An Automatic Change-Over Device
A. Pritchard · Journal of the Society of Motion Picture Engineers · 1934
A device proposed for use in all theaters as a standard method of changing from one projector to the other is described. The device is controlled by a constant frequency photographically recorded on the edge of the film a given distance from the end of the picture portion of a reel of film. Its purpose is to eliminate individual cueing and improve the presentation of talking motion pictures by enabling the projectionist to make change-overs more exactly without visible marks on the screen, and to avoid to a large degree the film mutilation and increased fire hazard that results from the practice of individual cueing.