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

862 ABSTRACTS [J. S. M. p. E. quired in the proposed Ukrainian National Theater. The plans include a flexibility never before attempted ; they propose a construction of stage and auditorium that may be instantly transformed by means of a central control into a concert hall, opera, multiple stage theater, circus, or convention hall. From analyses of models of all these arrangements it is concluded that excellent acoustical conditions can be secured. A. A. C. Prevention of Interfering Noises. P. T. SHERIDAN. Mot. Pict. Herald, 104, No. 5, Sec. 2, Aug. 1, 1931, p. 33. This is the second of three articles covering the prevention of noises in reproducing systems in theaters. This article covers noises of an intermittent nature. The sources of this type of noise may be any one or more of the following: run down batteries; corroded or dirty clip contacts on fuses or ferrule type resistors; loose connections throughout the sound system; dirty contacts on faders and volume controls; poor brushes and rough commutators on motor-generator sets. A. A. H. Acoustical Problems of Sound Picture Engineering. W. A. McNAiR. Proc. I. R. E., 19, No. 5, Sept., 1931, p. 1606. The author points out the fact that a great advance in acoustical engineering was necessary in order to control new conditions which have been brought up by sound pictures. The article mentions several problems encountered by the author and discusses one type of acoustical distortion encountered. Numerous curves and formulas give a concise explanation of these problems. A. A. H. Prevention of Interfering Noises. P. T. SHERIDAN. Mot. Pict. Herald, 104, No. 9, Sec. 2, Aug. 29, 1931, p. 28. This is the last of three articles covering the prevention of interfering noises in theater sound reproducing systems This article describes and gives suggested remedies for the following steady noises: ground or "rush" noise; a-c. pick-up from power circuits; a-c. light leaks into PE cells; sprocket hole and framing line noise; electrical disturbance due to mechanical vibration. A. A. H. The Reversal Process. W. RAHTS. Kinotechnik, 13, June 20, 1931, p. 207. The theory and practice of photographic reversal processes are reviewed. Sensitometric curves on Agfa Reversal Film are given to compare the following methods of compensating for variations in the camera exposure: (1) variation in the time of first development in a developer containing a solvent for silver bromide; (2) variation in the second or reversing exposure ; (3) bathing in 10 per cent hypo for various times before the second exposure; (4) reduction of the reversed image for various times in potassium permanganate. In the method of varying the second exposure, a sensitometric comparison is given of the effects of using the following bleaching and clearing baths: (1) potassium permanganate, followed by potassium metabisulfite; (2) potassium permanganate, followed by sodium sulfite; (3) potassium bichromate, followed by sodium sulfite. It is stated that (2) and (3) tend to allow re-reversal, and that therefore the controlled second exposure does not permit as wide a choice of bleaching and clearing baths as the controlled first development. Control by bathing in hypo is said not to give clear highlights, and reduction with permanganate is said to give a small range of control. M. W. S. Improvements for the Motion Picture Camera. F. EULDERINK. Focus, 18, August 15, 1931, p. 471. Favorable notice is given an article appearing in Der Filmamateur which suggests a number of features that should be added to the small film camera, presumably for the serious worker. These features are as