Imágenes de páginas
PDF
EPUB

winter to a temperature of about 68°. The doors of adjoining boxes being usually contiguous, it will be well to place a hot-air opening in the corridors before each pair of doors, so that during the momentary opening of one of these doors warm air may enter into the corresponding box. The same plan may be carried out by each door in the pas sage-way; but it is necessary that these hot-air openings be placed in vertical planes, and not at the floor-level. The passage-ways should have two doors opening outward and inward, and between them should be a hot-air opening.

126. Removal of foul air.—This air should be drawn out of the room by ventilating-openings at the back of the boxes or galleries, or in the risers of the amphitheater. The clear surface of these openings should be calculated on the condition that the air shall enter with a velocity of 28 or 30 inches a second.

Each box or each pair of adjoining boxes of the same tier should have a special ventilating-pipe. The section of these pipes should be calculated on the condition that the air drawn out should have a velocity of 3 feet a second. For the first, second, and third galleries, these pipes should be carried to the ventilator above the chandelier.

For the parquet, the orchestra, and the lower boxes, and, if possible, for the first gallery, the foul-air pipes should descend. In the parquet and the orchestra, gratings arranged around the whole lower circumference of the partitions, together with other openings placed on top or on the sides of pipes carried along by the feet of the seats, will serve to direct the foul air in an interjoist placed under the floor. This interjoist, made high enough to be cleaned, should be divided in large theaters into two parts by a longitudinal division in the mean plane of the edifice.

Each of these parts should communicate with a separate ventilatingchimney, of which the opening should be either in the basement or at the height of the floor of the passage-ways in the parquet.

In no case should the ventilating-openings be placed at the floor-level, as has nevertheless been done at the Lyric Theater.

The foul air drawn off from the lower boxes and the first gallery should likewise be carried underneath by means of special pipes, afterward united in collecting pipes terminating at the base of the chimneys just referred to.

The dimensions of these pipes should be determined on the condition that the velocity in them should be from 3 to 4 feet a second.

In small theaters, a single chimney will usually suffice for all the gal leries. The calculation of the dimensions to be given to the foul-air openings should be made for each gallery separately, from the corresponding number of spectators.

The cast-iron smoke-pipes of the heaters should be carried into the ventilating-chimneys, keeping them separate throughout their whole height; and at the lower part of the chimney a grate should be placed, to be used whenever required, to increase the draught, especially in sum

It would not be prudent, even in winter, to count upon the heat transmitted by the smoke-pipe to produce a sufficiently powerful draught. The sectional area of the chimney should be calculated so that the mean velocity in it may be 5 or 6 feet a second.

They should open, when possible, in a cupola placed above the center of the hall, which should also receive all the ventilating-pipes of the upper stories.

A main ventilating-chimney should be constructed of brick and not of metal, above this cupola, the latter to be as low as possible, while the chimney should be made as high as the nature of the building will permit, but at least 20 or 25 feet.

The sectional area of this chimney should be calculated on the condition that the mean velocity of the draught in it should be about 61⁄2 feet a second.

127. Utilization of the heat given out by the lights.-In addition to the pipes for carrying off foul air, the gases produced by the burners of the main chandelier or the other chandeliers suspended from the ceiling should also be carried into the cupola. The pipes intended to carry the gases there should be made as small as possible in order not to change the direction of the main draught in the vicinity of these places.

The diameter of the ventilating-pipe above a chandelier placed near the ceiling and supplied with a metal or glass reflector should be calculated under the condition that it shall only remove 150 cubic feet of air an hour with the velocity of 13 feet a second to a cubic foot of gas consumed by the chandelier.

The single burners in the boxes and corridors should take the air necessary to support the combustion in the interior of the boxes or from the adjoining ventilating-pipes. It will suffice to make their ventilating pipes or inch in diameter.

