In 1931, almost exactly one hundred years after Plateau, an engineering professor at the Massachusetts Institute of Technology named Harold Edgerton combined the stroboscope and the camera. He created an electronic version of the strobe in which the rotating disc was replaced by a special lamp. The lamp emits brief and rapid flashes of light. The frequency of the flash is adjusted so that it is a fraction of the object’s speed. At this point, the object appears to be stationary Although his original goal was to display and study the stresses on moving machine parts otherwise invisible to the naked eye, Edgerton later used very short flashes of light as a means of producing dramatic still photographs of fast moving objects in transit, such as bullets in flight, hovering hummingbirds, and falling milk drops splashing into a bowl. His camera had no shutter. The film was pulled through continuously as in motion picture cameras-but at much higher speeds-and exposed by a stroboscopic flash lasting 1/1,000,000 of a second or less. Edgerton’s invention was the basis for the built-in light flash found in nearly all cameras today Strobes are also popular as a lighting effect in nightclubs, where they create the appearance of dancing in slow motion. Other common uses are in alarm systems, theatrical lighting, and as high-visibility navigation lights.