International projectionist (Jan-Dec 1956)

Request for Wider Coverage To the Editor of IP: Please find enclosed an American Express Co. draft for the renewal of my subscription. I find your magazine most useful. It contains much technical information valuable to projection technicians throughout the world. My only objection is that IP concentrates to a great degree on projection techniques and problems current in the United States, Canada, Europe and Australia. I feel that you do not publish sufficient information regarding theatre equipment problems and projection techniques in Asia and Africa. Speaking from experience, I can tell you that Asian countries are in great need of improved projection techniques and equipment. I strongly suggest that you arrange for some kind of representation through a correspondent at Bombay for India, Pakistan, Ceylon, Japan and Hong Kong. Discussion of Eastern as well as Western problems in your magazine would be of great benefit. Yousuf Umar Karachi, Pakistan Comment: Your point is well taken, particularly when it is considered that the motion picture is the principal and sometimes the only means of entertainment or mass communication in large parts of Asia and Africa. The importance of the motion picture theatre in these areas was the subject of an editorial in the July issue of IP. In the future we plan to keep a closer eye on projection developments in the Orient, Far East, and Africa. Curved Splice Theory To the Editor of IP: This refers to comments on splicing methods in IP's August Letters to the Editor column. Isn't the theory behind the curved splice that it is stronger due to its supposedly providing a greater splice area than the normal straight splice? I hope that at sometime in the future the subject of exchange film inspection (or non-inspection) will be other than "Who Shot John?" Joseph J. Zaro Bijou Amusement Company Nashville, Tenn. Comment: a curved film splice contacts film-track parts (fire-valve rollers, pad rollers, gate runners, tension pads, etc.) at a small angle, and for this reason is not supposed to tear apart so readily as a straight splice. Of course, curved splices must be run in only one direction; that is, with the convex side of the splice leading. If the splice area in the perforation margins lead, then the curved splice is far more likely to tear apart than a normal straight splice. The presumed strength of the curved splice is not due to greater surface area. Compared with a straight splice having the same width of overlap — a straight hairline" splice, for instance, — curvature of the splice results in a surfacearea increase appreciably less than 1%. For example, if the radius of splicecurvature is /", then the length of the curve on a film iv inches wide is: 7T T 90 (sin^) In the case of a curvature-radius of 3% inches and a film width of 35 mm (1.3780 inch), 1 = 1.3887 inch. The length or area of the curved splice is thus only 1.0078 times that of a straight splice of the same overlap-width, an increase of only 0.77%. A comparison of "hairline" and "fullhole" straight splices, on the other hand, reveals that the full-hole, or positivetype, splice has 2.1673 times the area of the hairline, or negative-type, splice, and is therefore appreciably stronger when properly made. Hairline splice: 1.378 x 0.072 inches — 0.0992 square inches of surface area. Full-hole splice: 1.378 x 0.156 inches = 0.2150 square inches of area. The regular full-hole positive splice has a surface area fully 216.73% that of the hairline splices. We accordingly recommend the use of full-hole splices for repairing theatre-release prints in the exchanges as well as in theatre projection rooms. Film Lubrication Facts To the Editor of IP: Would you please ask Robert A. Mitchell, author of "Magnetic Tracks on Release Prints" (August 1956 issue), to read the article in the SMPE Journal, September, 1949, Volume 53, Page 285, before he submits another article? Seattle, Wash. Frank J. Cooke Comment: The article on page 285 of the September 1949 issue of the Journal of the SMPE is entitled "Lubrication of 16-mm Films" and written by Ralph H. Talbot of the Eastman Kodak Co. There is, however, little connection between the subject matter of Dr. Talbot's excellent paper and the discussion of mag netic-track CinemaScope prints written by R. A. Mitchell for the August issue of IP. For the information of readers of IP. Dr. Talbot's article describes materials suitable for the overall lubrication of 16-mm films. (35-mm prints are usually lubricated along the perforation margins on the emulsion side of the film only.) A number of carrier solvents for film wax are discussed, together with the precautions which must be observed in using them — the avoidance of inhaling carbon tetrachloride vapor, for instance. (Mr. Mitchell mentioned carbon tet in connection with film cleaning and stressed its dangerous toxicity.) Slower-evaporating solutions of wax in isopropyl alcohol for use when additional film-drying space is available are described in the Talbot paper. New formulas using Freon (trichlorotrifluoroethane). a rapid-drying noninflammable solvent of low toxicity, are suggested. (Although much more expensive than carbon tetrachloride, Freon, a du Pont product, has come into use as a safe film-cleaning agent.) A suitable surface treatment for use with films to be run on automatic "repeater" projectors is described. SCIENCE NOTES An underwater telephone cable soon will cross the Atlantic ocean for the first time, connecting Newfoundland and Scotland, covering a distance of 1,950 nautical miles. Previous cables, dating back almost 100 years, have carried only telegraph signals. Transatlantic telephony to date has been entirely by radio transmission which is impaired by magnetic storms. * * * A beta ray collecting device has been developed to harness part of the energy released in a nuclear reactor, following which the energy may be used for electrical power. The device extracts beta rays directly from the reactor through terminals. About 7 to 10% of a nuclear reactor's power is in the form of beta rays which ordinarily are dissipated as heat. * ■■■ * The fastest stop watch, an electronic tube timing atomic events down to a billionth of a second, was announced by the Westinghouse Research Laboratories. It is claimed that the new "watch" may be even 10 times faster than this. A transistorized auto radio will appear in the Chevrolet Corvette this year, according to General Motors Corp. New transistors are said to provide the radio 24 INTERNATIONAL PROJECTIONIST • OCTOBER 1956