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378
The Story of the Atlantic Telegraph
·
Henry M. Field
231
This
was
higher
by
forty
degrees
than
the
temperature
of
the
Atlantic.
The
insulation
is
improved
by
cold;
so
that,
if
it
remained
perfect
in
this
warm
water,
it
could
not
fail
in
the
icy
depths
of
the
ocean.
After
passing
through
such
elaborate
tests,
all
will
be
glad
to
see
the
final
product
of
so
much
care
and
skill.
As
the
long
line
begins
to
reel
off
from
the
great
wheels
and
drums,
we
may
examine
it
in
its
completed
and
more
perfect
form.
It
is
only
necessary
to
compare
it
with
the
cable
laid
in
1858,
to
show
its
immense
superiority.
A
glance
at
the
two
as
they
appear
on
the
preceding
page
will
show
that
the
cable
had
grown
since
first
it
was
planted
in
the
ocean,
as
if
it
were
a
living
product
of
the
sea.
This
growth
had
been
in
every
part,
from
core
to
circumference.
First,
the
central
copper
wire,
which
was
the
spinal
cord,
the
nerve
along
which
the
centre
current
was
to
run,
was
nearly
three
times
as
large
as
before.
Prof.
Thomson
had
long
seen
that
this
was
a
condition
of
success.
While
joining
heartily
in
the
attempts
of
1857-58,
he
felt
that
an
error
was
committed
in
the
smallness
of
the
cable;
that
the
copper
conductors
and
the
gutta-percha
covering
should
both
be
much
larger.
The
old
conductor
was
a
strand
consisting
of
seven
fine
wires,
six
laid
round
one,
and
weighed
only
one
hundred
and
seven
pounds
to
the
mile.
The
new
was
composed
of
the
same
number
of
wires,
but
weighed
three
hundred
pounds
to
the
mile.
As
it
was
made
of
the
finest
copper
that
could
be
obtained
in
the
world,
it
was
a
perfect
conductor.
Next,
to
secure
insulation,
it
was
first
imbedded
for
solidity
in
Chatterton's
compound,
a
preparation
impervious
to
water,
and
then
covered
with
four
layers
of
gutta-percha,
which
were
laid
on
alternately
with
four
thin
layers
of
Chatterton's
compound.
The
old
cable
had
but
three
coatings
of
gutta-percha,
with
nothing
between.
Its
entire
insulation
weighed
but
two
hundred
and
sixty-one
pounds
to
the
mile,
while
that
of
the
new
weighed
four
hundred
pounds.
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