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Thomas Edison. Portrait of Thomas Alva Edison (1847-1931), American inventor. Despite a lack of formal training, Edison was a prolific inventor, patenting about 1300 innovations. These included the phonograph, the electric light bulb and the alkaline battery. He solved problems by sheer weight of effort, claiming that "Genius is one percent inspiration and ninety-nine percent perspiration". He made only one scientific discovery, the Edison Effect. This Effect applies in vacuum tubes, where electricity will flow from a hot electrode to a cool one, but will not do the reverse; this formed the basis of the thermionic valve.
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