This collection includes miscellaneous letters and drafts of letters; genealogical notes, medical essays, copies of letters and essays sent to newspapers and magazines; bills and receipts; invitations; military and other commissions; and a biographical memoir of General John Lacey, 1823. There are also papers, principally official, of his son Lieut. B. S. B. Darlington, U.S.N.

These are to Darlington from Spencer F. Baird, Robert Carr, Edward D. Ingraham, Moses Marshall, George Ord, John Jay Smith, and John F. Watson, among others. A letter from Joseph Johnson encloses a sketch of the life of Stephen Elliott (1771-1830).

This collection includes letters, diaries, notebooks, and early photographs, relating primarily to the Wister family of Germantown and Philadelphia. Much of the correspondence concerns domestic news and consists of letters from or to Sarah Wister. These include interesting observations on Germantown and Philadelphia society from other families as well, such as the Bayntons and Bullocks. There are numerous letters from various Wisters, including Casper, Charles Jones, Elizabeth (including a journal of a trip to Bristol, 1783), Hannah, John, Owen Jones, and others. There is also poetry by Sarah.

Letters and papers to or from American scientists or about America, selected from the Linnean Society's collections. Includes letters to William Swainson from John Abbott, John J. Audubon, Constantine S. Rafinesque, Isaac Lea, and John E. LeConte; letters to Sir James Edward Smith from Jacob Bigelow, DeWitt Clinton, J.F. Correia da Serra, David Hosack, Theodore Lyman, William Dandridge Peck, Rafinesque, and Gotthilf H.E. Muhlenberg; letters to William Darlington; letters to Asa Gray; letters of John Bartram; letters of Peter Collinson to J.F. Gronovius; letters and papers of John Ellis, including letters from Alexander Garden, Samuel Martin, and Bernard Romans; letters to Carl Linnaeus from John Bartram, John Clayton, Cadwallader Colden, Correia da Serra, Peter Kalm, Adam Kuhn, James Logan, John Mitchell, and Charles Wrangel.

These letters of American Philosophical Society members and prominent early American scientists were selected from Carson's extra-illustrated draft of "A History of the Medical Department of the University of Pennsylvania" (Philadelphia, 1869).

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.