The Magician's Mirror
Construct a box of wood, of a cubical shape, A B C D, Fig. 23, of
about fifteen inches every way. Let it be fixed to the pedestal P, at
the usual height of a man's head. In each side of this box let there
be an opening, of an oval form, ten inches high, and seven wide. In
this box place two mirrors, A D, with their backs against each other.
Let them cross the box in a diagonal line, and in a vertical position.
the openings in the side of this box with four oval frames
and transparent glasses, and cover each with a curtain so contrived as
all to draw up together.
Place four persons in front of the four sides, and at equal distances
from the box, and then draw them up that they may see themselves in
the mirrors, when each of them, instead of his own figure, will see
that of the person next to him, but who will appear to him to be
placed on the opposite side. Their confusion will be the greater, as
it will be very difficult, if not impossible, for them to discover the
mirrors concealed in the box. The reason of this phenomenon is
evident; for though the rays of light may be turned aside by a mirror,
yet they always appear to proceed in right lines.