In 1857, he investigated the electro-static induction and retardation of
currents in insulated wires, a phenomenon which he had observed in 1850,
and communicated an account of it to the French Academy of Sciences.
'In these researches he developed mathematically Faraday's theory of
molecular induction, and thereby paved the way in great measure for its
general acceptance.' His ozone apparatus, his telegraph instrument
working with alternate currents, and his instrument for translating on
and automatically discharging submarine cables also belong to the year
1857. The latter instruments were applied to the Sardinia, Malta, and
Corfu cable.
In 1859, he constructed an electric log; he discovered that a dielectric
is heated by induction; he introduced the well known Siemens' mercury
unit, and many improvements in the manufacture of resistance coils. He
also investigated the law of change of resistance in wires by heating;
and published several formulae and methods for testing resistances and
determining 'faults' by measuring resistances. These methods were
adopted by the electricians of the Government service in Prussia, and by
Messrs. Siemens Brothers in London, during the manufacture of the Malta
to Alexandria cable, which, was, we believe, the first long cable
subjected to a system of continuous tests.
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