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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 companies and laboratories, and filed over 1000 patents. Other work included improvements to telegraphy, cameras, and motion picture cameras. He also discovered the Edison Effect, on which thermionic valves are based. Photograph by J. M. White, published in the 1890s.