The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 123
ONE HANDBOOK contact by a kind of rolling motion from metal to insulator,and vice versd. As the lever is long, and the contacts closeto the pivot, the leverage is great, the springs can bemade strong, and the contacts firm. There is also a smallamount of rubbing, which improves the contacts. In… … Fig. 94 America are made up in the style of that shown in Fig. 94.As the lever of this moves up or down it carries with itthe centre one of five springs, insulated from each other, andall clamped together by two insulated screws. When thelever is down the centre spring presses together the twolower…
Telephone
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