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brigadier-general in the provisional army, and he subsequently acquired the rank of major-general. His brigade was composed of five regiments of Vir- ginia infantry in the Army of northern Virginia. As a major-general he commanded Gen. Jubal A. Early's old division. He was engaged in all the campaigns of the Army of northern Virginia, and was killed in action at Hatcher's Kun. — John's brother, William Johnson, soldier, b. in Peters- burg, Va., in 1841 ; d. there, 2 April, 18G5, left the University of Virginia, where he was a law student, at the beginning of the civil war, to enter a Con- federate regiment of artillery as a private, and won promotion in that arm of the service at Cedar Run, Chancellorsville, and Gettysburg. Early in 18(55 he was made brigadier-general, and he was killed during the siege of Petersburg, Va.

PEIRCE, Benjamin (purse), librarian, b. in Salem, Mass., 30 Sept., 1778; d. in Cambridge, Mass., 26 July, 1831. He was graduated at Har- vard in 1801, and settled with his father as a mer- chant in Salem. For several years he represented Salem in the lower branch of the legislature, and in 1811 he was sent to the state senate. In 1826 he became librarian of Harvard, which post he then filled until his death. He published " A Catalogue of the Library of Harvard University " (4 vols., Cambridge, 1830-1), and "A History of Harvard University from its Foundation in the Year 1636 'to the Period of the American Revolution," issued posthumously by John Pickering, who prepared a sketch of his life for the preface of the work (1833). — His son, Benjamin, mathematician, b. in Salem, Mass., 4 April, 1809 ; d. in Cambridge, Mass., 6 Oct., 1880, was graduated in 1829 at Harvard, where he was tutor in mathematics, after first teaching for two years at Round Hill school, Northampton, Mass. In 1833 he was appointed uni- versity professor of mathematics and natural philosophy, and in 1842 he be- came professor of as- tronomy and mathe- matics, which chair he held until his death, when he had been connected with the university for a longer time than any other person ex- cept Henry Plynt, of the class of 1693. The pursuit of

mathematics as a

living science was the ambition of his life. Prof. Peirce was frequently called upon to assist in mat- ters connected with the U. S. coast survey, and in 1852-67 had direction of the longitude determina- tions of that service. On the death of Alexander D. Bache {q. v.) in 1867 he was appointed to the office of superintendent, which he then filled until 1874. During the civil war the regular work of the survey had been largely suspended, but under Prof. Peirce its continuation, according to plans laid down by his predecessor, was taken up, and its extension to a great geodetic system, stretching from ocean to ocean, was begun under his administration, thus laying the foundations for a general map of the country that should be entirely independent of detached local surveys. With this object the great diagonal arc was extended from the vicin- ity of Washington to the southward and west- ward along the Blue Ridge eventually to reach the Gulf of Mexico near Mobile. He also planned the important work of measuring the arc of the paral- lel of 39° to join the Atlantic and Pacific systems of triangulation ; and for determining geographi- cal positions in states where geological or geo- graphical surveys were in progress. Prof. Peirce took personal charge of the American expedition to Sicily to observe the eclipse of the sun in De- cember, 1870 ; and for the transit of Venus in 1874 he organized two parties from the coast survey — one to observe at Chatham island, in the South "Pacific ocean, and the other at a station in Japan. He re- signed from the superintendency in 1874, but after his retirement continued to hold the office of con- sulting geometer, exercising a general supervision over the scientific part of the work. Prof. Peirce also held the appointment of consulting astron- omer to the "American Ephemeris and Nauti- cal Almanac " from its establishment in 1849 till 1867, having direction of the theoretical depart- ment of that work, for which, in 1852, he prepared "Tables of the Moon" (Washington, 1853). Prof. Peirce's great fame was due to his mathematical ability, which was first brought to general notice by his announcement that Leverrier's discovery of the planet Neptune was a happy accident, not that Leverrier's calculations had not been exact and deserving of the highest honor, but because there were, in fact, two very different possible solutions of the perturbation of Uranus. Leverrier had cor- rectly calculated one, but the actual planet in the sky represented the other, and Leverrier's ideal one lay in the same direction from the earth only in 1846. This work verified Leverrier's labors suffi- ciently to establish their marvellous accuracy and minuteness as well as their herculean amount. His next investigation was in reference to Saturn's rings. Prof. Peirce demonstrated that the rings, if fluid, could not be sustained by the planet, that satellites could not sustain a solid ring, but that sufficiently large and numerous satellites could sustain a fluid ring, and that the actual satellites of Saturn are sufficient. His later mathematical work included a series of very laborious and exact calculation of the occultations of the Pleiades, fur- nishing an accurate means of studying the form of the earth and her satellite. His criterion for re- jecting doubtful observations is an ingenious and valuable extension of the law of probabilities to its own correction ; and his detection of the mental error of lurking personal preferences for individual digits is a curious specimen of that acuteness of observation that characterized his mind. The re- turn of Encke's comet in 1842, and the appearance of the great comet of February and March, 1843, afforded him an opportunity to attract public at- tention to the need of a well-furnished observatory for Harvard, and to his efforts the movement was due that resulted in the establishment of the present institution. In 1855 he was one of the scientific council that established the Dudley ob- servatory, and he took part in the struggle of 1859 between that body and the trustees of the institu- tion. In conjunction with Alexander D. Bache and Joseph Henry he published the defence of the director, Benjamin A. Gould {q. v.). Prof. Peirce received the degree of LL. D. from the University of North Carolina in 1847, and from Harvard in 1867. He was a member of the American acad- emy of arts and sciences and of the American philo- sophical society, and was elected an associate of the Royal astronomical society of London in 1847, and in 1852 an honorary fellow of the Royal society of London, besides membership in other foreign societies. In 1853 he presided over the Cleveland