WHEAT'STONE, Sir CHARLES (1802-75). An English physicist and inventor. He was born at Gloucester, and when twenty-one years of age entered into business in London as a maker of musical instruments. The prinei ples involved in their construction largely occu pied his attention, and in 1833 he conummieated his first paper, On Acoustic Figures, to the 'Royal Society, hieli was a discussion of the figures produced in Chladni's well-known experiment. This Was followed in 1831 by L.rperiments to Measure the Velocity of Electricity. in with a mirror revolving 800 times in a second, he demonstrated its velocity, ( See ClinoNo scoPE.) In the same year he was appointed professor of experimental physics in King's Col lege, London. In the course of experiments at the college on the velocity of electricity Ile de vised an telegraph for the transmission of messages. In May. 1837. a patent was taken omit in the joint names of Cooke and Wheat stone. "for improvements in giving signals and sounding alarms in distant places by means of elcetrie eurrents transmitted through metallic circuits." From this instrument, which had five needles, grew the system of electric telegraphs which was extensively used in Oreat Britain.
After the five-needle telegraph Caine apparatus where but two needles were employed, then the letter-showing dial telegraph, the type-printing telegraph, the magneto-elect ric dial telegraph, and the automatic telegraph system, in which great speed of transmission was obtained. In a paper on binocular vision before the Royal Society in 1838, he explained the principle of the stereoscope (q.v.), an instrument of his inven tion subsequently improved by Brewster. The
polar clock (q.v.), another invention of Wheat stone, was au interesting application of Brews ter's discovery that the plane of polarization of the light of the sky always made an angle of 90° with the sun. In 1840 he showed that by means of eleetro-magnetic regulating devices a num ber of clocks far apart could be kept going synchronously from a central clock. Wheat stone's bridge (q.v.), though not the invention of this famous electrician. but of Hunter Christy, was first brought into general use through his efforts in 1843, and has proved a fundamental method in the measurement of electrical resist ance. Wheatstone was one of the first to recog nize the importance of Ohm's law and to apply it in electrical measurements. lie also had a share in the development of the dynamo, de vising a method for making the magneto-ma chines then in use self-exciting by employing a shunt circuit passing around the field magnets. Wheatstone was far more successful as an ex perimenter and inventor than as a professor, and, though he held his chair for a number of years. he rarely lectured in public. owing to his great diffidence. In fact, many of his important discoveries were communicated to the So ciety by Faraday. This characteristic did not prevent his contributing many interesting papers to scientific journals and the Proceedings of various learned societies, and these were col lected and published in 1879 by the Physical Society of London under the title of Scientific Papers of Sir Charles Wheatstone.