632 
VENTILATION. 
thirdly, that from his lungs and skin he will add to this 
about 14 pounds 9 ounces of aqueous secretion ; I think 
we may proceed on to a further consideration of the details 
mentioned in the introduction of this paper, viz., the quan¬ 
tity of air vitiated by a single horse, and the quantity re¬ 
quired per diem to keep him in a healthy condition. 
You are doubtless aware that of so much importance to 
the community at large has been the subject of ventilation 
considered, that a few years ago the attention of the legisla¬ 
ture was directed to the matter. 
Their discussions led to the appointment of a commission 
to inquire into the warming and ventilation of dwellings. 
It would, however, be impossible for me in a paper like the 
present to do justice to their reports, or place before you the 
series of experiments by which they have been guided in 
their conclusions. They have proved themselves able pioneers 
in the cause of science, and all I can do is to follow the track 
they have traced, and show you how, from their observations, 
we may arrive at a sanitary regulation for the protection of 
those animals committed to our charge, and direct your 
attention to a few extracts from the reports themselves which 
contain matter bearing upon this portion of our subject. 
In their remarks on the amount of fresh air required by a 
man. thev state— 
“ We began the work by endeavouring to ascertain ap¬ 
proximately the amount of fresh air required to keep a 
sleeping-room healthy. Various attempts have been made 
at different times to settle this amount scientifically, but 
nearly every experimenter has arrived at a different estimate 
of the quantity. These differences in opinion have arisen 
from not sufficiently considering the various offices alreadv 
mentioned which fresh air has to perform in the ventilation 
of human dwellings, and from not looking at the practical 
rather than at the scientific side of the question/” 
(e One set of experimenters have based their calculations on 
the quantity of air required to dilute the carbonic acid pro¬ 
duced by respiration down to the proportion in which that gas 
exists in the external atmosphere. Other experimenters have 
taken the amount of air required to dissolve the aqueous 
vapour escaping from the skin and lungs; and to diffuse it so 
as to raise the hydrometric state of the air to the same healthy 
standard as that of the outer atmosphere.” 
“The estimates are hence very various, and differ to the 
extent of two, three, or four times, as to the amount of air 
required for health, a difference which proves how little is 
yet known scientifically on the subject.” 
