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Thomas Edison: Telephone, Electricity and Phonograph, 1915

Switch of Genius

Towards the end of the 1870s, Edison's inventive genius switched from telegraph to telephone applications. Western Union hired him to devise an improvement on the telephone recently invented by Alexander Graham Bell; the strength and thus the range of the sound signal needed to be increased. Edison chose to solve the problem by improving the transmitter; he adapted a characteristic of carbon, its high electrical sensitivity—the same characteristic that had doomed its use in an earlier invention. Eventually Bell Telephone Company adopted this transmitter design and it served in handsets for the next one hundred years.

In the beginning, the telephone was viewed as a replacement for the telegraph, and again, as with his printing telegraph, Edison set out to build a device that would create a permanent copy of a spoken telephone message. Edison's solution was a machine that recorded the vibrations of the spoken message received and then replayed the vibration patterns sufficiently slowly that the telegraph operator could transcribe it. Of course this new "talking machine" was the phonograph, but, apart from a private demonstration, there was no immediate commercial capitalization of this amazing invention. Ten years later, commercial production of the improved phonograph began, the recording industry was launched, and Edison's celebrity was sealed.