Modern practice of the electric telegraph. A handbook for electricians and operators (1872)
Pope, Frank L. (Franklin Leonard), 1840-1895 · New York : D. Van Nostrand · leaf 51
FIG. 19. are continuous with the screws, D D, passing through thetable and terminating in binding screws, to which thewires are attached. The spring F, pressing againstthe lever, insures a firm contact with the studs. Thiscircuit closer is sometimes, for special purposes, madewith four connections… … 63. Fig. 20 represents a Ground Switch (58). The lever THE MORSE, OR AMERICAN TELEGRAPHIC SYSTEM. 30 A is attached to a wire leading to the earth, and the twostuds, B, C, are connected to the line wire on each sideof the instruments.
Telegraph
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