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Title: Johann Philipp Reis, Telephone,1860
Caption: The Reis telephone was a rudimentary telephone invented by Johann Philipp Reis (German, 1834-1874). First built in 1860, it 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.
Credit: Album / Science Source
Image size: 3000 × 1924 px | 16.5 MB
Print size: 25.4 × 16.3 cm | 1181.1 × 757.5 in (300 dpi)