532 



AGRICULTURAL ENGINEERING 



excreta. The first of these is the all-important purpose; for 

 no animal can live more than a few minutes without air, but 

 is able to go for some time without either food or water. The 

 quantity of air breathed daily by an animal greatly exceeds 

 the total quantity of food and water. This is indicated by the 

 following table: 



Amount of air breathed by different animals. 

 (Collins Table.) 



To maintain the standard set by Professor King, which 

 requires that the air at no time shall contain more than 3. 3 

 per cent of air once breathed, the following amounts of air will 

 be required each hour for the various animals indicated. 

 This standard may be stated as 96.7 per cent, representing 

 the purity of the air, and, as before stated, it is equivalent to 

 between 16 and 17 parts of carbon dioxide per 10,000 parts 

 of air. 



Amount of air required per hour to maintain a standard of 96.7 per 

 cent. 



Horses. . 4296 cu. ft. per head 



Cows 3542 " " 



Swine 1392 " " 



Sheep 917 " " 



Hens 35 " " 



Man 537 " 



Ventilation finally resolves itself into the problem of find- 

 ing a process of dilution or mixing the air in the building with 



