Mr. Bell desired his assistant,
who was at the other end of the line, to pluck the reed, thinking it had
stuck to the pole of the magnet. Mr. Watson complied, and to his
astonishment Bell observed that the corresponding reed at his end of the
line thereupon began to vibrate and emit the same note, although there
was no interrupted current to make it. A few experiments soon showed
that his reed had been set in vibration by the magneto-electric currents
induced in the line by the mere motion of the distant reed in the
neighbourhood of its magnet. This discovery led him to discard the
battery current altogether and rely upon the magneto-induction currents
of the reeds themselves. Moreover, it occurred to him that, since the
circuit was never broken, all the complex vibrations of speech might be
converted into sympathetic currents, which in turn would reproduce the
speech at a distance.
Reis had seen that an undulatory current was needed to transmit sounds
in perfection, especially vocal sounds; but his mode of producing the
undulations was defective from a mechanical and electrical point of
view. By forming 'waves' of magnetic disturbance near a coil of wire,
Professor Bell could generate corresponding waves of electricity in the
line so delicate and continuous that all the modulations of sound could
be reproduced at a distance.
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