VENTILATION. 
635 
The answers, then, to our preliminary questions, viz., 
What is the quantity of air vitiated by a single horse ? and 
what quantity will he require in a given time to keep him in 
a healthy condition?—will be as follows : 
By respiration, 2000 cubic inches per minute; pulmonary 
and cutaneous transpiration, fifteen cubic feet per minute; 
by other means, faecal, urinary, &c., one cubic foot. That 
he also requires a space of not less than 2000 cubic feet, and 
the air of that changed not less than three times during the 
hour. 
Pass we on now another step in our deliberations, and 
consider how this desirable result is to be obtained. 
It has been proved by experience that all animals in their 
natural climate require very little more than food and shelter 
to preserve them in a healthy condition. As, however, it is 
considered that stables are absolutely necessary for their 
maintenance, it is requisite that we should consider how a 
proper system of ventilation in them is to be maintained. 
It would, I think, be out of place, nor could I within the 
reasonable limits of a paper like the present present to you 
even a faint outline of the various plans that have been sug¬ 
gested and put into operation to carry out this great work. 
With many of them you are already well acquainted, and are 
probably convinced that our present system of ventilation is 
defective. 
It will be better, therefore, if we confine our discussion to a 
fe\v simple plans, necessary to ensure the amount of ventila¬ 
tion required. 
It is a well-known fact that atmospheric air, like water, is 
governed by certain known laws, and that its ingress and 
egress into rooms and stables can be regulated by certain 
conditions. And it being now generally admitted that it is 
injurious to health to place any rooms or dwellings over 
stables, I shall assume, in the observations that I am about 
to make, there will be none. 
The first question that arises is, how can the atmosphere 
rendered unfit for the purpose of respiration be resupplied, 
and how is the vitiated air to find an escape? 
As is well explained by Dr. Pickford, respired air, being 
specifically lighter than pure, cold atmospheric air, ascends 
with the heated effluvia towards the ceilings and upper parts 
of dwelling rooms and sleeping apartments, where it becomes 
condensed and subsequently descends, commixes with, and 
contaminates equally, in accordance with the laws of diffusion 
of gases, the whole air of the room. A portion escapes by 
the upper part of the closed doors, and by the crevices and 
