Part 10

In recent years marked improvements in theater planning and equipment have been effected, and corresponding steps in advance have been made in matters relating to theater hygiene. It should therefore be understood that my remarks are intended to apply to the average theater, and in particular to the older buildings of this class. There are in large cities a few well-ventilated and hygienically improved theaters and opera houses, in which the requirements of sanitation are observed. Later on, when speaking more in detail of theater ventilation, instances of well-ventilated theaters will be mentioned. Nevertheless, the need of urgent and radical measures for comfort and health in the majority of theaters is obvious. Much is being done in our enlightened age to improve the sanitary condition of school buildings, jails and prisons, hospitals and dwelling houses. Why, I ask, should not our theaters receive some consideration?

The efficient ventilation of a theater building is conceded to be an unusually difficult problem. In order to ventilate a theater properly, the causes of noxious odors arising from bad plumbing or defective drainage should be removed; outside fumes or vapors must not be permitted to enter the building either through doors or windows, or through the fresh-air duct of the heating apparatus. The substitution of electric lights in place of gas is a great help toward securing pure air. This being accomplished, a standard of purity of the air should be maintained by proper ventilation. This includes both the removal of the vitiated air and the introduction of pure air from outdoors and the consequent entire change of the air of a hall three or four times per hour. The fresh air brought into the building must be ample in volume; it should be free from contamination, dust and germs (particularly pathogenic microbes), and with this in view must in cities be first purified by filtering, spraying, or washing. It should be warmed in cold weather by passing over hot-water or steam-pipe stacks, and cooled in warm weather by means of ice or the brine of mechanical refrigerating machines. The air should be of a proper degree of humidity, and, what is most important of all, it should be admitted into the various parts of the theater imperceptibly, so as not to cause the sensation of draught; in other words, its velocity at the inlets must be very slight. The fresh air should enter the audience hall at numerous points so well and evenly distributed that the air will be equally diffused throughout the entire horizontal cross-section of the hall. The air indoors should have as nearly as possible the composition of air outdoors, an increase of the CO_{2} from 0.3 to 0.6 being the permissible limit. The vitiated air should be continuously removed by mechanical means, taking care, however, not to remove a larger volume of air than is introduced from outdoors.

Regarding the amount of fresh outdoor air to be supplied to keep the inside atmosphere at anything like standard purity, authorities differ somewhat. The theoretical amount, 3,000 cubic feet per person per hour (50 cubic feet per minute), is made a requirement in the Boston theater law. In Austria, the law calls for 1,050 cubic feet. The regulations of the Prussian Minister of Public Works call for 700 cubic feet, Professor von Pettenkofer suggests an air supply per person of from 1,410 to 1,675 cubic feet per hour (23 to 28 cubic feet per minute), General Morin calls for 1,200 to 1,500 cubic feet, and Dr. Billings, an American authority, requires 30 cubic feet per minute, or 1,800 cubic feet per hour. In the Vienna Opera House, which is described as one of the best-ventilated theaters in the world, the air supply is 15 cubic feet per person per minute. The Madison Square Theater, in New York, is stated to have an air supply of 25 cubic feet per person.

In a moderately large theater, seating twelve hundred persons, the total hourly quantity of air to be supplied would, accordingly, amount to from 1,440,000 to 2,160,000 cubic feet. It is not an easy matter to arrange the fresh-air conduits of a size sufficient to furnish this volume of air; it is obviously costly to warm such a large quantity of air, and it is a still more difficult problem to introduce it without creating objectionable currents of air; and, finally, inasmuch as this air can not enter the auditorium unless a like amount of vitiated air is removed, the problem includes providing artificial means for the removal of large air volumes.

Where gas illumination is used, each gas flame requires an additional air supply--from 140 to 280 cubic feet, according to General Morin.

A slight consideration of the volumes of air which must be moved and removed in a theater to secure a complete change of air three or four times an hour, demonstrates the impossibility of securing satisfactory results by the so-called natural method of ventilation--i. e., the removal of air by means of flues with currents due either to the aspirating force of the wind or due to artificially increased temperature in the flues. It becomes necessary to adopt mechanical means of ventilation by using either exhaust fans or pressure blowers or both, these being driven either by steam engines or by electric motors. In the older theaters, which were lighted by gas, the heat of the flames could be utilized to a certain extent in creating ascending currents in outlet shafts, and this accomplished some air renewal. But nowadays the central chandelier is almost entirely dispensed with; glowing carbon lamps, fed by electric currents, replace the gas flames; hence mechanical ventilation seems all the more indicated.

Two principal methods of theater ventilation may be arranged: in one the fresh air enters at or near the floor and rises upward to the ceiling, to be removed by suitable outlet flues; in this method the incoming air follows the naturally existing air currents; in the other method pure air enters at the top through perforated cornices or holes in the ceiling, and gradually descends, to be removed by outlets located at or near the floor line. The two systems are known as the "upward" and the "downward" systems; each of them has been successfully tried, each offers some advantages, and each has its advocates. In both systems separate means for supplying fresh air to the boxes, balconies, and galleries are required. Owing to the different opinions held by architects and engineers, the two systems have often been made the subject of inquiry by scientific and government commissions in France, England, Germany, and the United States.

