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281
Heroes of the Telegraph
·
John Munro
90
The
speed
of
signalling
by
the
siphon
recorder
is
of
course
regulated
by
the
length
of
cable
through
which
it
is
worked.
The
instrument
itself
is
capable
of
a
wide
range
of
speed.
The
best
operators
cannot
send
over
thirty-five
words
per
minute
by
hand,
but
a
hundred
and
twenty
words
or
more
per
minute
can
be
transmitted
by
an
automatic
sender,
and
the
recorder
has
been
found
on
land
lines
and
short
cables
to
write
off
the
message
at
this
incredible
speed.
When
we
consider
that
every
word
is,
on
the
average,
composed
of
fifteen
separate
waves,
we
may
better
appreciate
the
rapidity
with
which
the
siphon
can
move.
On
an
ordinary
cable
of
about
a
thousand
miles
long,
the
working
speed
is
about
twenty
words
per
minute.
On
the
French
Atlantic
it
is
usually
about
thirteen,
although
as
many
as
seventeen
have
sometimes
been
sent.
The
'duplex'
system,
or
method
of
telegraphing
in
opposite
directions
at
once
through
the
same
wire,
has
of
late
years
been
applied,
in
connection
with
the
recorder,
to
all
the
long
cables
of
that
most
enterprising
of
telegraph
companies--the
Eastern--so
that
both
stations
may
'speak'
to
each
other
simultaneously.
Thus
the
carrying
capacity
of
the
wire
is
in
practice
nearly
doubled,
and
recorders
are
busy
writing
at
both
ends
of
the
cable
at
once,
as
if
the
messages
came
up
out
of
the
sea
itself.
We
have
thus
far
followed
out
the
recorder
in
its
practical
application
to
submarine
telegraphy.
Let
us
now
regard
it
for
a
moment
in
its
more
philosophic
aspect.
We
are
at
once
struck
with
its
self-dependence
as
a
machine,
and
even
its
resemblance
in
some
respects
to
a
living
creature.
All
its
activity
depends
on
the
galvanic
current.
From
three
separate
sources
invisible
currents
are
led
to
its
principal
parts,
and
are
at
once
physically
changed.
That
entering
the
mouse-mill
becomes
transmuted
in
part
into
the
mechanical
motion
of
the
revolving
drum,
and
part
into
electricity
of
a
more
intense
nature--into
mimic
lightning,
in
fact,
with
its
accompaniments
of
heat
and
sound.
That
entering
the
signal
magnet
expends
part
of
its
force
in
the
magnetism
of
the
core.
That
entering
the
signal
coil,
which
may
be
taken
as
the
brain
of
the
instrument,
appears
to
us
as
INTELLIGENCE.
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