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.

A miscellaneous collection of letters, mainly of English scientists, written to various people. There are mostly one or two letters, except for those of John Peter Gassiot, William Huggins, Edwin R. Lankester, James Mackintosh, David Prain, and William Whewell.

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

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

Alexander Dallas Bache (1806-1867) was an important scientific reformer during the early nineteenth century. From his position as superintendent of the United States Coast Survey, and through leadership roles in the scientific institutions of the time, Bache helped bring American science into alignment with the professional nature of its European counterparts. In addition, Bache fostered the reform of public education in America. The Alexander Dallas Bache Collection consists of 91 letters written primarily by Bache. In most cases, these are brief notes replying to letters that are not part of the collection. The majority of items relate to Bache's work as superintendent of the U.S. Coast Survey, including letters of recommendation and introduction, and there is minor correspondence regarding the National Academy of Sciences, scientific matters, his travels in Europe, or personal matters. Of particular interest is the letter from Louis Agassiz in 1856 expressing his view of what the natural history museum of the future should be.

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.