History, theory, and practice of the electric telegraph (1866)
Prescott, George B.(George Bartlett),1830-1894 · Boston, Ticknor and Fields · leaf 118
s the polesof this magnet; it swings on its centre towards a horizontal posi-tion, indicating on the graduated arc the force of electro-magnet-ism. It will indicate a current too feeble to vibrate the armature,and its position with reference to the electro-magnetic poles canbe instantly changed, so… … Fig. 58 represents binding-screws, connectors, &c, for screwingto zincs of local or main batteries as pole connections. 100 ELECTRIC TELEGRAPH APPARATUS. CHAPTER VI. THE NEEDLE SYSTEM. The essential part of the needle telegraph is the multiplier, theneedle of which, fixed vertically upon a…
Telegraph
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