This collection includes letters, diaries, notebooks, and early photographs, relating primarily to the Wister family of Germantown and Philadelphia. Much of the correspondence concerns domestic news and consists of letters from or to Sarah Wister. These include interesting observations on Germantown and Philadelphia society from other families as well, such as the Bayntons and Bullocks. There are numerous letters from various Wisters, including Casper, Charles Jones, Elizabeth (including a journal of a trip to Bristol, 1783), Hannah, John, Owen Jones, and others. There is also poetry by Sarah.

The collection contains information on Fox family speculation in western lands, two manuscript maps from the 1790's and 1830's depicting the family's holdings in northwestern Pennsylvania, and a photograph album from the 1890's documenting Chestnutwold, the Fox estate adjacent to Andalusia. Chief correspondents are Samuel and George Fox.

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).

After a brief career in the Congregational church, J. Peter Lesley (1819-1903) left the ministry in 1852 to work full-time as a geologist. Having gained experience in structural geology and stratigraphy with the First Pennsylvania Geological Survey (1836-1842), Lesley became an expert in the geology of coal, working for the Pennsylvania Railroad and other corporations and conducting some of the first systematic studies of the state's hydrocarbon resources. A long-time professor at the University of Pennsylvania, he was elected to the APS in 1856, serving variously as its librarian, secretary, and vice president, and he was selected as Director of the Second Pennsylvania Geological Survey (1875-1889). The Lesley Papers include letters to and from Peter Lesley and his wife, Susan on geology, coal and iron mining, abolition, educational reform, organized charity, and Unitarianism. The collection offers important insight into academic and applied geology in late 19th century Pennsylvania, the development of the coal and iron industries, as well as into the Lesleys' progressive social and intellectual milieu. It is divided into three series: Lesley's general correspondence, his correspondence with his brother Joseph, and microfilms of Lesley's research notes.

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.

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.