354: 



Rural Architecture. 



438, Amount of Air Used Compared with Feed and 

 Water. A 1,000-pound cow requires daily the equivalent 

 of about 30 Ibs. of hay and grain and 70 Ibs. of water or, 

 in round numbers, 100 Ibs. per head and per day of solid 

 and liquid food. 



A cubic foot of air weighs about .08 Ibs. hence, from 

 the table in (437), we have 



2804 X -08 Ibs. = 224.32 Iba. 



which shows that a cow needs to be supplied with twice 

 the weight of pure air that she does of food and water com- 

 bined. 



439. Degree of Impurity of Air Permissible. We are yet 



without sufficiently exact data to permit this problem to 

 be concisely seated for stables used for domestic animals. 

 In absence of exact data and in view of the unavoidable 

 leakage of air through the walls and about windows and 

 doors we have arbitrarily assumed that if the air is changed 

 in the stable ait such a rate that it at all times contains no 

 more than 3.3 per cent, of air once breathed fairly good 

 ventilation would be provided. 



440. Rate of Supply of Air to Stables. On the basis of 

 (4C9) the number of cubic feet of air per head and per 



