This notebook covers the period March 1886. All of the entries are by Edison and by Mina Edison, whose name also appears as a witness. Most of the notes by Mina Edison deal with lamp experiments. A few concern an electric engine and a hearing aid. The notes and drawings by Edison pertain to magnetism, the search for a new form of energy he called XYZ, and the direct conversion of heat into electricity. Also included is material relating to lamp experiments, the phonoplex, a balloon telegraph, a process to turn natural gas into lampblack for ink, a cash carrier system, a spectroscope design, a storage battery, a hearing aid, and a cotton picker. The book contains 288 numbered pages.

Blank pages: 110-Ill, 256-275, 282, 285.

Missing page numbers: 283-284.