American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 221
part, it would then be easy to cause ar-mature A to operate a local circuit at each reversal of the current. The instruments and apparatus presently to be described, for so reversing thedirection of the current and for responding to such reversals, constitute the moreimportant instruments of the… … Operation of pole-changer.—In Figs. 151 and 152 apparatus is shown forreversing the direction of the current. In those figures pc is a pole-changing trans-mitter, commonly termed a pole-changer, designed to transpose the position ofthe poles of the battery as regards the circuit in which it is…
Telegraph
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