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281
Heroes of the Telegraph
·
John Munro
165
The
discovery
of
the
microphone
by
Professor
Hughes
has
enabled
us
to
understand
the
reason
of
this
failure.
The
transmitter
of
Reis
was
based
on
the
plan
of
interrupting
the
current,
and
the
spring
was
intended
to
close
the
contact
after
it
had
been
opened
by
the
shock
of
a
vibration.
So
long
as
the
sound
was
a
musical
tone
it
proved
efficient,
for
a
musical
tone
is
a
regular
succession
of
vibrations.
But
the
vibrations
of
speech
are
irregular
and
complicated,
and
in
order
to
transmit
them
the
current
has
to
be
varied
in
strength
without
being
altogether
broken.
The
waves
excited
in
the
air
by
the
voice
should
merely
produce
corresponding
waves
in
the
current.
In
short,
the
current
ought
to
UNDULATE
in
sympathy
with
the
oscillations
of
the
air.
It
appears
from
the
report
of
Herr
Von
Legat,
inspector
of
the
Royal
Prussian
Telegraphs,
on
the
Reis
telephone,
published
in
1862,
that
the
inventor
was
quite
aware
of
this
principle,
but
his
instrument
was
not
well
adapted
to
apply
it.
No
doubt
the
platinum
contacts
he
employed
in
the
transmitter
behaved
to
some
extent
as
a
crude
metal
microphone,
and
hence
a
few
words,
especially
familiar
or
expected
ones,
could
be
transmitted
and
distinguished
at
the
other
end
of
the
line.
But
Reis
does
not
seem
to
have
realised
the
importance
of
not
entirely
breaking
the
circuit
of
the
current;
at
all
events,
his
metal
spring
is
not
in
practice
an
effective
provision
against
this,
for
it
allows
the
metal
contacts
to
jolt
too
far
apart,
and
thus
interrupt
the
current.
Had
he
lived
to
modify
the
spring
and
the
form
or
material
of
his
contacts
so
as
to
keep
the
current
continuous--as
he
might
have
done,
for
example,
by
using
carbon
for
platinum--he
would
have
forestalled
alike
Bell,
Edison,
and
Hughes
in
the
production
of
a
good
speaking
telephone.
Reis
in
fact
was
trembling
on
the
verge
of
a
great
discovery,
which
was,
however,
reserved
for
others.
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