One application of the Geneva drive is in film movie projectors and movie cameras, where the film is pulled through an exposure gate with periodic starts and stops. The film advances frame by frame, each frame standing still in front of the lens for a portion of the frame cycle (typically at a rate of 24 cycles per second), and rapidly accelerating, advancing, and decelerating during the rest of the cycle. This intermittent motion is implemented by a Geneva drive, which in turn actuates a claw that engages sprocket holes in the film. The Geneva drive also provides a precisely repeatable stopped position, which is critical to minimizing jitter in the successive images. (Modern film projectors may also use an electronically controlled indexing mechanism or stepper motor, which allows for fast-forwarding the film.) The first uses of the Geneva drive in film projectors date to 1896, with the projectors of Oskar Messter and Max Gliewe and the "Teatrograph" of Robert William Paul. Previous projectors, including Thomas Armat's projector, marketed by Edison as the "Vitascope", had used a "beater mechanism", invented by Georges Demenÿ in 1893, to achieve intermittent film transport.