Around this time the magic lantern was becoming a popular device to project photographic transparencies on a large viewing screen, and Muybridge had the insight to visualize his images projected quickly in an illusion of motion. He printed sequential images on a 6” disk that rotated in front of a bright light, and using a synchronized shutter and a focusing lens he projected the first motion pictures for a paying audience in 1880. He called this contraption a zoopraxiscope.The paying public didn’t get much for their money because the 12-20 image cycle lasted only a few seconds. It interested Thomas Edison, and he collaborated intermittently with Muybridge until roll film was invented. However there was much scientific interest in high speed still photography and Muybridge began 12 years of work at the University of Pennsylvania, Philadelphia in 1884.