William K. Dickson devised an early motion picture camera while employed by Thomas Edison. Following Edison’s filing of a second patent claim for a motion picture device, Dickson was assigned to build such a device. He invented the first practical celluloid film for the application and it was Dickson who decided on 35 mm as the size … a standard that lived on. He led a team at the Edison that developed the Kinetoscope, with the first prototype readied in 1891. Not a projector, as such, it was more of a peep show machine that showed a continuous loop of film.