These are letters written from America, to Murchison, discussing geology, natural history, and contemporary topics.

Mentioned in these letters are personal affairs, experiments, Babbage's calculating machine, and his "Bridgewater Treatise," second edition.

This is a miscellaneous collection of letters, almost all written to Smyth by prominent scientists. The topics discussed include astronomy, microscopes, nautical almanacs, and submarine excursions. Also of interest is a letter from Thomas Graves, reporting what the Beagle (Charles Darwin's voyage) was encountering in South American waters.

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.

Though the Miscellaneous Manuscripts collection is composed of items that do not fall readily into any other existing collection, the two dominant intellectual areas represented in the collection are Early American History and History of Science.