166 THE HORSE. 



draught falling upon the horses, and for regulating the amount of 

 air. The common round tube, with a bend at a right angle 

 downwards on the outside of the wall, is the cheapest form in which 

 this can be done ; but it is very apt to be rendered totally inefficient 

 by being stuffed with hay in cold weather, and left in this state 

 ever afterwards. Several patents have been lately taken out for 

 getting a down-draught by the side of the up-draught tube ; of 

 which Mr. Moir's four-sectioned plan is, perhaps, the best. In 

 this a large tube of iron is made to descend from the apex of the 

 roof to the stable ceiling ; and being divided into four tubes by 

 iron plates, which rise above the top, the wind always descends 

 through one or two of these tubes whenever there is the slightest 

 air moving. Unfortunately, however, it happens that when it is 

 most wanted it is totally inactive — namely, in the hot calm days of 

 summer. Ventilation is always easy enough when there is a wind 

 blowing; and, indeed, the difficulty then is to moderate it; but it 

 is when there is no air moving that stables become so hot and close. 

 I have known these down-current tubes tried in all sorts of places, 

 including stables, kennels, work-rooms, cigar-divans, &c. ; but 1 

 have always found that, without the power of moderating the down- 

 draught by closing-valves placed at the bottom of the tubes, they 

 are not only useless in calm weather, but highly dangerous in a 

 wind. Now, horses have not the sense to close valves, when a 

 wind rises in the night, and grooms are absent from 8 o'clock p. 

 M. till 6 A. M., during which time a whole stableful of horses may 

 be chilled to an alarming extent. Hence, if adopted, I should 

 never venture to leave these ventilators open during the night, and 

 this would take away from their efficiency sufficiently to forbid their 

 use. I greatly prefer the valvular window which I have described 

 at page 162, for the introduction of air, and a plain ventilating 

 shaft, such as I shall presently allude to, fr r carrying off the foul 

 air. Failing the window from any cause, nothing is better than a 

 latticed ventilator, which should be fixed in the head wall, or in 

 either of the side walls, near the head. 



Having thus provided for the admission of fresh atmospheric 

 air, the next thing to do is to carry it off, when it has been used 

 for the purposes of respiration. As I before remarked, it is not 

 safe to depend upon the wind for this purpose ; and the only re- 

 maining agent is ine diminution in its specific gravity when air is 

 warmed by respiration. By taking advantage of this principle, 

 the foul air is carried off from the upper parts of the stable if a 

 shaft is fixed there for its passage. Sometimes a small shaft is in- 

 troduced over the head of each horse; but in practice it is found 

 that one large shaft, about a foot square, will purify a stable con- 

 taining four or five horses. It is better to fix this about the mid- 

 dle of the stable, as regards its length, but near the heads of tha 



