On a recent trip to Princeton University, I had the opportunity to visit the Thomas Edison National Historic Park , in West Orange, New Jersey (about an hour drive from the campus). At this large laboratory complex, Edison invented the Kinetoscope, one of the first commercially successful motion picture viewers (the one in the photo is from the George Eastman House in Rochester, NY). Edison's interest in moving pictures was sparked in 1888 by a visit from Eadweard Muybridge who had already built a motion picture projector but one that could only present a dozen or so images in succession (e.g., a galloping horse). Edison's device was not a movie projector but instead a large one-person viewing console in which about 40 ft of 35 mm film strip passed by a peephole. The film was illuminated by stroboscopic flashes that were produced by a spinning opaque disk with an open slit that was placed between the film strip and a lamp. In this way, frames were flashed as ins