Emile Berliner had many trials and errors developing the gramophone. Some of them were described by the inventor in a lecture-demonstration he gave at the Franklin Institute in Philadelphia on May 16, 1888, which was printed in the institute's Journal (vol. 125, no. 60). Very early in his work, Berliner decided upon the disc format coupled with the lateral vibration used by Leon Scott in his phonautograph. Scott had developed this machine in the 1850s for the sole purpose of visually recording the vibrations of the voice so that they could be studied by those involved with human speech. The vibrations were made by speaking into the large end of a megaphone whose small end was a thin diaphragm that could freely vibrate. A thin brush attached to the diaphragm would make tiny tracks on blackened glass. These lateral vibrations could then be photographed and studied. Apparently it never occurred to Scott or anyone else at the time that, if these tiny tracks could be fixed and then the stylus repassed through them, the reverse process would take place and the sounds would be reproduced through the large end of the megaphone. The phonautograph did play a certain role in the development of the phonograph/graphophone, although these used cylinders instead of the disc, and they used up-and-down vibrations instead of side-to-side ones.

Berliner's Invention of the Gramophone

https://memory.loc.gov/ammem/berlhtml/berlgramo.html