American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 599
the central office, are shownin Fig. 368. The register case contains, on one side, the multiple pen apparatus,and, on the other side, apparatus used in connection with • answer back signals, orfor the automatic transmission of signals to indicate to an officer that he is desiredto use the… … POLICE SIGNAL TELEGRAPHS. 489 office nnd signal box, by means of which the various signals mentioned may be trans-mitted and received. CO is a central office, in which are placed a relay R, controlling,bv its armature, a reg- T FIG. -^66. ister g; an ordniaryduplex pole-changer PC,which, when…
Telegraph
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