VENTILATION 117 



There should be a number of medium-sized or even small 

 windows in this system, rather than a few large ones. The 

 same amount of air can be allowed to enter through the small 

 openings without direct draft and with much better distribution. 



For large and expensive stables there are systems of ventila- 

 tion based upon Prof. King's work. Competent architects 

 should be consulted concerning the plans or the Division of 

 Agricultural Engineering at your state agricultural college. 



Amount of ventilation needed. — The horse passes about 45 

 cubic feet of air through the lungs per hour. This, then, would 

 be the amount which the average horse would use if he were 

 out in the open where the supply is inexhaustible. It is impos- 

 sible to have the air of any occupied stable as pure as the out- 

 side atmosphere. The purpose of ventilation is to come as near 

 to this point as may be feasible. 



Air passing at the rate of 3 miles per hour, which is barely 

 perceptible, through total openings equal to 1 foot square, ad- 

 mits 15,840 cubic feet per hour. Inlet openings amounting to 

 4 square feet admitting a current of air moving at the average 

 rate of 3 miles per hour under average weather conditions are 

 estimated to provide sufficient ventilation for 20 cows. 



The following data will serve as a general guide : 



RELATIVE AMOUNT OP AIR BREATHED 



Horse 100 



Cow 82 



Hos- 32 



Sheep 21 



AIR NEEDED PER HOUR (King) 



Horse -^290 cubic feet 



Cow 3o42 " " 



Ho- v.m " " 



Sheep 917 " " 



Hen 35 " " 



Professor Stewart, University of Minnesota, has worked out 

 the following useful data for low outside temperatures : 



The amount of air that should be pi-ovided per cow ])or hour 

 is estimated by Stewart as follows: At — 10° F, 1800 cul)ic feet; 

 at 0° F, 2400 ; at + 10° F, 3000. This assumes an indoor tem- 

 perature of 35° to 37° F, and a stable of average construction. 



