SPERRY, ELMER AMBROSE (186o-193o), American inventor, was born at Cortland, N.Y., on Oct. 12, 186o. He began early to experiment with electric arc lights and in 1879 established a factory in Chicago to manufacture an improved model which was highly successful. He then turned his attention to the devel opment of electric mining machinery, invented the electric rotary and the chain undercutting machines, devised and built his own electric mining generator and other mining apparatus and estab lished another factory to manufacture this machinery. He next designed an electric locomotive for industrial work, and developed motor and transmission machinery for street cars, which resulted in the founding of the Sperry Electric Railway Co. of Cleveland. About 190o he established a research laboratory in electro-chem istry at Washington, D.C., where he invented the chlorine detin ning process and also the electrolytic process for producing white lead from impure by-product lead. In 1915 he announced his high-intensity arc searchlight, built upon an entirely new principle, allowing a brilliancy as high as 90o candle-power per square mille metre, whereas 16o was the highest obtainable previously. The electrical and mechanical means of operating, as well as the mechanism to control the high temperatures of the arc, represented a difficult engineering achievement. These searchlights have be come the standard for the principal armies and navies of the world and are in use for aircraft and coast beacons, the largest giving a white light of 1,500,000,000 candle-power which can be seen for upwards of 15o miles.
Sperry's most important inventions were based upon the appli cation of the gyroscope in which he was always greatly interested.
Chief of these is the gyro-compass (q.v.), first installed on the battleship Delaware in 191r. This compass, unaffected as it is by iron and steel, has entirely superseded the magnetic compass on submarines and battleships and is rapidly being placed on mer chant ships. Upon it the whole complicated system of modern naval gunnery has been developed. (See GUNNERY, NAVAL.) Sperry also designed and manufactured electrically sustained gyros for torpedoes which enabled them to complete long trajec tories with a high degree of accuracy. During the World War he also developed aerial torpedoes with automatic gyro-control which proved effective at a range of 35 miles. Quantity manu facture had begun when the war ended. Further experiments yielded the gyro-pilot for the steering of ships, the automatic gyro-pilot for stabilizing aeroplanes, the gyroscopic roll and pitch recorder for the testing of ships, and, finally, a gyroscopic ship stabilizer, which has been installed on a number of ships in the United States, British, Italian and Japanese navies and promises to find a wider application. The motion of a ship in the waves is almost completely neutralized by automatic counter movements of the gyroscopes. He served after 1915 as a member of the naval consulting board, and has published numerous scientific papers. He died at Brooklyn on June 16. 1930.
See "The Engineering and Scientific Achievements of Elmer A. Sperry," in Mechanical Engineering, vol. xlix. (1927).