02/10/1878 Bentley, Henry to Edison, Thomas Alva
(Philadelphia Local Telegraph Co; Western Union; Phelps, George May; Prescott, George Bartlett; Preece, William Henry; Orton, William) Music; Testing and quality control; Telephone [Attachment/Enclosure; Marginalia by Edison, Thomas Alva]
[Z005]  Institution of Electrical Engineers Archives, London, UK: William H. Preece Papers
[Z005AN; TAEM 0:0]
Courtesy of the Institution of Electrical Engineers Archives.