This notebook covers the period September 1880-March 1881. Most of the entries are by Charles Batchelor and Alex Welsh. There are also entries by Edison, Francis Upton, and W. A. Mills. The material all relates to the development of the electric lamp and consists primarily of notes and tables relating to lamps that were apparently made at the lamp factory and tested at the laboratory. Included are tests of lamps, made on vacuum pumps during September and October 1880, and resistance tests of lamps for the period November 1880-January 1881. There are also drawings of lamps and vacuum pumps, entries relating to carbon experiments, and a memorandum by Batchelor of things \"to be attended to immediately\"" at the lamp factory. The label on the front cover is marked \""Gedney.\"" The book contains 284 numbered pages.

Blank pages: 54-55, 82-83, 156-187, 190-191, 194-199, 202-203, 206-213, 232-265, 272-275, 278-279.

Missing page numbers: 147-148, 281-282."