American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 257
214 AMERICAN TELEGRAPHY. Smith condenser; cc are the boxes containing the 600 ohm coils; SP is the 3-point switch for putting line to ground at the desk; sc is the spark-coil withresistance equal to internal resistance of long end of the battery; se is the short end,le the long end of the main… … WESTERN UNION NEUTRAL RELAY. within its covers, are contained several separate series of resistance coils; rr and c^represent the retarding coils placed before the static compensating condensers c^ c^;
Telegraph
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