3 
cc Where respiration is performed naturally, 
there are about 18 respirations in one minute, 
1080 in the hour, and 25,920 in the 24 hours ; 
and that by each respiration a pint of air is sent 
into the lungs, that is 18 pints in a minute, or in 
the hour more than two hogsheads, and in 
the twenty-four hours more than 57 hogs- 
heads, the effect impurity may produce 
is evident. When the body is in a state 
of health, there will be 72 pulsations of the heart 
in a minute. Every pulsation sends to the heart 
two ounces of blood. Thus, 144 ounces are sent 
for purification to the lungs every minute. In 
one hour there are sent (1450 pints ; in 24 hours, 
nearly 11,000 pints. The blood performs a com- 
plete circuit in the system in 110 seconds. These 
figures show how great is the need for the air we 
breathe to be pure and wholesome.’’ 
Now it must be evident that until those causes 
which vitiate the air be removed, ventilation re- 
mains an impracticable scheme ; and the faster 
the streets get the yawning gaps filled in with 
building, the more difficult it becomes to venti- 
late, for wherever there is a cul-de-sac formed by 
clbsely erected houses, there will hang the germs 
of typhus and influenza ready to germinate when- 
ever their time comes. I have also been more 
anxious to bear upon this branch of my subject 
since reading the report of the New South Wales 
Government on the state of the working classes, 
which gravely sets forth that most of the degra- 
dation, illness, and misery of those classes arise 
froin the ill-ventilated drains, neighborhoods and 
dwellings where they reside, and urges upon the 
Executive the necessity of reforming the deplor- 
able state of their homes. 
Having, as far as I was able, without entering 
into the minutiae of drainage, cleared away the foul 
ah outside of our dwellings, it is necessary now to 
to walk inside and renovate them ; we therefore 
now come to the second proposition, viz, : The 
supply of pure untainted atmospheric air. The 
principal cause of bad air in rooms is the reten- 
tion of the expended air from the lungs, that is, 
the carbonic acid, which is, you all know, a heavy, 
colourless, inodorous gas, incapable of sustaining 
combustion, or respiration. Now the function of 
ventilation here is to dispel this gas. In its hot 
state, as it emerges from the nostrils, it is com- 
paratively light, and has a tendency to rise, 
whereas, as soon as cool, it falls like lead through 
the pure air, hence so many schemes of ventila- 
tion have been tried with a view to catching the 
warm gas and delivering it to the all-absorbing 
atmosphere : hence have arisen syphon ventila- 
tors, valve ventilators, revolving ventilators, and 
a host of others. Now there are certain subordi- 
nate conditions in ventilating, that require no 
mean consideration, in reference to the prevailing 
state of the atmosphere, and here the aspedt of the 
building has an important' influence. There 
may be long prevailing winds, and these may be 
in many directions and of various temperatures ? 
under such circumstances ventilation may be 
overdone. 
Again, there may be a dead calm, close and 
sultry ; this doubtless is the time of all others 
when the want of ventilation is unmistakeably 
felt. Certainly under such circumstances no 
other than some mechanical aid can sweep away 
the effete, sluggish, and noxious gases. It is in 
crowded churches, balls, and assembly rooms, that 
this state of the atmosphere becomes so fearfully 
oppressive, and I^would state, as my opinion, that 
in such a case no building enclosed by walls after 
our usual manner could be thoroughly and satis- 
factorily ventilated. The only way ito overcome 
such a difficulty would be to have winter halls 
and summer halls, and thus regulate ths wind. 
The following plan has been adopted in ventila- 
ting some schools, which were of course supposed 
to accommodate only a restricted number : — 
“ The supply of fresh air to the school is from 
the heating chambers (as they may be called) 
connected with the stove ; and that the fresh air 
therefore enters the rooms at a very high temper- 
ature, far higher than that of the vitiated air 
ascending from the children. The consequence 
is, that a large volume of fresh air, thus rendered 
specifically lighter than the vitiated air, is con- 
. tinually rushing up into the upper part of the 
room, and as it cools, descends till it meets with 
and greatly dilutes the much smaller volume of 
vitiated air that is generated in the room. So 
considerable is this dilution that the air breathed 
by the children in a school warmed by this 
apparatus is found to be sufficiently pure for 
health and comfort, and, in fact, as pure as we 
can probably hope to obtain it in a closed build- 
ing” 
It will be observed that in this plan no air is 
admitted into the chamber but through the 
heating apparatus, a case that would by no means 
answer in every state of the atmosphere. 
Before I conclude I will give an outline of a 
system of ventilation which lias been adopted on 
the continent and which to my mind is the most 
complete that has ever yet been tried. But it 
appears only feasible when applied to the parti- 
tic ular case, viz : the hospital with its stated 
number of inmates ; and who shall tell what 
humane results shall follow from its general intro- 
duction. 
1 would here state in few words what I 
conceive to be the simplest and most efficient 
means of freeing our own chambers and churches- 
of their vitiated air as they are, and v.ith the 
means at our command. I have gone into the 
necessity of outside drainage rather lengthily, 
and spoken of the utter hopelessness of its ever 
being accomplished without a running stream of 
water. But we can rid our chambers of foul air 
by having the floors perforated in different places, 
so that should the carbonic acid fall cold to the 
