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281
Heroes of the Telegraph
·
John Munro
38
The
idea
became
rooted
in
his
mind,
and
engrossed
his
thoughts.
Until
far
into
the
night
he
paced
the
deck
discussing
the
matter
with
Dr.
Jackson,
and
pondering
it
in
solitude.
Ways
of
rendering
the
electricity
sensible
at
the
far
end
of
the
line
were
considered.
The
spark
might
pierce
a
band
of
travelling
paper,
as
Professor
Day
had
mentioned
years
before;
it
might
decompose
a
chemical
solution,
and
leave
a
stain
to
mark
its
passage,
as
tried
by
Mr.
Dyar
in
1827;
Or
it
could
excite
an
electro-magnet,
which,
by
attracting
a
piece
of
soft
iron,
would
inscribe
the
passage
with
a
pen
or
pencil.
The
signals
could
be
made
by
very
short
currents
or
jets
of
electricity,
according
to
a
settled
code.
Thus
a
certain
number
of
jets
could
represent
a
corresponding
numeral,
and
the
numeral
would,
in
its
turn,
represent
a
word
in
the
language.
To
decipher
the
message,
a
special
code-book
or
dictionary
would
be
required.
In
order
to
transmit
the
currents
through
the
line,
he
devised
a
mechanical
sender,
in
which
the
circuit
would
be
interrupted
by
a
series
of
types
carried
on
a
port-rule
or
composing-stick,
which
travelled
at
a
uniform
speed.
Each
type
would
have
a
certain
number
of
teeth
or
projections
on
its
upper
face,
and
as
it
was
passed
through
a
gap
in
the
circuit
the
teeth
would
make
or
break
the
current.
At
the
other
end
of
the
line
the
currents
thus
transmitted
would
excite
the
electro-magnet,
actuate
the
pencil,
and
draw
a
zig-zag
line
on
the
paper,
every
angle
being
a
distinct
signal,
and
the
groups
of
signals
representing
a
word
in
the
code.
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