No. 4.] BARN BUILDING. 175 



jection to large areas of glass in the stable is the rapid cooling and 

 condensation on verj' cold nights, and this can be largely overcome 

 by the use of double glazed windows. 



Ventilation. — It is stated on good authority that the cow needs 

 to be supplied with twice the weight of pure air that she does of 

 food and water combined. The good feeder tries to furnish as much 

 good food and water as the animal can use to advantage. If the 

 best results are to be obtained, the same policy must be followed 

 with reference to pure air. The problem of furnishing this pure air 

 during the winter months without lowering the temperature of the 

 stable enough to decrease the milk flow has brought into use several 

 systems of stable ventilation. Each system has its advantages, and 

 the best one for any particular instance depends somewhat upon 

 local conditions and the kind of building. Whatever system is 

 adopted, it should be remembered that the warm air in the stable 

 rises to the ceiling. This may be taken advantage of for two pur- 

 poses : first, to warm the incoming air, and second, to cause a 

 draught in the out-take flue. The best results are obtained in any 

 system when the fresh air is taken in through a number of small 

 openings scattered through the different parts of the stable, and 

 when the out-take flues are few in number and of large size. If the 

 incoming air can be brought in near the ceiling and dropped through 

 the warm air that is always present, it will be an additional adva,n- 

 tage. Ventilating flues, especially the out-take, should be tight and 

 well built in order to give the best service. The out-take flue should 

 not be placed where it will be too easily chilled, as this will decrease 

 the rapidity of flow through the flue. It should not be placed be- 

 tween the rafters ; if necessary to follow the roof line, a tight wooden 

 flue should be built below rather than between the rafters. Well- 

 built ventilating flues under ordinary conditions will allow the air 

 to pass through at the rate of about 300 feet per minute without 

 mechanical forcing and without the aid of heat other than that 

 derived from the animals in the stable; 3,500 cubic feet per hour 

 per 1,000 pounds of live weight is usually considered about the 

 amount that should be supplied to dairy cattle. This is based upon 

 the assumption that a thousand-pound cow will breathe 2,804 cubic 

 feet of air in twenty-four hours, and that it is not desirable that 

 the air in the stable contain more than 3.3 per cent of air once 

 breathed. It has often been stated that the carbon dioxide thrown 

 off from the lungs which is detrimental if breathed again, settles 

 to the floor. It is a well known fact, however, that when different 

 gases come together a diffusion or mixing begins to take place at 

 once, and this probably happens in the stable. Recent tests re- 

 ported to the writer indicate that this is the case, and that the carbon 

 dioxide is fairly well diffused throughout the stable. 



