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Of recent years, great advances have, been made in the art of perfecting magic lanterns. The greatest invention in this line and the one productive of the weirdest results is the device for reproducing, in picture form, the movements of life, so naturally that one would believe the living objects portrayed were passing in review on the lantern screen. The first step in the discovery of the principle which underlies moving pictures was the invention of the zeotrope. This consisted of a disk, on the back of which were painted a number of pictures of some animal in various stages of motion. Underneath each picture was a narrow slit. The disk was a toy which was intended to be impaled on a pin so that it could be whirled around. By holding the picture side of the zeotrope near a mirror, and by looking through the slits as the disk was spun around, one could see a rapid succession of pictures in the mirror, the animal apparently moving forward by jumps. Inasmuch as the pictures were painted from imaginary positions which were not always true to life, the method of movement sometimes showed very odd phases. Gradually, the idea of portraying motion grew with inventors, and a principle, in which great development was involved, came to light. That was the method of passing a strip of pictures between the light and the lens of the lantern, and by the use of a light shutter, to close the lens from the light for an instant, between each picture. The most perfect cinematographs, or moving picture machines, now use this method of jerking pictures through a lantern, letting them pause momentarily, and then closing off the light and moving on to the next picture. The result is a continuous picture of the objects in motion, giving the effect of the progression. When this idea was evolved the next important thing to be discovered was a method for getting exact pictures of things in motion. One man tried the scheme of standing a number of photograph cameras in a row, and taking numerous pictures of the animal, or object, as it moved by. The result was a great improvement, but naturally the cameras could not be placed closely enough together or operated rapidly enough to catch the motions accurately. Then came Edison with his kinetoscope, by which he took instantaneous pictures on long strips of film, at the rate of about 30 photographs in a second. Thenceforth the moving picture problem was comparatively easy.
The next thing to be done was to devise a magic lantern arrangement that would practically duplicate the action of the shutter device on the camera, and also to develop the photographs taken on such long strips, without marring them. Several methods have been adopted for this latter work. Sometimes, the yards and yards of gelatine are wound on windlasses and run through the enveloping chemicals bit by bit. At other times, the strips are wound on pegs and the whole affair immersed at one time. It must be remembered that the pictures taken are negatives, that is everything naturally light shows black in the negative, and vice versa. Therefore, pictures must be made that will show on the picture screen in their proper tones. In order to do this, other strips of the sensitive film are placed over the negatives and exposed and developed. When these last strips are dried they are run through the cinematograph machine, but with a very powerful light behind them. The film is unwound and by means of the same shutter device on the camera, the light is turned on and off as the picture is behind the lens or moving into position. The lens throws the picture in enlarged form on the screen placed on the wall. Because of a phenomenon of optics called persistence of vision, the spectator sees the picture for a brief instant after the light is shut off. Thus when the strip is run through, the series of pictures appears as one picture in constantly changing shapes, giving an imitation of life. LARGEST AND FASTEST TROLLEY CAR |
In this method, long strips of sensitive gelatine films are prepared after the manner of any photographic plate. They are very narrow, are from 70 to 600 feet long, and are wound on spools. These films are run through a photograph camera specially adapted for the work. It is arranged so that only a tiny bit of the film is exposed at the focal point at a time. Then a shutter stops off the light, the film moves on an inch and is exposed, only to be shut off from the light again, and moved on once more. This is done very rapidly, in fact, so rapidly that about a thousand pictures can be taken in a minute, thus depicting marvelously the actions of moving beings and things.