eans of electric sparks, and its application in 1875 for
measuring the speed of the electric current in overland lines.

In January 1850, a paper on telegraph lines and apparatus, in which
the theory of the electro-static charge in insulated wires, as well as
methods and formula: for the localising of faults in underground wires
were first established. In 1851, the firm erected the first automatic
fire telegraphs in Berlin, and in the same year, Werner Siemens wrote
a treatise on the experience gained with the underground lines of the
Prussian telegraph system. The difficulty of communicating through long
underground lines led him to the invention of automatic translation,
which was afterwards improved upon by Steinheil, and, in 1852, he
furnished the Warsaw-Petersburg line with automatic fast-speed writers.
The messages were punched in a paper band by means of the well-known
Siemens' lever punching apparatus, and then automatically transmitted in
a clockwork instrument.

In 1854 the discovery (contemporaneous with that of Frischen) of
simultaneous transmission of messages in opposite directions, and
multiplex transmission of messages by means of electro-magnetic
apparatus. The 'duplex' system which is now employed both on land lines
and submarine cables had been suggested however, before this by Dr.
Zetsche, Gintl, and others.

In 1856 he invented the Siemens' magneto-electric dial instrument
giving alternate currents. From this apparatus originated the well-known
Siemens' armature, and from the receiver was developed the Siemens'
polarised relay, with which the working of submarine and other lines
could be effected with alternate currents; and in the same year, during
the laying of the Cagliari to Bona cable, he constructed and first
applied the dynamometer, which has become of such importance in the
operations of cable laying.

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