Modern practice of the electric telegraph : a handbook for electricians and operators (1874)
Pope, Frank L., 1840-1895 · New York : D. Van Nostrand · leaf 44
pon a base. The coils are usu-ally wound with No. 23 wire. Main Line Sounders are used in some offices, whichenables the operator to dispense with the local battery.The coils are wound with fine wire, usually No. 30, andare frequently made somewhat larger than those of therelay. A common form of… … Fig. 15. Fig. 15 (8. F. Day & Co.) shows an excellent form ofMain Line Sounder. The parts of the instrument aremounted upon a metallic plate, the centre of which israised slightly above the base, so as to form a bridge, asshown in the cut. The armature lever is of steel, andthe whole…
Telegraph
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