. The Americana : a universal reference library, comprising the arts and sciences, literature, history, biograhy, geography, commerce, etc., of the world . t from the point of higher to the point oflower water pressure. Analogously if a bat-tery be placed in the circuit at the far end ofwire I it will cause the potential or pressureat the terminus of the bridge wire to varyand current will flow from higher to lowerpressure in the bridge wire. There are two systems of duplex teleg-raphy in use in this country and elsewhere,namely, the Stearns duplex and thePolar duplex, and these combined compr
. The Americana : a universal reference library, comprising the arts and sciences, literature, history, biograhy, geography, commerce, etc., of the world . t from the point of higher to the point oflower water pressure. Analogously if a bat-tery be placed in the circuit at the far end ofwire I it will cause the potential or pressureat the terminus of the bridge wire to varyand current will flow from higher to lowerpressure in the bridge wire. There are two systems of duplex teleg-raphy in use in this country and elsewhere,namely, the Stearns duplex and thePolar duplex, and these combined comprisethe Edison Quadruplex, described later. The Stearns Duplex.— The Stearns duplexis operated by increment and decrement ofcurrent on the line, virtually as the singleMorse system is operated, namely, by send-ing a current over the line to actuate thedistant relay, which attracts its armature;and by removing the current from the line,whereupon the armature is withdrawn by itsretractile spring. The near or home batteryis prevented from affecting the near relay bywinding the relays differentially. The theoryof the Stearns duplex is shown in Fig. 14,. Theory of Stearns Duplex. which represents the apparatus at two sta-tions A and B. The relays m, m, are woundwith two coils, in opposite directions aroundtlie cores; one of the coils of each relay beingconnected to the main line and the other to arheostat, or resistance coils, r, r. k and kare transmitting keys. When key K is closedit puts a positive electromotive force to theline; when key k is closed it puts a negativeelectromotive force to the line. When thekeys are open the line wire is placed toground. Since the battery current will di- vide between the two coils of the relay inproportion to the resistance of the circuitsattached to each coil, a means must be pro-vided to make those circuits of equal resist-ance, otherwise unequal currents will flowthrough the coils, and the relays will beoperated by the home battery. This wou
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Keywords: ., bookcentury1900, bookdecade1900, bookidamericanauni, bookyear1903
