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 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.