136 PRINCIPLES AND PRACTICE OF MILK HYGIENE 
of glass and 2 square feet of cloth for each 1000 pounds of 
animal weight is a good proportion. When the air is still, a 
stable ventilated by means of muslin-covered windows will not be 
more than 1 to 8° F. colder than stables in which the King 
system is used, and there will be 7 to 10 per cent. less humidity 
in the stable air; but when high winds prevail, the animal heat 
will be rapidly dissipated and the stable will be colder. If the 
cloth becomes wet and freezes, ventilation will cease. 
(b) Cubic Air Space——This is determined by meas- 
uring the length and width of the stable, multiplying the 
length by the width, and then multiplying the result thus 
obtained by the height of the ceiling. After the total 
cubic feet of air space has been ascertained in this manner, 
the stanchions or ties should be counted and the total 
cubic feet of air space divided by the number of 
stanchions. The result will be the cubic feet of air space 
per animal. The number of stanchions or ties should be 
used for this purpose instead of the number of animals 
present because this method will give the minimum cubic 
feet of air space per animal under all conditions. 
The size of a stable in proportion to the number of 
animals in it bears an important relation to ventilation. 
The less air space per animal the more frequently the 
air in the stable must be changed. The heat given off by 
animals is only sufficient to warm a certain quantity of 
air, and if this limit is exceeded the stable will be cold in 
winter. A stable with insufficient cubic air spaces will also 
be hot and uncomfortable in summer. 
It is desirable to have 1 cubic foot of air space for 
_ each pound of animal weight, but this amount cannot 
always be provided because of the cost of building mate- 
rials and for other reasons. With suitable arrangements 
for ventilation, 500 to 600 cubic feet of air space per cow 
