Twentieth century manual of railway and commercial telegraphy (1905)
Meyer, Frederic Louis, b. 1875 · Chicago, New York, Rand, McNally & Company · leaf 32
k instruments or kind (positive ornegative electromotive force) can be made instantly,with ease and Avithout causing interruptions. Examjjle : One row of discs across the board isconnected to a sixty-cell copper positive battery,which, in turn, runs to ground; another row of discsconnects with the… … Fig. 31. 50-Strap Spring-Jack Board, with a disc by the insertion of a pin-peg, it issupplied with the electromotive force of positive ornegative polarity designated on that line. In case of a through wire, which does notterminate at the office, it is sometimes necessary touse an intermediate…
Telegraph
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