Correspondence, 1904-1946; photographs, juvenilia, and printed material. Correspondence includes that of Anna Hyatt Huntington, Audella Hyatt, Leon Kroll, Alfred G. Mayor, and Harriet Randolph Hyatt Mayor.

Correspondence, 1863-1897; personal documents, manuscripts, and published material of the American physicist.

Correspondence, diary, expedition journal, financial material, scientific notebook and sketches, photographs, published material, including articles and newspaper clippings, and scrapbooks. Correspondence (1854-1902) includes that of Alexander Agassiz, Charles E. Beecher, E.D. Cope, James D. Dana, J.S. Diller, G.K. Gilbert, G. Brown Goode, Asa Gray, Robert T. Hill, Anna Hyatt Huntington, Hyatt’s father, Alpheus Hyatt, Audella Beebe Hyatt, Jules Marcou, Harriet Randolph Hyatt Mayor, A.S. Packard, Charles Schuchert, and Charles Walcott.

Correspondence, incoming and outgoing (1860-1932); diaries; account books; notebooks; a partial autobiography; and sketches. Correspondents include Clara Carter Hyatt Coad, Mary E. Freeman, Anna Hyatt Huntington, Archer M. Huntington, Alpheus Hyatt, Leon Kroll, Alpheus Hyatt Mayor, and Harriet Randolph Hyatt Mayor.

Correspondence (1892-1960); diaries, genealogical materials, notebooks, photographs, printed material, including articles and clippings, scrapbooks, memorabilia, and sketchbooks. Correspondence includes that of Adelaide Cole Chase, Clara Carter Hyatt Coad, Anna Hyatt and Archer M. Huntington, Audella Hyatt, and Alfred G. Mayor.