Discoveries and inventions of the nineteenth century (1905)
Routledge, Robert · London : G. Routledge and Sons · leaf 625
Fig. 293.— Telegraph Post and Lisidators. tbe wire is simply lifted, and is protected above by a porcelain bell. Thisform, or some modification of it, is that most generally used. … Fjg. 294. It need hardly be remarkea that only a single wire is required with mostof the modern instruments for communication between any two places.Each of the many wires often seen attached to the telegraph posts along a 574 THE ELECTRIC TELEGRAPH. road or railway represents a distinct line of…
Inventions
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