The reader will scarcely require to be told that one of the great deceits practised by conjurors is that of duplication. In order to apparently execute the impossibility of conveying a large solid body invisibly through space, the conjuror has to cause the article itself to disappear by any means at hand, and to produce another similar article, or counterfeit thereof, at the spot to which the original one is supposed to be magically transported. In the case of Houdin's die trick a counterfeit die was made use of, and in many of the coin tricks duplicate coins were employed. Whatever the article used, the method is almost invariably the same; and the public are often invited to witness the exhibition of a new wonder, which is in reality only a variety of what has been done in hundreds of ways before.
One very effective variety of this particular deceit is the transposition of a ginger-beer bottle from one paper cover to another. The trick and its explanation are as follows: The performer brings forward a ginger-beer bottle and a glass, on a tray. If he pleases, he may have two ginger-beer bottles, and ask the audience to choose between them. He should ask them to select between the one on the right and the one on the left. If "right" is said, and the one with which the trick is to be performed is on the left of the audience, then the performer must say, "On my right. Thank you"; and instantly take up that bottle without more ado, and uncork it. He then pours out the ginger beer, to show that it is genuine—so he says, but the real object is to keep the spectators from suspecting that there is anything "uncanny" about the bottle itself. The peculiarity of the bottle is that it either never had a bottom to it, or else that portion of it has been forcibly removed. Some few conjuring trick makers supply bottles without bottoms; but any lapidary will perform the desired operation should the performer himself be unsuccessful in accomplishing it with a hammer. The chief thing is to obtain two bottles that match exactly in colour. Height is not of much consequence, as that is not so readily retained by the eye as is colour; still, it is as well to have them match in that even, but colour stands first in importance. One of these bottles is placed upon the righthand side of the shelf behind the table, and the other is fitted inside with either a piece of thick cork or gutta-percha. Whichever it is, it must fit very tightly, and be situated about an inch from the foot of the bottle. The cork must be left out until the last minute, or the fermentation of the ginger beer will cause the false bottom to come out unexpectedly with a "pop." This prepared bottle is the one that is brought on on the tray, with or without another genuine one, as the performer pleases. When two are brought on, the second one should always be left with the audience for them to open if they be so minded. It is sure to be examined with strict minuteness, and its unblemished innocence will reflect upon its late companion.
Under his vest band the performer has a small apple, a walnut, or little ball. This he gets down as he retires to the table, and slips it in the lower cavity of the bottle, holding it there suspended by means of the little finger. He then places the bottle upon the left-hand front corner of the table, and on the corresponding corner he places a duplicate of the article which he has secretly introduced under the bottle. This duplicate will have been lying on the table all the time, and can, of course, be examined. The performer now takes two cardboard or paper covers, each just large enough to cover a ginger-beer bottle easily, and shows them round. These covers can be made with very little trouble, and the plainer they are the better, in my opinion. Spectators think no more of a trick because of a cover of many colours covered with gold or silver stars. A fancy paper on the outside is all that is required, for it will not do to look "beggarly." These two covers are now taken back, and the performer goes behind his table. With the left hand he places one cover very slowly and deliberately over the bottle, and calls very particular attention to what he is doing. The cover in the right hand is meanwhile being placed over the bottle on the shelf. The conjuror's whole attention, eyes and everything, must be engrossed on what he is doing with the bottle which is visible. Any glance which he may want to take for ascertaining the exact position of the bottle on the shelf must take place as he goes behind the table; any downward look after this would be fatal. Directly it is felt that the hidden bottle is safe in the cover, the latter must be brought into view again; and care must be taken that it is held a little obliquely, the mouth being towards the performer. As an additional security, it is always as well to have the inside of the covers blackened, or lined with black paper, and the inside and base of the second bottle treated likewise. Any accidental exposure will then not be so likely to be attended by serious results.
When the first cover is fairly over the bottle, the second one, containing the other bottle, is placed over the little ball, or whatever it is. The performer next takes up his wand and says, "Now, what I am about to do is to cause the ginger-beer bottle and the little ball to change places. This, I am aware, anyone can do by simply lifting off the covers and altering the positions of the articles with the hand; but I shall do nothing so transparent. I will show you that the articles are still where I placed them, and that I have not already moved them from their positions." (The covers are alternately lifted, care being taken not to prematurely expose the wrong article.) "My method of procedure is as follows: First, I take out the little ball" (on the shelf there is a third article, similar to the other two, and this the performer palms in the left hand) "in this manner. You see, I simply run my wand up the side of the cover, and here I have the little ball in my hand." (Strike left hand with wand, and open it and put the ball on table.) "This cover is now empty. By means of my wand, I remove the ginger-beer bottle, large and cumbrous as it is, from the cover—here it is, see, on my wand!—and pass it gently, for fear of breakages, into the empty cover. This little ball I take thus, and pass into this cover, where the bottle was, not five seconds since." (Perform any pass with the ball, and put it back upon the shelf.) "On raising the covers, it will be seen that the change has actually taken place." Raise the left-hand cover first, grasping it firmly so as to ensure the bottle from slipping, and then show the second bottle on the right, bringing the left hand, at the same time, over the shelf, upon which the first bottle is permitted to drop, very gently, from the cover. Both covers should be afterwards shown round, although the trick can be repeated, i.e., done backwards, if the performer desires. If he does so, he should say, "Ah, I daresay everybody did not see how that was done, and, as I always like the method of my tricks to be understood by everybody, I will do it over again. There is no fun in a trick if one does not see how it is done." On removing the bottles at the close of the trick, care must be taken that the hidden ball, &c., is not knocked down on the floor, as is sometimes done by accident. This is a genuinely good trick, the opening of the ginger-beer bottle before the audience serving to throw that body off its guard.