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281
Heroes of the Telegraph
·
John Munro
263
'Whilst
completing
the
model
of
my
original
plan,'
he
wrote
to
his
mother
on
April
5,
'others
on
entirely
fresh
systems
suggested
themselves,
and
I
have
at
length
succeeded
in
combining
the
UTILE
of
each,
but
the
mechanism
requires
a
more
delicate
hand
than
mine
to
execute,
or
rather
instruments
which
I
do
not
possess.
These
I
can
readily
have
made
for
me
in
London,
and
by
the
aid
of
a
lathe
I
shall
be
able
to
adapt
the
several
parts,
which
I
shall
have
made
by
different
mechanicians
for
secrecy's
sake.
Should
I
succeed,
it
may
be
the
means
of
putting
some
hundreds
of
pounds
in
my
pocket.
As
it
is
a
subject
on
which
I
was
profoundly
ignorant,
until
my
attention
was
casually
attracted
to
it
the
other
day,
I
do
not
know
what
others
may
have
done
in
the
same
way;
this
can
best
be
learned
in
London.'
The
'fresh
systems'
referred
to
was
his
'mechanical'
telegraph,
consisting
of
two
letter
dials,
working
synchronously,
and
on
which
particular
letters
of
the
message
were
indicated
by
means
of
an
electro-magnet
and
detent.
Before
the
end
of
March
he
invented
the
clock-work
alarm,
in
which
an
electro-magnet
attracted
an
armature
of
soft
iron,
and
thus
withdrew
a
detent,
allowing
the
works
to
strike
the
alarm.
This
idea
was
suggested
to
him
on
March
17,
1836,
while
reading
Mrs.
Mary
Somerville's
'Connexion
of
the
Physical
Sciences,'
in
travelling
from
Heidelberg
to
Frankfort.
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