International projectionist (Oct 1931-Sept 1933)

34 INTERNATIONAL PROJECTIONIST December 1931 25'"ANNUAL SEAL YOUTH and STRENGTH Help fight tuberculosis Buy CHRISTMAS SEALS THE NATIONAL, STATE AND LOCAL TUBERCULOSIS ASSOCIATIONS OF THE UNITED STATES as was formerly obtained upon an opaque surfaced screen; also there is more wear on the film by the introduction of two more sprockets in the sound mechanism of the projector, and increased projection speed in some cases which adds to the wear of the sprocket holes on the film. Sound Pictures Motion pictures with sound are made possible by the combining of discoveries, some of which are older than moving pictures themselves. For instance, transformers or repeating coils, as they are called by telephone men, are much older than motion pictures. You have seen transformers, those big black boxes which hang at the top of power poles and which are used to change electric current from one pressure to another, or one voltage to another. Other things which have made sound pictures possible are photo-electric cells, or electric eyes as they are sometimes called, which very much resemble an ordinary radio tube and which work much the same as a tap in a water pipe, except that they are turned on and off by light rays and when they are turned on they permit an electric current to flowin a circuit instead of water flowing through a pipe. The mechanical features of sound picture apparatus involved nothing that was not already known to everyone in the industry. They simply needed to be adapted to their new uses. A modern sound picture installation looks very much like the panel board in a broadcasting station. There are two methods used for recording sound pictures; the sound-on-disc method and the sound-on-film method. Sound-on-disc. from a mechanical standpoint, is not however, faithful reproduction of sound is possible over a wider range of sound frequencies with discs than with soundon-film. Labor Organizations In the early days of the industry the motion picture projectionist had not yet been organized into labor unions, and as a consequence he labored long hours in projection rooms, which at that time were called booths, and under conditions which were deplorable. The pay was low. There were no facilities for sanitation or ventilation. As the industry grew and a better type of man was attracted to our profession they were organized into the International Alliance of Theatrical Stage Employees and Moving Picture Machine Operators of the United States and Canada. Prior to this time the stage employees were the only craft represented by this international union. Today all branches of the industry are served by members of the international union and we now have, in addition to the stage employees and moving picture operators, studio mechanics, motion picture cameramen, still photographers, laboratory workers and sound technicians. So, all technical departments in both the producing and reproducing sections of the industry are served by members of our RCA Portable Reproducer This unit comprises a projection machine, an amplifier, a loudspeaker and a carry-case for film and these have an aggregate weight of slightly more than 200 pounds. The projection machine is 19" high, 19" wide and its breadth is 10". The amplifier, which is built in a carry-case having a removable cover, is 26" long, 8%" high and 11" in breadth. The loudspeaker, which is of the flat baffle type, is contained in a carry-case, the dimensions of which are 8V2 x 19 X 14". Standard 35 mm. film is used and adequate sound reproduction is obtainable in a room or hall having a content of 75,000 cubic feet when using the 8-inch directional baffle. A 6-inch dynamic cone speaker is supplied when the cubic content does not exceed 12,000 feet. A picture about 8 x 10 feet in dimensions is obtained upon the screen from a throw of 75 feet. The equipment is AC-operated from an outlet of 105 to 125 volts, either 50 or 60 cycle, single-phase power source.