This pocket notebook was used by Edison, probably in 1898, primarily for calculations relating to Ogden operations. Included are calculations regarding costs, depreciation, profits, and losses, as well as financial obligations and resources. The book also contains some calculations that seem related to the production capacity of the Ogden works. In addition, there are notes and calculations regarding the Ortiz gold mine and a list of various types of mills. The pages are unnumbered. Approximately 70 pages have been used. Courtesy of Thomas Edison National Historical Park.