Film perforator made by Williamson, London, c. 1913.

An intermittent machine which perforates two films simultaneously. The films are run through face to face to avoid scratching the sensitised surfaces. At the centre of the machine eight punches (four on each side) are fixed on a sliding carrier over the guide channel. Beyond the punches there are another eight pins called the dowel or pilot pins the function of which is to enter and fit the previously perforated holes and so set the film in the exact position for next set of perforations to be made. The punch-carrier is moved up and down by a cam which is geared to a pair of reciprocating claws which move the film forward the required distance between successive descents of the punch-carrier. To ensure even tension a loose loop of film is arranged both before and after the claw and punch mechanism.