lamp, viewed individually through the window of a cabinet housing its components. William Dickson and his team created the illusion of movement by continuously moving the strip of perforated film, bearing sequential images, whilst illuminating it by brief flashes of light through the slit in a rotating shutter. They also devised the Kinetograph, a motion picture camera to photograph films for in-house experiments and eventually, commercial Kinetoscope presentations, at speeds of up to 46 frames per second. To govern the intermittent movement of the film in the camera, allowing the strip to stop long enough so each frame could be fully exposed and then advancing it quickly (in about 1/460 of a second) to the next frame, the sprocket wheel that engaged the strip was driven by an escapement disc mechanism—the first practical system for the high-speed stop-and-go film movement that would be the foundation for the next century of cinematography. In late 1894 or early 1895, William Dickson became an ad hoc advisor to the motion picture operation of the Latham brothers, Otway and Grey, who ran one of the leading Kinetoscope exhibition companies, and their father, Woodville Latham who had lectured in science. Seeking to develop a movie projector system, they hired former Edison employee Eugene Lauste, probably at Dickson's suggestion. In April 1895, Dickson left Edison's employ and provided some assistance to the Latham outfit. Alongside Lauste, he may have devised what would become known as the Latham loop, allowing the photography and exhibition of much longer filmstrips than had previously been possible. This idea had first been made public in 1890 in descriptions of the moving picture camera of William Friese-Greene. These former Edison associates helped to design the Eidoloscope projector system and a widescreen camera to film with, which would be used in the first commercial movie screening in world history on 20 May 1895. But Dickson soon parted company with them, to become part of the group that formed the American Mutoscope and Biograph Company, returning permanently to work in the United Kingdom in 1897 for the British side of the company. William Dickson was the first person to make a film of the Pope, and at the time his Biograph camera was blessed by Pope Leo XIII. The Mutoscope machines produced moving images by means of a revolving drum of photographs/frames, similar in concept to flip-books, taken from an actual piece of film.