The Bioscope (Oct-Dec 1931)

November 11, 1931 MODERN CINEMA TECHNIQUE THE BIOSCOPE l, Technical News and Notes Perpetual Motion Again A new dynamo is attracting a lot of attention in Germany. Invented by Herr Paul Hoffmann, of Steglitz, the new generator is said to give a power output of 120 to 125% of the power input, or, in other words, the machine has an electrical efficiency of over 120 per cent. So far, we have regarded 100 per cent, as the theoretical linnt of efficiency, and commercial generators never reach that figure, ranging from 70 to 90 per cent. To be able to put 100 h.p. into a machine and take 120 h.p. out of it would, of course, solve all our power problems to the end of time. The odd thing is that this new machine is said to have been tested by engineers of the big German electrical concerns, by university professors and by engineers in Sweden and Denmark, who all agree on the 120 per cent, efficiency claim. The inventor himself does not claimed to have solved the perpetual motion problem, but he does suggest that his device taps some source of energy hitherto unknown. There have been claims of this kind before, and they have proved to be ingenious fakes or stupid blunders in measurement. If I have to choose between a miracle or a mistake, I put my money on the mistake. Slowed Currents in Cable Experiments have shown that the speed of currents through wire circuits enclosed in cables is much slower than in the case of open circuits strung along poles. The velocity of a voice wave over cable lines is about 30,000 kilometres per second on long distance lines as compared with nearly 300,000 kilometres per second on open wire circuits. According to the International Projectionist, one of the results of the slower transmission is an echo effect which, if delayed sufficiently, would result in the speaker hearing the echo of his own voice. This is substantially reduced by the “ echo suppresser,” a device by means of which the transmission of voice waves in one direction interrupts the echo currents in the opposite direction. New Viennese Colour System A Viennese photographer has just demonstrated a process of colour photography with rather unusual characteristics. At a recent demonstration to local pressmen he explained that an ordinary lens in a standard press camera could be used and any kind of plate or film could be employed. By mirrors the light was diverted on to three negatives— yellow, red and blue. Pictures could be taken by snapshot, and, after development, the negatives are transferred to specially prepared gelatine sheets, costing 2d. each. The secret of the process is said to be a chemically prepared paper, the result of seven years work, over which the gelatine sheets are placed. With this paper, washing and fixing are eliminated, the photographs being printed in ordinary light in three minutes. Different tones were secured by placing the coloured plates at slight angles and in different sequences, and, obviously, any number of coloured prints are possible. The secret paper only costs £d. per sheet. Sound to Silent Western Electric announce a device for recentralising projection when changing sound to silent pictures. A pivoted sub-base is placed under the front feet of the projector and a slidable sub-base under the rear feet. A foot lever is provided, by depressing which a portion of the rear sub base is moved, shifting the rear of the projector laterally about the feet at the front, and moving the direction of projection through a small angle. The sound picture is masked off to the same relative dimensions of the silent picture and enlarged to cover the same screen as the silent picture. The new invention, which has been patented, is simple and efficient in operation. " Keepalites For Scialytics When the Public Works Exhibition opens at the Royal Agricultural Hall on Monday next visitors will see a particularly interesting exhibit on the Chloride Electrical Stand No. 122. It consists of a neat " Keepalite ” panel suitable for a typical hospital theatre, complete with a scialytic lamp and an operating table. The Keepalite panel is so arranged that in the event of any interruption to the ordinary electricity supply the lighting is automatically switched over to a battery fed circuit, so that there is no perceptible interruption of the light possible during an operation. The panel provides for the emergency batteries being constantly fed with a small trickle of current from the mains, so that they are always at maximum charge, though they can, if desired, be charged at maximum rate. ,1 have myself known of an operation being continued by the light of tapers when current failed, but the possibilities of accident are enormously increased in such circumstances as this particular case demonstrated only too clearly. A scialytic lamp is a new indirect projector fixed above the operating table and throwing an image of the operation on to a screen in an adjacent room so that students may watch without actually being present in the theatre. Clever Composite" Device I notice in some recent patent abstracts details of an invention of considerable significance concealed under its formal wrappings. The inventor is Roy J . Pomeroy, and it apparently relates merely to the making of “ composite photographs.” Two distinct films are exposed simultaneously to the same object, positioned before a nonactinic ground. One of the films is relatively over-exposed and this film is developed to produce an opaque image. This film is then used to mask the other film during its exposure to a desired background, so that the subject image of the second film may be combined with an image of that background. In this simple way is described a system which should be patentable and theoretically quite efficient for enabling an artist to be photographed in a studio in Hollywood and appear on the screen as if taken in a moving African forest or a European crowd. The old trouble was to avoid high lights of the background showing through the figure image, but this travelling black mask solves the problem cheaply and accurately. Why did not you or I think of it ? New Long-Playing Discs The American Victor Co. has just demonstrated a new long-playing gramophone record on which production has just begun. These new records will run for half-an-hour, using both sides of the disc. The effect is obtained by slowing down the machine’s turntable speed and doubling the number of surface grooves. The discs are made of a new composition, one-fifth as heavy as present records, and the surface noise is said to be less than one-half that of the ordinary record. Beethoven’s Fifth Symphony has been recorded on one disc, and eminent composers were loud in praise of the quality of reproduction. No details are yet available as to how, with double the number of surface grooves, the breakdown of groove walls is prevented. Television and Cinema It is disappointing to find film executives so widely opposed in opinion over the recent Broadway demonstration of television. A scene from a Broadway play was televised from the Theatre Guild stage to a 10 ft. screen in the Broadway Theatre. The heads of the players filled the screen and are said to be " easily distinguishable ” — the synchronisation being good. The visual portion of the broadcast was, according to one reliable spectator, “ hard on the eyes,” and hot lamps caused a ten minute breakdown. Other leaders of the film industry apparently regard the show as " marvellous.” The television screen is described as being " a large magnifying glass placed against a receiving disc which was making 900 revolutions per minute.” When I have visited television demonstrations with film people I have frankly marvelled at the critical and disparaging attitude they adopt. Presumably they do not remember when the film picture itself was every bit as indistinct, wobbly and tiring to the eye, and, therefore, cannot recognise in the newcomer the same possibilities of colossal technical growth. Another ” Advance ” of Science A new sound development consists in the recording of a business conversation, so that it may take the status of a legal contract. Recently Eddie Cantor wanted to close a new deal with Samuel Goldwyn, but whereas Cantor was in New York, Goldwyn was at Hollywood. Regular telephonic communication was established after arrangements had been made for recording the conversation both vocally and visually. The affair obviously had a certain publicity element, but the fact remains that the sound film secured does actually constitute a fcimal contract, duly signed vocally on the variable area track. There might be difficulties in the way of legal enforcement of such a contract. The association between the sound track and the picture would have to be proved and all possibilities of visual impersonation and vocal duplication disproved — not by any means an easy task. But the idea has possibilities and will probably be developed as a means of securing evidence. An amorous conversation by telephone may in t’me be as disastrous as the old-fashioned “ compromising letters,” and an indiscreet business talk into a telephone may subsequently appear in court later as evidence in a libel suit. The Recording Engineer may in time be the bugbear successor to the Recording Angel ! A Dark Subject Eastman Kodak have just made a specially sensitised film by means of which it is possible to take photographs in the dark. A demonstration was given last week, tut we are not told how the film has developed. Our correspondent, S. T. Upid, wants to know how they keep the film from getting fogged : does it have to be stored in daylight with an electric lamp shining in the spool box till the cameraman is ready to turn ? F.F.