International projectionist (Jan-Dec 1946)

The Modern Means of Converting A. C. to D. C. as a stable power supply for projection arc lamps STRONG COPPER OXIDE AND TUBE-TYPE RECTIFIERS Low original, operating and maintenance cost. Quiet operation. Distributed through leading Independent Theatre Supply Dealers. The Strong Electric Corp. 87 City Park Avenue TOLEDO 2, OHIO The World's Largest Manufacturers of Projection Arc Lamps is that in the Allenby Theatre. Tel-Aviv, which uses the RCA PG 139 system, Einemann V projectors, and Strong H. I. arc lamps. Prints with Hebrew sub-titles are not available, thus Hebrew translations are projected on a separate screen which is one-quarter as wide and the same length as the picture screen. This is accomplished by using a 500-watt incandescent lamp and a lens of four times the focal length of the regular projection lens. The translation is written on blank film and is projected by a continuous movement. Technical literature and any comment on projection matters will be welcome not only by myself but by all projectionists here. Arie Unger Tel-Aviv, Palestine. 77 Dizengoff Road. MORE ANENT V-TYPE BELTS To the Editor of I. P.: I noticed Corporal G. A. Wagner's letter about the use of V-type belts for take-up assembly drives (p. 24, Oct. 1945 ) . The Corporal and other projec SIGHT ALONE or SIGHT and SOUND * New type — positive action, perfectly synchronized Strong Changeovers are now available in three standard models — Strong Special changeover for porthole installation, Strong Zipper picture changeover for projector-head mounting, and the new Strong Dual-Purpose Zipper changeover for sight and sound. Essannay Electric Manufacturing Co., 1438 N. Clark St., Chicago 10. UNION LABEL STRONG'S CHANGEOVERS AN ESSANNAY //ELECTRIC MANUFACTURING PRODUCT JPuudM Soundman— You Can and Should help yourself by investigating the ASSOCIATED ELECTRONIC ENGINEERS— a society of union Theatre Sound Engineers whose members are represented in 129 Local Unions of the International Alliance. R. W. KAUTZKY For information write to 4108 CASE ST. ELMHURST, L. I., N. Y. tionists may be interested to know that I have been using this type of belt for more than a year now — and with excellent results. Having had no trouble since installing these belts, I am convinced that they can be used on any modern projector without any mechanical changes being necessary. I use Motiograph projectors, with their grease-lubricated take-up clutch, and RCA soundheads. Ours is a continuous show policy, averaging IIV2 hours daily, so you see that the belts really take a beating. The only possible difficulty is that of installation, and the trouble involved is a small price to pay for the excellent results obtained. On most projector heads it will be necessary to remove at least one gear in order to insert the belt. After replacing the gear, everything goes along normally. I use the Gates Truflex #2400 belt sold in almost all automobile supply stores at $1. This #2400 size just fits my equipment. When purchasing these belts, . get one 2V2" longer ih inside circumference than the round leather belting, as it does not seat securely in the round belt pulley and allowance must be made for that in order to avoid a very tight belt. Although these belts are not represented to be oil-resistant, they are standing up very well and show little sign of wear. I estimate I will get at least another year's wear from these belts, thus they average about two years service. Herbert Schwartz Bronx 66. N. Y. Watching Atoms Die Radium is one of several unusual chemical elements whose atoms go to pieces of their own accord — a process called radioactivity. When a radioactive atom breaks up, energy may be given off in the form of penetrating waves, or the energy may be expended by means of super-fast particles of electrified atom fragments. The paint on a lurnjnous watch dial contains a tiny amount of a radium compound. As the radium atoms break up, they jolt the molecules of the paint, causing them to give off the familiar greenish glow that is visible in the dark. Using a lens or magnifying glass of short focus, you can observe the deaththroes of the radium atoms. First rest your eyes and thus make them more sensitive by remaining in a perfectly dark room for five minutes or more. Then examine the watch dial with the magnifier. In place of the soft, uniform glow seen with the unaided eye, you now see pin-point flashes of light — scores of them at one time. What you observe are the flashes produced when, here and there, a radium atom blows up by throwing out a high-speed particle. Atoms are so numerous that this can go on for thousands of years without using up all the original bit of radium. — Science Illustrated. 32 INTERNATIONAL PROJECTIONIST