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281
Heroes of the Telegraph
·
John Munro
173
Reis
had
seen
that
an
undulatory
current
was
needed
to
transmit
sounds
in
perfection,
especially
vocal
sounds;
but
his
mode
of
producing
the
undulations
was
defective
from
a
mechanical
and
electrical
point
of
view.
By
forming
'waves'
of
magnetic
disturbance
near
a
coil
of
wire,
Professor
Bell
could
generate
corresponding
waves
of
electricity
in
the
line
so
delicate
and
continuous
that
all
the
modulations
of
sound
could
be
reproduced
at
a
distance.
As
Professor
of
Vocal
Physiology
in
the
University
of
Boston,
he
was
engaged
in
training
teachers
in
the
art
of
instructing
deaf
mutes
how
to
speak,
and
experimented
with
the
Leon
Scott
phonautograph
in
recording
the
vibrations
of
speech.
This
apparatus
consists
essentially
of
a
thin
membrane
vibrated
by
the
voice
and
carrying
a
light
stylus,
which
traces
an
undulatory
line
on
a
plate
of
smoked
glass.
The
line
is
a
graphic
representation
of
the
vibrations
of
the
membrane
and
the
waves
of
sound
in
the
air.
On
the
suggestion
of
Dr.
Clarence
J.
Blake,
an
eminent
Boston
aurist,
Professor
Bell
abandoned
the
phonautograph
for
the
human
ear,
which
it
resembled;
and,
having
removed
the
stapes
bone,
moistened
the
drum
with
glycerine
and
water,
attached
a
stylus
of
hay
to
the
nicus
or
anvil,
and
obtained
a
beautiful
series
of
curves
in
imitation
of
the
vocal
sounds.
The
disproportion
between
the
slight
mass
of
the
drum
and
the
bones
it
actuated,
is
said
to
have
suggested
to
him
the
employment
of
goldbeater's
skin
as
membrane
in
his
speaking
telephone.
Be
this
as
it
may,
he
devised
a
receiver,
consisting
of
a
stretched
diaphragm
or
drum
of
this
material
having
an
armature
of
magnetised
iron
attached
to
its
middle,
and
free
to
vibrate
in
front
of
the
pole
of
an
electro-magnet
in
circuit
with
the
line.
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