. American telephone practice . lls for the four differ-ent stations are shown in the left-hand portion of Fig. 334. It isquite evident that a small ball so mounted will vibrate more rapidlythan a large one, and the balls have therefore been proportionedso that in operation they will respond respectively to alternationstaking place, 2000, 4000, 6000 and 8000 times a minute respectively. Mr. Dean found that the placing of the bell or gong in such aposition as to be struck by the ball changed the natural rate ofvibration of the ball. For this reason he tuned the device so thatthe proper rate was
. American telephone practice . lls for the four differ-ent stations are shown in the left-hand portion of Fig. 334. It isquite evident that a small ball so mounted will vibrate more rapidlythan a large one, and the balls have therefore been proportionedso that in operation they will respond respectively to alternationstaking place, 2000, 4000, 6000 and 8000 times a minute respectively. Mr. Dean found that the placing of the bell or gong in such aposition as to be struck by the ball changed the natural rate ofvibration of the ball. For this reason he tuned the device so thatthe proper rate was secured when the bell or gong was in place,rather than tuning with respect to the vibration of the reed alone,as had been the case in most former efforts in this direction. He also found that a polarized device was absolutely necessaryin order to secure the proper promptness in response, and that aflexibility of connection between the armature and the ball wasalso necessary in order that the contact of the ball might not damp-. 155 456 AMERICAN TELEPHONE PRACTICE. en and destroy the vibration of the armature. He used one gonginstead of two because he found it impossible, when using twogongs, to make the ball strike more than one of them with anydegree of certainty. The machine for supplying the currents of the various frequen-cies in ringing in this system is shown in Fig. 335. In this fourgenerators are directly coupled on the same shaft, all with a single
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