This notebook covers the period January 1879-March 1880. The entries are by Edison, Charles Batchelor, Francis Upton, Julius Hornig, John Kruesi, and Charles P. Edison. The name of Martin Force appears as a witness. All of the material relates to experiments on electric lighting and on the telephone. The electric light material includes notes and drawings of lamps; notes on filaments; notes, drawings, and calculations about generators; calculations relating to electric power distribution systems; notes by Batchelor on the cost and design of steam engines and boilers; and notes by Hornig on the design of a large central station and the extension of the Menlo Park machine shop to house dynamos. There is also a drawing by Hornig that is the earliest design for a large generator directly connected to a steam engine on the same bedplate. The telephone material includes notes and drawings by Batchelor and Charles Edison; notes by Batchelor on parts and prices for the telephone; and notes by Kruesi on making and packing the telephone receiver. The book contains 280 numbered pages.

Blank pages: 236-237.