A Story of the Telegraph

by John Murray

Retancourt and Dr. Salva, in 1798, appear to have made experiments on the transmission of the charge through wires of great length.

A somewhat similar form of apparatus involving the same principle was constructed by arranging the several wires in succession with a single break in each. The various wires bore the names of the different letters or figures, and any required signal was indicated by passing the charge through the proper wire, when the spark visible at the interruption of the circuit would denote the letter to the observer at the farther end. This was the point to which invention had advanced at the commencement of the nineteenth century.

The discovery of Volta in 1800, of the Pile, which bears his name forms the commencement of a new era in electric telegraphs. Although there was no immediate application of the phenomena of the galvanic current to the purpose, indeed several important discoveries had to be made before an electric telegraph of any value was possible.

In 1807 Sommering, at Munich, proposed to construct an electric telegraph on the principle of the decomposition of water, by the Voltaic current discovered in 1800, by Nicholson and Carlisle. The form of apparatus was the following:

In a glass trough containing water, thirty-five gold pegs or pins were arranged vertically, this number of pegs corresponding to the letters of the alphabet together with the nine digits; each of those pins was connected by a wire which extended to the place whence the signal was to be transmitted; at this point they terminated in brass strips arranged in a frame side by side, but like the wires and pins insulated from each other, each brass strip bore the name of the letter or figure which belonged to the pin to which it was connected. The operator, when wishing to send any communication, connected the two poles of the battery with the brass strips bearing the names of the two first letters required—decomposition of the water in the trough at the distant end was instantly indicated by the evolution of bubbles of gas from the two gold pins which thus became the two electrodes or poles of the battery. The letters forming any communication were to be in this manner denoted in pairs, the inventor ingeniously availing himself of the different quantities of the two gases, evolved to point out the relative position of the letters in each pair, the hydrogen being employed to indicate the first letter.

Schweigger proposed to add to this system a plan for calling the attention of the correspondent at the distant station by the discharge by the current of a pistol charged with the mixed gases.

In 1816 Mr. Ronalds, of Hammersmith, invented an electric telegraph in which the use of frictional electricity was recurred to.

This telegraph, which was shown to several scientific men at the date above given, was fully described by the inventor by a work published by him in 1823.

Mr. Ronalds employed the divergence and collapse of a pair of pith balls as the telegraphic indication in which respect the principle was the same as that adopted by Mr. Lomond, but to this simple apparatus a distinct contrivance was appended in order to render the communication more rapid and easy.

A single wire, perfectly insulated by being suspended by silken strings, or buried in glass tubes, surrounded by pitch and protected by wooden troughs, was extended between the stations; from the end of this wire was suspended in front of the dial of a clock, a pair of pith balls so that whilst the wire was charged the balls would remain divergent, but would instantly collapse when the wire by contact with the earth, or with the hand of the operator was discharged.