The Principles of Ventilation. 



225 



any one that the wheel is turned by the current of air entering the 

 room, and that if it were removed the current of air would be in- 

 creased. However, it gives information to the eye and ear that fresh 

 air is coming in. ' 



The particular system of ventilation and heating to be applied to a 

 building depends upon its use, size, etc. For dwellings, the plan 

 described for Mr. Van Slyke's.house, or the open-stove apparatus, is pre- 

 ferable to any others, but a small open grate, working in combination 

 with an ordinary hot-air furnace, will give very good results. Merely 

 providing exit flues for the hot air will make a furnace a very fair 

 ventilator and heater. 



For schools and churches the indirect method is, I believe, the only 

 one practicable; since any direct radiation, to be effective, will prove 

 unpleasant to those in its immediate neighborhood. A method of 

 heating and ventilating such buildings as churches and the theaters 

 very satisfactorily is to force air by a fan through a pipe chamber, and 

 then through a system of pipes to long boxes, the front sides of 

 which are the risers of the platforms on which the seats are placed, 

 these risers being perforated. A series of vertical slits in the side 

 walls communicate with au exhaust stack or flue, in which a coil of 

 steam-pipe is placed. The distributing pipes from the fan are care- 

 fully arranged, their dimensions and directions being such as to secure 

 the delivery by each one of the same amount of air. A separate system 

 of pipes supplies each gallery, and the chancel or stage, as the case 

 may be. This plan is in actual operation in one very large theater in 

 Italy, and in several theaters and churches in New York City. 



It is quite practicable, however, to ventilate such buildings as I have 

 described, and also schools, by heat alone, all that is necessary being 

 to provide an upcast shaft of sufficient height, and kept at a high 

 enough temperature. 



A school building in Bridgeport, CfoUn., now in course of erection, 

 is to be ventilated according to this plan. Four rectangular flues, 

 measuring in cross section 10 by 14 feet, extend from the basement to 

 the upper story. At the bottom of each are several steam-pipe cham- 

 bers — one for each room to be heated — from which hot-air pipes ex- 

 tend (within the main flue) to the school-rooms. The hot air enters the 

 room, in one corner, eight feet above the floor, and escapes, after tra- 

 versing the room, through an aperture at the floor level, in the same 

 corner with the inlet. The outlets open into the main ventilating flue, 

 which is kept warm by the hot-air flues within. 



When a very large building is to be ventilated — as for instance the 

 Capitol at Washington, or the New Capitol at Albany — the problem 

 of so apportioning the ducts that from one central point a sufficient 

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