The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 108
sed.The B section is of exactly the same size and shape as the A sectionpreviously described ; but a strip of five five-point switch-springs is addedto accomodate the additional junctions. In addition to this six pairs ofcords, together with the necessary ringing and speaking keys, are furnished.In… … Figure 8o. The junctions all terminate upon five-point switch springs, and noindicators whatever are fitted upon them. The local contacts are preciselyas described in the case of the A section. The arrangement of theapparatus upon the switch is shown in Figure 80, and requires no further 94…
Telephone · Postal service
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