Thomas Alva Edison (1847-1931), US inventor. Edison is famous for inventing or improving devices such as the phonograph and the electric light bulb. He founded several laboratories and companies, and filed over 1000 patents. Other work included improvements to telegraphy, cameras, and motion picture cameras, as well as his DC (direct current) electrical distribution systems. In 1880, Edison founded the journal Science. He also discovered the Edison Effect, on which thermionic valves are based. This photograph, from circa 1922, is by the Bachrach Photography Studio.