DUFFIELD, John Thomas, clergyman, born in McConnellsburg, Pennsylvania, 19 February 1823. He is a descendant of George Duffield, an early settler of Pennsylvania. He was graduated at Princeton in 1841, and assumed charge of the mathematical department, Union academy, Philadelphia. He afterward studied in the Theological seminary at Princeton, was appointed tutor of Greek in Princeton College, and served as adjunct professor of mathematics from 1847 till 1850. He was licensed to preach in 1849, and in the following year was elected stated supply of the 2d Presbyterian Church of Princeton, and was ordained by the Presbytery of New Brunswick in 1851.

During the two years that he had charge of that Church, in connection with his duties in College, he published the" Princeton Pulpit," a volume containing a sermon by each of the Presbyterian clergymen then residing in Princeton. He was professor of mathematics in Princeton from 1850 till 1871, and also professor of mechanics from 1862 till 1871. He was chosen moderator of the New Jersey synod in 1865. The degree of L.L.D. was conferred upon him by Princeton in 1872. His publications include a sermon on the "Second Advent" (1866)" a "History of the Second Presbyterian Church of Princeton"" and review articles on "The Philosophy of Mathematics " (1866) and "Evolution as it Respects Man and the Bible " (1878).