WARMING AND VENTILATION. 



273 



haviug an eartlieu-ware flue 11 inches square and QQ feet higli, tbe amount 

 of air drawn up the chimney to each foot of gas burned will be greater 

 the less gas is burned and the less the temperature in the flue, following 

 pretty nearly the following decreasing series : 



These approximate figures may serve to determine the number of 3J 

 feet burners that will be required to produce any desired rate of change of 

 air in an apartment. 



When the chimney is much lower than that just mentioned, it will be 

 necessary to correct the calculated volume of air in the proportion of 

 the square roots of the heights of the flues. 



The pipe which conveys the gas to the flue may be easily taken away 

 when not in use, and closed by a blind socket. 



This mode of ventilation may be employed to advantage in drawiug- 

 rooms on reception -days, provided that registers be placed at conven- 

 ient points for the introduction of moderately warm fresh air. 



During the summer, the system of ventilating by means of gas-jets 

 will also allow the room to be maintained at a lower temperature than 

 that of the external air, by drawing in the air from clean cellars to 

 replace that carried off. 



Example. — The directors' room at the Conservatory of Arts and Trades 

 is ventilated in this way during the summer ; and, although the air from 

 the basement is admitted through but a single opening, entirely too small 

 for the purpose, and the doors of the room are constantly being opened, 

 yet the temperature is always 4° lower than the room of the subdirector, 

 which has a precisely similar exposure, but is unventilated, and it is 7° 

 lower than the temperature of the external air in the shade. 



57. Auxiliary ventilating-flucs. — For unusually large gatherings, in 

 addition to the chimneys, additional flues may be cut in the thickness 

 of the front or party walls, in which gas-jets may be used to i)roduce a 

 strong draught. This method has been tried with success in a house in 

 the Champs Elysees, Paris. 



INFANT- ASTLIBIS. 



58. In these charitable institutions, in addition to securing space and 

 cleanliness, provision should also be made for obtaining an abundant 



18 s 



