. American telephone practice . d circuits of the WTesternElectric Company. The small hook-shaped spring on the inside ofthe group of listening springs is that used for completing the cir- MULTIPLE SWITCH-BOARD APPARATUS. 527 cuit of the restoring coil of the clearing-out drop when the listeningkey is thrown. The upper cut in Fig. 375 shows a top view of the key with itsupper hard rubber finishing strip removed. This discloses a topview of a lever, a, carrying a white and red target, b. This target isdisplayed to the view of the operator through a hole in the rubberfinishing strip. The lever,
. American telephone practice . d circuits of the WTesternElectric Company. The small hook-shaped spring on the inside ofthe group of listening springs is that used for completing the cir- MULTIPLE SWITCH-BOARD APPARATUS. 527 cuit of the restoring coil of the clearing-out drop when the listeningkey is thrown. The upper cut in Fig. 375 shows a top view of the key with itsupper hard rubber finishing strip removed. This discloses a topview of a lever, a, carrying a white and red target, b. This target isdisplayed to the view of the operator through a hole in the rubberfinishing strip. The lever, a, is so arranged as to be moved by theslotted link rods, c and d, pivoted respectively to the key levers, Land JJ. By virtue of the pin and slot connection between theselinks and the lever, a, the target will be moved into the positionshown (and will therefore appear white) when the lever L is throwninto its ringing position. It will not be moved by subsequentoperation of this lever, but if lever L is thrown the target will be.
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