This includes communications or correspondence from such figures as A.D. Bache, Amos Bonsall, John F. Frazer, and M. F. Maury. There are reports by committees, such as those on agriculture, botany, horticulture, and meteorology.

This microfilm contains correspondence from scientists, including Friedrich Wilhelm Bissell, 1816-1846 [from Deutsche Akademie der Wissenschaften, Berlin]; Matthew F. Maury, 1849-1859 [from National Archives, Washington, D.C.]; Paulus Usteri, 1789-1821 [from Bibliothèque Universitaire, Zurich; and Johann G. Galle, 1836-1858 [from Frau von Heinz, Schloss Tegal]. There is also correspondence from the Royal Society, London; Bibliothèque Nationale, Geneva; Göttingen University Library; British Museum; Massachusetts Historical Society; Bancroft Library of the University of California; Yale University; Henry E. Huntington Library; Library of Congress; the Alexander von Humboldt Kommission; Westdeutsche Bibliotek, Marburg; and Deutsche Staatsbibliotek, Berlin. The materials were, in general, collected by Helmut de Terra and contain correspondence with various scientists. A few items pertain to Humboldt's travels and general comments on American Indian linguistics.

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

The manuscripts of father William Mitchell and daughter Maria Mitchell are not easily separated, and are treated here together. The collection includes William Mitchell's autobiography, his memoir of Judge Walter Folger of Nantucket, astronomical and meteorological observations, lectures, family and other correspondence.