This notebook covers the period July-September 1886. All of the entries are by Edison. The name of John F. Ott appears frequently as a witness. The book contains notes, drawings, and calculations relating to lamp experiments. The lamps are numbered 21 through 158. Loose pages containing the results of lamp tests have been pasted onto many of the notebook pages. The spine is labeled \"29.\"" The pages are unnumbered. Approximately 250 pages have been used."