Miller, Kempster Blanchard, 1870-1933 · New York : McGraw publishing company · leaf 395
, ringing keys, etc. In Fig. 293 two subscribers lines terminating at different officesare shown through a trunk circuit extending between these offices. Remembering that the relay, 5, is energized when the answeringplug of the A operators cord is inserted in the jack of the callingsubscribers… … \>-vm-^
Telephone
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