VENTILATING SHAFT. 



167 



VENTILATINO SHAFT. 



horses, as shown in the above section of a stalled stable. The tube 

 may be made of wood and, indeed, this material is better than 

 iron, because it does not condense the steam as it ascends nearly 

 so much as metal, and there is less dropping of water from it. The 

 upper end of this shaft should be guarded from down-draughts, 

 either by a cowl which will turn with the wind, or by a covered 

 ventilator of galvanized iron fixed on the ridge of the roof, the 

 price of which will depend on 

 the size. At the bottom, a sheet 

 of iron, considerably larger than 

 the shaft, should be fixed about 

 three inches below the mouth, so 

 as to prevent any down-draught 

 striking the horses } and also to 

 catch any drip from the conden- 

 sation of the steam of the stable, 

 as it comes in contact with the 

 interior of the shaft. This, however, will be almost entirely 

 avoided by making the shaft of wood, as I have already mentioned. 

 Loose boxes must be ventilated separately, if they are not open to 

 the stable; but if they are, the same shaft will take off their foul air 

 as is used for the stalls, provided there are not more than four or 

 five horses in the same space. A shaft about six inches in diam- 

 eter is amply large enough for one box ; and this, with the venti- 



HEAD OF SHAFT. 



