Scientific, personal and family correspondence and papers, including laboratory notebooks, 1885-1914; other working papers mainly relating to photography, 1863-1911, electric lighting, 1876-1905, and the gas cell, 1903-1914; business papers including records of Swan Electric Light Co., 1881-1896; drafts of lectures and speeches, ca. 1863-1914; papers relating to public affairs, ca. 1872-1914; autobiographical writings, 1906-1914; and 108 letters to Lady Swan, 1881-1914.