National Telegraphic Union · New York : N.T.U. · leaf 128
ng this subtle agent, and preventing itsescape from conducting bodies. Little by little thescanty stock of knowledge upon the subject was increasedby successive experimenters until the year 1816, whenRonalds constructed his Pith-ball Electric Telegraph.From this time forward the progress of the… … With the practical introduction of the Electric Tele-graph in America and England, which took place atnearly the same period (1844), came also the necessity ofsome effectual means of confining the electric fluid to thesuspended line wires, which formed the medium of com-munication between the…
Telegraph
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