Modern Magic: A Practical Treatise on the Art of Conjuring

These card-boxes are frequently worked in pairs, as follows:--The boxes are prepared by placing a different card secretly in each, say an ace of hearts in the one, and a knave of spades in the other. The performer brings them forward to the company, each hanging wide open, and held by one corner only, with the first and second finger inside, and the thumb outside the box, taking care, however, to hold each by the side containing the false bottom, which is thus kept in position by the pressure of the fingers. So held, the boxes appear absolutely empty. Having drawn attention to the entire absence of any preparation, the performer lays them open upon the table, and, taking up a pack of cards, requests two of the company each to draw one. They, of course, imagine that they are making a free choice, but in reality he forces (either by sleight-of-hand, or by means of a forcing pack) the ace of hearts and the knave of spades. Again bringing forward the two boxes, he requests each person to place his card in one of them, taking care so to arrange that the person who has drawn the ace of hearts shall place it in the box already containing the concealed knave of spades, and vice versâ. Closing each box with the portion containing the false bottom uppermost, he now announces that at his command the cards will change places, which, on re-opening the boxes, they appear to have done. By again turning over the boxes, they may be made to return to their original quarters.