International projectionist (Jan-Dec 1947)

response, distribution index, and distortion, all but the first being functions of frequency. These terms were defined and discussed, with special emphasis on simple objective and subjective acceptance tests. Only direct radiator speakers were considered. METHOD AND EQUIPMENT FOR CHECKING FILM APPARATUS SPEEDS By C. T. Owlett Eastman Kodak Company The operation of a spring-driven motion picture camera is seriously effected if a mechanical tachometer is used to measure the speed. Equipment has been developed, and made to give a direct reading of camera speed utilizing a light beam as the connecting link. MOVIES ON WHEELS— SOUND MOTION PICTURES FOR PASSENGER TRAINS By John G. B'rtel Comprehensive Service Corp., N. Y. City This paper discusses the practicability of converting existing railway diner cars for the presentation of motion pictures' as a medium for relaxation while still retaining the use of the car for restaurant service. Determining factors for selecting available 16-mm standard projection equipment are given and problems presented by the moving train with respect to good screen results are outlined. Necessary modifications to standard equipment are described and details regarding a rigid demountable screen and an adequate loudspeaker system are given. The large power capacity of the car's battery system, in conjunction with the G. E. amplydine convertor, is used to fully operate the complete motion picture installation. The paper cites the final results obtained, passenger comments received, and the general public reaction to the installation made for the Chesapeake and Ohio Railway. EFFECT OF FEED AND HOLDBACK TENSION ON PROJECTION LIFE OF 16-MM FILM By C. F. Vilbrandt Eastman Kodak Co., Rochester, N. Y. With the advent of 16-mm film into the educational and commercial fields has come tie demand for increased projection film ife. At the same time, to avoid loose, unsatisfactory winding of the large projection rolls in use today, higher windup tensions are required. In this paper the effect of the wind-up tension on the projection life of film is described and compared with the effect of feed tension. The importance of the relationship between sprocket pitch, film pitch, tooth shape, and film wear is discussed. A high speed motion picture was shown to illustrate several of these effects. PROPOSALS FOR 16-MM AND 8-MM SPROCKET STANDARDS By J. S. Chandler, D. F. Lyman and L. R. Martin Eastman Kodak Co., Rochester, N. Y. This report describes the background and derivation of proposals to replace Specifications 222.6—1941 and 222.18—1941. The proposed new specification consists of four parts: illustrations, formulas, nomenclature, and appendix. The standard has been developed to give the designing engineer an opportunity to specify the dimensions of circular pitch or root diameter, tooth thick ness, and tooth profile for a particular application or condition. Formulas are based upon the range of film shrinkage to be accommodated and the amount of contact between film and sprocket. Graphic illustrations are given of the various relationships existing between the film and sprocket as considered in arriving at the proposed formulas. Indications are given of the probable type and extent of modifications desirable to establish complete agreement with test data obtained to date. Special consideration is given to lateral dimensions and to shape of the tooth in relation to the path of the film. [Note: This paper and the one by Dr. Vilbrandt are revisions of papers under similar titles presented at the Fall 1946 convention in Hollywood. They were represented at the Chicago convention before Journal publication in order to include additional experimental information.] MY FIRST FIFTY YEARS IN MOTION PICTURES By Oscar B. Depue Chicago, Illinois This is intimate, chronological account of experiences as a partner of the world's leading travelogue exponent, Burton Holmes. Mr. Depue describes their first meeting back in 1893; their world-wide wanderings through the years up to 1917; and the problems he met in devising camera, developing, projection and film printing equipment in those early days. The period from 1917 to the present is covered with remarks regarding the establishment of the Burton Holmes Films Laboratory; the theatrical release of a weekly travelogue for sixs years, and Mr. Depue's invention and manufacture of 35 and 16-mm printers and automatic light control boards. PYSCHOLOGY OF THE SOUND FILM By L. Mercer Francisco Francisco Films, Chicago, III. As an educational instrument the sound film is particularly effective for influencing people in groups, bringing to bear factors in social as well as individual psychology: social facilitation, the impression of universality, and prestige. The physical conditions under which its message is received and the absorption of the audience in the continuity PUT MORE LIGHT ON YOUR SCREEN • All reflectors gradually deteriorate to a state where replacement cost is insignificant. A drop of onlylO%in reflective efficiency results in a corresponding decrease in screen brilliancy, and represents a loss amounting to 10% of the cost of your current and carbons. Replace yours now, and regularly. Available for all types and makes of arc lamps. NATIONAL ■lilfMWLUi Division of Notional •5impl8K*filUtffwt»tti "There's a Branch Near You' U. L. approved . . . eliminates fire hazard. MicroSwitch safety cut-off — when door opens, motor stops! Motor does not transmit torque to operating parts. Reel-drive Dog... prevents broken keys. Available through Theatre Supply Dealers. GoldE Manufacturing CO. LowMaintenanceCost 1220-R West Madison St. Dept. R, Chicago 7 Positive Friction . . . Will Not Clinch Film "Tilt-back" Case . . Reels Can't Fly Off „S INTERNATIONAL PROJECTIONIST April 1947 33