Motography (Jan-Jun 1915)

January 23, 1915. MOTOGRAPHY 131 A Small But Model Operating Room FIRE DANGER MINIMUM THE extraordinary popularity of moving-picture displays has in the past few years directed close attention to safeguarding such theaters and particularly the operating room, which is the chief source of the fire hazard in such establishments and therefore, also, of the resulting danger to life. Nearly all communities of even moderate size have special ordinances regulating the installation and equipment of movingpicture machines, and the National Board of Fire Underwriters has drawn up regulations for the installation, operation and maintenance of such machines which are intended to reduce the hazards to a minimum. In a theater of this kind of considerable size the outlay for the equipment can, of course, be more generous than in a theater erected in a very small town or in the outlying district of a city. Nevertheless, even in the latter case, equipment of high character and a thoroughly satisfactory installation can be made at moderate cost, as is shown by the illustrations herewith. These illustrations are from photographs taken at the Windsor Park theater, Chicago. This establishment is of moderate size and is located at Seventy-fifth street and Railroad avenue, which is in one of the outlying districts in the southeastern portion of the city. Although the theater is r i • • ji Model op of medium size and has r all its seats on the ground floor, it is a new establishment and thoroughly up to date. The operating room is the center one of a series of three rooms located directly above the foyer. To the north of it, that is to the left of the room as shown in this illustration, is a separate room for a powerful motor-driven ventilating fan. To the right of the operating room is a separate room. This contains the rotary converter for supplying direct current from the three-phase, 60-cycle, 220-volt alternating current distributing system of the Commonwealth Edison Company ; it also contains a control board for this machine and a switch and cut-out cabinet. The brick wall shown in the picture is the rear wall of the theater auditorium. The brick wall on the opposite side of the room has a convenient tool rack. The floor in the operating room is of concrete, the partitions between this room and the two adjoining rooms referred to are of tile, and the entire surroundings are made as fireproof as possible. The display equipment consists of two hand-driven Sim plex motion-picture machines shown at the left in the illustration: there is also a spotlight shown at the right. The openings in the brick wall between the operating room and the auditorium are closed by gravity-operated steel sliding doors. These and the damper in the ventilating flue running up from the ceiling of the operating room can be held open by means of light fishline, in the manner prescribed, so that in case a fire breaks out in one of the film machines these cords will be destroyed and the openings immediately close. The bottom one of the three conduits shown along the brick wall carries the 220-volt supply circuit and runs to the steel cabinet. The upper conduit supplies the spotlight and also the first picture machine. The middle conduit supplies the further picture machine. The conduits are run to a point overhead each of the proecting arc lamps so as to make the flexible connection between the conduit outlet and its corresponding lamp as short as possible. It had been intended originally to use a mercury-arc rectifier for obtaining direct current for the projecting lamps from the alternatingcurrent supply. It was finally decided, however, to install a Martin fiveilowatt rotary converter instead of a mercury-arc rectifier. This machine develops direct current at 70 volts and runs at a speed of -rating room. 1>8qq revolutions per minute; it was supplied by the Northwestern Electrical Company, Chicago. The control panel directly above the machine contains a three-pole switch ; it also contains a direct-current voltmeter. Mounted back of the panel is a transformer for reducing the 220-volt alternating current to an appropriate voltage so as to give 70 volts direct "current after passing through the rotary. Above this are two grid resistances; one for each of the moving-picture machines. In the steel cabinet shown in Fig. 2 there is a double-pole, double-throw switch at the top, by means of which the circuit for the projecting lamps can be thrown from the direct current supplied from the rotary to the alternating-current supply, the current in the latter case passing through the Compensarc transformer mounted on pipe standards. This reduces the alternating current to a suitable voltage for the lamps and makes it possible to run the lamps if something should happen to the rotary converter and thus make direct current unavailable. There is a switch for each lamp and also a main supply switch at the