In July 1877 Edison came up with an idea for a device that would make it possible to record and play back sounds. One of his researchers set about trying to make it, and in November, Edison recited the first verse of the poem “Mary Had a Little Lamb.” To everyone’s amazement, the device played back Edison’s voice. The phonograph indented sound vibrations on to a sheet of tinfoil wrapped around a cylinder turned by a hand crank.
