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Thomas Edison (1847-1931), American inventor. Edison sitting next to his favourite invention, the phonograph, which could record sound. The phonograph consisted of a foil wrapped around a cylinder. When recording, a free-floating needle connected to a sound receiver was skimmed over the foil as the cylinder was rotated. The needle vibrated in time to the sound waves and made etchings in the foil. These etchings could then be 'played back'. Despite a lack of formal training, Edison was a prolific inventor, patenting about 1300 innovations. He made only one scientific discovery, the Edison Effect, which formed the basis of the thermionic valve. Photographed in 1878.
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