The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 126
sses through the Method of Working. Ill visual indicator, along the signalling wire, through the section visual,to the middle spring. The top and outer springs and the lower andinner springs are connected together to the positive and negative poles ofthe ^ignalling battery respectively. When a peg… … f of ot^r circuit dis Figure 97. combination key, thus putting her speaking apparatus across the circuit.The section operator states the town required, and the transfer operator thenputs the peg in connection with the circuit into a B circuit in connectionwith the section upon which the required…
Telephone · Postal service
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