Journal of the Society of Motion Picture Engineers (1930-1949)

568 ABSTRACTS [j. s. M. p. E. Frequency Ranges of the Phonograph Record. Filmtechnik, 5, Oct. 12, 1929, pp. 447-8. Dr. W. Hagemann, in the A. E. G. "Mitteilungen," gives the following data on phonograph record reproduction. The recording space of 100 mm. contains approximately 360 grooves (assuming 41/* minutes per record), and 80 revolutions per minute. The pitch of the grooves is 0.28 mm., 0.15 mm. of which represents the groove width proper, and 0.13 mm. the width of the interval between the grooves. Toward the end of the record, the velocity of the record with respect to the needle is approximately 40 cm. per second. Under these conditions a sound of vibrating frequency of 4000 per second will consist of oscillations each occupying 0.1 mm. Phonographic reproduction is satisfactory for frequencies from 50 to 10,000 per second. Photomicrographs are given of phonographic records having recorded frequencies of 4000, 6000, and 10,000 per second. — Kodak Abstr. Bull. Question of Large Picture Films. L.. KUTZLEB. Kinotechnik, 11, Oct. 5, 1929, p. 507. It is the author's opinion that the installation of equipment for projection of wide films is likely to be a very gradual process in Europe. He believes that the Fear method of rotating the image through 90 degrees from the usual position on the film would be much more economical and equally satisfactory for obtaining a larger picture with a longer and wider sound track. — Kodak Abstr. Bull. Expanding Core for Film Rewinding. M. ENGELMANN. Lichtbildbuhne, 22, July 6, 1929, p. 15. A core for film rolls is constructed with a wedge center so that it is easily removable or replaceable without damaging the film. A re winder using the new core is illustrated. C. M. T. Relations between Mirror, Film Gate Illumination, and Light Output in Motion Picture Projection. H. NAUMANN. Kinotechnik, 11, June 20, 1929, p. 311. In place of the screen there were set up a number of lenses in various areas of the picture so that a series of images of the condensing system, one for each portion of the picture area, were thrown on a screen farther back. By this means the light distribution over the face of a condensing mirror could be studied in relation to each part of the picture area. Diagrams and plates are reproduced. — Kodak Abstr. Bull. Analyzing the Acoustics of Sound Motion Picture Theaters. W. KEITH FRIEND. Projection Eng., 2, No. 2, February, 1930, p. 19. This article is an elaboration on a former discussion (Projection Eng., December, 1929) dealing with the effect of theater seats on acoustics. Relations given by F. R. Watson and by W. C. Sabin are used. E. E. R. The Super Simplex. Projection Eng., 2, No. 2, February, 1930, p. 29. A description of the new features which include a fan in the rotating shutter for reducing heat at the aperture plate and a semi-automatic framing and picture centering device. E. E. R. New 16 mm. Film System. Projection Eng., December, 1929. This system uses the standard 16 mm. motion picture film, but four frames are photographed in the space now occupied by one. The film is moved horizontally as well as vertically across the front of the camera, the two movements taking place alternately The projector can also be used to project regular 16 mm. film. A 100 ft. reel taken with this apparatus is equivalent to a 400 ft. reel of regular 16 mm. film. G. L. C.