Page:Popular Science Monthly Volume 90.djvu/151

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��MANY persons would like to make motion-pictures of their friends, but the machines on the market are too high-priced for the average purse. The large companies take, print and pro- ject their pictures with separate machines. Following is the description of an arrange- ment combining all three mechan- isms, the chief cost being the lens.

The heart of the machine to be de- scribed is the cylinder-shutter and intermittent shifting device shown at B, as in detail in the upper left-hand corner of the drawing. It consists of a round wooden cylinder of the dimensions given. Through one of the diame- ters of this cylin- der is mortised a rectangular hole I in. by ^ in. The sprockets or pro- jecting pins C are set at a distance of ^ in. from the 90 deg. point, using the center a base. These forations in the film accurately, be rounded so

����The camera consists of very few parts and is used for taking, printing and projecting the pictures

��of the mortised hole as

pins should fit the per-

standard motion-picture

and the points should

that they may enter the

perforations without difficulty.

��In the drawing of the inside of the camera, may be seen the shutter in position to admit light to the film. The cylinder revolves backward, and the pins engage the perforations in the film, pulling it downward exactly % in., while the light passing through the lens is cut off from the film. After the film comes to rest, the cylinder continuing in its revolution, the light is again ad- mitted to the film through the opening in the cylinder, thus making the exposure. After this the film is again shifted ready for the next ex- posure, and so on as fast as the cylinder revolves. The usual speed is sixteen pictures per second, which means eight revo- lutions of the cylinder per second.

The film is taken from the upper roll, sup- ported in the top of the camera box by the bracket D i , and after passing behind the spring-actuated roller-guides El £2, it passes downward to the take-up roll, which is connected on the outside of the camera, by means of a belt, to a 4-in. diameter driving-wheel. This belt is left loose, so that it will pull the film only when

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