The person holding the slates unwraps them and finds the card in between the two slates, and the conjurer finishes by suggesting that the fairy has saved the situation.
The only "move" in the trick which is not quite easy is that which the conjurer makes to get the card out of his sleeve and hidden behind the slates. A very little practice, for preference in front of a looking-glass, will enable the conjurer to get over this difficulty; he should bear in mind that what he is apparently doing is to lift the slates with the right hand and take them by the sides with the left hand. If those movements are practised until the conjurer can make them without having to stop to think about them he can then go on to practise making the same movements while, at the same time, he gets the card out of his sleeve and hides it behind the slates, keeping it there with the fingers of his left hand. This is quite easy, but for the benefit of beginners who may wish for a still more simple method of doing the trick I suggest the following.
The card is "forced"; that is to say, the conjurer apparently allows the person who is taking the card to have a free choice, but he really makes sure that the person takes one particular card. An expert card conjurer can "force" one particular card from an ordinary pack, but to do this is not easy, and even an expert cannot be absolutely certain of forcing the card which he wishes to use in a trick. Therefore, since the beginner is out to make the trick as simple and sure as possible he should use a "forcing pack," which consists of one card repeated, say, forty times; a few other indifferent cards are placed on the top and below the forty. The conjurer who is going to use a "forcing pack" should do some other card trick with an ordinary pack and then exchange it for the "forcing pack"; of course, the backs of the two packs must match. The conjurer must also take care to hold the cards down when he is having one selected, so that no one may get a glimpse under the cards.
The card is taken and placed on the top of the pack as in the first method, and the card is got rid of by being pushed down the left sleeve, but the procedure afterwards is greatly simplified.
One of the two slates used is a "flap" slate; that is to say, a loose piece of cardboard painted to resemble a slate is laid inside it. The cardboard is painted on both sides, and, therefore, when the ordinary slate is placed on the top of the flap slate and both are turned over together the "flap" falls into the ordinary slate.
The working of this part of the trick will now be obvious. A card similar to the one which has been forced is placed under the flap of one of the slates. When the conjurer picks up this slate he must be careful to hold the flap firmly with his thumb to prevent it from falling away. He lightly sponges both sides of the slate (in reality one side of the flap and one side of the slate); he then cleans the ordinary slate in the same way and places it on the top of the flap. He cannot give the slates to a member of the audience to hold, and, therefore, after he has turned them over, to get the flap to fall, the conjurer merely places a broad elastic band on them and stands them up for a moment against a candlestick or some piece of apparatus on the table after he has written the message to the fairy.
By using a flap slate in this way the conjurer can produce a message on one of the slates in addition to producing the card. The message is written on one of the slates and is then covered with the flap; when the flap falls the message and the card are both disclosed. Since the conjurer apparently cleans all four sides of the two slates and leaves them slightly damp he ought really to dampen the underside of the flap and the side of the slate concealed by the flap before he begins the trick; otherwise, someone with a very alert mind may point out at the conclusion of the trick that although the conjurer wiped all four sides of the slates with a damp sponge, two of them (really the underside of the flap and the side of the slate which was concealed by the flap in the first instance) are not quite dry. It is always as well to be prepared for interruptions of that kind.