280 



WARMING AND VENTILATION. 



room, which, in the evening, is lighted by 90 gas-burners. The capac- 

 ity of this room corresponds to 200 cubic feet to each person. 



Ventilation in the two rooois during the day is limited to 350 cubic 

 feet to each person, which necessitates the renewal of 140,000 cubic feet 

 an hoar in the second story and 70,000 cubic feet an hour in the third 

 story. 



The rooms are warmed by two heaters found by direct experiment to 

 have a heating-capacity equal to 81 per cent, of the heat generated by 

 the fuel,* and having proportions corresponding to 4^ square feet of 

 heating-surface for every 1,000 cubic feet of room-area, supposed to be 

 ventilated by a complete change of air twice an hour. 



The warm air is carried to each floor by three vertical flues leading 

 into a large and long j)ipe extending throughout the whole length of 

 the rooms, which receives fresh air from without in order to regulate the 

 temperature of the air admitted into the room. This air enters hori- 

 zontally near the ceiling. 



The volume of warm air, at a temperature of from 140° to 150° ascend- 

 ing in the flues before being mixed with cold air, was found to be, in 

 the second story, 106,000 cubic feet an hour; in the third story, 73,000 

 cubic feet an hour ; and this has been found sufficient to maintain in 

 the rooms a temperature of from 00° to 70°, when that of the exterior 

 air was 35° or 40°. 



According to the instructions given to the builder, the foul air should 

 have been carried away from the second story by thirteen flues, the pro- 

 portions of which had been determined by applying the rule adopted 

 in § 51, which fixes 28 inches a second as the velocity which the foul air 

 should have in the first series of ventilating-flues, as indicated in the 

 following table : 



SCHOOL-KOOMS, (SECOIirD FLOOE,) 



ART-SCHOOL, (THIKD PLOOK.) 



71,000 cubic feet. 



20 cubic feet 9 square ft. 



■ 4 of 1 foot 5 inches x 1 foot=1.5 sq. ft . . 

 3 of 1 foot 1 inch x 1 foot=l.l sq. ft . . 



C 

 3.3 



Anuales du Conservatoire des arts et metiers, 6^ vol., p. 325. 



