CHAPTER XV.

OPERATING ROOM EQUIPMENT.

_Construction and Ventilation._--The operating room should be built of fireproof material, such as cement, brick, or tile. If it is of wood, it may be made nearly fireproof by lining the inside with heavy sheet iron. It will be well if asbestos is placed between the sheet iron and the wood which it covers. All woodwork, whether window frames, doors, or shelving should be thus lined. It may be taken as practically certain that sooner or later one or more reels of film will be burned in the room and every precaution should be taken to prevent the fire from spreading. If this is done there will probably be no serious results, for in the past there have been so many film fires which have been successfully confined to the operating room that audiences have become pretty well accustomed to them. If all operating rooms are strongly built and of ample dimensions, with all openings as small as practicable, it will help to inspire confidence in the audience and there will be but little likelihood of a panic.

The chief danger is to the operator. It is true that he is generally to blame, but it is not always possible even with the utmost care to prevent a fire. Above all the operator should be given every possible chance to get away in case of fire. An operator who feels that he can get away at the last moment is far more likely to stay and fight a fire than one who is penned up in a coop from which it is difficult to get out rapidly. There are in existence, at the present time, operating rooms where it is necessary to crawl on hands and knees some twelve or fifteen feet to get from the machine to the exit, and where the exit is by means of a trap door at the head of a ladder. Such operating rooms are an abomination and no self respecting operator would work in one of them.

The entrance and exit from the booth should be by means of a door at the right hand or crank side of the machine. The door should be self closing and should open into a space having a floor level with the floor of the operating room. The door should preferably be kept closed but if the provision illustrated in Figure 128 is made there can be no serious objection to leaving the door open for ventilation. A thin bar of iron is fastened to the door by a screw eye and is used to block the door open. A person rushing out will naturally knock this away and the door will close. The door could also be arranged to be held open by means of the strings, to be described later, which hold the shutters in place.

The ventilation of the operating room should be by means of a fireproof duct leading to the outer air. This flue should preferably extend above the highest point of the roof and should be of good size. The smoke from burning film is heavy and does not rise very fast but it is generated with extreme rapidity. Film burns at a temperature of 284 degrees Fahrenheit. If it is incased in a tank and fire communicates with it, the whole body of the film will be raised to this temperature in a very short time and will burn with the rapidity of an explosion. In the magazines, which are in general use in the newer houses, the combustion will be slower but nevertheless will take not more than about one minute.

It has often been suggested that a motor be provided in the ventilating flue, this motor to be kept running during the time the machine is in operation. This would no doubt help clear away all smoke very quickly but there is no assurance that it will be running at the time when it is most needed. A simple way to help out the ventilation without the expense and noise of a motor, would be to arrange the ventilating flue directly above the arc lamps so that heat rising from these would cause a draft. This can be further helped out by locating all resistances in this flue. They will then be out of the way in a safe place and assist in ventilating the room. The ventilating flue will need to be fitted with a damper for use in cold weather. This damper should be arranged to open by gravity and be held closed by a string connected to the shutter strings so that the damper may open when the shutters close.

The floor of the operating room is a very important part of it. It should, above all, be extremely rigid so that the machine may be fastened solid and thus obviate any vibration which will cause movement of the picture. All floors that are constructed of wood are somewhat elastic and aid this vibration. Movement of the picture is especially noticeable and annoying to those compelled to sit close to it. Floors must furthermore be lined with fireproof material and the only material used is sheet iron which, upon the floor, is very noisy and can hardly be nailed sufficiently to eliminate the noise. A metal floor lining has the further disadvantage of affording a good “ground,” so that any one standing upon it and touching a live part of the lamp is liable to receive a severe electrical shock. It will also soon wear through, make pockets to catch dirt, and allow a fire to communicate with the woodwork beneath it. The best floor material is cement, but this, when wet, also becomes a fairly good conductor and shocks may easily be obtained while standing upon it. There is no reason, however, why it should ever be wet in an operating room and it is therefore advisable to use cement.

The floor of the operating room should be kept clear as far as possible. Careless operators often allow their take-up magazines to become deranged and when they fail to work, allow the film to run on the floor. A thousand feet of film scattered loosely about occupies considerable space and is very likely to become badly tangled in case there is anything on the floor for it to tangle with. The writer has witnessed cases where it was necessary to take some of the film outside of the booth in order to get it straightened out. Any operator who has been in a similar predicament will appreciate the advantage of having every possible obstacle to a speedy re-adjustment removed. Above all, resistances and other sources of heat should be kept off the floor.

Every moving-picture machine requires at least two openings; one through which the picture is projected, which need not be very large; another through which the operator must view his picture, and this must be large enough to allow him to sit in comfort while watching the picture. In some operating rooms the opening through which the picture is projected is closed by a metal funnel which covers the opening and extends back enclosing the front of the projecting lens. This arrangement is very simple in the case of machines in which the revolving shutter is behind the lens. With many machines, however, this shutter works in front of the lens and the funnel would have to be extended so as to enclose the revolving shutter.

