The Boy's Book of New Inventions

by Harry E. Maule

After the little hole at the bottom of the weld, through which the redhot shaft inside shows, is plugged up, the thermit is ignited.

Of the recent developments in cinematography the ones we hear most about are colour pictures and talking pictures. So far, these two points which would give the last touch of realism to the scenes thrown on the screen are in a very imperfect state of development, but it is safe to say that it will not be very many years before we will have them duplicating what we see and hear in actual life just as faithfully as the black and white pictures now duplicate motion.

Science so far has not given us a method of actually taking a motion-picture negative in the natural colours, such as now can be taken in still photography, so at first the pictures were coloured by hand, and later by stencils. This is a difficult and a tedious undertaking, however, and newer methods have been introduced.

Although there are several systems being worked out the one best known is the Kinemacolour, which achieved its greatest fame by showing the pictures of the coronation of King George in England, and the Durbar in India in colours. The Kinemacolour system is simply one of photographing and projecting through screens of red and green. The shutter of the camera is made up of four parts, as follows: a transparent red screen, an opaque space, a transparent green screen, and another opaque space. Thus, by the law of colours laid down by science, when one picture is photographed through a red screen, all the different tones but red are arrested by the screen, and only the objects having shades of red are photographed. Next, when the green screen exposes the next space of three quarters of an inch, only the objects having green tints are photographed, as all other tints are arrested by the green screen.

The film itself shows no colour other than black and white, but when it is projected through a shutter that works exactly the same as the camera shutter the pictures show the objects in their natural colours. That is, the alternating pictures taken through the red screen and shown through a screen of the same colour show all the tones of red, while the alternating pictures taken through the green screen and likewise projected through a green screen show all the tones in which appear green. Thus, with the aid of the persistence of vision and a somewhat faster system of photographing and projecting, the tones blend and we see on the screen at the same instant red-coated soldiers marching past beautiful green trees, and so on. In order to make this possible it is necessary to give the films a treatment in a solution that makes them more sensitive to all light than they would be for ordinary cinematography.

The drawback to the system, as you will have noticed if you have seen these pictures, is that red and green do not make up all the primary colours of light. In the direct rays of light (not reflected light as from a painted wall) the primary colours, from which all the other tones are obtained, are red, green, and violet, but it has been found a little too difficult a mechanical process to use the three screens instead of only two.

The hardest job of the inventors of talking pictures was to work out a mechanical device that would make a good phonograph and a motion-picture projector keep step, so that, for instance, the actor would not be heard singing after the pictures had shown him close his mouth and leave the stage. Ever since his invention of the Kinetoscope, Edison has had this very thing in mind, and has prophesied that in the near future grand opera with motion pictures and phonographs will be within the means of every patron of the motion-picture theatre. Edison's idea for obtaining this is to make the phonographic and the cinematographic records at the same time in order to insure perfect accuracy of sound and appearance, and his experiments are meeting with success.

A fairly successful device for giving the phonograph and the projector synchronism, or, in other words, keeping them in step, has been worked out by the Gaumont firm of Paris. The phonograph and the projector are run by two motors of exactly the same size and power, from the same wires. The armatures of the motors are divided into an equal number of sections, and each section of one is connected with the corresponding section in the armature of the other, so that one cannot rotate for the fraction of a second unless the other rotates with it. A little switch working on another motor, which works on a set of gears, will speed up or slacken down the talking machine so that if the armatures get "out of step" one can be speeded up or slowed down so that the figures in the pictures will appear to be talking, laughing, or singing, just as they do in real life.

Another of the recent developments in cinematography is the di-optic system which aims to show every stage of the motion of figures, instead of the stage of motion every sixteenth of a second, as is in the case with the usual apparatus. The di-optic camera is simply two machines set side by side in one. It takes two loads of film, has two film gates, and two lenses, but works by turning one crank. The single shutter revolves in front of the twin lens, so that when one side is exposing a length of film the other is closed and the film is advancing. The two rolls of negative exposed in this way record the complete motions of the figures before the camera. The projector also is a di-optic machine working in the same manner as the double-eyed camera, so that when the pictures are thrown on the screen they are seen practically constantly, instead of every sixteenth of a second, for while one is hidden by the shutter, another is thrown on the screen. Also inventors are working on a scheme for taking motion pictures on glass plates instead of on films.

As was mentioned previously the use of the motion-picture machine has been very valuable to science, and by adapting the cinematograph to a powerful microscope a great many motion pictures of the life of bacteria have been obtained. Also motion pictures are sometimes made of surgical operations. Carrying this work even farther still, animated photography and X-ray photography have been joined so that science now can make motion pictures of the processes that go on inside small animals.