The positive film is inserted in the unexposed film-box of the camera and is threaded up as if for taking photographs. As the emulsion side is uppermost, when the unexposed film meets the negative in the gate, the two films are brought together with their emulsion sides in contact. As one film is laid squarely over the other, and with the perforations in line, it will be seen that the claws engage with both, so that the two films are jerked together intermittently through the gate.
Emerging from the gate the two films part company. The exposed positive ribbon passes into the exposed dark box, while the negative film passes through another velvet-lined slot in the bottom of the camera, and then is wound up on another spool.
It will be seen that in this case printing is carried out in a manner similar to photographing. The film is run through the camera in the ordinary way by turning the handle, and the number of exposures per second can be varied within wide limits to suit the density of the film. The camera is supplied with a second spindle and gearing upon which the handle may be slipped. The ratio of this gearing is one exposure per revolution, or as it is termed "one turn per picture."
Owing to the positive film being contained within the camera, and therefore in a light-tight space, the electric light or other illuminant may be mounted upon the bench within the dark room, so that the operator can work in a lighted apartment. In this arrangement, however, the camera should be clamped firmly to a rigid foundation, so that it may not move during exposure. This also ensures that the light should remain at a constant distance from the machine.
This camera can be adjusted easily and cheaply for the purpose of daylight printing. All that is required is a square funnel, about two feet in length, made of wood and so designed that the smaller open end fits into the front recess of the camera after the shutter panel is removed or opened. This funnel should be made after the manner of a Kodak enlarger, and blackened on the inside, with a dull medium, so that no reflections of light are set up. When this funnel is attached it is only necessary to stand the camera on its rear face so that the opening of the funnel points directly to the clear sky overhead, not towards the sun, and to turn the handle upon the one turn one picture gear. The printing speed will vary with the intensity of the light and the density of the film. Obviously the camera can be run more rapidly on a bright summer than on a dull winter day. In the first case it is safe to turn the handle as fast as possible, but in the second the speed would need to be about one picture, or handle turn, per second.
The Williamson Printer.
(For explanation see [p. 85].)
From the "Cinema College," by permission of the Motograph Co.