This is the first instrument for recording and reproducing sound. A sheet of heavy tin foil is wrapped around the grooved central drum. A recording horn is inserted in the shorter of the two diaphragms. The user shouts into the horn and a vibrating stylus mounted in the center of the diaphragm indents a groove into the tin foil, making an impression of the sound waves. The spiral groove winds its way the length of the tin foil as the user turns the crank. Then the horn is placed on the opposite diaphragm and it becomes a reproducing horn. The user reverses the crank, bringing this diaphragm back to the beginning of the tin foil. Its stylus, attached to the diaphragm by a thin metal wire, "reads" the grooved impression and reproduces the sound just recorded. Edison was surprised by the immediate success of the device, and in later life said it was his favorite invention. He soon took it to New York to demonstrate it to the editors of Scientific American, and to Washington where he exhibited it to members of Congress and to President Rutherford B. Hayes at the White House. Edison manufactured entertainment phonographs and recordings until 1929. His business phonographs for office use continued until the 1960s. The process of preserving and retrieving sound, including the entire recording industry, derives from this one little instrument.