226 Captain Wauchope's Plan for CooUiig Rooms and 



apartment to be ventilated. The pipes are piled, in the man- 

 ner shewn, round the fanners, which are worked by the gin ; 

 these must be wetted from time to time, and in this way a very 

 great evaporation takes place on the outer surface of the pipes, 

 which cools the air in its passage through them. One pair of 

 fanners may in this way act upon three or four hundred yards 

 of pipe, as there may be a double or treble pile connected toge- 

 ther in the same way as the one represented in the model. 



The pipes should be covered over by a shed, open at the 

 sides, with a flat roof of straw or leaves, impervious to the sun, 

 but not to the rain ; so that during the rains, there need be no 

 necessity for wetting the pipes by hand : and should there be 

 any wind, the gin may be stopped, and the funnel will then 

 convey the air into the pipes ; so that when there is any wind, 

 the air may be cooled and conveyed to the apartment without 

 any mechanical operation. 



The gin, which is worked by a bullock, will be therefore only 

 required during the dead calms, when not a breath of wind is 

 stirring ; and at such a time the cooled and refreshing air will 

 come as medicine to the sick soldier in his hospital, and impart 

 vigour and sound sleep to him in his barracks. 



The cooled air should be introduced into the apartment 

 through a hole in the ceiling, with a screen, a few inches in 

 front of it, and of a larger circumference than the hole, to spread 

 the cooled air over the room, which will of course fall by its 

 greater specific gravity ; and there ought to be openings in the 

 upper part of the wall of the room, to permit the hot displaced 

 air to escape. 



Should the mode of wetting the pipes by hand be thought 

 too laborious, the best plan would be to have a cistern upon 

 the roof, filled by a pump made to work by the gin, and when 

 they required wetting, a valve might be opened, and the water 

 spread over them by the same means as that employed for wa- 

 tering the streets. 



The hydrostatic bellows employed in the model was suggest- 

 ed to me by Mr Howel, as that which is easiest to work, and 

 the least friction. I also feel indebted to him for making the 

 model I have the honour of laying before you *. 



" It is evident that this apparatus will work but imperfectly when the air 

 is very moist.«P>£i>iT. 



