Kinematograph Year Book 1942 (1942)

220 The Kincmatogvaph Y car Book. construction of Ashcraft arcs and Century projectors and, of course, the Century " Sure-fit " spares. These are supplied sealed and can be fitted without any tools other than a screwdriver, an immense advantage in these days of technical staff shortage. There has been a continued demand for the Ashcraft " Suprex " projection arcs, the standard illuminant for the Century projector. * The Century Model C is adaptable to all existing types of sound-heads. Ball bearings and " oilless " bearings are employed throughout to provide quiet operation and long life. Ball-races are hermetically sealed in high temperature lubricating grease, consequently they never heed oiling and are permanently protected against dirt. Low-speed shafts rotate in oil-less bearings of porous composition, each equipped with an oil reservoir. Lubricating oil reaches the shaft through the pores of the bearing material, which serves as a filter, preventing the entry of dirt. The projector main frame is a one-piece casting providing rigid support to the operating parts. .The interior of the mechanism housing is enamelled in white for maximum visibility and to encourage cleanliness. The main drive shaft, vertical shaft and shutter shaft are removable as integral units. The intermittent movement is of direct drive design and readily removable. The intermittent is oiled, and removed when necessary, from the operating side of the projector. The film gate is readily removable for inspection and cleaning ; film trap shoes are interchangeable and reversible. A guide provides antomatic indication of correct loop length. A framing lamp is provided, and there is a spot sight aperture in the shutter guard. A 90 deg. single-shutter is supplied as standard equipment, a double shutter attachment being available at slight additional cost. Walturdaw Cinema Supply Co., Ltd., have long been recognised as specialists in all matters affecting projection and screen illumination, and although the war has stopped one source of supply a considerable volume of business has been carried on during the year by the provision of rebuilt and reconditioned mechanisms. Fortunately the firm has held large stocks of spares, so that there will be no difficulty in meeting customers' requirements, while the country-wide efficient service of the company is being well maintained both at 46. Gerrard Street, W.l, and at their provincial branches. PROJECTION LENSES. ONE of the newer types of plastic materials — the methacrylate class — has found three applications to photography. Isobutyl methacrylate has proved of considerable interest for cementing both lenses and light filters and has proved an excellent substitute for Canada balsam. When applied to film base before coating it with emulsion, it keeps it sufficiently watertight tc maintain accurate spacing of the sprocket holes. These methacrylates are very resilient as dry films, but they can be rendered more pliable by the use ot the well-known plasticisers, such as dibutyl, phthalate. In America the Du Pont organisation has used this application in the production of lenses. It is revolved into a glass-clear material from which mass-produced cheap lenses can be moulded with a high degree of precision and at trifling cost. Taylor, Taylor & Hobson, Ltd. — Taylor-Hobson's activities have been fully absorbed by the provision of equipment to meet the greatly increased production demands in a number of branches of the national effort, particularly in the fields of scientific instruments, precision gauging apparatus. machine tools and photographic lenses of all types. A number of optical and precision-mechanical devices perfected by this firm, mainly for Government purposes, were demonstrated to the B.K.S. in May. Two of the most interesting features afforded a great contrast — one was an enormous lens made for the purpose of television projection upon a large screen, it was of 12 in. focus and worked at f /1.5 and weighed about 70 lb. ; the other was a tiny lens especially made for B.T.H., of 12|-mm. focus, f/2.5, the glasses about \ in. in diameter.