THURSTON, Robert Lawton, mechanical engineer, born in Portsmouth, Rhode Island, 13 December, 1800; died in Providence, Rhode Island, .13 January, 1S74. He early developed talent as a mechanic, and on attaining his majority began to learn the trade of a machinist. His skill attracted the attention of John Babcock, who invited his assistance in the manufacture of an experimental steam-engine which was placed in a small ferry-boat for use near Fall River. Its success led to the construction of engines for the " Rushlight" and the "Babcock," which ran between Providence and New York. He then entered the iron business in Fall River, but in 1830 returned to Providence, where, with the son of John Babcock, he founded in 1834 the first steam-engine building establishment in New England, known as the Providence steam-engine company. They purchased the Sickles patent for the "drop cut-off" for steam-engines, and were the first either in America or in Europe to manufacture a standard form of expansion steam-engine. For a series of years they were engaged in litigation with George H. Corliss, against whom they brought suit for infringement of the Sickles patent. This case, which was one of the most noted patent suits that was ever tried, called for the services of several of the most eminent lawyers and mechanical experts of the time. The Greene engine, which they introduced, is now claimed by many engineers to be one of the best of modern steam-engines. In 1863 the unsettled condition of affairs resulting from the civil war, with incidental lack of business, led to Mr. Thurston's withdrawal.--His son, Robert Henry, mechanical engineer, born in Providence, Rhode Island, 25 October, 1889, received his early training in the workshops of his father and was graduated in the scientific course at Brown in 1859. After two years' experience with his father's company, he entered the United States navy as third assistant engineer, and served on various vessels during the civil war. He was present at the battle of Port Royal and at the siege of Charleston, and was attached to the North and South Atlantic squadrons until 1865, when he was detailed as assistant professor of natural and experimental philosophy at the United States naval academy in Annapolis, where he also lectured on chemistry. In 1870 he visited Europe for the purpose of studying the British iron manufacturing districts, and on 1 April, 1872, he resigned from the navy, after attaining the rank of 1st assistant engineer. Meanwhile, in 1871, he had been called to the chair of mechanical engineering at the Stevens institute of technology, where he remained until 1885, when he was appointed director of the Sibley college of Cornell university with the professorship of mechanical engineering. In 1871, on behalf of a committee of the American institute, he made a series of experiments on steam-boilers, in which for the first time all losses of heat were noted, and, by condensing all the steam that was generated, the quantity of water "entrained" by the steam was measured. Professor Thurston was appointed a member of the United States commission to the World's fair in Vienna in 1878, and, besides serving on the international jury, edited the " Reports of the United States Commissioners to the International Exhibition, Vienna, 1873" (4 vols., Washington, 1875-'6), which includes his own special "Report on Machinery and Manufactures." He was a member of the United States commission on the causes of boiler-explosions, and of the United States board to test iron, steel, and other metals. His extensive knowledge of matters connected with mechanical engineering has led to his being called upon frequently to testify in court on disputed points as an expert. The degree of doctor of engineering was conferred on him by Stevens institute of technology in 1885, and he is a regular, honorary, or corresponding member of various scientific and technical societies at home and abroad. He was vice-president of the American association for the advancement of science in 1877-'8 and 1884, vice-president of the American institute of mining engineers in 1878-'9, and president of the American society of mechanical engineers in 1880-'3. Professor Thurston has invented a magnesium burning-lamp, an autographic-recording testing-machine, a new form of steam-engine governor, an apparatus for determining the value of lubricants, and various other devices. He is the author of about 250 papers, including contributions to "The Popular Science Monthly," "Journal of the Franklin Institute," "Van Nostrand's Magazine," "Science," "The Forum," and like periodicals, and addresses before scientific and other societies. His books are " History of the Growth of the Steam-Engine" (New York, 1878);" Friction and Lubrication" (1879); "Materials of Engineering" (3 vols., 1884-'6) ; "Friction and Lost Work in Machinery and Mill Work" (1884); "Text-Book of the Materials of Construction" (1885) ; "Stationary Steam-Engines for Electric Lighting Purposes" (1884);" Steam-Boiler Explosions in Theory and in Practice" (1887); and "A Manual of Steam Boilers: their Design, Construction, and Management" (1888).