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 56
o the ground wire.Other plates of brass rest upon this, being separatedfrom it by a thin sheet of insulating material. Theselast mentioned plates are provided with binding screws,for the attachment of the line wires. Any surpluscharge of atmospheric electricity, entering by the linewires, forces… … The plates in connection with the line wires arefirmly held in their places by a wooden cross piece,secured by screws at each end, as shown in the cut. Athin sheet of gutta percha, or paper, is used to separatethe plates. When paper is used it should be saturatedwith paraffine. Mica is, perhaps,…
Telegraph
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