42 



Sheringham valve or window opening inward. * 



One way to remove the foul air is to construct round galvanized 

 iron or even wooden shafts, the latter made of tightly fitted matched 

 boards. The interior opening of the shafts should be about a foot 

 from the floor with a flap near the ceiling to be opened or shut 

 as required ; the exterior opening should be several feet above the 

 highest point of the barn roof. The shaft should contain a damper 

 to regulate the outgo. It is difficult without having a particular 

 stable in mind, to give specific directions concerning location, or the 

 number and size of shafts. In general it may be said that one 

 large flue will prove more effective than several small ones ; this 

 arrangement, however, must be governed somewhat by the form of 

 the stable. Allowing some 400 cubic feet of air space for each 

 animal, a flue 2 by 2 feet, inside measure, should change the air 

 sufficiently often for a stable containing 20 cows. Whenever the 



* From Experiment Station Work, \'ol. II, No. 4. 



