Chiefly letters written to Simeon G. Fish, son of shipbuilder Nathan G. Fish, owner of Maxon, Fish & Co., containing descriptions of social life and daily activities in Mystic during the mid-19th century. Other persons represented include members of the Miner and Randall families.

Letters to family members and diaries (1862-1870) describing Lyon's experiences during the Civil War and his later life in Vermont; together with a typewritten account (1903) of Hatsell's Civil War service written by his son, Arthur H. Hatsell. There are no papers dated 1871-1902.