Houses and other Buildings. 239 



might contain a self-adjustment, by the action of which its area 

 would always be in the inverse ratio of the velocity of the wind ; 

 by which means equal quantities of air would always be admitted 

 in equal times. 



The turn-cap for the escape of foul air is placed at the top of 

 the building, and is made common to the roof. Under this ar- 

 rangement all the rooms into which the warm air is admitted 

 have each a foul air flue terminating in the cavity of the roof. 



The contents of all the foul-air flues are therefore ultimately 

 discharged at the turn-cap. This arrangement is adopted at 

 the Derbyshire General Infirmary, and at the Wakefield Lunatic 

 Asylum. In the summer season, when the stove is not in 

 action, the ventilation will depend on the wind, which at 

 some periods may not be adequate to that change of air re- 

 quired in hospitals. In such cases I have adopted an addi- 

 tional means of ventilation. Instead of making the foul-air 

 turn-cap common to the roof, I have placed it at the top of a 

 cylindrical cavity built in the roof. Into this cavity I bring 

 all the foul-air flues, which also in this case may be smoke- 

 flues, if constructed with brick. I also connect with the same 

 cavity, the stove chimney, and, if possible all the other smoke- 

 flues in the building. By this means, it may be expected, 

 that some degree of rarefaction in the cylindrical cavity in the 

 roof will be constantly going on, and that hence a perpetual 

 current will be established from every room towards the general 

 outlet. It would be difficult to adapt such an arrangement 

 to old buildings, without great alteration in the roof. But it 

 would be easily introduced into new houses. The advantages 

 derived from it in ordinary dwellings would be very great. In 

 the first place, there could not be an instance of a smoky 

 chimney ; in the next, a down current in an unoccupied chimney 

 could not occur, and therefore the passage of the smoke of one 

 chimney down another would always be prevented ; and lastly, 

 by having only one outlet for smoke in every house, and that 

 an object which may be made ornamental, we should ultimately 

 get rid of the great deformity which arises from the present ap- 

 pearance of chimneys in buildings. 



