This notebook covers the period January-May 1881. The entries are by Charles L. Clarke and relate to tests of steam engines and to the design of the Porter-Allen engine for the central station dynamos. The label on the front cover is marked "Steam Engine Tests" and "C.L. Clarke." The book contains 254 numbered pages. The pagination is irregular. Between pages 20 and 21 is a set of 26 pages numbered OD through 19a.
Blank pages: 19a-254 Courtesy of Thomas Edison National Historical Park.