You have a glass of water. You borrow a penny, throw a handkerchief over it and ask someone to hold it over the glass; the penny is held by the edges. You instruct the person helping you to drop the penny into the glass of water when you say "Go!" They obey your instructions and the penny is heard to drop into the water. (You will understand, of course, that the handkerchief is draped round the glass, and so the penny is not seen to fall.) You pull the handkerchief away and hold the glass up to the light. The penny has vanished.
The old way of doing this trick was with an eyeglass, which was concealed in your hand. In throwing the handkerchief over the penny you brought the eyeglass up and under the handkerchief while you kept the penny concealed in your hand. The eyeglass was therefore dropped into the glass and it sank to the bottom. By using a glass of the right size it is possible to pour out the water without giving the trick away; the eyeglass adheres to the bottom of the little tumbler.
In all probability, therefore, at the conclusion of the trick the small boy in your audience will say:
"Now let's look at the tumbler."
You pass it to him at once; he thinks he has "got you," but he hasn't. The glass is empty.
The little "twist" I have mentioned consists in using an eyeglass with a hole in it. The hole enables you to attach the eyeglass by a short piece of cotton to one corner of the handkerchief. The trick is doubly effective when done in this way because at the beginning you can show that you have only the penny in your hand. Arrange the handkerchief in your pocket before commencing the trick; you will find it convenient to have it either in your right trousers pocket or the left-hand inside pocket of your coat; then you will be able to get at it easily. The prepared corner, with the eyeglass resting on it, should be at the top. When you take the handkerchief by the prepared corner from your pocket the eyeglass will hang down behind the handkerchief and be hidden there. Then take the handkerchief by the prepared corner in your left hand and apparently place the penny under the handkerchief, but of course you conceal the penny in your hand and bring up the eyeglass. Someone grasps the eyeglass by the edge (through the handkerchief) and lets it fall into the tumbler. You then take the handkerchief by the prepared corner and pull it upwards quickly and then away from the glass. Put the handkerchief into your pocket as you pour the water out of the glass to show that the penny has vanished. The small boy may ask to see the handkerchief again, and so you have taken the precaution to have another handkerchief, bunched up in your pocket, in readiness. And this is the handkerchief that you produce for inspection—if someone insists on seeing "the handkerchief" but not otherwise.
A Quaint Mixture
A soda-water tumbler, a jug containing from a quarter to half a pint of water, and a cup of coffee with a little milk in it are needed for this experiment.
The trick is to pour both the coffee and the water into the big tumbler and then separate them again. Possibly somebody will attempt this feat by first placing a small tumbler in the large one, pouring the coffee into the small tumbler and the water around it. But can it be said that you pour both the coffee and the water into the tumbler when you really pour the coffee into another glass placed inside the tumbler? No, that solution does not work.
Here is the way in which you carry out your intentions.