Brown, Joseph Rogers   (b. Jan. 26, 1810, Warren, R.I., U.S.--d. July 23, 1876, Isles of Shoals, N.H.)

American inventor and manufacturer who made numerous advances in the field of fine measurement and machine-tool production. After training as a machinist, Brown joined his father in a successful clock-making business, which he operated himself from 1841 to 1853. He perfected and produced a highly accurate linear dividing engine in 1850, and in the succeeding two years he developed a vernier caliper reading to thousandths of an inch and also applied vernier methods to the protractor. In 1853 Brown took Lucian Sharpe into partnership; the firm later became the Brown and Sharpe Manufacturing Company. Brown's micrometer caliper, widely used in industry, appeared in 1867. He also invented a precision gear cutter in 1855 to produce clock gears, a universal milling machine in 1862, and, perhaps his finest innovation, a universal grinding machine (patented in 1877), in which articles were hardened first and then ground, thereby increasing accuracy and eliminating waste.