STRONG, Theodore, mathematician, born in South Hadley, Massachusetts, 26 July, 1790; died in New Brunswick, New Jersey, 1 February, 1869. He was graduated at Yale in 1812, and became a tutor in mathematics at Hamilton. He held the professorship of mathematics and natural philosophy from 1816 until 1827, and then accepted a call to Queen's college (now Rutgers), where he filled a similar chair He continued an active member of the faculty until 1861, when he was made professor emeritus, but in 1863 he severed his connection with the college, of which he had served also as vice-president from 1839. His original work was entirely in the line of pure mathematics, and in his knowledge of this subject it may be doubted whether he had a superior. He succeeded in solving by a direct method the irreducible case of cubic equations left by Cardan, which had baffled the best mathematicians of Europe, and he also discovered a method of extracting by a direct process, for the first time, any root of any integral number. The honorary degree of A. M. was conferred on him by Hamilton in 1815, and that of LL. D. by Rutgers in 1835. He was a member of the chief scientific societies of the United States, and was named by congress in 1863 as one of the corporate members of the National academy of sciences. His papers, about 60 in number, are devoted almost exclusively to mathematics, and appeared principally in the "American Journal of Science," and in the " Mathematical Miscellany." Among the memoirs that he read before the National academy of sciences are " Notes on the Parallelogram of Forces and on Virtual Velocities" (1864) ; " On the Integration of Differential Equations of the First Order and Higher Degrees" (1864) ;" A New Theory of the First Principles of the Differential Calculus" (1865); " A New Theory of Planetary Motion " (1866); and " On a Process of Integration used in the Case of a Planet's Orbit disturbed by Small Forces " (1867). He also published "A Treatise on Elementary and Higher Algebra" (New York, 1859), and "A Treatise on the Differential and Integral Calculus" (1869). See a sketch of his life by Joseph P. Bradley in "Biographical Memoirs of the National Academy of Sciences" (Washington, 1886).