A hint to the drawing-room performer. After the performance see that the water is poured away at once; otherwise, if some of the younger and more inquisitive members of your audience come round behind your screen at the close of the performance they will be sure to want to know how this trick was done, and if they get a glimpse of the water they may possibly notice grease floating on the surface!
Various other methods have been invented for keeping certain portions of sand dry when other sand of similar colour is placed in water. Some conjurers have done the sand up in little packets of grease-proof paper. I have also heard of tiny air balloons being filled with sand. The great drawback of any of these other methods is that when the conjurer is letting the dry sand trickle away from his hand into the goblet he cannot immediately let the audience see that he has nothing concealed in his hand. He has to go at once to the bowl for the next handful and leave the "fake," whatever it may be, in the bottom of the bowl. By using the method I have described the conjurer gets the most convincing effect, and if he prepares a large quantity of the different blocks of sand at the same time the trick is really not troublesome. The exact quantity of tallow required must be determined by experiment; it will depend, of course, on the amount of sand which is being prepared.
The object of using goblets for the display of the dry sands is to enable the members of the audience in the front rows of seats to see the sands. When one is performing to an audience composed chiefly of children the first two or three rows of seats are usually occupied by very small children, and from their positions they cannot see the top of the table. Raise the object which you are going to place on the table and you bring it within the view of everyone.
Every good trick has a clear, logical conclusion. Although the conjurer is apparently reversing one of Nature's laws he must also be more or less reasonable in his performance. For example, if he tears up a piece of paper into little pieces and then causes these pieces to form together into four strips equal in length when laid end to end, to the original piece, the conjurer is not behaving in a reasonable manner; he should cause the little pieces to join together into one strip and the audience must be led to believe that that strip is the original piece of paper and that in some mysterious manner the conjurer has joined the pieces together. The conjurer who does that brings his trick to what may be called a "logical conclusion."