. American telephone practice . n up in talking or listening to the sub-scriber in order to ascertain his wishes, and that while she is doing- MAGNETO SWITCH-BOARD FOR SMALL EXCHANGES. 195 this she may restore the drops by hand without loss of time. Not-withstanding this, however, the number of exchanges using self-restoring drops is rapidly increasing, and many inventions haverecently been made and put into practice to bring about this result. Nearly all of the so-called independent manufacturing com-panies are supplying combined drops and jacks, the drop andjack being associated so as to for
. American telephone practice . n up in talking or listening to the sub-scriber in order to ascertain his wishes, and that while she is doing- MAGNETO SWITCH-BOARD FOR SMALL EXCHANGES. 195 this she may restore the drops by hand without loss of time. Not-withstanding this, however, the number of exchanges using self-restoring drops is rapidly increasing, and many inventions haverecently been made and put into practice to bring about this result. Nearly all of the so-called independent manufacturing com-panies are supplying combined drops and jacks, the drop andjack being associated so as to form a single piece of apparatus. Inthese the drop is so arranged as to be restored by some mechanicalmovement brought about by the insertion of a plug into the cor-responding jack. The Bell companies, where they use self-re-storing drops (which they seldom do in small boards), accom-plish the result electrically, a restoring coil being placed on the drop,to retract the shutter when energized by the insertion of a plug intoa FIG. ITS.—BELL SELF-RESTORING DROP. In Fig. 178 a side elevation and partial section is given of the elec-trically restoring drop of the Bell companies, this being the productof the Western Electric Company. In this, a, is a tubular electro-magnet, carrying on its rear end an armature, C, pivoted at c, whicharmature carries an arm, r\ which projects forward and is pro-vided with a catch, c4, on its extremity. So far the arrangement isalmost identical with that of the Warner tubular drop already de-scribed. A second tubular electromagnet, d, is secured to the frontof the mounting strip, b, which also supports the magnet, a. Thissecond magnet has its poles facing the front of the board. An arm-ature, e, is pivoted at its lower side. The catch, c4, on the rod, r\is adapted to engage a lug, e3, on the armature and retain it in itsvertical position. Pivoted on the bracket, /, which is insulated fromthe magnet, is a light shutter, g, of aluminum. The tenden
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