The collection is divided into two series. The first contains disparate letters from Airy relating to his publications and his position as Astronomer Royal of England, with mentions of topics such as: electrical experiments, magnets, Observatoire de Paris, stars, and telescopes. Correspondents in this series include: Edward Wedlake Brayley, James Challis, Alexander S. Herschel, Balfour Stewart, Septimus Tebay, John Washington. The second series features a group of documents put together by George May of the Harton Colliery at South Shields (1889) relating to Airy's pendulum experiments at Harton Pit in 1854 to measure the density of the earth.

Adam Sedgwick (1785-1873, APS 1860), geologist, was an important figure in the development of the modern discipline of geology. He was educated at Cambridge, being ordained in 1817. An excellent field geologist, he did significant work interpreting complex old rock in such places as Devonshire (naming the Devonian Period after that location), Cornwall, and the Lake District, correlating his findings with strata in places such as Germany. Sedgwick first interpreted strata from the period he named Cambrian. He served in many professional organizations and was honored for his work with the Wollaston and Copley medals. Sedgwick, a Liberal in politics, served on committees that reformed the administration of university education. Despite being a friend of Charles Darwin's, Sedgwick was critical of the materialist bent of Darwinian thought. The 37 letters in the collection were acquired at various times, mainly through purchase, and assembled for the collection. The letters span the dates 1825-1870. Individually most letters are not especially significant, but collectively they touch on most aspects of Sedgwick's life and career. There are letters about Sedgwick's work on university reform, the Geological Museum at Cambridge, lectures, colleagues, travel, health, and family. Only one letter in the collection delves into detail about Sedgwick's geologic work.

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.

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.