This pocket notebook is from box 13 in Series 1 of the William J. Hammer Collection. It was used by Hammer during April-May 1880 while he was working in Edison's Menlo Park laboratory. The entries relate primarily to incandescent lamps. In addition to technical notes and drawings, there are entries recording the number of hours worked. The first page is inscribed "W. J. Hammer -- Private -- Menlo Park 1880 Note Book." An entry for May 13, 1880 is inscribed "first trial electric locomotive about 4 pm." The pages are unnumbered; approximately 50 pages have been used.

Courtesy of the NMAH Archives Center.