Popular Scientific Recreations: in Natural Philosphy, Astronomy, Geology, Chemistry, etc., etc., etc.Tissandier, Gaston
Science
Popular Scientific Recreations: in Natural Philosphy, Astronomy, Geology, Chemistry, etc., etc., etc.
Tissandier, Gaston
Scientific recreations
The _Electric Telegraph_ has had considerable antiquity claimed for
it, but it is pretty certain that the discovery made by Doctor Watson,
in 1747, that electricity would pass through wires, and that the earth
would complete the circuit, gave the first impetus to the Electric
Telegraph. Doctor Watson was enabled to transmit shocks across the
Thames, and made experiments at Shooters Hill. Franklin did likewise
across the Schuykill in 1748, and De Luc performed the same experiments
on the Lake of Geneva. Both Lesage and Lomond caused pith balls to
diverge at distant points, and in 1794 Reizen made use of the electric
spark for transmitting signals, and made strips of foil show out
certain letters when the spark passed. He had a wire and a return wire
for each letter of the alphabet.
These were all slow advances, and subsequently many learned men in
Europe sought to improve upon the ideas then promulgated. We read
of telegraphs constructed at Madrid by Salvá and Betancourt in 1797
and 1798, one extending for more than twenty miles. The first-named
gentleman finally proposed to substitute the Voltaic pile for the usual
machine, and Ronalds and Dyar in England and New York respectively
employed frictional electricity with some success. The latter sent
charges of frictional electricity through a wire, and they were
recorded by being made to pass through litmus paper. The distances
between the discharges were intended to indicate the letters of the
alphabet, but even if the experiment was fairly tried it failed, for
little was heard of the result.
After the invention of Volta’s pile, which Salvá wished to adopt,
Sömmering began his experiments. He used thirty-five wires, set up
vertically at the bottom of a glass reservoir of water, and terminating
in gold points. These wires ended in the opposite direction in brass
plates attached to a bar of wood. At one end the points and at the
other the plates bore the same letters respectively; hydrogen at one
gold point, and oxygen at another, and two different letters were
indicated when the current was sent through any two plates. This
arrangement was afterwards improved upon, and only two wires retained.
It was not until electro-magnetism had been developed, however, that
Œrstead found out the power of electricity to deflect the magnetised
needle, and in 1820, Scheweigger added a “multiplier.” Then came
Arago into the field with his discovery, that a “wire carrying a
current could magnetise a steel rod.” Ampère substituted a helix for
a straight wire, and Sturgeon used soft iron for steel, and developed
the electro-magnet. Daniell’s battery, and Faraday’s discoveries of
magneto-electricity and the induction coil were the means of putting
a constant supply of electricity at the service of the telegraph and
so on, till 1830 brought out a more practical method introduced by
Schilling.
Public-domain text, read in full here on John Shaqi.
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