This notebook covers the period April 1886. The entries are by Edison and Mina Miller Edison. Many of the notes and drawings concern fundamental experiments on magnetic fields and lines of force, including those of the sun, earth, and other planets in the solar system. There is also some material relating to the conversion of heat directly into electricity. Other notes and drawings deal with the coating of carbon filaments, armature design, carbons for arc lights, electric railway motors, telephones, phonographs, quadruplex and phonoplex telegraphs, balloon telegraphs, marine telegraphs, a battery for the grasshopper telegraph, a cotton picker, a larynxial piano, a hearing aid, a device for indicating the depth of steamboats, the testing of metals, the expansion of steam engines, spectroscopy, artificial silk, and the separation of cream. Many of the entries are duplicated in Fort Myers Notebook N-86-04-03.1. The first page contains the notation: \"Fort Myers Fla April 3 1886 Ideas T A Edison.\"" The book contains 280 numbered pages.

Blank pages: 244-245, 248-249."