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.

These are primarily scientific letters from Buckland. The subjects mentioned include Milne-Home's seismological investigations, Wheatstone's self-registering instruments, geology (glacial phenomena in Scotland, mineralogy, etc.), numerous references to fossils, and mentions of Mastodon bones and sloths.

Series I is a miscellaneous collection of letters concerning geology, geological exploration of Russia, entomology, glaciers, appointments in the British Museum, Geological Society of London business, Royal Geographical Society, references to David Livingstone, and zoology. Series II consists of letters written from America, to Murchison, discussing geology, natural history, and contemporary topics.

A miscellaneous collection of letters written by naturalist Louis Jean Rodolph Agassiz concerning a wide range of topics: natural history and naturalists, geology, mineralogy, fossils, publications, expeditions, and the Museum of Comparative Zoology at Harvard, which he founded.

The natural historian Richard Harlan was a pioneer in the study of comparative anatomy and vertebrate paleontology in the United States during the years following the War of 1812. Having received his medical degree from the University of Pennsylvania in 1818, Harlan was employed as an instructor of anatomy at Joseph Parrish's school and at the Philadelphia Museum. A practicing physician and member of the Academy of Natural Sciences of Philadelphia and the American Philosophical Society, Harlan made important contributions in comparative neuroanatomy, paleontology, herpetology, and systematic zoology. He died shortly after moving to New Orleans in 1839. Harlan's journals document two of the three overseas voyages he undertook during his lifetime. The first took place in 1816-1817 when Harlan was still a medical student, accompanying an East Indiaman to Calcutta as ship's surgeon. The second took place when Harlan was at the peak of his career in 1833, venturing to England, France, and Italy to strengthen contacts with European colleagues. Interesting travel narratives in themselves, the journals mingle enthusiasm for the new and exotic with a touch of Harlan's truculance. The European journal includes a valuable account of the 3nd meeting of the British Association for the Advancement of Science at Cambridge at which Harlan delivered a paper on fossil reptiles.

This collection contains miscellaneous letters and papers relating to explorations of South America, Cuba, and Mexico; scientific investigations; Latin American antiquities and linguistics; and publications. There are also copies of 26 letters from Humboldt to Pierre Hyacinth Azais and Jules Berger de Xivrey, from originals at the Duke University Medical Center Library.

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.

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.

One of the most important natural historians in nineteenth century Britain, Charles Darwin provided the first compelling mechanism to account for organismal evolutionary change. Although lacking a coherent model of heredity, Darwin's natural selection has exerted an enormous influence over the biological sciences and since the introduction of Mendelian genetics, had remained the key unifying principle in the discipline. The APS Darwin Papers are a large a valuable assemblage of Darwin's correspondence with scientific colleagues, including Charles Lyell and George J. Romanes. They are included in the print version of the Correspondence of Charles Darwin (Cambridge Univ. Press).