The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 322
Fig. 297 fitted for certain junctions lines between two exchanges situatedin opposite directions, which are merely brought into thisexchange for convenient testing and the localising of faults. Order Wires.—Test-jacks are also used with the outgoingorder wires, but these are in addition connected… … Fig. 298 arresters, as shown in Fig. 298, and have four jacks, whichenable them to be tested in various ways. The horizontal side, h s, of the intermediate frame has 15rows or shelves, each of 36 20-line sections, thus providing for,36x20 = 720 lines. The total capacity is 720x15 = 10,800lines. The…
Telephone
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