92 POPULAR SCIENCE MONTHLY. 



and boxes; in the gallery the openings for fresh air were located 

 in the risers of the steppings. The air was exhausted by numerous 

 openings under the seats in the parquet. This ventilating system 

 was carried out at the Theatre Lyrique, the Theatre du Cirque, 

 and the Theatre de la Gaiete. 



Dr. Tripier ventilated a theater in 1858 with good success 

 on a similar plan, but he introduced the air partly at the rear of 

 the stage and partly in the tympanum in the auditorium. He 

 removed the foul air at the floor level and separately in the rear 

 of the boxes. He also exhausted the foul air from the upper gal- 

 leries by special flues heated by the gas chandelier. 



The Grand Amphitheater of the Conservatory of Arts and In- 

 dustries, in Paris, was ventilated by General Morin on the down- 

 ward system. The openings in the ceiling for the admission of 

 fresh air aggTegated 120 square feet, and the air entered with a 

 velocity of only eighteen inches per second; the total air supply 

 per hour was 630,000 cubic feet. The foul air was exhausted by 

 openings in steps around the vertical walls, and the velocity of the 

 outgoing air was about two and a half feet per second. 



The introduction of the electric light in place of gas gave a 

 fresh impetus to the downward method of ventilation, and me- 

 chanical means also helped to dispel the former difficulties in 

 securing a positive downward movement. 



The Chicago Auditorium is ventilated on this system, a part of 

 the air entering from the rear of the stage, the other from the 

 ceiling of the auditorium downward. This plan coincides with the 

 proposition made in 1846 by Morrill Wyman, though he admits 

 that it can not be considered the most desirable method. 



A good example of the downward method is given by the ISTew 

 York Music Hall, which has a seating capacity of three thou- 

 sand persons and standing room for one thousand more. Fresh 

 air at any temperature desired is made to enter through perfo- 

 rations in or near the ceilings, the outlets being concealed by the 

 decorations, and passes out through exhaust registers near the floor 

 line, under the seats, through perforated risers in the terraced 

 steps. About 10,000,000 cubic feet of air are supplied per hour, 

 and the velocity of influx and efflux is one foot per second. The 

 air supplied per person per hour is figured at 2,700 cubic feet, and 

 the entire volume is changed from four and a half to five times per 

 hour. The fresh air is taken in at roof level through a shaft of 

 seventy square feet area. The air is heated by steam coils, and 

 cooled in summer by ice. The mechanical plant comprises four 

 blowers and three exhaust fans of six and seven feet in diameter. 



The downward method of ventilation was suggested in 1884 



