Most of this collection is original letters and drafts of Herschel's replies, with some miscellaneous papers other than letters. There are about 400 letters between Herschel and Charles Babbage.

This collection concerns astronomical observations, earthquakes, meteorology, photography, physics, professional associations, publications, and scientific instruments. The correspondents include Augustus De Morgan, Dionysius Lardner, Sir Francis Beaufort, and Sir Edward Ryan.

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.

This microfilm of Somerville's papers was compiled by Elizabeth C. Patterson for her book, "Mary Somerville and the Cultivation of Science, 1815-1840" (Boston: Martinus Nijhoff, 1983). It includes Somerville's scientific writings, personal writings, "letters from celebrities," family papers, genealogy, and photographs. Subjects of some of her writings include astronomy, Halley's comet, effects of light, and physical geography.

These are letters to Quetelet primarily on the subject of astronomy (meteorological observations), including charts showing directions of shooting stars.

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.

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.

This collection includes letters to and from Americans (including South America and the West Indies) and letters about America selected from the Society's manuscripts (Classified Papers, Letter Books, Letters and Papers, Royal Society Letters, Miscellaneous Correspondence, and other official groups) and from collections of private papers (Sir Charles Blagden, William Buckland, John Canton, Sir John F. W. Herschel, Sir Edward Sabine, and others). The documents range in time and character from John Winthrop, Jr., "A Description of the Artifice & Making of Tarr & Pitch in New England" (1662), to letters from Sir Thomas Edward Thorne to his wife describing the American West, where he was on a surveying party in the 1880s.

There is correspondence concerning geology, botany, natural history, natural selection, evolution, British science and scientists, and other scientific topics. Most of the letters are written by Lyell, with a very few items by others.