History, theory, and practice of the electric telegraph (1866)
Prescott, George B.(George Bartlett),1830-1894 · Boston, Ticknor and Fields · leaf 65
; —in a word, we 46 PRELIMINARY NOTIONS. can cause the wire to make a very great number of convolutions,and can so multiply by a considerable quantity the action of thecurrent upon the magnetized needle. A very feeble current,whose action would be scarcely visible if the wire by which it… … In constructing it we employ a copper wire covered with silk,which we coil round a wooden frame solidly fixed upon a stand,and which leaves between its lower and upper surface the MAGNETISM. 47 smallest possible space ; it is in the interior of this space that themagnetized needle is suspended :…
Telegraph
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