ed, in 1824 the chemical telegraph would have
come into practical use.

In 1806, Ralph Wedgwood submitted a telegraph based on frictional
electricity to the Admiralty, but was told that the semaphore was
sufficient for the country. In a pamphlet he suggested the establishment
of a telegraph system with public offices in different centres. Francis
Ronalds, in 1816, brought a similar telegraph of his invention to the
notice of the Admiralty, and was politely informed that 'telegraphs of
any kind are now wholly unnecessary.'

In 1826-7, Harrison Gray Dyar, of New York, devised a telegraph in
which the spark was made to stain the signals on moist litmus paper by
decomposing nitric acid; but he had to abandon his experiments in Long
Island and fly the country, because of a writ which charged him with
a conspiracy for carrying on secret communication. In 1830 Hubert
Recy published an account of a system of Teletatodydaxie, by which the
electric spark was to ignite alcohol and indicate the signals of a code.

But spark or frictional electric telegraphs were destined to give way
to those actuated by the voltaic current, as the chemical mode of
signalling was superseded by the electro-magnet. In 1820 the separate
courses of electric and magnetic science were united by the connecting
discovery of Oersted, who found that a wire conveying a current had the
power of moving a compass-needle to one side or the other according to
the direction of the current.

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