The one dated entry in this notebook is from April 1892. All entries are by Edison. The book contains extended theoretical notes relating to gravity and other astronomical forces, the nature and structure of the solar system, and the transmission of light waves and electrical energy. Also included are notes, drawings, and calculations regarding electrical experiments. The pages are unnumbered, and several pages have been removed from the book. Approximately 30 pages have been used. Four loose pages have been inserted into the book. Courtesy of Thomas Edison National Historical Park.