These letters to Hunt concern geology, physics (photography and light), and scientific instruments.

The William Hutton Papers relate primarily to geology and botany, and there is also much on the Newcastle Natural History Society, of which Hutton was the secretary. There is much correspondence with Alexandre Brongniart, H. S. Davis, John S. Henslow, John Lindley, David Milne, Roderick I. Murchison, George Steuart MacKenzie, and John Phillips.

These letters are to the British geologist, Harry Govier Seeley. Lushington was apparently a friend or mentor, and he advises Seeley to become a geologist, and praises his poetry. Some of the letters concern paleontology, university education at Cambridge, and an observation on Robert Browning.

These notebooks contain lectures or reports on lectures, with corresponding watercolor and pen-and-ink drawings. There are volumes on geology (Great Britain and elsewhere), natural history, mechanics (sketches of levers, valves, and weighing machines), and steam engines (sketches of mechanics of boilers).

Luna Bergère Leopold (1915-2006, APS 1972), son of prominent conservationist Aldo Leopold (1887-1948), worked during seven decades to bring the field of hydrology and fluvial geomorphology into the conscience of urban planners and those who would restructure the flow of rivers and streams. He established the first practical, major field methods by which the geometry of streams and the waterflow in them are measured and how these data are analyzed. His work is based on meticulous field studies over the course of a multifaceted career as a meteorologist, hydrologist, geomorphologist, professor, and conservationist. This collection comprises his extensive incoming correspondence and other papers mostly during his active retirement years (1986-2006), with some earlier papers. The collection also contains his profusely illustrated personal journal in 12 volumes (1931-2003) that include world travels; some 70 field notebooks (1937-2006) embracing localities in the Western and Northeastern United States, in Hawaii, and some foreign locations (chiefly in India and Israel); more than a hundred original plane table maps from locales in the United States; a significant set of correspondence and papers (1956-1986) from hydrologist and sedimentologist Ralph Alger Bagnold (1896-1990), who in his own right was a pioneer in modern sedimentology and hydrology; and publications and manuscripts over the course of Leopold's multidisciplined career.

One of the most prominent scientific refugees from the political turmoil of 1848, Arnold Guyot made fundamental contributions to the study of geology, glaciology, and meteorology on two continents. After emigrating to the United States, Guyot established himself as Professor of Geology and Physical Geography at Princeton, remaining untilhis death in 1884. The Guyot Collection consists of 61 letters written by Louis Agassiz (15 items), his wife Elizabeth (32), and their son Alexander (14), to their friend and fellow naturalist, Arnold Guyot. Primarily personal in nature, the letters reflect a long and intimate friendship, making frequent mention of family and mutual friends. There is, however, comparatively little in the collection relating to their respective scientific endeavors, with only a few references to the situation at the Museum of Comparative Zoology and at Princeton, to publications of various sorts, to the difficulties of their mutual friend Leo Lesquereux, and to other colleagues.

This small collection of lectures and papers, mostly undated, concerns Ohio geology, cyclones, and theology and geology of the manuscript items by E. W. Claypole.

These are letters written from America, to Murchison, discussing geology, natural history, and contemporary topics.

This correspondence is with Charles Francis Adams, Jr., Edgar Fahs Smith, and Thomas Sovereign Gates, about undergraduate days at Harvard College, his interest in Harvard, the University of Pennsylvania, and the Wistar Institute. The papers include a list of publications, biographical data, papers on Robert G. LeConte and Daniel Moreau Barringer, a certificate of membership in the Governor Thomas Dudley Family Association, and 25 drawings of crystals and 35 original sketches made to accompany his Harvard thesis, "The Nature and Origin of Deposits of Phosphate of Lime."

Benjamin Silliman (1779-1864, APS 1805) was a scientist and educator. As a professor of chemistry at Yale University from 1802 to 1853, and pioneering teacher of chemistry, mineralogy and geology, Silliman was largely responsible for the conversion of Yale College to Yale University, with strong medical and scientific departments.

Geologist George Alexander Louis Lebour was a minor figure in nineteenth century England. Educated at the Royal School of Mines, Lebour served as Professor of Geology at Durham College of Science and then Vice-Principal of Armstrong College, formerly Durham College of Science and presently University of Newcastle-upon-Tyne. He was most associated with his publication on the geology of Durham and Northumberland and he wrote more then 100 papers mainly on carboniferous geology, heat-conductivity of rocks, and the transfer of heat through the earth's crust. The Lebour Papers are comprised of 0.25 linear feet of correspondence relating to Lebour's interest in the analysis and sharing of geological specimens, geological surveying, and underground temperatures. There are a few letters with the Geological Society of London and with Richard Howse, the curator of the Natural History museum of Newcastle-upon-Tyne regarding the loaning of specimens.

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.

This collection of Morton letters forms part of a bound volume of incoming correspondence. It is a companion volume to the original letters in the Morton collection at the American Philosophical Society, which were also originally bound. Most of the subjects of the two collections overlap, but additional subjects in the microfilmed collection include American Indians, archaeology, Egyptology, and phrenology.

This collection includes letters to Maclure, journals of travel in Europe and America, notes and essays. Also included are manuscripts, transcripts, and notes relating to Maclure.

This is primarily a collection of letters, with some additional documents, concerning Young's interest in botany, geology, mineralogy, and natural history. There is information about Bowdoin College, where he studied under Parker Cleaveland. There is also much on the natural history of Maine, where he was the State Botanist in 1847-1849, and also on the Bangor Natural History Society. There are materials on Brazil in relation to Young's service there as the U.S. consul to Rio Grande do Sul from 1863 to 1873. There are also letters from his brother, John C. Young, and his sister, Sarah Augusta Young.

From negative microfilm held by Dr. Leonard G. Wilson, the collection consists mostly of incoming correspondence from English and American scientists, with a small section of correspondence from Lyell.

The collection is a miscellaneous group of letters of mainly British scientists and physicians, purchased as an existing autograph collection. There are a few American signatures. The letters are primarily from the nineteenth century and focus on medical and geological topics, but also there are some earlier and later dates. In addition to the letters are anatomical drawings of surgery, sketches of bones, and one geological notebook.