History, theory, and practice of the electric telegraph (1866)
Prescott, George B.(George Bartlett),1830-1894 · Boston, Ticknor and Fields · leaf 95
sheet of paper a steel point(Fig. 35) with which it is furnished. This lever is depressed bymeans of the electro-magnet, which attracts the armature fixed tothe levers; every time that the current passes in the wire ofthe electro-magnet, the armature draws the lever to which it isfixed, and thus… … Fig. 35. a helical spring attached to the under side of the lever compelsit, by its elasticity, to separate itself from the electro-magnet,when the current ceases to act, \vhich*causes the point no longerto press. The other part of the apparatus is intended to cause a
Telegraph
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