Motography (Jan-Jun 1913)

.March 1, 1913. MOTOGRAPHY 161 Vanoscopy a Continuous Projection System By Lewis C. Van Riper WHEN Latham added the loop to the film and Pross added the extra leaf to the shutter of the motion-picture projector some ten years ago it was thought that about the highest stage of perfection h a d been reached, or at least that any further i m p r o v e m ents would be merely in the nature of refinements in the mechanisms a n d part s — in details only. The intermittent movement of the old Swiss watch was believed to be about the acme of perfection. Manufacturers of picture projecting machines, as a rule, were satisfied to let good enough alone. True, a few variations of the old star wheel and sprocket movement have been brought out. such as in the Gaumont camera and in the Power's projector, but all manufacturers have to this day retained the intermittent movement and the shutter. In the meantime, inventors in all parts of the world were striving to produce a projecting machine which would throw a continuous picture upon a screen from a film containing a series of continuous photographs of an object in motion, in such manner that each successive picture would dissolve into the one preceding it, on the principle of the dissolving stereopticon. In fact, it might almost be said that the earliest attempts at projecting motion pictures were directed to that end. We find among the oldest patents that of the Zoetrope or Praxinoscope invented by M. Reynaud of France, who for the first time in 1877 enabled a large audience to see animation upon the screen. About the first thing a student in physics learns is the rule that "action and reaction are equal" and that "the angle of reflection equals the angle of incidence." This rule not only applies to light but to practically all the forces of nature, including heat, sound and all forms of energy. Light travels at the enormous velocity of 186,330 miles per second and therefore for all earthly purposes may be considered as moving instantaneously. It has no atomic weight and therefore is not affected by the laws of gravity, but moves in straight lines unless diverted from its path by striking or entering substances of differ The Vanoscope — End View with Casing Cut Reflectors. The Arrow ent density. It will penetrate and pass through vacuums without hindrance. Paradoxical as it may seem too, light of itself has no color and is absolutely invisible. It consists simply of waves of different lengths, while color is subjective and exists only in the brain. We see light only by reflection and color by sensation. To the color blind green often appears as red and red as green does to one of normal vision, while in the dark there is no sense of color. Thus we know that color is not an element but merely a sensation conveyed to the brain through the optic nerves. But this is a subject which will be treated of more fully in another chapter. At the beginning it may be well to state for the benefit of those not thoroughly conversant with motion picture projection as it is carried on today, that a large number of successive photographs are taken upon a strip of celluloid or film. Each individual picture is about the size of a postage stamp ; sixteen pictures are. placed in position upon one foot of film. The pictures are projected upon the screen one at a time and an opaque shutter is interposed to cut off the light while the film is being moved rapidly forward to expose each succeeding picture. This film movement is usually accomplished by what is known as the star wheel and sprocket. The movement of the film is very rapid and is more in the nature of a series of quick jerks, each of which usually takes about one-quarter of the time given to the projection of each picture ; that is 25 per cent of the time is taken up in moving the pictures forward, and 75 per cent is consumed in projecting them upon the screen. During the one-quarter period, the light is cut off entirely from the screen, and prior to the invention of the Pross shutter (about 1903) this irregular timing of the picture while adding to the illumination, as a matter of fact, made the flicker very severe and trying on the eyes of the spectator. The Pross shutter improvement consisted of an additional shutter or rather leaf to the shutter being interposed during the period that each picture was being projected on the screen and while it stood in a stationery Away, Showing the Rotating and Rocking s Indicate the Film.