This notebook covers the period July 1879-January 1880. Most of the entries are by Charles Batchelor. There are also entries by Edison and A. Poinier. The name of James Seymour appears occasionally as a witness. The first part of the book contains notes and drawings of experiments on metal filaments. Many relate to insulating materials used for coating the filaments. The second part of the book contains notes and drawings relating to the important series of experiments conducted in October 1879, which led to the invention of the carbon filament lamp. There are also notes and drawings documenting the development of the carbon filament through the end of 1879. A special cover placed over the book contains a label indicating that this notebook was used as an exhibit in the case of Edison Electric Light Company v. United States Electric Lighting Company, in which Edison's patent on the carbon filament was sustained (see Litigation Series). The book contains 280 numbered pages. Some pages have been torn out of the book.

Blank pages: 54-55, 108-109.

Missing page numbers: 217-218.