Notebook #20 N-79-02-24.1 (1879)
This notebook covers the period February-June 1879. The entries are by Edison, Charles Batchelor, and Francis Upton. All of the material relates to experiments on electric lighting and on the telephone. The electric light material includes notes and drawings of lamps, coating filaments, and generators, among which is a caveat drawing by Edison. There are also notes and calculations about electric power distribution systems and notes on experiments to be performed. The telephone material relates to a series of experiments by Edison and Batchelor, many of which were on chalks. The label on the back cover is marked \"Caveat,\"" \""Thompson,\"" and \""Jose Husbands.\"" The book contains 284 numbered pages.
Blank pages: 54-55, 259-260, 266-269.
Missing page numbers: 271-272."