The bulk of this series consists of copies of letters sent to Mason Fitch Cogswell (1761-1830), the Connecticut physician whose backing and leadership helped fund Thomas H. Gallaudet’s American Asylum. This general correspondence is arranged by the surname of the sender.

There is also a collection of letters between Mason Cogswell and his various family members, including his father, Rev. James Cogswell (1720-1807); Mason’s daughter, Mary A. Cogswell (1801-1868), later Mary Cogswell Weld; her husband, Lewis Weld (1796-1853); and Mason’s brother, Sam Cogswell (1754-1790). Also includes some copied diaries from Mason F. Cogswell and Rev. James Cogswell, and some of Mason’s personal papers.