. The Americana : a universal reference library, comprising the arts and sciences, literature, history, biograhy, geography, commerce, etc., of the world . opularlyknown as the magic lyre, but which he calledthe telephone. This is historically the first useof the word. Wheatstones device consisted ofa number of solid rods connecting musical in-struments with sounding boards. These sound-ing boards were placed at a distance from theinstruments themselves, and reproduced themusic successfully. This apparatus was ex-hibited before the Polytechnic Institute in Lon-don in 1831. During the next deca
. The Americana : a universal reference library, comprising the arts and sciences, literature, history, biograhy, geography, commerce, etc., of the world . opularlyknown as the magic lyre, but which he calledthe telephone. This is historically the first useof the word. Wheatstones device consisted ofa number of solid rods connecting musical in-struments with sounding boards. These sound-ing boards were placed at a distance from theinstruments themselves, and reproduced themusic successfully. This apparatus was ex-hibited before the Polytechnic Institute in Lon-don in 1831. During the next decade, thediscoveries of Faraday and Henry in electro-magnetism, and the inventions of IMorse in teleg-raphy, gave a new impetus to researches in elec-trical science. By 1837 C. G. Page of Salem,Mass., had observed the sounds which an elec-tro-magnet makes when the current which flowsthrough its coil is rapidly made and had also discovered that these sounds, whensufficiently rapid, produce a musical note. Hisdiscoveries were followed by the investigationsof MM. Wertheim, De la Rive, Beatson, Wart-man, Marrian, Matteucci, Guilleman and Fig. 4.— hn Original Reis Receiver. The magnet is composed of a bobbin inclosing a knitting needle, whoseends e.\tend beyond the bobbin, and are received in bridges on the resonant case. Tlie terminals of the bobbinare connected with the electrodes of the transmitter, a battery being placed in the circuit. Sounds utteredin the mouthpiece of the transmitter cause the membrane of the transmitter to vibrate, and so producechanges in the current at the contact of the electrodes. The fluctuations of the current affect the magnetof the receiver, so that sounds are produced in the receiver like those uttered in the transmitter. tries. The multiple switchboard of the West-ern Electric Company has been largely adoptedin the United States and England. The under-lying principle of a switchboard is to bringeach line wire to a perforated meta
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