FARM SANITATION 221 



healthy cows have tuberculosis aud in many places 

 where milk is sold to cities the cows are examined 

 and tested for this disease. 



Ventilating the Barn. The average barn is not 

 very tightly built and plenty of air enters for the 

 stock through the cracks, but the newer barns are 

 now built tight and warm, and in this case some 

 means should be planned to ventilate, because bad 

 air is the cause of the spread of tuberculosis among 

 cows as well as among the human family. Window 

 ventilation is far better than none, but the cold draft 

 should not strike the cows and other stock. (Fig. 

 107.) 



Cold Air Heavier than Warm. Every boy and 

 girl knows that cold air is heavier than warm air 

 and so the warmest air in the room is always near 

 the ceiling. One reason smoke goes up the chimney 

 is because it is carried up by warm, light air, while 

 heavy, cold air is crowding in to take the place left 

 by the warm air. 



Best Barn Ventilation. The best way to ventilate 

 any building, home, school, or barn that must be 

 kept warm is to take out the colder air near the 

 floor instead of the warm air near the ceiling. For 

 this purpose there should be an air shaft leading 

 from near the floor to the roof to carry out the air. 



Home Ventilation. The best way to heat and 

 ventilate a homo is probably the hot-water system, 

 placing the radiators in each room near the wall. 

 Behind each radiator is an opening through the 



