The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 92
nd drops the shutter. The shutter is re-stored by completing the circuit of a battery through the short coil bymeans of the speaking key when in the speaking position. It will beobvious that the indicator is not required to be down when speaking on thecircuit to which it is attached. The object of… … FlGDRE 66. not taken the lines of force would pass through the contiguous indicators,thus inducing currents which would reproduce the conversation uponthe first circuit. A very little consideration shews that two con-tiguous unclad indicators are equivalent to an induction coil. Besidespreventing…
Telephone · Postal service
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