This notebook covers the period January-May 1890. All entries are by Edison. The book contains extended theoretical notes about electricity and electromagnetism, including an entry in which Edison compares his own theories with those of James Clerk Maxwell. There are also notes and drawings relating to unidentified electrical equipment, ore milling and bricking machinery, electric traction, and electric lighting experiments for both incandescent and arc lamps. In addition, there is a list of chemical compounds to be tested. The front cover is labeled "#580." The inside front cover is inscribed "#580 T A Edison Jan 4. 90." The pages are unnumbered, and the book has been used in both directions. Approximately 160 pages have been used.