204 STABLES. 



has of passing into the space occupied by another ; supposing 

 that these gases have no mutual chemical action. Conse- 

 quently, if a stable which was full of foul air, had only one 

 opening (say, a window) in it, and even if the atmosphere both 

 inside and outside was absolutely still, the air in the stable 

 would after a time become comparatively pure ; provided of 

 course, that fresh supplies of deleterious gas were not fur- 

 nished. It is evident that the greater the extent of com- 

 munication between the stable and the outside air, the 

 more rapidly will diffusion take place. 



The foregoing principles of ventilation may be applied in 

 the following ways : 



A. By ventilation on or close to the level of the floor 

 obtained by means of " air bricks," gratings or other narrow 

 openings. These air passages should be small enough to 

 prevent the entrance into the stable of undesirable visitors, 

 such as mice, and are specially applicable to outside walls 

 which are at the head of boxes or stalls, or to doors. In 

 order to prevent a draught coming on the horses from these 

 air passages, we may utilise the principle of the " Tobin tube " 

 (Fig. 14) to give a vertical direction to the current of incoming 

 or outgoing air. We may obtain under a door the same form 

 of ventilation by cutting off, say, an inch from the bottom of 

 the door and attaching a plank to the inside of the door, so as 

 to cover the gap thus made and to allow a space of about an 

 inch between the door and the plank (Fig. 15). A plan which 

 would be equally efficacious, and which would not disfigure 

 the appearance of the door so much, would be to apply the 

 plank in the same manner, but a little higher up, and instead 

 of cutting away the bottom of the door, to bore one or more 

 rows of holes in the door (Fig. 16). This method of ventila- 

 lation is similar to that which was proposed many years ago 

 by Dr. Parkes for ventilating dwelling rooms by ordinary 

 " guillotine " windows. The lower half of the window is 



