This undated non-standard-size pocket notebook was used by Edison during 1918 or 1919 to record ideas about business matters, experiments to be tried, and other tasks to be performed. Some of the items have been crossed out and marked "ent." Included are notes relating to various electrical phenomena such as x-rays and "xyz rays." Also included are entries pertaining to the electromotograph and chalk telephone, battery cells, acoustic experiments on shipboard, audions, disc records, radium, and a chemical paper sensitive enough to print wireless signals like a printing telegraph. The business-related entries include minor items on salaries and labor. The front cover is stamped "Ledger." The book contains 144 numbered pages, some of which are blank. Courtesy of Thomas Edison National Historical Park.