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In the spring of 1895, Robert Dempsey Gray, a lens maker at a shop on Beekman Street in New York City developed a unique double image camera and projector that he patented in both America and Germany.Gray’s two patents describe an apparatus using the same fundamental approach to moving pictures, but have important practical differences. Gray’s approach was to makea single-lens device, with a rotating disk set at a 45% angle behind the lens. Half of this disk was mirrored, so that as it rotated it directed the image to be recorded to two different locations at right angles to each other on a band of film as it moved around the inside of the machine. Intermittent movement was provided by a double claw engaging perforations on the film, and the synchronization of the entire apparatus was established by linking all moving parts to a master gear turned by a crank.In projection, two lamphouses at right angles to each other were placed at the appropriate aperture where the image has been recorded, with the revolving half-mirrored disk now recombining the alternately spaced images before the single lens.


 Gray Camera mechanism