The phonomotor or "vocal engine" was a device invented by Thomas Edison

Thomas Edison

Thomas Alva Edison was an American inventor and businessman. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. In addition, he created the world’s first industrial...

 in 1878 to measure the mechanical force of sound. It converted sound energy or sound power into rotary motion which could drive a machine such as a small saw or drill. It derived from his work on the telephone and phonograph

Phonograph

The phonograph record player, or gramophone is a device introduced in 1877 that has had continued common use for reproducing sound recordings, although when first developed, the phonograph was used to both record and reproduce sounds...

.

Construction

Sound waves entering a mouthpiece and falling on a diaphragm were conveyed by a piece of rubber tubing and a spring to a pawl, which vibrated against a very fine-toothed ratchet wheel. The diaphragm and mouthpiece were similar to those used on the phonograph. Vibrations caused by the voice caused a shaft and flywheel to rotate. Steady pressure from breath produced no motion, but some voices could produce rapid motion. The speed of rotation depended on the pitch of the sound. It was able to operate a small drill or saw which could bore or cut wood. When a long sustained sound got the flywheel up to an appreciable speed, considerable force was required to stop it.

Impact

The Chicago Tribune in May 1878 predicted that it would be the basis for sound powered toys such as dolls which bow when spoken to, though none are known to have been marketed. Edison described it as a scientific toy. A U.S patent application was filed for the "Vocal Engine" in 1878, and a patent was granted on December 10 of that year. An 1884 Nature

Nature (journal)

Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...

article on sound mills, similar devices to the phonomotor, reported that Edison's device, "literally accomplished the feat of talking a hole through a deal board." A restored model of the phonomotor is in the Edison Menlo Park laboratory exhibit at the Greenfield Village Museum in Dearborn, Michigan

Dearborn, Michigan

-Economy:Ford Motor Company has its world headquarters in Dearborn. In addition its Dearborn campus contains many research, testing, finance and some production facilities. Ford Land controls the numerous properties owned by Ford including sales and leasing to unrelated businesses such as the...

, and was exhibited in operation for visitors in the 1930s.

External links

• http://edison.rutgers.edu/patents/00210767.PDF T.A. Edison, "Vocal Engine." US Patent 210,767, Patented December 10, 1878.