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Reis telephone, engraving. This rudimentary telephone by the German inventor Johann Philipp Reis (1834-1874) was first built in 1860 and was based on the principle of magnetostriction. Wire coiled around iron cores and needles caused contraction when a current flowed, producing an audible click in a resonator. However, the sounds were faint, and there was little interest in the invention. The practical development of the telephone was achieved by others, such as Alexander Graham Bell.
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