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.) 





Per hour 



Per 24 houra 





Cu. ft. 



Pounds 



Cu. ft. 



Horse 



141.7 



272 



3402 



Cow 



116.8 



224 



2804 



Pig 



46.0 



89 



1103 



Sheep 



30.2 



58 



726 



Man 



17.7 



34 



425 



Hen 



1.2 



2 



29 



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 g6.y 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 



