On this day November 21, 1877

Photograph of Edison with his phonograph, taken by Mathew Brady in 1877

Edison with his phonograph, taken by Mathew Brady in 1877

Edison announces his invention of the phonograph, a machine that can record and play sound. Thomas Alva Edison conceived the principle of recording and reproducing sound between May and July 1877 as a byproduct of his efforts to “play back” recorded telegraph messages and to automate speech sounds for transmission by telephone.

He announced his invention of the first phonograph, a device for recording and replaying sound, on November 21, 1877, and he demonstrated the device for the first time on November 29 (it was patented on February 19, 1878 as US Patent 200,521).

Edison’s early phonographs recorded onto a tinfoil sheet phonograph cylinder using an up-down (“hill-and-dale”) motion of the stylus. The tinfoil sheet was wrapped around a grooved cylinder, and the sound was recorded as indentations into the foil. Edison’s early patents show that he also considered the idea that sound could be recorded as a spiral onto a disc, but Edison concentrated his efforts on cylinders, since the groove on the outside of a rotating cylinder provides a constant velocity to the stylus in the groove, which Edison considered more “scientifically correct”.

Edison’s patent specified that the audio recording be embossed, and it was not until 1886 that vertically modulated engraved recordings using wax coated cylinders were patented by Ater Bell and Charles Sumner Tainter. They named their version the Graphophone. Emile Berliner patented his Gramophone in 1887.

The Gramophone involved a system of recording using a lateral (back and forth) movement of the stylus as it traced a spiral onto a zinc disc coated with a compound of beeswax in a solution of benzine. The zinc disc was immersed in a bath of chromic acid; this etched the groove into the disc where the stylus had removed the coating.

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