Hold the pack in the left hand, with the ace of clubs at the top. Take the ace of diamonds in the right hand, between the first and middle fingers, and, bringing it briskly across the pack from front to back, take off the ace of clubs by means of the first finger and thumb, the ace of diamonds being left in its place. The little finger of the left hand should be curled up behind the cards, and so prevent more than the top one being removed, as will sometimes be the case if this precaution is not observed. This change is shown at Fig. 38.
Besides the part it takes in regular set tricks, the change is of the utmost utility to the conjuror in cases of emergency, especially when he makes, as he infallibly must at various times, a mistake. On eventually producing a card which turns out to be a wrong one, the performer must not appear in the least discomfited, for that would commit him at once, but ask the chooser of the card if the one now exhibited really is what he or she states it to be. Of course, an affirmative will be received in reply, and the performer must say, "Well, I would not for worlds contradict you, but really I think in this case you are wrong. Will you, madam" (here give the card, rapidly changed in the transit to someone else), "say if this card is the seven of diamonds, which this gentleman says it is?" As it has been changed for the ten of hearts, or whatever the desired card may be, a laugh will ensue, and it will appear as if the climax of the trick had been arrived at, and no one will know that you intended doing anything else. One of the great arts in conjuring is that of turning all mistakes and unexpected occurrences to the best advantage, and a thorough knowledge of all the various artifices and dodges is necessary to accomplish this.