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Modern Magic: A Practical Treatise on the Art of Conjuring
·
Professor Hoffmann
635
This
singular
illusion
depends
upon
the
well-known
principle,
common
to
optics
as
to
mechanics,
that
“the
angle
of
reflection
is
equal
to
the
angle
of
incidence.”
Thus,
if
a
person
standing
at
the
point
a,
in
Fig.
296,
look
into
a
mirror
placed
in
the
position
indicated
by
the
line
b
c,
he
will
see
reflected,
not
himself,
but
whatever
object
may
be
placed
at
the
point
d.
By
an
ingenious
application
of
this
principle
a
looking-glass
may
be
used
to
conceal
a
given
object
behind
it,
while
at
the
same
time
an
image
reflected
in
the
glass
may
be
made
to
represent
what
would
be
presumably
seen
if
no
glass
were
there,
and
thus
prevent
the
presence
of
the
mirror
from
being
suspected.
This
is
the
secret
of
the
Sphinx.
The
table,
as
already
mentioned,
has
three
legs,
one
in
front,
and
one
at
each
side.
Between
these
legs
the
spectator
sees
apparently
the
curtains
at
the
back
of
the
recess,
but
really
a
reflection
of
the
curtains
at
the
sides.
The
space
between
the
middle
leg
and
that
on
either
side
is
occupied
by
pieces
of
looking-glass
(see
Fig.
297,
which
represents
a
ground
plan
of
the
arrangement),
extending
from
a
to
b,
and
a
to
c.
The
glass
extends
quite
down
to
the
floor,
which
is
covered
with
cloth
of
the
same
material
and
colour
as
the
surrounding
curtains.
The
spectators,
therefore,
looking
towards
the
table,
see
above
it
the
curtains
at
the
back,
and
below
it
the
reflection
of
the
curtains
at
the
sides;
which,
however,
if
the
relative
angles
are
properly
arranged,
appears
to
be
simply
the
continuation
or
lower
portion
of
the
curtains
at
the
back.
The
illusion
is
perfect,
and
the
spectator,
from
the
position
assigned
to
him,
cannot
possibly
discover,
by
the
evidence
of
his
senses,
that
he
is
looking
at
any
other
than
an
ordinary
bare-legged
table,
with
the
background
visible
in
the
usual
way.
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