MITCHEL, Ormsby McKnight, American astronomer: b. Morgansfield, Ky., 10 July 1810; d. Hilton Head, S. C., 30 Oct. 1862 He was graduated from West Point in 1829, and was made assistant professor of mathematics there, which post he held for two years. From 1832 to 1834 he was counsellor-at-law in Cincinnati, Ohio; from 1834 to 1844 professor of mathe matics, philosophy and astronomy at Cincinnati College; and 1836-37 chief engineer of the Lit tle Miami Railroad. He lectured in various parts of the United States on astronomy in 1842-48, raised funds for the building of an observatory at Cincinnati, the cornerstone of which was laid 9 Nov. 1843, and was its director in 1845-59. In 1859 he became director of the Dudley Observatory at Albany, A. Y. He was known as a popular lecturer on astronomy, and scarcely less distinguished for his mechanical skill. He perfected a variety of apparatus of great use to astronomy. One of the most im portant of his constructions was an apparatus for recording right ascensions and declinations to within yaia of a second. He also invented
an instrument for the measurement with great accuracy of large differences of declination, such as the ordinary method by micrometer was unable to reach. In 1861 he entered the Federal army as brigadier-general of Ohio volunteers, and on 11 April 1862 was promoted major-general. From 17 September he com manded the Department of the South and the Tenth corps, operating in South Carolina. He was known in the army as "Old Stars." He was a Fellow of the American Academy of Arts and Sciences and an associate of the Royal Astronomical Society of London. He published and edited The Sidereal Messenger (1848-58), and wrote 'The Planetary and Stellar Worlds' (1848) ; 'The Orbs of Heaven' (1851); Popular Astronomy' ; 'A Concise Elementary Treatise of the Sun, Planets, Satellites and Comets' (1860), both republished (London 1892), and 'The Astronomy of the Bible' (1863). Consult Mitchel, F. A., 'Life of Ormsby McKnight Mitchel> (Boston 1887).