These letters relate to natural history, zoology, and the Muséum national d'histoire naturelle, as well as current events.

An evolutionist before Darwin, an embryologist, paleontologist, and comparative anatomist, Étienne Geoffroy Saint Hilaire was a Professor of Vertebrate Zoology at the Musée National d'Histoire Naturelle in Paris for the half century following the Reign of Terror. Following in the footsteps of Lamarck, Geoffroy held tenaciously to a belief in the underlying unity of organismal design, to the great change of being, and the possibility of the transmutation of species in time, amassing evidence for his claims through research in comparative anatomy, paleontology, and embryology. The Geoffroy Collection is comprised of 0.75 linear feet of lecture notes and correspondence relating to Geoffroy's diverse interests in natural history, Egypt, comparative anatomy, analogies, paleontology, and embryology, and it is particularly rich for his studies of teratology. All items are in French.

This volume was kept while Piggott was imprisoned by Napoleon at Fontainebleau. Subjects mentioned include astronomy, comets, and botanical gardens.

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.