American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 163
able. Post office wheatstoxe bridge.—One form of the Wheatstone bridge as con-veniently arranged for actual testing is outlined in Fig. 107. It is commonly knownas the Post Office pattern. The bridge is contained in a box represented in thefigure by the dotted lines, r and r represent the arms of… … Fig. 107 the 1,000 ohm coils in r, r, are shown as in use, making the ratio of thosearms equal, b is an adjustable rheostat, having resistance coils amounting in the ag-gregate to 11,110 ohms. K, k, are keys which, normally, keep the battery and gal-vanometer circuits open, but w^hen depressed…
Telegraph
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