Lab
Library
Journal
Shop
Sign in
to keep
Share image
1
378
The Story of the Atlantic Telegraph
·
Henry M. Field
54
The
progress
of
invention,
so
rapid
on
land,
at
length
found
a
way
of
penetrating
the
sea,
and
even
of
turning
up
its
bottom
to
the
gaze
of
men.
To
measure
the
depth
with
something
like
mathematical
accuracy,
an
instrument
was
introduced
known
among
nautical
men
as
Massey's
Indicator,
the
method
of
which
is
very
clearly
explained
in
an
article
which
appeared
in
one
of
the
New
York
papers,
(The
Times,)
on
the
deep-sea
soundings
made
for
the
Atlantic
Telegraph:
"The
old
system
is
with
a
small
line,
marked
at
distances
of
one
hundred
fathoms,
and
with
a
weight
of
thirty
or
fifty
pounds,
the
depth
being
told
by
the
length
of
line
run
out.
This
is,
of
course,
the
most
natural
apparatus
that
suggests
itself,
and
has
been
in
use
from
the
earliest
ages.
Experience
has
given
directions
for
its
use,
avoiding
some
of
the
grosser
causes
of
error
from
driftage
and
other
causes.
Yet
its
success
in
immense
ocean
depths
is
problematical,
and
a
problem
decided
in
the
negative
by
many
of
the
first
scientific
authorities
at
home
and
abroad.
In
the
mechanical
improvements
of
the
last
half-century
substitutes
for
this
simple
but
rather
uncertain
method
began
to
be
devised.
It
was
proposed
to
ascertain
the
depth
by
the
amount
of
pressure,
or
by
explosions
under
water,
with
other
equally
impracticable
plans.
At
last
was
noticed
the
perfect
regularity
of
the
movements
of
a
spirally-shaped
wheel,
on
being
drawn
through
the
water.
Experiments
proved
that
this
regularity,
when
unaffected
by
other
causes,
could
be
relied
on
with
perfect
accuracy,
and
that
an
arrangement
of
cog-wheels
would
register
its
revolutions
with
mathematical
precision.
Very
soon
it
came
in
use
as
a
ship's
log.
So
perfect
was
their
precision,
that
they
were
even
introduced
in
scientific
surveys.
Base
lines,
where
the
nicest
accuracy
is
required,
were
run
with
them,
and
we
have
the
highest
authority
of
the
Royal
Navy
for
believing
that
they
never
failed.
At
this
point
it
was
proposed
to
apply
them
in
a
perpendicular
as
well
as
in
a
horizontal
motion
through
the
water.
Massey's
apparatus
promising
to
solve
those
problems
of
submarine
geography
left
unsolved
by
the
old
method
of
obtaining
depth
with
a
simple
line
and
sinker,
and
this
more
especially
as
some
causes
of
error,
considerable
on
the
surface,
disappear
in
the
still
water
below."
Marker
Marker
Fine marker
White-out
Fine white-out
Circle
Paint
Unmarker
Hand
Scalpel
Dice
Sieve
Purify
Undo
Redo
Start over
