, half way from open end to
closed end, should be cut a hole, just large enough to comfortably
admit a hand and arm.

Next, the box should be painted black both inside and out, and
finally lined inside with black cloth. This lining must be done
neatly-no folds must show and no heads of tacks. The interior must
be a dead black. The box is painted black first so that the cloth
used need not be very heavy; but if the cloth be sufficiently
thick, no painting inside is required. The whole inside is to be
cloth-lined, floor, top, sides and end.

[Illustration: Candle stand]

Next, the illumination in front must be arranged. If you can have
a plumber make you a square frame of gas-piping, with tiny holes
all along it for the gas to escape and be lit, and connect this by
means of a rubber tube to the gas in the house, so much the
better; but a plentiful supply of short candles will do just as
well, although a little more trouble. The candles must be close
together and arranged on little brackets around the whole front of
the "cave" (see small cut), and should have little pieces of
bright tin behind them, to throw the light toward the audience.
The whole function of these candles is to dazzle the eyes of the
spectators, heighten the illusion, and prevent them seeing very
far into the black box.

Finally, you must have an assistant, who must be provided with
either black gloves or black bags to go over his hands and arms,
and several black drop curtains, attached to sticks greater in
length than the width of the box, which are let down through the
slit in the top.

The audience room should have only low lights; the room where the
cave is should be dark, and if you can drape portieres between two
rooms around the box (which, of course, is on a table) so much the
better.

The whole secret of the trick lies in the fact that if light be
turned away from anything black, into the eyes of him who looks,
the much fainter light reflected from the black surface will not
affect the observer's eye. Consequently, if, when the exhibitor
puts his hand in the cave, his confederate behind inserts his
hand, covered with a black glove and holding a small bag of black
cloth, in which are oranges and apples, and pours them from the
bag into a dish, the audience sees the oranges and apples appear,
but does not see the black arm and bag against the black
background.

The dish appears by having been placed in position behind a black
curtain