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Heroes of the Telegraph
·
John Munro
19
In
1835,
at
the
Dublin
meeting
of
the
British
Association,
Wheatstone
showed
that
when
metals
were
volatilised
in
the
electric
spark,
their
light,
examined
through
a
prism,
revealed
certain
rays
which
were
characteristic
of
them.
Thus
the
kind
of
metals
which
formed
the
sparking
points
could
be
determined
by
analysing
the
light
of
the
spark.
This
suggestion
has
been
of
great
service
in
spectrum
analysis,
and
as
applied
by
Bunsen,
Kirchoff,
and
others,
has
led
to
the
discovery
of
several
new
elements,
such
as
rubidium
and
thallium,
as
well
as
increasing
our
knowledge
of
the
heavenly
bodies.
Two
years
later,
he
called
attention
to
the
value
of
thermo-electricity
as
a
mode
of
generating
a
current
by
means
of
heat,
and
since
then
a
variety
of
thermo-piles
have
been
invented,
some
of
which
have
proved
of
considerable
advantage.
Wheatstone
abandoned
his
idea
of
transmitting
intelligence
by
the
mechanical
vibration
of
rods,
and
took
up
the
electric
telegraph.
In
1835
he
lectured
on
the
system
of
Baron
Schilling,
and
declared
that
the
means
were
already
known
by
which
an
electric
telegraph
could
be
made
of
great
service
to
the
world.
He
made
experiments
with
a
plan
of
his
own,
and
not
only
proposed
to
lay
an
experimental
line
across
the
Thames,
but
to
establish
it
on
the
London
and
Birmingham
Railway.
Before
these
plans
were
carried
out,
however,
he
received
a
visit
from
Mr.
Fothergill
Cooke
at
his
house
in
Conduit
Street
on
February
27,
1837,
which
had
an
important
influence
on
his
future.
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