La Place, the illustrious mathematician, at once saw that this fact
could be utilised as a telegraph, and Ampere, acting on his suggestion,
published a feasible plan. Before the year was out, Schweigger, of
Halle, multiplied the influence of the current on the needle by coiling
the wire about it. Ten years later, Ritchie improved on Ampere's method,
and exhibited a model at the Royal Institution, London. About the same
time, Baron Pawel Schilling, a Russian nobleman, still further modified
it, and the Emperor Nicholas decreed the erection of a line from
Cronstadt to St. Petersburg, with a cable in the Gulf of Finland but
Schilling died in 1837, and the project was never realised.
In 1833-5 Professors Gauss and Weber constructed a telegraph between the
physical cabinet and the Observatory of the University of Gottingen.
At first they used the voltaic pile, but abandoned it in favour of
Faraday's recent discovery that electricity could be generated in a wire
by the motion of a magnet. The magnetic key with which the message was
sent Produced by its action an electric current which, after traversing
the line, passed through a coil and deflected a suspended magnet to
the right or left, according to the direction of the current. A mirror
attached to the suspension magnified the movement of the needle,
and indicated the signals after the manner of the Thomson mirror
galvanometer. This telegraph, which was large and clumsy, was
nevertheless used not only for scientific, but for general
correspondence. Steinheil, of Munich, simplified it, and added an alarm
in the form of a bell.
In 1836, Steinheil also devised a recording telegraph, in which the
movable needles indicated the message by marking dots and dashes
with printer's ink on a ribbon of travelling paper, according to an
artificial code in which the fewest signs were given to the commonest
letters in the German language. With this apparatus the message was
registered at the rate of six words a minute. The early experimenters,
as we have seen, especially Salva, had utilised the ground as the return
part of the circuit; and Salva had proposed to use it on his telegraph,
but Steinheil was the first to demonstrate its practical value. In
trying, on the suggestion of Gauss, to employ the rails of the Nurenberg
to Furth railway as the conducting line for a telegraph in the year
1838, he found they would not serve; but the failure led him to employ
the earth as the return half of the circuit.
Public-domain text, read in full here on John Shaqi.
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