CONDITION OF HUNTERS RESUMED 317 



in the stable will live and enjoy the highest health, 

 yet my common sense points out to me the necessity 

 of the means of ventilation. These means, however, 

 should, for hunters or race-horses, be limited. No 

 streams of air ; no broken windows (for a horse 

 should stand in an equal temperature, and this he can 

 never have if the windows of his stable are broken, as 

 it will then depend on the point the wind blows from) ; 

 but small wooden tunnels, ascending through the roof, 

 the tops of which should be constructed so as to 

 prevent the rain descending through them. 



It does not require a philosopher to point out to us, 

 that, when the air of any building becomes more 

 rarified than the external air, a wind or current of air 

 is pouring in from the crevices of the windows and doors, 

 to rest the equihbrium ; but the hght air with which 

 the room is filled must find vent, in order to make 

 way for the heavy air which enters. This fact is 

 proved in the following way, and has often been the 

 sport of children. If we set a door a-jar, and hold a 

 candle near the upper part of it, we shall find that the 

 flame will be blown outwards, shewing there is a 

 current of air flowing out from the upper part of the 

 room. Now if we place the candle on the floor, close 

 by the door, we shall perceive, by the inclination of 

 the flame, that a current of air sets into the room, 

 and therefore the flame will be blown inwards. In 

 fact, the current of warm Hght air is driven out to 

 make way for the cold air which enters ; and this, 

 I believe, is the case in the grander scale of Nature. 

 The light air about the equator, which expands and 



