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
Fjci.S9. … The Ting Switch. The Plug. The plug switch is a stout brass spring placed firmly againsta stationary pin whose pressure is regulated by a set-screw A.The binding screws at the top of the figure connect with themain-line. The wedge or plug consist of twopieces of brass insulatedfrom each other by…
Telegraph
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