This indeed was the condition of affairs at the time when the
young Italian transmitted messages from France to England in
March, 1899, and it is a method that since has been found useful
over limited distances. But to the inventor there seemed no reason
why wireless telegraphy should be limited by any such distances.
Accordingly he immediately developed his method and his apparatus,
having in mind the transmission of signals over considerable
intervals. The first question that arose was the effect of the
curvature of the Earth and whether the waves follow the surface of
the Earth or were propagated in straight lines, which would
require the erection of aerial towers and wires of considerable
height. Then there was the question of the amount of power
involved and whether generators or other devices could be used to
furnish waves of sufficient intensity to traverse considerable
distances.
Little by little progress was made and in January, 1901, wireless
communication was established between the Isle of Wight and Lizard
in Cornwall, a distance of 186 miles with towers less than 300
feet in height, so that it was demonstrated that the curvature of
the Earth did not seriously affect the transmission of the waves,
as towers at least a mile high would have been required in case
the waves were so cut off. This was a source of considerable
encouragement to Marconi, and his apparatus was further improved
so that the resonance of the circuit and the variation of the
capacity of the primary circuit of the oscillation transformer
made for increased efficiency. The coherer was still retained and
by the end of 1900 enough had been accomplished to warrant Marconi
in arranging for trans-Atlantic experiments between Poldhu,
Cornwall and the United States, stations being located on Cape Cod
and in Newfoundland. The trans-Atlantic transmission of signals
was quite a different matter from working over 100 miles or so in
Great Britain. The single aerial wire was supplanted by a set of
fifty almost vertical wires, supported at the top by a horizontal
wire stretched between two masts 157 1/2 feet high and 52 1/2 feet
apart, converging together at the lower end in the shape of a
large fan. The capacity of the condenser was increased and instead
of the battery a small generator was employed so that a spark 1
1/2 inches in length would be discharged between spheres 3 inches
in diameter. At the end of the year 1901 temporary stations at
Newfoundland were established and experiments were carried on with
aerial wires raised in the air by means of kites. It was here
realized that various refinements in the receiving apparatus were
necessary, and instead of the coherer a telephone was inserted in
the secondary circuit of the oscillation transformer, and with
this device on February 12th the first signals to be transmitted
across the Atlantic were heard. These early experiments were
seriously affected by the fact that the antennae or aerial wires
Public-domain text, read in full here on John Shaqi.
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