A French scientist, Darcet, was the first to suggest a scientific system of theater ventilation. He made use of the heat from the central chandelier for removing the foul air, and admitted the air through numerous openings in the floor and through inlets in the front of the boxes.

Dr. Reid, an English specialist in ventilation, is generally regarded as the originator of the upward method in ventilation. He applied the same with some success to the ventilation of the Houses of Parliament in London. Here fresh air is drawn in from high towers, and is conducted to the basement, where it is sprayed and moistened. A part of the air is warmed by hot-water coils in a sub-basement, while part remains cold. The warm and the cold air are mixed in special mixing chambers. From here the tempered air goes to a chamber located directly under the floor of the auditorium, and passes into the hall at the floor level through numerous small holes in the floor. The air enters with low velocity, and to prevent unpleasant draughts the floor is covered in one hall with hair carpet and in the other with coarse hemp matting, both of which are cleaned every day. The removal of the foul air takes place at the ceiling, and is assisted by the heat from the gas flames.

The French engineer Péclet, an authority on heating and ventilation, suggested a similar system of upward ventilation, but instead of allowing the foul air to pass out through the roof, he conducted it downward into an underground channel which had exhaust draught. Trélat, another French engineer, followed practically the same method.

A large number of theaters are ventilated on the upward system. I will mention first the large Vienna Opera House, the ventilation of which was planned by Dr. Boehm. The auditorium holds about three thousand persons, and a fresh-air supply of about fifteen cubic feet per minute, or from nine hundred to one thousand cubic feet per hour, per person is provided. The fresh air is taken in from the gardens surrounding the theater and is conducted into the cellar, where it passes through a water spray, which removes the dust and cools the air in summer. A suction fan ten feet in diameter is provided, which blows the air through a conduit forty-five square feet in area into a series of three chambers located vertically over each other under the auditorium. The lowest of these chambers is the cold-air chamber; the middle one is the heating chamber and contains steam-heating stacks; the highest chamber is the mixing chamber. The air goes partly to the heating and partly to the mixing chamber; from this it enters the auditorium at the rate of one foot per second velocity through openings in the risers of the seats in the parquet, and also through vertical wall channels to the boxes and upper galleries. The total area of the fresh-air openings is 750 square feet. The foul air ascends, assisted by the heat of the central chandelier, and is collected into a large exhaust tube. The foul air from the gallery passes out through separate channels. In the roof over the auditorium there is a fan which expels the entire foul air. Telegraphic thermometers are placed in all parts of the house and communicate with the inspection room, where the engineer in charge of the ventilation controls and regulates the temperature.

The Vienna Hofburg Theater was ventilated on the same system.

The new Frankfort Opera House has a ventilation system modeled upon that of the Vienna Opera House, but with improvements in some details. The house has a capacity of two thousand people, and for each person fourteen hundred cubic feet of fresh air per hour are supplied. A fan about ten feet in diameter and making ninety to one hundred revolutions per minute brings in the fresh air from outdoors and drives it into chambers under the auditorium arranged very much like those at Vienna. The total quantity of fresh air supplied per hour is 2,800,000 cubic feet. The air enters the auditorium through gratings fixed above the floor level in the risers. The foul air is removed by outlets in the ceilings, which unite into a large vertical shaft below the cupola. An exhaust fan of ten feet diameter is placed in the cupola shaft, and is used for summer ventilation only. Every single box and stall is ventilated separately. The cost of the entire system was about one hundred and twenty-five thousand dollars; it requires a staff of two engineers, six assistant engineers, and a number of stokers.

Among well-ventilated American theaters is the Madison Square Theater (now Hoyt's), in New York. Here the fresh air is taken down through a large vertical shaft on the side of the stage. There is a seven-foot suction fan in the basement which drives the air into a number of boxes with steam-heating stacks, from which smaller pipes lead to openings under each row of seats. The foul air escapes through openings in the ceiling and under the galleries. A fresh-air supply of 1,500 cubic feet per hour, or 25 cubic feet per minute, per person is provided.

The Metropolitan Opera House is ventilated on the plenum system, and has an upward movement of air, the total air supply being 70,000 cubic feet per hour.

In the Academy of Music, Baltimore, the fresh air is admitted mainly from the stage and the exits of foul air are in the ceiling at the auditorium.

Other theaters ventilated by the upward method are the Dresden Royal Theater, the Lessing Theater in Berlin, the Opera House in Buda-Pesth, the new theater in Prague, the new Municipal Theater at Halle, and the Criterion Theatre in London.

The French engineer General Arthur Morin is known as the principal advocate of the downward method of ventilation. This was at that time a radical departure from existing methods because it apparently conflicted with the well-known fact that heated air naturally rises. Much the same system was advocated by Dr. Tripier in a pamphlet published in 1864.[7] The earlier practical applications of this system to several French theaters did not prove as much of a success as anticipated, the failure being due probably to the gas illumination, the central chandelier, and the absence of mechanical means for inducing a downward movement of the air.

