This collection contains correspondence, financial and legal documents, ledgers, inventories, estate records, ephemera, books, and journals pertaining to the business transactions, family relationships and the estates of Augustus Hemenway, his wife, Mary Tileston Hemenway, and various other family members. Their biographer and extended family member, Frederic A. Eustis, compiled these materials in his research. As one of the foremost "merchant princes" in the 19th century, Augustus Hemenway's business dealings in Chile, Cuba, Maine, New York, and Boston are extensively documented. Also of note is the detailed personal correspondence between Augustus and Mary Tileston Hemenway during their courtship in 1838-1839. Mary Tileston Hemenway's philanthropic, business, and cultural activities are described in correspondence, business records, and records of her estate. There are many original letters from her wide circle of literary, artistic, and civic connections such as Dorothea Dix, Booker T. Washington, Lucy Larcom, Childe Hassam, Sophia and Una Hawthorne, John Greenleaf Whittier, and Lucy Stone. Eustis' notes, drafts, and papers, acquired during his research and writing of Mr. Hemenway's biography, are extensive, and include original documents provided by Hemenway family members. The collection is organized into five series.