The box must be altered first.  One end is removed, and a slit, one-third of the length from the remaining end, cut in one side.  This slit should be as long as the width of the box and about five inches wide.  On either side of the box, 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, which is snatched swiftly away at the proper moment by the assistant.  Any article thrown into the cave and caught by the black hand and concealed by a black cloth seems to disappear.  Any object not too large can be made to “levitate” by the same means.  A picture of anyone present may be made to change into a grinning skeleton by suddenly screening it with a dropped curtain, while another curtain is swiftly removed from over a pasteboard skeleton, which can be made to dance either by strings, or by the black veiled hand holding on to it from behind, and the skeleton can change to a white cat.