Notebook #7 N-78-12-11 (1878-1879)
This notebook covers the period December 1878-April 1879. The entries are by Edison, Charles Batchelor, and Francis Upton. Almost all of the material relates to experiments on electric lighting. Included are drawings of lamps; notes on filaments; drawings of generators, including one labeled \"Edison 1st drawing\""; comparisons to gas lighting costs; and calculations for an electric lighting system. There are also notes on chalks for telephones and a drawing of a Gramme machine combined with an induction coil for the telephone. The book contains 282 numbered pages and one unnumbered page.
Blank pages: I, 76-77, 226-227, 246-275. Missing page numbers: 233-234."