The invention of the phonograph happened quite by accident. Thomas
Edison moved to Menlo Park, New Jersey, in 1876, where he established an
industrial research laboratory. There Edison worked on a carbon telephone
transmitter to improve the existing Bell system. In that laboratory a year later
Edison invented the phonograph while trying to improve a telegraph repeater.
He attached a telephone diaphragm to the needle in the telegraph repeater to
produce a recording that could be played back. After some improvements to the
machine, he recited “Mary Had a Little Lamb” and played the recognizable
reproduction of his voice back to an astonished audience.