DAYLIGHT CARTRIDGES This term is applied to spools of flexible film used in cameras specially adapted for them. The strip of film is attached to a considerably longer strip of black paper. The spool is placed in position in the camera, and one end of the black paper is put through a slot in an empty spool and wound taut. The camera is then closed. By continuing the winding, the first section of the film is brought into position for exposure, and the successive sections are in turn wound along. A number on the black paper behind each section can be observed through an open ing in the back of the camera, thus regulating the winding and indicating the number of the exposure. When the last section has been exposed, the rest of the black paper is wound on to the spool to protect the film, and the camera can then be opened, the exposed spool removed, and a fresh one inserted. The film
thus exposed may be cut up into sections, or developed in the strip either by hand or by means of developing machines made specially for the purpose. The device is an exceedingly convenient and popular one. The smallness and lightness of the cartridges as compared with plates, and the ease with which successive spools may be used are strong points in their favour, especially with travellers.
One precaution in the use of film cartridges may be mentioned : care should be taken not to allow the black paper to run loose on the spool, as this will allow light to creep in at the edges. Also, in folding cameras, avoid winding the film while the camera is closed, as some part of the bellows or lens may touch the film and cause scratches upon it.