PECK, William Guy, mathematician, born in Litchfield, Connecticut, 16 October, 1820. He was graduated at the United States military academy in 1844 at the head of his class, was assigned to the topographical engineers, served in the third expedition of John C. Fremont in 1845, and was with the Army of the West under General Stephen W. Kearny during the Mexican war. He was assistant professor of natural philosophy at West Point in 1846, and of mathematics from 1847 till 1855, when he resigned from the army. After declining a chair in Kenyon college, Ohio, he was professor of physics and civil engineering in the University of Michigan till 1857. In that year he became adjunct professor of mathematics in Columbia, and since 1861 he has held the chair of mathematics, mechanics, and astronomy there, also teaching in the School of mines. He received the degree of Ph.D. from Columbia in 1877 and that of LL.D. from Trinity in 1863. In 1868 he was a member of the board of visitors to the United States military academy. He assisted his father-in-law, Professor Charles Davies, in compiling his "Dictionary and Cyclopaedia of Mathematical Science" (New York, 1855), and is the author of a full set of school and college text-books on mathematics, including a "Calculus" and an "Analytical Geometry" ; an edition of Ganot's "Natural Philosophy" (New York, 1860 ; last revised ed., 1881) ; "Elementary Mechanics" (1859) ; and "Popular Astronomy" (1883).