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Maltese Cross, Geneva Drive/Movement
The name comes from the mechanisms of the first watches, especially due to the similarity of the mechanism to the ‘cross of Malta’. It was generally used in professional movie cameras and projectors, moving every ‘frame’ separately and discontinuously in front of the entrance of the ‘door’ of the projection (or shooting) of the image. The mechanism system that moves the ‘cross’ leads it to a discontinuous movement at 90° each time, driving the next ‘frame’ forward for projection. This ‘periodicity’, in combination with a semicircular shutter that ‘blocks’ the light during the movement of the film up to the moment that it again stops at the opening of the ‘door’ to receive light, is based on the principle of the ‘persistence of vision’. This is the phenomenon whereby an optical image is recorded on the brain and remains visible even after the disappearance of the object which caused it, resulting in the illusion of movement. This example is of unknown origin, manufacture and date. The specific exhibit is an ‘accessory’ of a projector.