There is no reason why strong clear glass could not be used in the operator’s peep hole. This would of course interfere slightly with the clearness of his vision for focusing, but every operator should be provided with an opera glass for this purpose anyway, so that this objection would be easily overcome.

The same considerations which apply to motion-picture machines also applies to stereopticon lamps.

In the more pretentious houses a spot light is generally maintained. This is for the purpose of illuminating vaudeville performers. The opening, provided for this lamp, must be large enough to allow the light to follow an actor about the stage, and glass cannot well be used in it.

The best color for the operating room is green but it must be a dull dark green. Every vestige of light maintained in the room helps dull the vision of the operator to the light upon the screen. There is, furthermore, much light reflected from the film where the light strikes it and it is unavoidable that the operator should be bothered by this at times. All other light should be kept away from his eyes while the picture is running.

All of the openings in the room must be equipped with fire shutters. These are generally made of heavy iron and are arranged so that, if necessary, they can be instantly released and made to close all the openings, thus preventing the escape of fire and smoke into the auditorium.

The best arrangement of such a shutter is illustrated in Figure 130 at _A_. The shaded portion shows the opening; above is the iron slide, preferably one-sixteenth inch metal held up by a string. At the top is a step which will prevent the shutter from being pulled up out of the guides, for many operators would do this if the step were not there.

It is best to mount the shutter on a large piece of heavy metal which can then be bolted to the wall of the room. The hole in the wall can then be cut to the right proportions. When the machine is in place the shutter can be placed very accurately. In this way it will be possible to arrange for the smallest possible opening through which the machine can work.

Making up the shutter, as suggested above, is further of great advantage in old operating rooms of flimsy wood construction. If the guides in such places are fastened independently to the wall it is possible that they will not always remain in line with each other. A slight giving of the flimsy wall on one side may cause them to bind the shutter and prevent its free descent. If the metal on which the shutter guides are mounted is strong and heavy and the guides themselves substantially made, there will be but little chance to get them askew.

In that part of the guides in which the shutter runs there must be no screws, rivets, or anything else that could work loose and obstruct the shutters. Good methods of making up the guides are shown in Figure 130, at _B_ and _C_. They should be loose enough to work without lubrication. At the bottom there should be a bumper to stop the fall at the proper place. This bumper should be padded with some fireproof or slow-burning material and should be narrow. If it is made wide the operator is apt to use it as a shelf for tools or other things and this would prevent it from closing properly in case of fire.

All of the shutters must be normally self-closing and must be held open by some arrangement which can readily be worked by the operator; or, in case he fails to close them, they should be arranged so that the flames will cause them to close automatically. This is often arranged for by simply attaching a light strong string to each shutter, running it through a hook eye directly above and attaching it to a master string which is led over every place at which there is thought to be a likelihood of fire. The idea is, that the first spread of flames shall strike this string and by burning it, release all of the shutters. In order to enable the operator to drop the shutter perhaps before the flames have spread at all, the string is carried to the door and fastened so that he, on leaving the room, may quickly release it. It is even better to carry it still farther so that one can release it from the outside.

Some people have recommended that these strings be soaked in oil to make them more inflammable and tarred rope has even been made mandatory for similar purposes in ordinances. This might make the string more readily inflammable, but it would at the same time make it last longer. A string or rope so treated would act like a lamp wick and the better soaked or tarred it might be, the longer would it last and thus fail to its purpose.

The principle of the arrangement of strings is shown in Figure 131. The string is fastened at the door in a manner allowing of easy and quick removal. Instead of the strings, light chains may be used provided that at a sufficient number of places fusible links are inserted. Such links are made up of an alloy which melts at a low temperature and allows the shutters to drop just as they would in the case of a string burning in two.

In many cases the strings are run over grooved pulleys. This is, however, inadvisable. Experience has proved that very often the string has come out of the groove and is wedged in between the shaft of the pulley and the side so that it will not allow the shutter to descend at all. A substantial hook eye is much better than any pulley. The strain being taken off the string when it separates, there is no friction and it slides through the eyes very readily. The door and the vent flue may all be brought under control of the same string so that all will operate together, the vent of course opening while the others close.

Where there is but one door there is little need of connecting it with the shutters, since, if it is provided with spring hinges it will naturally close after the operator has passed through it. In some operating rooms, however, there are two doors and both are often found open. In case of fire in such a booth it is extremely likely that one of the doors would be left open unless it is provided with some automatic manner of closing.

At _D_, Figure 130 is shown a shutter, provided with strong spring hinges, which closes over the opening from the outside. Such shutters should not be used where there is room for the drop shutters. Where it is necessary to have them, they should always be arranged on the outside of the booth; if on the inside there is too much chance of obstacles being in the way to prevent their closing.

It is very desirable that all of the shutters be closed after each show. If this is done there will be strong assurance that they will be in working order in case of need and this is about the only way in which they can be kept in order. The string arrangement above described is, however, not well suited to this purpose unless each shutter string be detachable from the main string. There are also various other ways of accomplishing this which will readily suggest themselves to the operator.

