This notebook covers the period March 1879-Nebruary 1880. Many of the entries are by Edison. There are also entries by Charles Batchelor and Francis Upton. The names of John Kruesi and John Ott appear occasionally as witnesses. The material relates to experiments on electric lighting and on the telephone. Among the electric light material are notes and drawings of metal and carbon filament lamps, including vacuum experiments; notes, drawings, and calculations about generators; calculations for electric power distribution systems; and drawings of test apparatus. The telephone material consists of notes and drawings by Edison and Batchelor. The book contains 281 numbered pages.

Blank pages: 104-113, 120-123, 126-129, 132-133, 138-143, 146-147, 194-205, 210-211, 226-235, 266-267.

Missing page numbers: 115-116, 153-154.