This notebook covers the period April 1886. All of the entries are by Edison. Many of them concern the direct conversion of heat into electricity, magnetic fields, and lines of force of the sun, earth, and other planets in the solar system. Other notes and drawings deal with the coating of carbon filaments, armature design, carbons for arc lights, multiplex and phonoplex telegraphs, a battery for the grasshopper telegraph, telephones, a cotton picker, a larynxial piano, and a hearing aid. Many of these entries are duplicated in Fort Myers Notebook N-86-04-03.3. The spine is labeled "27." The book contains 284 numbered pages.

Blank pages: 226-255, 264-267, 274-275.