Principally covering botany and agriculture, this collection includes many manuscripts on trees, shrubs, and plants of different species, copies of botanical essays by others, essays on fruit trees, etc., by Auguste Denis Fougeroux de Bondaroy (1732-89), notes and drafts for the latter's revision of Duhamel's Traité des Arbres et Arbustres. Also miscellaneous essays, sketches, and memoranda on bones of birds and animals, electricity, fish, steam engines, ventilation, temperature and air pressure, mathmatics, paleontology ("Observations sur les os d'éléphants fossiles"), chemistry, metallurgy, entomology, architecture, taxidermy ("Méthode pour empailler les oiseaux"); lists of plants; notes on England, Canada, Mexico, China; notes of reading in Pliny, John Evelyn, Alexander Russell, William Derham, and others. An unpublished translation of Jethro Tull's Horse-Hoeing Husbandry, with additions and revisions by Duhamel du Monceau. An alphabetical catalogue of Duhamel's gardens, prepared by Fougeroux de Bondaroy. The collection has manuscript material in pre-publication form along with published material with marginalia for improvements of later editions. There are a multitude of sketches, botanical materials and seed packets. The collection includes lists of American trees and seeds shared with European scientists. Benjamin Franklin acts as a go between French and American botanists and John Bartram sends seeds to France from his garden. Also correspondence (ca. 170 pieces) with, among others, Peter Collinson, Duc d'Aven, Duc de Noailles, Louis J. M. Daubenton, Mathurin Jacques Brisson, Jean François Gauthier, Comte de La Galissonière, Chrétien Guillaume de Lamoignon de Malesherbes, Emerich Vattel. The collection has been described in part by Gilbert Chinard, "Recently Acquired Botanical Documents," APS Proc. 101 (1957): 508: and by Joseph Ewan, "Fougeroux de Bondaroy (1732-1789) and his Projected Revision of Duhamel du Monceau's Traité (1755) on Trees and Shrubs. I. An Analytical Guide to Persons, Gardens, and Works mentioned in the Manuscripts," APS Proc. 103 (1959): 807.

The correspondence is principally to Zaccheus Collins (1810-1840), with bills, receipts, and notes on Rafinesque vs. Parker; letters from Collins, L.A. Tarascon, Lewis C. Beck, John Torrey, and Charles W. Short (1817-1835); and miscellaneous correspondence and documents relating to Rafinesque vs. Parker, with an account of the Felician Society of Feliciana County, Illinois (1820). The writings are chiefly on botanical topics, and include notes and essays on Indians, Blacks, grapes and wine-making, banking, and speculation. Rafinesque's growing interest in Indian antiquities, linguistics, and history is apparent in letters after 1820. There is an account of Rafinesque's scientific travels in North America and southern Europe (1800-1832), and a bibliography. The botanical notes include descriptions of specimens collected by Lewis and Clark, Patrick Gass, and Henry Muhlenberg.

This collection includes letters from, and drafts of letters to, scientists, artists, musicians, soldiers, political figures, and court personages throughout Europe, especially Italy and France. Topics covered range from personal and social affairs to agriculture, botany, geology, natural history, coinage, museum management, politics, weights and measures, current affairs. The collection also includes four diaries, housed separately with manuscript volumes.

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).

Through his craniometic studies of human races, the Philadelphia physician Samuel George Morton (1799-1851) exerted a profound influence on the development of physical anthropology in antebellum America, and made substantial contributions to mineralogy, paleontology, and natural history. Relating primarily to Morton's scientific interests, the Morton Papers include insights into Morton's perspectives on education, medical practice, geology and mineralogy, craniology, paleontology, the Wilkes Exploring Expedition (also known as the United States Exploring Expedition 1838-1842), and his two major monographs, the Crania Americana and Crania Aegyptiaca. Several of the letters were written by Morton in his capacity as corresponding secretary of the Academy of Natural Sciences of Philadelphia. Also included in this collection are Morton's "Some Remarks on the Infrequency of Mixed Offspring Between the European and Australian Races" (1850), Joseph Barclay Pentland's notes on the aborigines of Peru (ca. 1840?), and newspaper clippings on Morton's death; a diary of Morton's trip to the West Indies, 1834, a set of craniological sketches for use in Crania Americana, and a microfilm of letters in private hands, written to Morton, 1838-1844