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1
281
Heroes of the Telegraph
·
John Munro
112
Siemens's
researches
on
this
subject,
as
published
in
the
JOURNAL
OF
THE
SOCIETY
OF
TELEGRAPH
ENGINEERS
(Vol.
I.,
p.
123,
and
Vol.
III.,
p.
297),
included
a
set
of
curves
graphically
representing
the
relation
between
temperature
and
electrical
resistance
in
the
case
of
various
metals.
The
electric
pyrometer,
which
is
perhaps
the
most
elegant
and
original
of
all
William
Siemens's
inventions,
is
also
the
link
which
connects
his
electrical
with
his
metallurgical
researches.
His
invention
ran
in
two
great
grooves,
one
based
upon
the
science
of
heat,
the
other
based
upon
the
science
of
electricity;
and
the
electric
thermometer
was,
as
it
were,
a
delicate
cross-coupling
which
connected
both.
Siemens
might
have
been
two
men,
if
we
are
to
judge
by
the
work
he
did;
and
either
half
of
the
twin-career
he
led
would
of
itself
suffice
to
make
an
eminent
reputation.
The
success
of
his
metallurgical
enterprise
no
doubt
reacted
on
his
telegraphic
business.
The
making
and
laying
of
the
Malta
to
Alexandria
cable
gave
rise
to
researches
on
the
resistance
and
electrification
of
insulating
materials
under
pressure,
which
formed
the
subject
of
a
paper
read
before
the
British
Association
in
1863.
The
effect
of
pressure
up
to
300
atmospheres
was
observed,
and
the
fact
elicited
that
the
inductive
capacity
of
gutta-percha
is
not
affected
by
increased
pressure,
whereas
that
of
india-rubber
is
diminished.
The
electrical
tests
employed
during
the
construction
of
the
Malta
and
Alexandria
cable,
and
the
insulation
and
protection
of
submarine
cables,
also
formed
the
subject
of
a
paper
which
was
read
before
the
Institution
of
Civil
Engineers
in
1862.
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