These papers consist chiefly of essays presented by the members, with such titles as "Ambition," "On Avarice," "State of Literature in the United States," and "Consequences of the French Revolution." Also included are several letters, including one from Benjamin Say, Jr.

The commission of the Institut de France was charged with offering a prize on linguistics, under the will of Count Volney. Formerly, this essay was thought to have been by Baron Nicolas Massias (1764-1848), who won the Volney prize in 1828. However, the note that the volume was shipped from New York precludes that.

This collection includes correspondence to and from Boskovic; a travel journal in Europe; and a large number of manuscripts on astronomy, hydrography, hydro-mechanics, mathematics, geometry, mechanics, and optics; and a volume of poetry.

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.