The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 118
s is tosome extent a disadvantage, as the ring served the subscriberas an indication that the circuit was complete. Many other forms of automatic cut-out are in use, butthe above are probably the most important types. The Polarised Ringer.—As the currents which work thisbell (sometimes called the… … Fig. 85.—Scale £ ?<5 PRACTICAL TELEPHONE HANDBOOK each second, thus producing forty separate currents pelsecond), it follows that the bell must be very sensitive torespond to each of these pulsations. The speed of turningthe handle of the generator also varies greatly with differentpersons, so…
Telephone
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