This double projector for film 2.375 inches wide is the result of a collaboration between William Friese-Greene (1855-1921) and the engineer J A Prestwich. They claimed that it removed flicker and that projection speeds could be reduced below 16 pictures per second without losing the moving effect. The idea for the projector was probably due to Friese-Greene who had shown moving pictures some years earlier. The mechanical details, such as the epicycle intermittent motion, are due to Prestwich.
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