THOMSON, ELIHU (1853-1937), American inventor, was born in Manchester, England, March 29, 1853, but removed to Philadelphia, Pa., with his parents in 1858. He received a public school education and in 1876-80 was professor of chemistry and mechanics at the Central High School in Philadelphia. In 188o he went to New Britain, Conn., as electrician for the American Electric Company and two years later he united with Edward J.
Houston to found the Thomson-Houston Electric Company in Lynn, Mass. In 1892 a merger took place between this company and the Edison General Electric Company to form the General Electric Company, the largest manufacturer of electrical equip ment in the world. Thomson remained as director of the large laboratory in Lynn, renamed after him the Thomson laboratory. Thomson made the first important research into the nature of the laws governing the electric arc, disclosing the fact that the resistance of the arc varies inversely with the current. He in vented and constructed an arc light dynamo with a spherical three-coil armature, and the first with an automatic regulator, which went into commercial use in 1880. He was the first to utilize a magnetic field to move an electric arc, a principle which found many uses, notably in the construction of the magnetic blow-out switches. In his notable discovery of the so-called
alternating current repulsion phenomena he laid the basis for successful alternating current motors. He made the first high frequency dynamo in 1890 and shortly afterwards the first high frequency transformer, and was a pioneer in the development of other high frequency apparatus. In 1886 he invented the art of electric welding by the incandescent method which was simpler and less expensive than previous methods and applicable to a wider range of metals. He also invented the electric watt-hour meter, while the arc lamp, incandescent lamp, alternator, alter nating current transformers, and railway motors found improve ment at his hands. He made many contributions to the field of radiology and was the first to make stereoscopic X-ray pictures. He published many articles in scientific journals, held over 700 patents, and received the Rumford, John Fritz, Kelvin and Fara day medals as well as other honours.