. Electrical world. Fig. 14.—Circuit Map, United States Telephone Company. ELECTRICAL WORLD and ENGINEER. XLIII, No. 14. which delivers to the line a comparatively high-frequency current,which operates a specially-designed relay, which in turn operatesthe line drop, thus signalling the operator at the distant FIG. 15.—MAP OF TOLL LINES IN , IXDI.^NA AND OHIO. The disadvantage of the high-frequency currents is that they tendto produce noise on the lines. When lines are coinposited. the tele-phone connections are usually ordered up by telegraph or order

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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectri, bookyear1883