for public and private            
buildings1 ,i take this opportunity to  
acknowledge the value     of the aid    
thus given2 and as ,i feel assured1 from
 a lengthened     personal experience1  

that your thorough knowledge of the     
subject1     both theoretically and     
practically1 is calculated to render    
your     assistance particularly        
valuable in the adjustment of complex   
and intricate plans1 ,i trust that one  
result of the circulation     of your   
interesting pamphlet may be to introduce
 you more widely     to members of the  
architectural profession4      ,i       
remain1 ,dear ,mr4 ,leeds1              
,yours faithfully1                      
,,calvert ,,vaux4      ,,lewis ,w4      
,,leeds1         ,heating and           
,ventilating ,engineer4         99      
99       99       99       99           
#aaj ,broadway1 ,new ,york1 ,aug4 #cjth1
 #ahfg4      ,mr4 ,,lewis ,w4 ,,leeds   
was employed early in the war of the    
rebellion     by the ,sanitary          
,commission1 as an agent to urge the    
necessity to     the health and strength
 of the army1 of the thorough           
ventilation     of tents and quarters1  
and to devise and suggest to the proper 

officers the adoption of the best means 
for this purpose4      ,at a later      
period of the war1 at the suggestion of 
the ,commission1     the                
,quartermaster's ,department engaged his
 services1 and gave him     large       
discretionary powers for the ventilation
 of hospitals4 ,he     was thus employed
 during all of the war1 with great      
advantage1     and the improvements     
which he brought about were             
unquestionably     the means of saving  
thousands of lives4 99 99 99 99         
,mr4 ,leeds has a special talent for    
making improvements in houses of        
ordinary construction1 by means which   
may be readily adopted1 and     with    
materials which may be anywhere procured
 without difficulty     or great        
expense4      ,mr4 ,leeds' course of    
lectures on ,ventilation is calculated  
to     supply instructions of great     
practical utility4 ,an invaluable       
addition to the health1 happiness and   
wealth of the nation     would result1  

if they could be delivered before every 
school in     the country4              
,,fred4 ,,law ,,olmsted1                
,first ,general ,secretary of the       
,sanitary ,commission4         99       
99       99       99       99           
,treasury ,department1                  
,office of the ,supervising ,architect1 
,sept4 #aath1 #ahfg4      ,my ,dear     
,friend4      ,your valuable ,lectures  
on ,ventilation have been received1 and 
have     been read with much pleasure1  
more especially as you are about     the
 only person ,i have ever met1 who1     
after making the ventilation     and    
heating of buildings a specialty1 has   
condescended to follow     the laws of  
nature1 and provide the means of        
adapting them to our     artificial     
modes of life4 ,your lectures show a    
thorough study     and knowledge of the 
principles involved1 which are1 like all
     natural principles1 very simple if 
once understood4 ,i have also     to    
take this means of acknowledging the    

valuable aid that ,i have     received  
from you on many occasions1 and to      
express a hope that     you will not    
despair1 but relying on the adage that  
truth is     mighty c41 go on with your 
exposures of the absurdities of the     
complicated and costly humbugs that are 
so fashionable at present1     and trust
 you will succeed not only in your      
missionary labors1     but find them    
pecuniarily profitable4      ,very      
respectfully1                           
,a4 ,b4 ,,mullett1                      
,supervising ,architect4      ,,lewis   
,w4 ,,leeds1 ,esq41     ,engineer       
,ventilation and ,heating1              
,germantown1 ,penn'a4         99        
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,,footnotes4  ,footnote #a3 ,i mean     
merely pecuniarily--in dollars and      
cents2--the cost in physical pain and   
mental anxiety1 of course1 cannot by    
computed in dollars and cents4          
,footnote #b3 ,in addition to which     
there appeared to be a deficiency in the

 arrangements for ventilation4