Born May 26, 1750, to the niece of Benjamin Franklin, Jonathan Williams was a prominent merchant, scientist and soldier. Elected to the APS in 1787 as a result of his observations on temperature and barometrical readings, as well as work on sugar production, Williams had a distinguished military career highlighted by his appointment as first superintendent of the Military Academy at West Point. The Jonathan Williams Papers consists of 46 letters and documents, written by or to Jonathan Williams Sr. and Jr., dealing primarily with financial and legal matters. The collection includes five letters written by Benjamin Franklin and many of the others are signed by Williams' father-in-law and brother-in-law, William and Robert Alexander.

These papers relate principally to Smyth's career in New Jersey before the American Revolution, and includes addresses to grand juries and their reports, and a copy of a petition to the Earl of Carlisle and its response (1778).

Jasper Yeates (1745-1817) was a lawyer and Pennsylvania Supreme Court justice, one of the state's most successful colonial-era legal practitioners. After moving to Lancaster County in 1765, he became active in colonial and early federal affairs, first by supporting the Revolutionary struggle and later by serving as one of Lancaster's delegates to the State Convention of 1787, which ratified the U.S. Constitution. The Jasper Yeates Papers (1728-1910, bulk 1760-1816) consist mainly of correspondence and business and court/legal records related to the Yeates family. The bulk of this three linear foot collection reflect Yeates' personal life as husband, father, son, and friend, as well as his professional life as lawyer and judge in Pennsylvania; much of the material dated after Yeates' death was created by children and/or grandchildren.

Three volumes contain letters, laws, charters, reports, proclamations, petitions, and other official and semi-official documents relating principally to early Pennsylvania and New Jersey, signed by or addressed to William Penn, among others. A fourth volume is Penn's cash book, 1699-1703, which records expeditures, payments of quit rents, etc. Tipped in is "Catalogue of Goods left at Pensbury," and of goods left at Philadelphia, 1701.

A product of the distinctive culture of reform in antebellum Philadelphia, William Parker Foulke was the scion of the old elite who put a conservative stamp on social change. Trained as an attorney, Foulke spent much of his adult life engaging his deep amateur interest in natural history and mental philosophy and devoting himself to a variety of civic and philanthropic causes, including the colonization of formerly enslaved persons, penal reform, and cultural institutions in his native Philadelphia. The Foulke Papers are the product of the diverse social and intellectual interests of the Philadelphia attorney and philanthropist William Parker Foulke. Consisting primarily of correspondence, notes, and essays, the collection touches on Foulke's many interests. The collection includes numerous lectures delivered by Foulke along with material on the Lancaster County Prison, New York Prison Association, and the Philadelphia Society For Alleviating the Miseries of Public Prisons; notebooks concerning prisons and prisoners, including a 1846-1852 diary, and a listing of prisoners, their race, age, crime, sentence, and observations; a diary concerning the American Colonization Society (1852); a copy of an arctic diary (1853-1854) by John Wall Wilson, in the hand of Isaac Israel Hayes, which recounts much of the journey aboard the brig Advance, commanded by Elisha Kent Kane. There is also a list of buildings (1820-1841) designed by John Haviland, and material on the American Academy of Music, Philadelphia.

A collection of letters, legal papers and financial records of three generations of the prominent Philadelphia family. Spanning 1745-1955, detailed are the legal cases and political advocacy work of John Kintzing Kane (1795-1858), Robert Patterson Kane (1827-1906), and Francis Fisher Kane (1866-1955). Also includes correspondence, architectural drawings, and photograph albums of the Cope family. Robert Patterson Kane's daughter Eliza Middleton Kane (1863-1952) married the Philadelphia architect Walter Cope (1860-1902) in 1893. The APS papers of Elisha Kent Kane are in call no. B K132.

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.