It was this principle upon which Morse was working at this time. Davy
did not carry his suggestions into effect, however. He emigrated to
Australia, and the interruption in his experiments left the field open
for those who were finally to bring the telegraph into usable form.
Davy's greatest contribution to telegraphy was the relay system by
which very weak currents could call into play strong currents from
a local battery, and so make the signals apparent at the receiving
station.




IV


INVENTIONS OF SIR CHARLES WHEATSTONE

Wheatstone and His Enchanted Lyre--Wheatstone and Cooke--First
Electric Telegraph Line Installed--The Capture of the "Kwaker"--The
Automatic Transmitter.


Before we come to the story of Samuel F.B. Morse and the telegraph
which actually proved a commercial success as the first practical
carrier of intelligence which had been created for the service of man,
we should pause to consider the achievements of Charles Wheatstone.
Together with William Fothergill Cooke, another Englishman, he
developed a telegraph line that, while it did not attain commercial
success, was the first working telegraph placed at the service of the
public.