If, as is most probable, the plan of lighting through a glass ceiling, tried at the Théâtre du Cirque and the Lyric Theater, be not adopted, it will be advisable to place a circle of gas-jets at the base of the ventilating-chimney, to be used only to increase the draught in summer, when the elevation of the temperature of the external air tends to reduce it. It may be assumed that under similar conditions each cubic foot of gas consumed will carry off about 800 cubic feet of air.

A valve should be placed at the foot of the chimney to moderate its draught, and particularly to stop the draught after the close of the play, to prevent useless loss of heat and the entrance of cold air during the night.

128. Ventilation of the stage.-For theaters where great quantities of smoke are frequently produced during sham fights, grand illuminations, displays of fire-works, &c., it is well to keep up a strong draught in the upper part of the stage, in order to prevent the gases from being drawn into the auditorium by the draught kept up there, as happened at the Châtelet Theater, where these precautions were not taken. Further

more, in order that this stage-ventilation may not interfere with that of the body of the house, it is necessary to connect the two systems with each other.

For this purpose, a chimney or an auxiliary ventilating-flue should be made above the stage and joined with the main chimney, the draught of which should be increased by means of gas-jets lighted at the proper time, a little while before the smoke is produced.

129. Precautions to be taken to prevent re-entry of the external air on the stage. The introduction of external cold air on the stage should also be avoided, in order that currents from the stage to the hall may not be produced, which would be disagreeable both to the actors and to the audience. This result has taken place at the Théâtre du Cirque, where large openings in direct communication with a court and public way have not been closed.

130. Lighting-apparatus for the auditorium.-Without wishing to specify here the arrangements to be adopted for lighting theaters, we will confine ourselves to stating that glass ceilings, which require to be ornamented with colored designs, occasion a considerable loss of light, while they produce in the room an amount of heat very unpleasant for the spectators in the upper tiers, and which is also very expensive for the directors, who are naturally led unduly to restrict the number of gas-jets, thus rendering useless the expense gone to in introducing this method of illumination. Although this consumption, even when thus restricted, assists the removal of foul air, the amount carried off is seldom more than 450 cubic feet to a cubic foot of gas burned, while with suitable arrangements the amount of 600 to 800 cubic feet of air might be carried off to every cubic foot of gas.

131. Arrangements to be made to secure and regulate the amount of warmth and ventilation.-Warmth and ventilation can only be properly secured by an attentive observation of atmospheric conditions and of the number of spectators, and by prompt application of the proper means. There is, in fact, no difficulty in the arrangement or the management of the apparatus; but it is necessary to take care, and not to trust to ordinary firemen, nor even to the managers of theaters, always interested in using as little coal and gas as possible.

It is then indispensable to confide this trust to special agents, responsible directly for the authority and the regularity of the service, and obliged to make daily reports. Without such control, independent of theatrical managers, the best apparatus may give imperfect results or even fail entirely.

132. Application.-The preceding rules have been adopted, after long discussion and many experiments,* to serve as bases for the plans to be adopted at the Lyric Theater and the Châtelet Theater. The city

* The commission charged with the investigation of the question and the examination of projects was composed of Dumas, member of the Institute, president; Chaixd'Est-Ange, Pelouse, Rayer, Gilbert, Caristie, Baltard, General Morin, members of the Institute; Grassi, chemist.

government has scarcely any control over the latter, and but little over the former. Still, as the results obtained at the Lyric Theater have, in the main, been somewhat satisfactory when the apparatus has been properly managed, I will describe this first application, in spite of its imperfections.

The auditorium, intended to accommodate 1,700 spectators, has really but 1,472 seats, distributed as follows:

Orchestra, parquet, and lower boxes.....

