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
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… … Fjci.S9.
Telegraph
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