The collection documents in photographs, manuscripts, notes, books, pamphlets, and excerpts, the beginnings of electrical technology. Included in the four series are both original documents and papers generated by Hammer and by various companies and individuals with whom he was associated. Series 1 consists of correspondence, mostly incoming from 1879-1935, but also includes diaries, notebooks, biographical information, patent material, pamphlets, writings by Hammer, and a badge, 1925. Also in this series, is correspondence on Hammer's Historical Collection of Incandescent Electric Lamps. Series 2 contains information on Thomas A. Edison's inventions including copies of agreements, copies of Edison's patents, and other patent materials, correspondence, data relative to the Edison Central Stations, Edison storage battery data, exhibits to legal cases, etc. Series 3 consists of reference materials including advertisements, articles, bulletins, catalogs and guides, gazettes, journals, pamphlets, newsclippings, portraits, scientific papers, scrapbooks, and theses. Series 4 consists of photographs from the Hammer papers, Edisonia, and reference materials. Individuals and subjects include: Thomas A. Edison, Edward H. Johnson, Pierre Curie, Marie Curie, Francis R. Upton, Francis Jehl, Nichola Tesla, Frank J. Sprague, George Batchelor, Alexander Graham Bell, Emile Berliner, electrical engineering, incandescent electric lighting, light bulb, selenium, radium, cathode rays, x-rays, ultraviolet rays, phosphorescence, flourescence.
