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.

One of the oldest houses in Philadelphia, Wyck is now a non-profit museum listed on the National Register of Historic Places. Nine generations of the Jansen-Wistar-Haines family owned the Wyck property from 1690 until 1973. The last family owner deeded 2.5 acres of land, the house and its contents, several outbuildings, a landscaped garden, and a small endowment to the Wyck Charitable Trust. The Wyck Charitable Trust and the Wyck Association now administer the preservation of the property and its educational services to the public. This collection contains diaries, letters, accounts, bills and receipts, deeds, and photographs. The collection as a whole is deepest for the period 1770-1970. Items of particular note include accounts of household expenses at Wyck from ca. 1790-1970; papers pertaining to the Academy of Natural Sciences of Philadelphia, Quaker schools, and social reform groups; agricultural and horticultural practices; and correspondence to and from cultural leaders of 18th and 19th century Philadelphia. The papers of the John S. Haines family (Ms. Coll. 52A) form part of the Wyck Papers. The papers cover the years 1845 to 1949 and are arranged into eight series.

The most stellar member of a stellar family, Elisha Kent Kane was among the most popular American explorers of the mid-nineteenth century, a hero in the tragic mode. Born in Philadelphia in 1820, the son of John Kintzing Kane and Jane Duval Leiper, Kane studied medicine at the University of Pennsylvania before earning a commission as a naval surgeon. While in the Navy, Kane embarked on the succession of voyages to exotic locales that became the basis for his extraordinary fame. In 1843, he attended Caleb Cushing's first diplomatic mission to China as ship's physician, and subsequently traveled to the Philippines and Western Africa. Distinguishing himself in the Mexican War, Kane's greatest fame came from two expeditions to the arctic, aiming to locate the lost explorer, Sir John Franklin and to explore for evidence of the open polar sea. Kane died in 1857 while attempting to organize a third arctic voyage. Part of the Kane Family Collection, the Papers of Elisha Kent Kane contain a mix of personal and family correspondence with correspondence relating to all of Kane's explorations. Intelligent, articulate and very much a romantic, Kane's letters are expressive and passionate. The collection provides fine documentation of youth, his relationship with the Spiritualist Margaret Fox, and of course his travels to China and off the coast of Africa in 1846. Kane's two expeditions to the arctic are particularly well documented, with correspondence, notes, logbooks, diaries, and sketches, as well as Kane's post-expedition notes, writings, and lectures recounting his experiences.

This rich collection of letters and documents, which was assembled by Sol Feinstone (1888-1980) over a period of fifty years, includes material on almost all notable Americans from before the Revolution to the 1850's, as well as prominent Europeans, and there are documents relating to military affairs. There are substantial groups of letters from: John Adams, Henry Dearborn, Alexander Hamilton, Jedediah Huntington, Thomas Jefferson, Lafayette, George Washington, and a long run of letters from a Massachusetts military surgeon named Samuel Adams. Many letters, though written by Revolutionary figures, relate to events that occurred before or after the War.