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281
Heroes of the Telegraph
·
John Munro
163
In
1837-8
Professor
Page,
of
Massachusetts,
had
discovered
that'
a
needle
or
thin
bar
of
iron,
placed
in
the
hollow
of
a
coil
or
bobbin
of
insulated
wire,
would
emit
an
audible
'tick'
at
each
interruption
of
a
current,
flowing
in
the
coil,
and
that
if
these
separate
ticks
followed
each
other
fast
enough,
by
a
rapid
interruption
of
the
current,
they
would
run
together
into
a
continuous
hum,
to
which
he
gave
the
name
of
'galvanic
music.'
The
pitch
of
this
note
would
correspond
to
the
rate
of
interruption
of
the
current.
From
these
and
other
discoveries
which
had
been
made
by
Noad,
Wertheim,
Marrian,
and
others,
Reis
knew
that
if
the
current
which
had
been
interrupted
by
his
vibrating
diaphragm
were
conveyed
to
a
distance
by
a
metallic
circuit,
and
there
passed
through
a
coil
like
that
of
Page,
the
iron
needle
would
emit
a
note
like
that
which
had
caused
the
oscillation
of
the
transmitting
diaphragm.
Acting
on
this
knowledge,
he
constructed
a
rude
telephone.
Dr.
Messel
informs
us
that
his
first
transmitter
consisted
of
the
bung
of
a
beer
barrel
hollowed
out
in
imitation
of
the
external
ear.
The
cup
or
mouth-piece
thus
formed
was
closed
by
the
skin
of
a
German
sausage
to
serve
as
a
drum
or
diaphragm.
To
the
back
of
this
he
fixed,
with
a
drop
of
sealing-wax,
a
little
strip
of
platinum,
representing
the
hammer-bone,
which
made
and
broke
the
metallic
circuit
of
the
current
as
the
membrane
oscillated
under
the
sounds
which
impinged
against
it.
The
current
thus
interrupted
was
conveyed
by
wires
to
the
receiver,
which
consisted
of
a
knitting-needle
loosely
surrounded
by
a
coil
of
wire
fastened
to
the
breast
of
a
violin
as
a
sounding-board.
When
a
musical
note
was
struck
near
the
bung,
the
drum
vibrated
in
harmony
with
the
pitch
of
the
note,
the
platinum
lever
interrupted
the
metallic
circuit
of
the
current,
which,
after
traversing
the
conducting
wire,
passed
through
the
coil
of
the
receiver,
and
made
the
needle
hum
the
original
tone.
This
primitive
arrangement,
we
are
told,
astonished
all
who
heard
it.
[It
is
now
in
the
museum
of
the
Reichs
Post-Amt,
Berlin.]
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