[merged small][merged small][ocr errors][merged small]

440

[blocks in formation]

The amount of air to be renewed for each spectator had been limited to 1,060 feet an hour, which, with the above number of places, corresponded to a total volume of 1,560,000 cubic feet an hour. The conditions imposed upon the contractor, based on the hypothesis of 1,700 spectators, would require a renewal of 1,800,000 cubic feet of air an hour. 133. External-air supply.-The air-supply was taken in St. Jacques Square from a circular well 12 feet in diameter, which, by a subterranean passage, at first circular, 11 feet in diameter, and afterward of variable form, but of the same sectional area, carried it to the subbasement of the building, and spread it over the whole extent occupied by the heaters and the air-chambers. The sectional area of the passage-way was therefore but 93 square feet; and experiment (December 9, 1862*) having shown that the velocity in it was as much as 6 feet a second, the volume of fresh air introduced by this gallery was that day 1,090,000 cubic feet. It was only deemed necessary to introduce 1,060,000 cubic feet, since the unavoidable admission of air through the doors, the passages, and the stage would easily and without inconvenience furnish the balance, as has been found to be the case. It would, nevertheless, be more prudent in such cases to calculate the dimensions of the fresh-air trunk to furnish the entire amount.

134. Alteration of the adopted plans.—But a little while after the opening or the lease of the theater to the manager, the external fresh-air passage was closed, and even the pit in St. Jacques Square covered with ivy. Thus the introduction of air by these passages, as well as by the pipes leading to the interjoists of the boxes, is almost entirely prevented, while the outward draught is as strong as ever. It therefore follows that, to replace the air carried off, cold air enters through the halls, passages, &c., which is very unpleasant for the spectators, and which the public. attribute to the general arrangements adopted, while they are only the result of want of care and of the exercise of authority.

* Études sur la ventilation, vol. 2.

In spite of the influence which these changes, and others equally serious, in part of the apparatus have had on their operation, I will describe the results which have been obtained by continuous service when the ventilation has been regularly kept up.

135. Ground floor.-Part of the air supplied by the air-trunks passes into two heaters placed under the main hall; the rest flows into two mixing-chambers, having together a capacity of 6,500 cubic feet. The two heaters have a sectional area of 97 square feet, and the amount of warm air which they can supply to the mixing-chamber being at a maximum 883,000 cubic feet an hour, or 245 feet a second, this corresponds to a velocity of 2 feet a second.

From the air-chamber, and from each of its compartments, branch off six pipes, of which

Two are intended to supply fresh air to the different galleries.

Two were to supply air entering the room by the floor of the stage, concentric with the foot-lights. This method of introduction had to be abandoned, as it was unpleasant to the musicians.

Two were to carry air in vertical pipes placed by the stage-opening against the wall which separates it from the auditorium.

There are, in addition, four heaters for warming the vestibules, the staircases, waiting-rooms, dressing-rooms, &c.

136. Removal of foul air.-In the orchestra and parquet, the air is drawn off under the floor by 101 openings, having altogether a clear area of about 65 square feet. The passage under the floor, which should have had a clear area of 118 square feet, has been reduced to 40 square feet.

The air drawn off at this height, carried by two pipes to the right and left, is drawn to two ventilating-chimneys, which contain the smokepipes of the heaters of the hall, and may also, when necessary, be heated by a small special fire.

Direct experiments, made during five consecutive evenings in May, 1863, with external temperatures comprised between 560 and 73°, have shown that a mean consumption of 441 pounds of coal, costing about $2 for each performance, effects the removal of about 600,000 cubic feet of air an hour, which corresponds to about 1,400 cubic feet to a seat. By means of this abundant ventilation, the temperature of the orchestra and parquet may be maintained within proper limits.

But the managers of the theater do not use the two ventilating-chimneys; and if they have not been closed, instead of promoting the removal of foul air, they may cause the entrance of cold air, in consequence of a reversal of the direction of the motion of the air caused by the greater power of the upper draught.

For the first, second, third, and fourth galleries, the foul air is carried out at the floor of the galleries or through the steps of the amphitheater, as was remarked in § 126; and the observations made in May, 1863, have shown that the amount of foul air extracted at the base of the

« AnteriorContinuar »