Theory and practice of the electric telegraph; a manual for operators and students (1875)
Churchill, Charles Henry, d. 1904. [from old catalog] · Oberlin, Ohio, Sherman & bros. · leaf 71
Box Sounder, or Relay.9. Describe the pocket relay. In the pocket relay the lever is brought down so as to packIt is a main-line sounder and is used by line m a caserepairers. Fig. 36. rocket Relay,10. What is the switch: The switch, or commutator is a contrivance for quicklychanging the current… … Ground Switch.and C. The ground switch has a lever A at-tached to a wire leading to the earth.Two studs B and C connect with theline wire on either side of the instru-ments. By means of an ebonite buttonthe lever A may be used to connecteithei line with (he ground. 12. The button switch? In the…
Telegraph
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