. American telephone practice . used in making a connection, or by the B operator whereconnection was made through a trunk. In some of the exchangesbuilt by the Western Electric Company this necessary act of ringingon the part of the B operator is partially or entirely eliminated, andthe method by which this is accomplished is called automatic ring-ing. An automatic ringing device, as applied to an incoming trunkcord circuit, is shown in Fig. 288, from which figure all portions of TRUNKING SYSTEM BETWEEN COMMON BATTERY OFFICES. 365 the apparatus save that actually concerned in ringing the call
. American telephone practice . used in making a connection, or by the B operator whereconnection was made through a trunk. In some of the exchangesbuilt by the Western Electric Company this necessary act of ringingon the part of the B operator is partially or entirely eliminated, andthe method by which this is accomplished is called automatic ring-ing. An automatic ringing device, as applied to an incoming trunkcord circuit, is shown in Fig. 288, from which figure all portions of TRUNKING SYSTEM BETWEEN COMMON BATTERY OFFICES. 365 the apparatus save that actually concerned in ringing the called sub-scriber are omitted. In this the ringing key, K, is provided with a clutch magnet, m,which, when the key is depressed into its ringing position, after theplug has been inserted in a jack, holds the springs of the key in thisposition and allows ringing current to flow from one brush of thegenerator, G, through the interrupter, /, the winding of relay, R,over the ring side of the line, through the bell and condenser at the. j<m*t FIG. 288.—WESTERN ELECTRIC AUTOMATIC RINGING CIRCUIT. subscribers station and back on the tip side of the line to thegrounded generator brush. The interrupter is constantly is arranged so that the circuit of the generator will be closed tothe ringing key for one second out of every six, but the resistance ofthe bell and condenser in the subscribers instrument is great enoughto prevent the ringing current from operating relay, R, and thus re-storing the key. The interrupter is so arranged that during theother five seconds of each revolution the live or non-grounded sideof the battery is connected to the wire leading to the ringing key. 366 AMERICAN TELEPHONE PRACTICE. When, therefore, the ringing key is depressed the subscribers bellrings at intervals of six seconds for a period of one second, the bat-tery being thrown on the line during the five-second intervals. Bat-tery current, however, finds no path, on account of the presenc
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