PLYMPTON, George Washington, civil engineer, born in Waltham, Massachusetts, 18 November, 1827. He learned the machinist's trade, and then was graduated with the degree of C. E. at Rensselaer polytechnic institute in 1847. For a time he remained at the institute as instructor in mathematics, but in 1850 he turned his attention to professional work in New York state, and later in Cleveland, Ohio, and in 1852 he held the chair of engineering and architecture in Cleveland university. In 1853-'5 he taught mathematics in the State normal school in Albany, New York, and in 1857-'9 he had charge of physics and engineering in the Normal school in Trenton, New Jersey He was called in 1863 to the chair of physical science in the Brooklyn polytechnic institute, and in 1869 was appointed to that of physics and engineering at Cooper Union, New York city, from which he was advanced in 1879 to the post of director of the Cooper Union night-school. In 1844-'5 he was professor of chemistry and toxicology in the Long Island college hospital, and in 1867-'8 he was chief engineer of the water board of Bergen, New Jersey, haying charge of the drainage of that place. Professor Plympton was appointed commissioner of electrical subways of Brooklyn, and has been very prompt in placing the wires underground. He received the honorary degree of A. M. in 1854 from Hamilton college, and in 1877 that of M. D. from the Long Island college hospital. He is a member of the American society of civil engineers, and of other scientific associations. From 1870 till 1886 he edited" Van Nostrand's Engineering Magazine," and he has published "The Blowpipe, a Guide to its Use in the Determination of Salts and Minerals" (Cincinnati, 1858); " The Star Finder, or Planisphere with a Movable Horizon" (New York, 1878) ; " The Aneroid, and how to use it" (1880); and a translation of Jannettaz's " Guide to the Determination of Rocks" (1877).