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281
Heroes of the Telegraph
·
John Munro
11
In
1837,
Professor
Stratingh,
of
Groninque,
Holland,
devised
a
telegraph
in
which
the
signals
were
made
by
electro-magnets
actuating
the
hammers
of
two
gongs
or
bells
of
different
tone;
and
M.
Amyot
invented
an
automatic
sending
key
in
the
nature
of
a
musical
box.
From
1837-8,
Edward
Davy,
a
Devonshire
surgeon,
exhibited
a
needle
telegraph
in
London,
and
proposed
one
based
on
the
discovery
of
Arago,
that
a
piece
of
soft
iron
is
temporarily
magnetised
by
the
passage
of
an
electric
current
through
a
coil
surrounding
it.
This
principle
was
further
applied
by
Morse
in
his
electro-magnetic
printing
telegraph.
Davy
was
a
prolific
inventor,
and
also
sketched
out
a
telegraph
in
which
the
gases
evolved
from
water
which
was
decomposed
by
the
current
actuated
a
recording
pen.
But
his
most
valuable
discovery
was
the
'relay,'
that
is
to
say,
an
auxiliary
device
by
which
a
current
too
feeble
to
indicate
the
signals
could
call
into
play
a
local
battery
strong
enough
to
make
them.
Davy
was
in
a
fair
way
of
becoming
one
of
the
fathers
of
the
working
telegraph,
when
his
private
affairs
obliged
him
to
emigrate
to
Australia,
and
leave
the
course
open
to
Cooke
and
Wheatstone.
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