VENTILA TION. 



63 



upon for the thorough ventilation of stables. Where the tem- 

 perature is suddenly raised and vitiated by the introduction of 

 horses warm from their work, something more is required, 

 which will, especially in hot weather, aftbrd an additional 

 impetus to the immediate escape of the foul air whilst it is 

 heated and buoyant^ and for this purpose fanlights and louvres 

 in the roof are the most effective provisions.* 



A fanlight over the door, except in the case of a smithy or Fanlights and 

 washer's room, is preferable to fixed louvres, as the fresh air °^^^^^' 

 is admitted too much in the character of a draught, especially 

 in the cold winter nights, when the louvres in the roof will be 

 found sufficient, and the window over the door can be closed. 



The blades, moreover, of louvres are often fixed at an im- Constrnction 

 proper angle, and allow a current of cold air to pass in without of louvres, 

 impinging, as it should do, on the slats. A draught will often 

 strike a wall and rebound, and thus reach a part of the stable 

 it could not otherwise affect. This may exist to a serious 

 extent in a gale, and often leads to louvres being 

 rendered non-effective by a stuffing of straw. 

 The slats to fixed louvres should not be at a 

 less acute angle than 55°. They shoi.ld be 

 6 inches wide, and the frames have at least five 

 slats in every 2 feet of height ; by this arrange- 

 ment they overlap each other sufficiently to 

 give an upward direction to the air, as shown on 

 Fig. 35, and they may be made, by a simple 

 arrangement, to open and close like a Venetian 

 shutter. 



The stable illustrated on Plates 40 and 41 is, with the excep- Lantern venti- 

 tion of a fanlight over the door, entirely lighted from the roof l^tio"- 

 by eight fanUghts, which form a continuous lantern. These 



* Supposing the air to be changed three times in every hour, a stable 

 containing 1200 cubic feet per horse, would give to each animal 3600 cubic 

 feet of air per hour ; being at about one fourth the velocity at which it 

 could be removed in that time, without creating a draught, at a tempera- 

 ture of 60° Fahr. 



