This collection of Morton letters forms part of a bound volume of incoming correspondence. It is a companion volume to the original letters in the Morton collection at the American Philosophical Society, which were also originally bound. Most of the subjects of the two collections overlap, but additional subjects in the microfilmed collection include American Indians, archaeology, Egyptology, and phrenology.

The collection of Charles Coleman Sellers (1903-1980) contains copious and detailed documentation of the art of Charles Willson Peale and his family. It consists of working files for Sellers's numerous publications, including his Portraits and Miniatures by Charles Willson Peale (1952); Charles Willson Peale with Patron and Populace (1969); C. W. Peale's Portraits of Washington (1951); Benjamin Franklin in Portraiture (1962); Mr. Peale's Museum (1980). Most files include photographs of the art work, notes on the piece, and correspondence with authorities or owners. Other series include one relating to the paintings of various other Peales, including Anna C., James, Mary Jane, Raphaelle, Rembrandt, Rubens, and Sarah Miriam, and a miscellaneous artist file, which includes the same type of material and information on many eighteenth- and nineteenth-century artists, including Thomas Eakins, George Healy, Robert Edge Pine, William Rush, Thomas Sully, Benjamin West, James Abbott McNeill Whistler, etc. There is a separate Sellers collection at Dickinson College, primarily personal in nature.

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