[7] Dr. A. Tripier. Assainissement des Théâtres, Ventilation, Éclairage et Chauffage.

In 1861 a French commission, of which General Morin was a member, proposed the reversing of the currents of air by admitting fresh air at both sides of the stage opening high up in the auditorium, and also through hollow floor channels for the balconies 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 Théâtre Lyrique, the Théâtre du Cirque, and the Théâtre de la Gaieté.

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 galleries by special flues heated by the gas chandelier.

The Grand Amphitheater of the Conservatory of Arts and Industries, in Paris, was ventilated by General Morin on the downward system. The openings in the ceiling for the admission of fresh air aggregated 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 mechanical 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 New York Music Hall, which has a seating capacity of three thousand persons and standing room for one thousand more. Fresh air at any temperature desired is made to enter through perforations 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 for the improvement of the ventilation of the Senate chamber and the chamber of the House of Representatives in the Capitol at Washington, but the system was not adopted by the Board of Engineers appointed to inquire into the methods.

The downward method is also used in the Hall of the Trocadéro, Paris; in the old and also the new buildings for the German Parliament, Berlin; in the Chamber of Deputies, Paris; and others.

Professor Fischer, a modern German authority on heating and ventilation, in a discussion of the relative advantages of the two methods, reaches the conclusion that both are practical and can be made to work successfully. For audience halls lighted by gaslights he considers the upward method as preferable.

In arranging for the removal of foul air it is necessary, particularly in the downward system, to provide separate exhaust flues for the galleries and balconies. Unless this is provided for, the exhaled air of the occupants of the higher tiers would mingle with the descending current of pure air supplied to the occupants of the main auditorium floor.

Mention should also be made of a proposition originating in Berlin to construct the roof of auditoriums domelike, by dividing it in the middle so that it can be partly opened by means of electric or hydraulic machinery; such a system would permit of keeping the ceiling open in summer time, thereby rendering the theater not only airy, but also free from the danger of smoke. A system based on similar principles is in actual use at the Madison Square Garden, in New York, where part of the roof consists of sliding skylights which in summer time can be made to open or close during the performance.

From the point of view of safety in case of fire, which usually in a theater breaks out on the stage, it is without doubt best to have the air currents travel in a direction from the auditorium toward the stage roof. This has been successfully arranged in some of the later Vienna theaters, but from the point of view of good acoustics, it is better to have the air currents travel from the stage toward the auditorium. Obviously, it is a somewhat difficult matter to reconcile the conflicting requirements of safety from smoke and fire gases, good acoustics and perfect ventilation.

The stage of a theater requires to be well ventilated, for often it becomes filled with smoke or gases due to firing of guns, colored lights, torches, representations of battles, etc. There should be in the roof over the stage large outlet flues, or sliding skylights, controlled from the stage for the removal of the smoke. These, in case of an outbreak of fire on the stage, become of vital importance 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 overcrowded, 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 increases the safety of human life in theaters and other places of amusement, its use is in many city or building ordinances made imperative--at least on the stage and in the main body of the auditorium. Stairs, corridors, entrances, etc., may, as a matter of precaution, be lighted by a different system, by means of either gas or auxiliary vegetable oil or candle lamps, protected by glass inclosures against smoke or draught, and provided with special inlet and outlet flues for air.

Passing to other desirable internal improvements of theaters, I would mention first the floors of the auditorium. The covering of the floor by carpets is objectionable--in theaters more so even than in dwelling houses. Night after night the carpet comes in contact with thousands of feet, which necessarily bring in a good deal of street dirt and dust. The latter falls on the carpets and attaches to them, and as it is not feasible to take the carpets up except during the summer closing, a vast accumulation of dirt and organic matter results, some of the dirt falling through the crevices between the floor boards. Many theater-goers are not tidy in their habits regarding expectoration, and as there must be in every large audience some persons afflicted with tuberculosis, the danger is ever present of the germs of the disease drying on the carpet, and becoming again detached to float in the air which we are obliged to breathe in a theater.

As a remedy I would propose abolishing carpets entirely, and using instead a floor covering of linoleum, or thin polished parquetry oak floors, varnished floors of hard wood, painted and stained floors, interlocked rubber-tile floors, or, at least for the aisles, encaustic or mosaic tiling. Between the rows of seats, as well as in the aisles, long rugs or mattings may be laid down loose, for these can be taken up without much trouble. They should be frequently shaken, beaten, and cleaned.

Regarding the walls, ceilings, and cornices, the surfaces should be of a material which can be readily cleaned and which is non-absorbent. Stucco finish is unobjectionable, but should be kept flat, so as not to offer dust-catching projections. Oil painting of walls is preferable to a covering with rough wall papers, which hold large quantities of dust. The so-called "sanitary" or varnished wall papers have a smooth, non-absorbent, easily cleaned surface, and are therefore unobjectionable. All heavy decorations, draperies, and hangings in the boxes, and plush covers for railings, are to be avoided.