Peter S. Du Ponceau translated Gérard de Rayneval's "De la liberté des mers" (Paris, 1811) as an exercise, but not for publication.

These papers concern business and legal affairs, and include Price's writings on the law of real and personal property, and private wrongs. Also includes a letter to Daniel Webster.

The Lusanna, a seventy-ton brigantine, was owned by Elisha Doane of Massachusetts, and sailed with his son-in-law Shearjashub Bourne as supercargo. She sailed from Massachusetts in 1775 at the onset of the American Revolution. On the return voyage from London in 1777 she was captured by the privateer McClary out of Portsmouth, NH. In the prize case that followed in the New Hampshire maritime court, Bourne and Doane unsuccessfully tried to defend their ship. Their appeal eventually made its way to the Continental Congress. The Lusanna Prize Case Records is a written transcript of the proceedings in Admiralty Court of the armed brigantine McClary vs. the brigantine Lusanna in the State of New Hampshire. The transcript contains the entire proceedings of the case including the libel, statements of the crew and passengers, invoices for items shipped aboard the Lusanna, bills of lading, copies of letters pertaining to the voyage and cargo, copy of the prize case against the Industry (another vessel owned by Doane captured by the British in 1775), testimony in support of the owners of the Lusanna as loyal to the United States, the decision of the court, and the appeal.

A pioneer in ethnographic and linguistic studies of the American Indian and one of the most active members of the American Philosophical Society, Peter Stephen Du Ponceau helped to establish the American Philosophical Society's reputation as one of the world's foremost centers for the study of American Indians and their languages. The Peter Stephen Du Ponceau collection consists of correspondence on legal matters, Indian linguistics, silk culture, maritime law, the American Philosophical Society, and various publications of the early nineteenth century. The collection also includes several essays by Du Ponceau, most of which deal with maritime law.