Modern Magic: A Practical Treatise on the Art of Conjuring

The secret lies in the use of a prepared penny, consisting of similar halves (in the case above described two “tails”) soldered together, so as to be “tail” on either side. This the performer palms in his right hand. After first going through the operation with the genuine coins, as above, he picks them up with his left hand; and apparently transferring them to the right, really transfers three of them only. He then performs the trick with these and the prepared coin, when the apparently miraculous result above described becomes a matter of course. It is best not to repeat the trick too often, and a little practice is necessary in order to be able to return the three genuine coins neatly to the left hand (in which the fourth borrowed coin must be retained throughout the trick), at the same time secretly retaining your own. It is a frequent occurrence for one or other of the company, imagining that the seeming wonder is, in some unexplained way, a result of some natural principle, to request to be allowed to try for himself. It is obvious that, under such circumstances, it would not do to hand him the prepared coin, and hence the necessity for some quick and natural method of again getting the four genuine coins together.