International projectionist (Oct 1931-Sept 1933)

32 INTERNATIONAL PROJECTIONIST November 1931 verging rays, coming through the scaning disc, onto the photo-electric cell. Rotation of the transmitting scanner is obtained by mounting it directly on the shaft of a 1/10-h.p. synchronous motor, rotating at 1800 r.p.m. The film is driven by this motor, being connected to it by an eight-to-one reduction gear, thus moving the film at the rate of 15 "frames" per second. A unique "phase shifter" is also provided to enable positive or negative film to be televised. In this manner, the use of either kind of film is permitted without necessitating the addition or removal of a step of amplification. New Cathode Ray Tube Great Aid to Art TELEVISION is expected to take a big step forward with the perfection of the cathode ray tube. The cathode ray tube looks very much like a coneshaped vacuum bottle, on the flat end of which, on a flourescent screen, images are formed. The images obtainable with the cathode ray tube are considered to be far superior to those produced by scanners or neon tubes. At the same time, the cathode tube can copy a greater number of lines than do the scanners or neon tubes. In speaking of cathode ray tubes, Sanabria, the 25-year-old television worker who "stole the show" at the recent Radio World's Fair held in New York by televising the largest images so far offered the public, says: "The mechanical method seems best if a large image is desired. The scanning disc and its associated devices are much less complicated than electrical scanning, which calls for expensive and complex apparatus. However, progress is being made with the cathode ray scanner and it shows promise for the future." The cathode ray accomplishes its work by employing elements which bend the electronic stream back and forth and gives the same effect as scanning. The cathode ray cannot, however, be incor The New Yark Television Demanstration THE recent television demonstration by U. A. Sanabria, 26-year-old Chicago "wizard," at the Broadway Theatre in New York City, has set to wagging the tongues which for several years past have been predicting "television just around the corner." Many of our readers have expressed interest in this demonstration and have inquired as to its significance. The answer is that the demonstration is significant only in that it generated not a little worthwhile interest in the television art — and that is all. Technically, the week's run was just so so. It would be idle to deny that much progress has been made and is daily being made in the television art. But just at present there is nothing to indicate that television will soon enjoy any great degree of popularity. Its use in the theatre still is a matter of years and not days, weeks, or months, as is predicted by many television promoters. The Sanabria demonstration was nothing more or less than conventional. True, he did produce a 9-foot picture but only at a great sacrifice of detail. We saw the picture and it wasn't any great shakes. We haven't seen a larger picture anywhere, but we have seen much better quality — which, after all, is what counts. The Sanabria picture required much squinting and peering to distinguish the image, and it proved a dull show to us. That which Sanabria gave us at the Broadway could have been done by any number of television workers. Jenkins, Western Electric, Radio Corporation of America and one or two others we could mention could have done as well, if not better. The answer to the question of "Why don't they?" is that these companies are working for quality images and not quantity. Mr. Sanabria got his 9-foot picture all right, but in so doing he sacrificed quality — that is, the sort of quality to which we are accustomed. The best television we have seen thus far has been that of Bell Telephone Laboratories, and this particular system, according to the Laboratories' own admission, is far from being a commercial possibility. We had a "commercial" television set in our home for several weeks, but the images were so poor that we gladly loaned the set to a friend and were glad to be rid of it. To those projectionists who are anxious about the early arrival of television in the theatre we say "Forget it." It is all very well to maintain a lively interest in the progress of the art, but getting excited about "television just around the corner" is a waste of energy. There is nothing to it. JAMES J. FINN porated in the ordinary receiver without the use of special equipment that will allow but an extremely small amount of current to pass at a high voltage. Suggests Multi-Screen for Four Televised Images WRITING in the current issue of Television News, C. Maggi suggests a multi-screen receiver that will, by projecting images on four sides of the cabinet, permit observers to see television images not only from the single position straight in line with the lens, but from four (or more), angles. The essential parts needed to build a multiscreen receiver are: four scanning discs, four neon tubes, four screen assemblies, one upright motor, and five gears. In assembling the multi-screen receiver, the motor is mounted to the baseboard. The master gear is mounted at the end of the motor shaft, and four gears are mounted about the master gear (90 degrees from each other) with a 14inch shaft 7 inches long. One end of the shaft goes to the scanning disc and the other to the scanning gear, which is revolved by the master gear. The four scanning shafts are supported by a foursided frame, with its associated collars, etc. Complete details and drawings for building the multi-screen receiver are contained in the Maggi article, which is recommended to television "fans." VACUUM TUBE PRODUCTION The production of a vacuum tube parallels a tremendous industrial task, in miniature. Aside from the numerous fine elements used in the construction of a tube which could be termed analagous to minute girders, braces, cross-members, etc., there are 186 various spot welds in the final assembly of the elements. This is equivalent to the number of welds required in laying a %-mile pipe line, with each section of pipe 20 feet long. This would be sufficient to weld all steam and water pipe connections in the average home; or, in the marine field, to weld a mammoth anchor chain 93 feet long for one of the big ocean liners. In aviation, a complete plane including the frame and fuselage could be securely welded with this large number of operations. It is hardly believable that this great number of welds are necessary in a small article like a vacuum tube. But fine wire and small parts are used which require a weld no larger than a pin-head. H. & C. NEW H.-I. LAMP Hall & Connolly, Inc., have developed a new and radically different high intensity projection lamp for amperages from 75 to 200, the result of intensive research for more than a year. The design lor the lamp includes a number of new principles that will appreciably improve projection and facilitate operation.