The Cine Technician (1939)

June-July, 1937 THE CINE-TECHNICIAN 15 Herschel was the first man to use the words "negative" and "positive" in connection with photographs). From this paper negative (which he made translucent with wax), he was able to produce any number of contact prints. * ' * * Now this all happened nearly a century ago. It was the beginning of photography. The whole world started thinking, and minds of many great men started improving and improving on this great discover)', which was destined to be one of the greatest sciences of the age. As time went by, it became known that a Swiss chemist had discovered that if ordinary cotton wool was immersed in a mixture of nitric and sulphuric acids, it became highly explosive. A little later there was a substance produced by dissolving gun cotton in a mixture of ether and alcohol. The resulting material was called "collodion," being so named because of its adhesive qualities. Collodion was used in surgery to form a film over wounds, and thus prevent contact with air. Several scientists suggested that collodion might be used for holding chemicals together on the photographic plate. It was a London sculptor, Frederick Scott-Archer, who brought these suggestions into a practical form and made it known in 1851. The collodion process quickly displaced Daguerreotype and Talbottype, and made photography a popular art. It was necessary, however, that these collodion plates should be exposed in the camera while the chemicals were moist, and they had to be developed before the chemicals dried. Chemists succeeded in arranging the chemicals so that the plates might remain moist and sensitive for a week or more. Later, it was found possible to make plates that would remain sensitive when dry. Improvements in dry plates KANDEM BritishMade STUDIO LIGHTS FOR BRITISH FILMS A complete range of Silent Arcs up ro 300 amperes and Incandescenrs up ro 10 k.w. are available for Hire and Purchase 150 Ampere Arc Spot. USED IN ALL THE LEADING BRITISH AND EMPIRE STUDIOS KANDEM ELECTRICAL Ltd. 769 FULHAM ROAD LONDON, S.W.6 KANDEM 'Phone : FULHAM 238719 Works : PARSUHS GREEN, S.W.6 continued, and gelatine was substituted for the more dangerous collodion (the silver salts being dissolved in the gelatine). And so the chemical side of photography went on and is still improving. * ^ * As the speed of emulsions became faster, so it became possible to take photographs instantaneously, and this possibility started the thoughts of man in the direction of reproducing inurement by photographic means. It is as well for me now to take you back to the starting point of Motion Pictures, a history which could nevei ha 1 been written were it not for the physiological phenomenon of Persistence of Vision, that basis upon which rests every one of the mechanical appliances for producing the illusion of motion. One of the stock experiments which proves Persistence of Vision is of so elementary a character that man must be supposed to have noticed the effect long before he was capable of theorising upon its cause. If a stick with a lighted or glowing point is taken and whirled in a circle (an action doubtless performed in prehistoric times) it will be at once noticed, if the speed is great enough, that the glowing end of the stick is no longer seen as a point, but a luminous circle filling its whole path is visible instead. Again, take a flat steel spring and fix it at one end, strike the other so as to cause it to vibrate, and the spring will appear to fill the whole space over which it moves. Now, it certainly does not require much proof that neither stick nor spring can be in two places at once ; and the only possible solution to the "mystery" is that the luminous point or spring appears to be in any given spot after it has moved away, and continues to appear there until its return to the same position, when its image again falls on the We are the Leading People in the Recording Business Nine out of every ten shorts recorded in this country are "Recorded by Imperial." We are fully equipped to handle every phase in the business, including THREE CHANNEL RE-RECORDING and a COMPLETELY EQUIPPED MOBILE RECORDING UNIT at very favourable terms. Imperial Sound Studios 84 WARDOUR STREET GERRARD 1963