These nine documents were selected from box 20 in Series 1 of William J. Hammer Collection. They relate to Edison's demonstration central station at the Holborn Viaduct in London, which began operation on January 12, 1882. Included are technical notes and drawings by chief engineer Hammer and general manager Edward H. Johnson; a 25-page report made to the Edison Electric Light Co., Ltd., by John Hopkinson and John Ambrose Fleming; and a copy of Britain's Electric Lighting Act of 1882 providing for local licenses for the supply of electricity. Also included are retrospective notes regarding the Holborn Viaduct made by Hammer in 1888 and a copy, made by Hammer in 1927, of Johnson's notes of 1881-1882. Courtesy of the NMAH Archives Center.