In every operating room there should be ample provision for keeping tools but it is advisable to have all tools, that are not kept in the lockers, on hooks instead of shelves. It is best to limit the amount of shelving to what is actually necessary. Shelving offers great temptation for the accumulation of rubbish. There must be a shelf upon which to locate the rewinding apparatus and upon which to place the machine while looking it over or making repairs, also a shelf to hold a small vise, etc. But this is all; any additional shelving will be inexpedient. A locker for tools can easily be arranged under the rewind shelf. A good safe place is an encouragement to an operator to keep a supply of good tools and nothing is more essential to the proper management of a machine than good tools.

If the operating room is large enough, it may also contain a locker for clothes but this should be fireproof. Preferably, however, the clothes locker should be outside of the room, since a film fire gives one but little time to pick up clothes or anything else.

There should, further, be a metal pail or receptacle of some kind for hot carbons taken from the lamps from time to time. A wise operator will also provide himself with a small receptacle in which he can keep the pieces of film which he finds it is necessary to cut out of films received from the exchanges. The inspection of films in the exchange is often very perfunctory and many lengths are left in that should be cut out. Cutting them out and saving them for a time will often help an operator to win out in disputes with his film exchange. There are operating rooms which have film boxes built into the wall in fireproof manner, some of them even surrounded by water. At the present time there are a number of good portable boxes on the market so that this is unnecessary.

_Wiring of Operating Room._--Every operating room must have at least two circuits run into it; one for the arc lamp and another for one or more incandescent lights. In the larger cities an emergency lighting system is required for all parts of the house used by the audience. This system is always entirely independent of the main service and is supposed to furnish sufficient light for the audience in case the other lighting system should fail. It will be well if one light connected to the emergency system is arranged in the operating room. If this is done, there must be special provisions that no cords, fan motors, or portables be connected to it. A short circuit, or trouble of any kind on this light might put the whole emergency system out of operation. If such a light is installed, it should be at the ceiling and protected by a strong wire guard fastened to the outlet box. All wires carried into the operating room should be in conduit, with the exception of the asbestos covered wires used with arc lamps and resistances.

In addition to the incandescent light above mentioned, there should be several other lights so arranged that good light can be obtained in any part of the room. The color of walls being dark there is but little reflection and a single light will only illuminate a small space. One light should be arranged above the rewind reel and there is often another arranged under a piece of glass in a shelf above which films are patched. Only the best reinforced cord should be used and all work that is stationary should be in conduit. Several outlets should be arranged for portable cords so that one may have a light to bring down to the take-up reel or close to the floor if necessary. Every incandescent lamp in the operating room should be protected by a substantial wire guard fastened to the socket.

Fan motors should be provided with strong brackets located near the ceiling and close to the outlet from which the motor is to be run. Fan motors should never be allowed upon the floor.

Where rewinding is to be done by motor, it will be well to arrange a separate circuit for this motor independent of all lights. The commutator part of the motor should be enclosed so that there may be no possibility of a spark igniting the film.

Figure 132 is a sketch illustrating the arrangement of wiring by which two arc lamps may be connected to mains of sufficient carrying capacity for one only. _F_ is the fuse box in which the arc lamp fuses are enclosed and may be large enough to accommodate a set of fuses for the incandescent-lamp circuit also. In many cases these are, however, taken from the house circuit since the meter rate for arc lamps is usually different from that for incandescent lamps. _S_ is the main arc-lamp switch by which the whole installation in the room can be cut off. This is necessary especially if so-called compensarcs, economy coils, or transformers are used, for these always take some current if left alive even if the arc lamp be not burning. At _C_ is the resistance or economy coil which serves for both lamps and at _S_ is the throw-over switch. This switch is provided to make it impossible to burn the two arcs at the same time as this would overload the small capacity mains. The above is a cheap arrangement and is installed only where a set of mains exists which is too small to supply more than one arc at a time. It is not to be advised for a new installation because it is of great advantage to be able to burn both arcs at the same time. When changing rapidly from one machine to the other it is of advantage to have the second one on for a short time before the first is off, not only to save a little time, but also for bringing electrode points to the proper shape. Wherever it is possible to do so always provide mains of sufficient size to feed all of the arcs and give each lamp its own fuse, switch, and resistance or transformer.

Figure 133 shows a method by which it is possible to arrange for either one of two arcs to be run from a rectifier _R_, indicated by the square at the left, or transformer _T_, at the right. In case rectifiers, heavy transformers that cannot well be raised to the ceiling, or motor generators are to be installed, they should be located in a separate enclosure which must be fireproof.

In general, all of the wiring in the operating rooms must be installed in accordance with the rules given in the chapter on Theater and Stage Wiring. These are the rules of The National Board of Fire Underwriters and are familiarly known as the “National Electrical Code,” or “N.E.C.”