Merchant, F. W. (Francis Walter), 1855-1937, Chant, Clarence Augustus, 1865-1956 · Toronto : Copp Clark · leaf 437
5i6.-Magnetic field of currents in Opposite directions (Fig. 516). in opposite directions. 506. Practical Applications of the Magnetic Effects of theCurrent. No sooner were the principles of electromagnetismmade known by the researches of the early investigators thantheir practical applications… … THE ELECTRIC TELEGRAPH—TELEGRAPH KEY 427 Amp^-e, in 1821, suggested the possibility of transmittingsignals by electromagnetic action. Joseph Henry used anelectromagnet at Albany, in 1831, for pioducing audible signals.In 1837, Morse devised the system by which dots and dashes,representing letters…
Physics
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