About the same time that Guglielmo Marconi was experimenting with radio transmissions in the late 1890s, other scientists were exploring the possibility of transmitting visual images. The first inventor to do so was Abbe Caselli, an Italian-born priest who succeeded in sending very elemental shadow pictures via the French telegraph lines in 1866. Almost twenty years later an Englishman named Shelford Bidwell developed a device that he called an electric distant vision apparatus. This machine used a selenium cell mounted on a box that moved up and down to scan an image.

While still a student, the German scientist Paul Nipkow designed an electric telescope that divided its target into scanned lines. Using this as a base he developed a photomechanical image scanner in 1884 that he called a Nipkow disk . The device was comprised of a metal or cardboard disk perforated with a series of square holes in a...