60 DISEASES OF CATTLE, SHEEP, GOATS, ETC. 



most rapid in rooms that have the greatest amount of wall-space ex- 

 posed to the free outside atmosphere. 



A third natural aid to ventilation is the wind. When the fresh 

 air inlets are on the windward side of the building, there will be no 

 question about plenty of ventilation. But when the wind blows from 

 the side opposite the inlets, there is little or no ventilation. To make 

 free use of the wind, therefore, it is necessary, either to have inlets at 

 all sides of the buildings, or to have inlets that always face the wind. 



Under the second head, namely, distribution of fresh air in the 

 stable, it is necessary to admit the air directly into the stable through 

 a number of small openings rather than one large opening. 



The third point, namely, temperature, constitutes a great diffi- 

 culty in the ventilation of stables in winter. To introduce fresh cold 

 air into a stable at any considerable rate and to draw off warmer air, 

 necessarily cools the stable, and may cool it below the point of com- 

 fort and safety. Without artificial heating, the only safeguards 

 against a temperature too low are: (1) A crowded stable, in which the 

 animal heat given off is sufficient to warm large quantities of incom- 

 ing air; hence the amount of ventilation may be, as it should be, in 

 proportion to the number of animals in the stable. (2) A naturally 

 warm, tight stable, which allows but little cold or drafts to enter the 

 stable, other than by ventilating arrangements. (3) Shut-offs in 

 the inlet and outlet pipes, so that the amount of ventilation can be 

 controlled according to the temperature of the incoming air, the prin- 

 ciple being to get as much fresh air as is consistent with a proper sta- 

 ble temperature between 35 and 45. (4) A sub-earth duct, by 

 means of which the fresh air, before being admitted to the stable, is 

 carried for some distance through an underground pipe, 6 feet deep 

 or more. The earth temperature at that depth being much higher 

 than that of the outside air, the air is warmed in passing through 

 the duct, and enters the stable at a much higher temperature than it 

 would if admitted directly. (5) Provision for drawing off the foul 

 air at the floor, as an alternative to ceiling outlets. With floor outlets, 

 the air drawn off is colder than that drawn off at the ceiling, and 

 hence the stable is not chilled so much. Ceiling outlets, however, en- 

 courage a more rapid ventilation, and it is therefore advisable to pro- 

 vide both by extending the foul air box to the floor, leaving the 

 lower end open, and providing a flap in the box near the ceiling, to 

 open or shut as is required. 



The fourth problem in ventilation is to prevent dripping, or 

 condensation of moisture in the stable. In an ill-ventilated stable, 

 the moisture from the breath and from other sources often condenses 

 on the cold ceiling or wells. In a well-ventilated stable, the moist- 

 ure is carried off with the impure air before condensation can occur. 

 There are two cases, however, in which ventilation is sometimes the 

 cause of dripping. First, the moisture may condense on the pipes 

 or boxes carrying the cold fresh air. This is more likely to occur if 

 these pipes are at the ceiling of the stable, and especially if the cold 

 air is admitted at the ceiling the condensation occurring where the 

 cold air comes in contact with the warm moist air at the ceiling. Sec- 



