This notebook from box 13 (Series 1) of the William J. Hammer Collection was used by Hammer in 1882 in his capacity as chief engineer of Edison's demonstration central station at the Holborn Viaduct in London. It contains notes, drawings, and published illustrations pertaining to a variety of dynamos. The book was badly damaged along the spine by either fire or acid. It contains 310 numbered pages, of which 48 have been used. Courtesy of the NMAH Archives Center.