The son of William Franklin, Royal Governor of New Jersey, William Temple Franklin worked as aide to his grandfather, Benjamin Franklin, when the latter served as minister to France during the American Revolution. A bonvivant, Temple received his highest public appointment as Secretary to the American delegation at the Treaty of Versailles in 1782-1783, largely through the influence of his famous grandfather, but never again attained a significant post. As Franklin's literary heir, he edited and published a three volume set of his grandfather's writings in 1817. He married his long time mistress a few months before his death in Paris in 1823. The William Temple Franklin Papers provides a richly detailed portrait of the life of the grandson of Benjamin Franklin, and consists largely of letters received during the years that Temple served as his grandfather's aide in France, 1776-1785. Although much of the correspondence is routine, during this period, Temple received regular reports from friends and diplomatic colleagues relaying information on the American Revolution, the course of diplomatic and peace negotiations, and French public opinion on Benjamin Franklin and the new United States. The collection is also a rich resource for information on the personal lives of the Franklins, including interesting correspondence from Temple's relatives William Franklin, Elizabeth Franklin, Sarah Franklin Bache, and Jonathan Williams, and his mistress Blanchette Caillot.

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.