. American telephone practice . und, but not its timbre and relative loud-ness. For the next fifteen years no apparent advance was made in theart of telephony, although several inventors gave it their attention. In 1876 Professor Alexander Graham Bell and Professor ElishaGray almost simultaneously invented successful speaking has been one of the principal claimants for the honor of beingthe first inventor of the telephone, but Bell has apparently estab-lished his right to it, and has also reaped the profit, for, after longlitigation, the United States Patent Office and the cour
. American telephone practice . und, but not its timbre and relative loud-ness. For the next fifteen years no apparent advance was made in theart of telephony, although several inventors gave it their attention. In 1876 Professor Alexander Graham Bell and Professor ElishaGray almost simultaneously invented successful speaking has been one of the principal claimants for the honor of beingthe first inventor of the telephone, but Bell has apparently estab-lished his right to it, and has also reaped the profit, for, after longlitigation, the United States Patent Office and the courts haveawarded the priority to him as against Gray and many others. AMERICAN TELEPHONE PRACTICE. Bell possessed a greater knowledge of acoustics than of electricalscience, and it was probably this that led him to appreciate whereinothers had failed. His instrument consisted of a permanent bar-magnet, B (Fig. 9), having on one end a coil of fine wire. In frontof the pole carrying the coil a thin diaphragm, D, of soft iron was so. FIG. 11.—BELLS CENTENNIAL TRANSMITTER. Two of mounted as to allow its free vibration close to the pole,the instruments are shown connected in a circuit in Fig, 9. Two points will be noticed which have heretofore been absent:that no battery is used in the circuit, and that the transmitting and THE MAGNETO TELEPHONE. 9 receiving instruments are exactly alike. When the soft-iron dia-phragm of the transmitting instrument is spoken to, it vibrates inexact accordance with the sound waves striking against it. Themovement of the diaphragm causes changes in the magnetic fieldin which lies the coil, which changes, as already pointed out, causecurrents to flow in the circuit. These currents flow first in onedirection, and then in the other, varying in unison with the move-ments of the diaphragm, the waves being very complex, and repre-sented graphically, similar to those of the voice shown in Fig. along the line wire, these electrical impulses, so feeb
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