This notebook covers the period February-November 1890. It contains transcriptions by Arthur E. Kennelly of material from the rough record books used by experimenters in the Galvanometer Room. There are notes, drawings, tables, and calculations regarding a variety of electrical experiments, including tests of meters, batteries, induction coils, the magnetic permeability of iron, the carrying capacity of copper wire, and the production of copper by electrolysis. In addition, there are notes and design drawings of electric railway motors, including experiments conducted at the Edison General Electric works at Schenectady, and of low-horsepower motors for fans, dental equipment, and the phonograph. Also included are notes regarding 3-wire electric power systems, lighting plans for the Lick Observatory, tests comparing a Westinghouse and an experimental Edison transformer, and theoretical notes concerning physics, electricity, and mathematics. Among the experimenters whose work appears in this book are Jonas Walter Aylsworth, Reginald Fessenden, and Alfred J. Thompson. At the end of the book is a subject index; it appears at the beginning of the book in the digital edition. The front cover is marked "III" and "1890." The book contains 160 numbered pages. Some pages were removed before the book was paginated. Graphs, blueprints, and other items have been pasted into the book. Courtesy of Thomas Edison National Historical Park.