Moving Picture World (Nov-Dec 1927)

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December 31, 1927 47 Hall and Connolly Lamps By F. H. Richardson THE proprietors of the Hall & Connolly Company were formerly employed as designing and construction engineers by the Sperry Gyroscope Company of Brooklyn. Their work with that corporation was chiefly development of high intensity arc lamps for army and navy searchlights, in which field of endeavor they were eminently successful. In the year 1918 they developed a high intensity lamp designed for motion projection work at the works of the Sperry Company. This lamp was fully automatic; also it was rather complicated. It was self striking, self feeding and even self focusing. The lamp worked well, giving good results in screen illumination, but was not sufficiently sturdy for use in the steady grind of the average theatre projection room. So far as this editor knows this was the first attempt at high intensity arc motion picture projection. It was followed, about a year later, by a more rugged, less automatic, simplified lamp, which was supplied with better means for adjustment of the spot; also it was more convenient in the matter of re-trimming the carbons. All Sperry high intensity searchlight lamps were air cooled by means of high pressure blowers, which plan was followed in the earlier models of the lamps built for motion picture projection work. Later, however, this was discontinued. The Sperry Company, not wishing to invade the motion picture projection field, licensed another company under its patents, which organization proceeded to manufacture and market the Sperry high intensity projection lamp, then known as the “Sunlight Arc Lamp,” which was installed in a goodly number of the higher class theatres. Screen results were excellent, but the operation of the lamp was not altogether satisfactory, so that after a time the company discontinued their manufacture, and the men who had developed the apparatus proceeded to form the Hall & Connolly Company, which has since become toct well known to projectionists and theatre men to require an introduction. The new company proceeded to re-design the old Sperry Lamp, making it more simple and sturdy, incorporating into it many! of the various suggestions made by projectionists, so that at last a really practicable apparatus for high intensity projection work was available. As is well known, the HC High Intensity Lamp has come into wide use, and is now considered as standard equipment for high intensity work. The reason the lamp, has succeeded so well is that the manufacturers have studied the requirements of the projectionist, and have given him what he needs and wants; also they have supplied real service cheerfully. They base all changes and improvements on their lamps upon the findings and criticisms of the men who use them, which I might remark is not only a correct way, but also is the only correct way. About the time the first HC high intensity lamp experiments were in progress, those now comprising the Hall & Connolly Company (then members of the Sperry Company engineering staff) were working on a scheme for projection lantern slides on clouds. In these experiments a 75 ampere high intensity searchlight lamp was employed. The light was collected and projected through the slide by means of a 24" glass reflector. This is believed to have been the very first high intensity reflector lamp used for picture! projection. At that time the experimenters discussed the possibility of using such a lamp for motion picture projection, but came to the conclusion that it would be a tooi radical departure from established methods, especially when combined with the then new projection light source, the high intensity arc. It was only about a year ago that Hall & Connolly, Inc., began the construction of a high intensity reflector arc lamp along the lines of the one they now have placed before the industry. Figure i At that time indications pointed to the fact that the time had come for the introduction of radical changes in projection illuminants, to the end that a more brilliant and more even screen illumination be made possible, and that this be accomplished with greater efficiency in operation. Various schemes of arc feeding and positioning were tried out. Many different kinds of reflector were made and tested, with results that what was considered as being a “happy medium” was finally arrived at, and the new type H. I. R. (High Intensity Reflector) lamp was perfected. The Hall & Connolly H. I. R. lamp is not a modification of the reflector type lamps now in general use. Such a modified lamp was tried out thoroughly, but was very unsatisfactory because the method of burning the carbons in such a lamp would not produce high intensity results, besides which the arc proved to be unmanagable, which of course would not do for projection work. It was found necessary to use a real high intensity burner, which same was designed along the lines indicated by years of experience in high intensity lamp work. The new outfit is designed as follows: Fig. 1 is the lamp itself ; Fig. 2 is the assemblage as a whole, including the mirror, which is of such focal length as will locate the light source a sufficient distance away to prevent breakage and still with ample diameter to collect the maximum amount of light or, in the language of the scientific gentlemen, subtend the greatest possible solid angle, and at the same time keep the physical dimensions of the complete assemblage within practical limits. The reflector is, as you will observe in figure 2, not mounted upon the lamp itself, but upon the lamphouse, the rear wall of which it forms. It is carried by spring cushions and is bedded in asbestos rings. Should the reflector be broken by some accident the fragments will be retained in place and may be used for projection until a new reflector can be obtained and mounted. The mirror is accurately mounted and will always remain in fixed position. Projectionists will appreciate the ease with which the reflector may be swung into position for convenient cleaning or examination. Figure 2 How is the spot adjusted if the mirror is in fixed position? Very simple, Willie! You just move the light source (lampf forward, backward or up, down or sidewise! No, don’t apolo ( Please turn to following page)