Lab
Library
Journal
Shop
Sign in
to keep
Share image
1
281
Heroes of the Telegraph
·
John Munro
230
'The
phonograph,'
said
Edison
of
his
favourite,
'is
my
baby,
and
I
expect
it
to
grow
up
a
big
fellow
and
support
me
in
my
old
age.'
Some
people
are
still
in
doubt
whether
it
will
prove
more
than
a
curious
plaything;
but
even
now
it
seems
to
be
coming
into
practical
use
in
America,
if
not
in
Europe.
After
the
publication
of
the
phonograph,
Edison,
owing,
it
is
stated,
to
an
erroneous
description
of
the
instrument
by
a
reporter,
received
letters
from
deaf
people
inquiring
whether
it
would
enable
them
to
hear
well.
This,
coupled
with
the
fact
that
he
is
deaf
himself,
turned
his
thoughts
to
the
invention
of
the
'megaphone,'
a
combination
of
one
large
speaking
and
two
ear-trumpets,
intended
for
carrying
on
a
conversation
beyond
the
ordinary
range
of
the
voice--in
short,
a
mile
or
two.
It
is
said
to
render
a
whisper
audible
at
a
distance
of
1000
yards;
but
its
very
sensitiveness
is
a
drawback,
since
it
gathers
up
extraneous
sounds.
To
the
same
category
belongs
the
'aerophone,'
which
may
be
described
as
a
gigantic
tympanum,
vibrated
by
a
piston
working
in
a
cylinder
of
compressed
air,
which
is
regulated
by
the
vibrations
of
the
sound
to
be
magnified.
It
was
designed
to
call
out
fog
or
other
warnings
in
a
loud
and
penetrating
tone,
but
it
has
not
been
successful.
The
'magnetic
ore
separator'
is
an
application
of
magnetism
to
the
extraction
of
iron
particles
from
powdered
ores
and
unmagnetic
matter.
The
ground
material
is
poured
through
a
funnel
or
'hopper,'
and
falls
in
a
shower
between
the
poles
of
a
powerful
electro-magnet,
which
draws
the
metal
aside,
thus
removing
it
from
the
dress.
Marker
Marker
Fine marker
White-out
Fine white-out
Circle
Paint
Unmarker
Hand
Scalpel
Dice
Sieve
Purify
Undo
Redo
Start over
