Page:Popular Science Monthly Volume 56.djvu/102

94 in preventing the smoke and fire gases from being drawn into the auditorium and suffocating the persons in the gallery seats.

Where the stage is lit with gaslights it is important to provide a separate downward ventilation for the footlights. This, I believe, was first successfully tried at the large Scala Theater, of Milan, Italy.

The actors' and supers' dressing rooms, which are often over-crowded, require efficient ventilation, and other parts of the building, like the foyers and the toilet, retiring and smoking rooms, must not be overlooked.

The entrance halls, vestibules, lobbies, staircases, and corridors do not need so much ventilation, but should be kept warm to prevent annoying draughts. They are usually heated by abundantly large direct steam or hot-water radiators, whereas the auditorium and foyers, and often the stage, are heated by indirect radiation. Owing to the fact that during a performance the temperature in the auditorium is quickly raised by contact of the warm fresh air with the bodies of persons (and by the numerous lights, when gas is used), the temperature of the incoming air should be only moderate. In the best modern theater-heating plants it is usual to gradually reduce the temperature of the air as it issues from the mixing chambers toward the end of the performance. Both the temperature and the hygrometric conditions of the air should be controlled by an efficient staff of intelligent heating engineers.

But little need be said regarding theater lighting. Twice during the present century have the system and methods been changed. In the early part of the present century theaters were still lighted with tallow candles or with oil lamps. Next came what was at the time considered a wonderful improvement, namely, the introduction of gaslighting. The generation who can remember witnessing a theater performance by candle or lamp lights, and who experienced the excitement created when the first theater was lit up by gas, will soon have passed away. Scarcely twenty years ago the electric light was introduced, and there are to-day very few theaters which do not make use of this improved illuminant. It generates much less heat than gaslight, and vastly simplifies the problem of ventilation. The noxious products of combustion, incident to all other methods of illumination, are eliminated: no carbonic-acid gas is generated to render the air of audience halls irrespirable, and no oxygen is drawn to support combustion from the air introduced for breathing.

It being now an established fact that the electric light