History, theory, and practice of the electric telegraph (1866)
Prescott, George B.(George Bartlett),1830-1894 · Boston, Ticknor and Fields · leaf 196
Pig. 73. the elements of a cylinder and tangent in respect to their gutta-percha envelope. The placing one of them in the centre isavoided, except in the case where there is but one, when thesingle wire is necessarily in the centre. The outer circumference,as well as the wires themselves, are…
Telegraph
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![An illustration from [Electric engineering.] (1902)](https://img.insideoutlibrary.com/img/200/ia-electricengineer03inte-134-73.webp)
