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. The astronomical observations include the moon, Jupiter, Saturn, comets, and solar eclipses. Correpondents include George Biddell Airy, A. D. Bache, James Dwight Dana, Benjamin Apthorp Gould, Edward Everett Hale, Joseph Henry, John Herschel, and Alexander von Humboldt.