Designed for teaching

Practically every school or college now possesses a good 16 mm projector, designed to project silent film or to add sound from optical film track or magnetic stripe. Many such machines also enable the user to add sound by recording, on the magnetic stripe, a suitable commentary as he views the projected film. Simple methods of adding sound accurately synchronized from tape run through a tape recorder are less common, but this can be achieved if one is prepared to go to some trouble to ensure mechanical synchronization.