Alfred Darling (1862-1931), an English engineer, devised this apparatus to high specifications. It punched evenly-spaced holes or sprockets in unexposed film stock as it pased through the rollers, enabling the film to be used in any 35mm camera. The film was moved through cameras and projectors by similar sprocket rollers or claw mechanisms. In Thomas Edison's films, each picture was four sprockets in height and this later became the industry standard. In 1898, Darling also took on production of Charles Urban's Bioscope.
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