474 Transactions. — Miscellaneous. 



without adding much to the original cost of building a 

 house. 



Under this limitation let us consider what we have to do 

 in order to maintain a reasonably pure and cool air in any 

 room. Our aim must be twofold — viz., to remove the warm 

 and vitiated and to introduce cool and pure air. It is very little 

 use to provide for either one of these operations without the 

 other, while the intelligent carrying-out of both tends to render 

 the working of each more effective. Thus, if the warm air is 

 removed freely it is reasonable to expect that cool air will 

 flow in more readily, and, if the entrance of cool air is facili- 

 tated by easy and suitable passages, then the warm air is 

 likely to be withdrawn more readily. 



First, then, as to the removal of warm air. The restriction 

 imposed upon us in doing this is that we must avoid any 

 arrangement which will allow of a downdraught. Naturally, 

 the removal must be effected at the upper part of the room — 

 the warmest place. Above the top of windows and doors in 

 an unventilated room, especially in one which is artificially 

 lighted, there is a close reservoir of hot and impure air which 

 cannot escape. It is prevented from going upwards because 

 it finds no vent, and it cannot descend because it is lighter 

 than the air below it. No person could long endure it without 

 fainting ; its effects are seen upon the bindings of books on high 

 shelves ; and I know of nothing for which it is good except, 

 perhaps, for keeping cigars dry. In designing a new house I 

 should endeavour to prevent this accumulation by providing 

 an opening through the ceiling above a perforated centre- 

 flower, because this is at the very highest point and because it 

 is central, and if over a gas-pendant it would prevent the 

 vitiated air from the latter from spreading over the ceiling. 

 After entering the centre-flower the warm air should be con- 

 ducted by an air-tight passage containing as few bends as 

 possible up to an exhaust ventilator on the roof. The type 

 of head which I prefer to fit on the top of the pipe is a fixed 

 exhaust ventilator, such as the Torpedo, or one of Boyle's 

 make. Any form of revolving ventilator is less certain than 

 these except in high winds, while a cowl to turn from the wind 

 may fail to do so in a calm, and will sometimes stick fast. It 

 is of no use to discharge the warm air direct into the roof or 

 into the space between two joists, however well provided the 

 roof may be with means of exhaust, or the joist-space with 

 gratings through the walls. In either case you are sure at 

 times to be troubled with a serious downdraught, and are not 

 likely, even occasionally, to find the warm air carried off. In 

 old houses it might in many instances be costly to fit up a 

 tubular arrangement. Where the cost stands in the way the 

 best substitute will be one or two non-return ventilators, such 



