William Clark kept this diary on an expedition to make a treaty with the Osage Indians in the Missouri Territory. A sketch drawn under the September 16 entry is apparently a draft of Clark's Fort Osage map, while the first page of notes presents color scheme used on another draft. See Kate L. Gregg, Westward with Dragoons (1937: 48) for the map in printed version.

Letters relating to American Indian languages, Moravian missionaries, various Heckewelder publications. Some of the replies from Du Ponceau are copied in the letter books of the Historical and Literary Committee.

This diary is a journal of a trip from Philadelphia by stage to Pittsburgh, then afoot through Franklin, LeBoeuf, and Erie to the Huron River; thence by boat to Detroit, where he remained 26-29 July, when he set out by canoe for Michilimackinac. Included are descriptions of Detroit, plants, animals, springs, Indian mounds, and notes on goitre.

The papers include miscellaneous letters, letterbooks, books, certificates, and diplomas of various members of the Muhlenberg family. Among them are photostats of letters and papers of General John Peter Gabriel Muhlenberg and officers of the Continental Army on military affairs in the Southern Department during the American Revolution (1772-1804); photostats of letters to Albert Gallatin, Nathanael Greene, Edward Hand, Winthrop Sargent, Baron von Steuben, William Alexander, and George Washington; photostat of General Muhlenberg's journal of trips to the Ohio (1784, 1797); photostats of letters and notes of Gotthilf H. E. Muhlenberg, including a diary kept at Halle (1771) and extracts of thirty letters to Stephen Elliott of Beaufort and Charleston, South Carolina (1808-1815); photostats of letters of Henry A. Muhlenberg about his biography of General Muhlenberg (1848-1849); and photostats of letters of Henry Melchior Muhlenberg (1711-1787). Also included is an original letterbook of Peter Muhlenberg, paymaster of the United States Army, kept at Augusta and Savannah, Georgia (1836-1842). Henry Muhlenberg's notebooks (1784-1813), written in Latin or German script, in a small hand, includes a wealth of botanical observations, with a focus on Lancaster, Pennsylvania. The Henry Muhlenberg journals are a record of daily occurrences, with many features of a commonplace book, containing prescriptions, notes of questions asked candidates for the Lutheran ministry, and the plan of a barn. There is also a biographical account of Rev. Henry Melchior Muhlenberg (1711-1787).

James Burd (1726-1793) was well-known in colonial Pennsylvania through his role in the French and Indian War, as well as his connections to many of the colony's leading families (most notably the Shippen family). Initially starting out as a merchant in Philadelphia, Burd became increasingly involved with colonial affairs after moving to Lancaster County with his family in 1752. It would be on the frontier where Burd would make his mark first as a soldier, and later as a magistrate. The Burd-Shippen Papers consist mainly of letters and business documents sent to James Burd, with the bulk of the collection relating to the French and Indian War, 1754-1763, in which Burd served as an officer commanding troops at Fort Augusta and elsewhere. The collection reflects all aspects of Burd's life in Pennsylvania as a merchant, soldier, and magistrate; as well as his involvement with the Shippen family professionally and personally. Intermixed with items sent to Burd are receipts to his wife Sarah Shippen Burd, and correspondence between Edward Shippen and James Hamilton regarding land matters and Indian affairs in Lancaster.

A physician, natural historian, and professor at the University of Pennsylvania, Benjamin Smith Barton (1766-1815) was one of the central figures in Philadelphia's early national scientific establishment. Having received his medical training in European universities, Barton was appointed Professor at the University of Pennsylvania in 1789, lecturing on botany, materia medica, natural history. A prolific author, he established his reputation as one of the nation's preeminent botanists through his botanical text book The Elements of Botany (1803), but his contribtions to zoology, ethnology, and medicine were equally noteworthy. Barton's monograph on the "fascinating faculty" of the rattlesnake and his efforts in historical linguistics (New Views of the Origin of the Tribes and Nations of America, 1798) were widely read, and his Philadelphia Medical and Physical Journal (1804-1809) was one of the nation's first medical journals and an important outlet for natural historical research. The Barton Papers offer a comprehensive view of the professional work of Benjamin Smith Barton from the time of his return to the United States in 1789 until his death. The collection is divided into five series: Correspondence, Subject Files, Bound Volumes, Graphic Materials, and Printing Plates. The collection includes a particularly valuable series of botanical, medical, and natural historical drawings collected by Barton for research, reference, and publication. Among the many artists represented are William Bartram, Frederick Pursh, Pierre Turpin, and Benjamin Henry Latrobe.