Kinematograph year book (1948)

466 The Kinematograph Year Book. that it is generally not desirable that the arc current should be regulated during the show. Single-phase rectifiers made by Nevelin and by Hewittic are specifically intended for mounting in the projection room. The latter firm has also introduced a smaller model than their standard type, with an output of 35 to 45 amps. Known as the Unitarc Minor and measuring only 34 in. in height it is designed for mounting alongside, or even underneath, its projector. * The opposite policy is favoured by the Electric Construction Co., whose name and that of Western Electric are combined in the name of the Ecwelite rectifier, which was demonstrated in conjunction with the Westar and Westrex equipment. A feature of this outfit is that a single bulb provides entirely independent supplies for the two arcs by means of twin sets of anodes. Remote Control Current control is effected by means of a reactive transformer. The equipment is intended for remote control, although it may if desired be put alongside the projectors. Two makers of metal rectifiers have changed over from copper oxide to selenium : Westinghouse (whose admirable resonant control circuit has the advantage of providing a high-power factor) and Runbaken. Both firms insist that three-phase working is desirable — a system to which the metal rectifier of course lends itself. Both, too, favour positioning the rectifier away from the projection room, although willing to meet the views of customers. In many directions, the foundations are being laid for future technical progress. That the arc lamp has not attained its ultimate efficiency is suggested by experimental work described by G.E.C., Morganite, and in America the National Carbon Co. While the mercury discharge lamp does not appear as yet to be able to compete with the carbon arc, its development is nearing that stage ; by the admixture of cadmium vapour with mercury, the lack of red rays in the light is largely remedied. Novel Light Source A novel light source, the zirconium concentrated-arc, appears to hold considerable possibilities, although the small dimensions of the actual source may call for new optical systems. The need for improvement in the standard of slide projection has been realised, and action is to be expected during the coming year which will result in a higher standard of showmanship. I will venture a prediction that the coming year will see also a minor revolution in the technique of screen manufacture and installation ; the lines it will follow I indicated in the Ideal Kinema of October, 1947. Remarkable advances have been made in recent years in the recording of sound magnetically. The best results seem to be achieved by the use of metallic powder, and the process is stated to be especially adaptable to sub-standard films. Television progress in the kinema has been held up less for technical reasons than for lack of a concordat between the B.B.C. and the film Trade. Cinema Television has demonstrated its ability to fill a 15-ft. screen with a well-lit picture when at the Conservative Conference at Brighton, they reproduced the proceedings to a second audience, via the screen of When— It's Slides: S ALL THE ORGANISTS ARE MORGANISTS ! MORGAN'S SLIDES LTD. 309, GRAY'S INN ROAD, LONDON. W.C.I. TtUplimt : Ttrmimu i)}6 (s lima)