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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 wbich sbould be increased by means of gas-jets lighted at the propei 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 spec. ify 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 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 commission charged with the investigation of the question and the examination of projects was composed of Dumas, member of the Institute, president; Chaisd'Est-Ange, Pelouse, Rayer, Gilbert, Caristie, Baltard, General Morin, members of the Institute; Grassi, chemist.
The auditorium, intended to accommodate 1,700 spectators, has really but 1,472 seats, distributed as follows: Orchestra, parquet, and lower boxes ..
...... 440 First tier ....... Second tier..
302 Third tier ......
178 Fourth tier .....
1, 472 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, wbich, 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, aud spread it over the whole extent occupied by the heaters and the air-chambers. The sectional area of the passage way was therefore but 98 square feet; and experiment (December 9, 1862*) har. ing 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 introiluce 1,060,000 cubic feet, since the avoidable 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 pas. sage 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 unpleasaut 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 wbich these changes, and others equally serious, in part of the apparatus have bad on their operation, I will describe the results wbich have been obtained by continuous service when the ventilation bas 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 bave 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 24 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, bas 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 730, have shown that a mean consumption of 441 pounds of coal, costing about $2 for each performance, eftects 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
cnipola was as much as 1,361,000 cubic feet for 736 places, equal to 1,348 cubic feet to a place. For the whole audience-room, containing 1,472 places, the total amount of air removed on an average during the five evenings in May, 1863, when the observations were made, was as much as 1,970,000 cubic feet, or 1,338 cubic feet instead of 1,060, which was all demanded. The total amount was even raised on December 3, 1862, to 2,121,000 cubic feet an hour.
137. Maintenance of equality of temperature in the different galleries.I have given in my investigations iu regard to ventilation * the results of experiments which have been made under very different temperatures, and which have shown that the results obtained have exceeded what was required as to the amount of air removed from the room at the different galleries. The results relative to keeping up the temperature have not been less satisfactory. In fact, by means of this regular ventilation, the temperature at the different galleries has been maintained at a very remarkable state of uniformity, as shown by the following results for the first and fourth galleries, which alone will be cited here:
It is well to repeat that in a place strongly ventilated a temperature of 750 does not feel unpleasant, and that if the direct external air. openings required for the summer season bave been made it will be easy, if required, to obtain a still smaller difference between the external and internal temperatures.
At the old Opera, the Italian Theater, and most of the unventilated theaters, it is not unusual to observe temperatures of 930 and 1050.
138. Temperature on the stage.- When the heaters designed to warm the stage are well managed, a proper degree of temperature may always be maintained there. Thus, in November, 1863, with an external temper. ature of 390, was obtained
OF. On the stage .................
66. 02 In the orchestra-stalls .............
70.88 In the gallery-boxes, (average) ......
72.32 In the amphitheater, (fourth gallery) ......
* Études sur la Ventilation, vol. 2.
In May, with external temperatures of from 640 to 680 at 7 o'clock, and from 550 to 570 at midnight, the temperature on the stage was on an average 710 to 730.
139. Volume of air carried off at the cupola to a cubic foot of gas burned. During the experiments of May, 1863, the volume of gas burned an hour in the main room was on an average 2,940 cubic feet, and the volume of air was 1,361,000 cubic feet, which corresponds to 462.5 cubic feet of air carried off by a cubic foot of gas consumed. But in the above-mentioned consumption is included that of a large number of burners which had no direct influence on the ventilation. A removal of 600 to 800 cubic feet of air to a cubic foot of gas directly consumed to produce it may be calculated upon when proper arrangements are made.
140. Consequences of the preceding facts.—The results of direct experiment made in different seasons show that the arrangements adopted for warming and ventilating the Lyric Theater are capable of producing satisfactory results. The same is true of the Gaîtés.
It is a pity to see the public, in consequence of the senseless parsimony of the manager of a theater, deprived of the advantages which the administration of the city of Paris has, at considerable expense, undertaken to secure them.
STABLES AND COW-HOUSES.
141. The capacity of stables should be 1,800 cubic feet to each animal ; this was the proportion adopted in 1841 by the war.minister for cavalry. stables. In all constructed since that time for the army-service, the width allowed for each horse is about 4f feet.
This increase of space produced from 1835 to 1858 a reduction in the number of horses lost in 1,000, from 51 deaths by glanders in the period from 1835 to 1845 to 10 only during that from 1845 to 1858, and from 94 deaths from all diseases in 1835 to 1845 to 22 only from 1848 to 1858.
Large corporations, such as the General Omnibus Company and the railroad-companies, are the wrong in restricting the capacity of their stables to 700 or 900 cubic feet of air to a head.
142. Permanent opening of doors and windows.-Experiments carried on for several years in cavalry-regiments in garrison in the north, center, or south of France, have proved that horses have better health and greater strength when kept in stables where the doors and windows are constantly kept open night and day in all seasons than where they are kept shut. Similar observations have been made in stables containing a great many cattle, which are thus relieved from epidemic affections of the respiratory organs.
143. Amount of air to be allowed. When stables are not arranged so as to admit air throughout their whole length and by two opposite walls, it is proper to make in the roof at the middle of the alleys, if they are double or above the passage behind the horses, ventilating-chimneys of brick sufficiently large to secure a ventilation of 0,400 to 7,000 cubic feet