This notebook covers the period September 1910-November 1912. It contains a log by Edison and several unidentified experimenters of endurance tests on storage battery cells. The book appears to be part of a test series, but the other books have not been identified. One page has been removed from the book, although the sequentially numbered test entries are not interrupted. Inserted into the book is a one-page cell test report by George H. Hooper, Jr., dated July 1906. The front cover is labeled "Very Important," and "Iron 4508 to 1 to." The pages are unnumbered. Approximately 170 pages have been used.