FIG. 7.—ACRES’ PROJECTING DEVICE.
The picture film is drawn from an upper reel, passed over a sprocket pulley, downward through a retaining clamp, and over a second pulley to the bottom or winding reel. The film passes over both sprocket pulleys at a uniform speed, between a stationary and swinging clamp operated automatically from the shaft of the shutter and which holds the film stationary when the opening of the shutter is behind the lens, during the interval the picture is projected on the screen. The clamp is released; then the pivoted lever below, with a roller on the upper end, is pulled inward at the other end by a spring and immediately takes up the slack (as [shown] by the dotted lines), and causes, by such sudden movement, the bringing of the next picture into position.
THE “MUTOGRAPH” AND “MUTOSCOPE.”
THE DARK ROOM AND REEL FOR DEVELOPING FILMS.
The “mutograph” and “mutoscope” are names of very interesting machines for presenting moving photographs. The camera frame is mounted, by means of three adjustable legs, upon a triangular turntable, which may be placed upon any suitable support. Upon the top of the frame is bolted a two horse-power electric motor which is driven by a set of storage batteries; the combination of the turntable with a vertical adjustable enables the camera to be shifted so as to take in the required field. In the front of the camera is fixed a lens of great light-gathering quality which produces an image of exceedingly clear detail. Inside the camera is a strip of gelatine film two and three-quarter inches wide, and usually about one hundred and sixty feet in length, which is wound upon a small pulley and drum. The length of the film varies for different subjects. In case of a prolonged scene it may extend several thousand feet. The film is led through a series of rollers, and is caused to pass directly behind the lens of the camera, and is finally wound upon a drum. The object of the rollers is to cause the film to pass behind the lens with an intermittent instead of a continuous motion. At ordinary speeds this could be easily accomplished, but the difficulties are increased when it is remembered that the impressions are taken at the rate of forty per second, and that the film, which is running at the rate of seven or eight feet a second, has to be stopped and started with equal frequency. The film comes to a rest just as the shutter opens, and starts again as the shutter closes. The impressions vary in actual exposure between one one-hundredth and one four-hundredth of a second. While the ordinary speed is forty a second, the mutoscope can take equally good pictures at the rate of one hundred per second, if it is necessary. The highest speed would be used in photographing the flight of a projectile or other object which was in extremely rapid motion. After the mutograph has done its work, the films are carefully packed and sent to the New York establishment of the American Mutoscope Company. Here they are taken to the dark room, the interior of which is shown in our [engraving]. Arranged along each side of this room is a series of troughs, above which are suspended large skeleton reels three feet in diameter and seven feet long, the axes of the reels being journaled in brackets attached to the end of the trough. The films are wound upon the reels and subjected to the action of the various solutions for developing, fixing, etc., the reels being transferred from bath to bath until the films are ready to go to the drying-room. In this room are also prepared positive transparent strips for use in the biograph and the bromide prints for the mutoscope.