Modern Magic: A Practical Treatise on the Art of Conjuring

Another very telling incident is the transformation of an eight to a seven, or a seven to a six. A seven of spades, say, has been one of the drawn cards, but when it is summoned an eight of spades appears. The performer apologizes for the mistake, and, giving the card a touch of his wand, shows it instantly transformed to a seven. This is effected by sticking (with a little bees’-wax) a loose spade pip in the appropriate position on an ordinary seven of spades. The performer takes out the supposed eight with one hand, and thence transfers it to the other. In so doing he draws off, with the hand which first held the card, the loose pip, and, holding the card face downwards, touches it with the wand, and shows that it has apparently changed to the card drawn.