Provide yourself with a tall, thin, and well-sounding glass vase. At a pinch a thin soda water tumbler will do. Across the room and above the table have a piece of thread or fine wire. Show the tumbler or vase round, and then place it upon the table, or on the top of an inverted tumbler, which will serve for the purpose of showing that there is no deception beneath, and will also act as a sounding medium. An assistant at the side draws the thread close against the side of the glass, and it is stretched as tight as is consistent with safety. The glass is now made to talk by means of sharply emitted sounds in answer to questions, a small code of signals being established. One sound means "yes," two "no," and so on. These sounds are caused by the assistant catching at the thread sharply with the nail, which will cause a distinct ring to come from the glass. The principle is very simple, but I have never known anyone but myself adopt it. The performer must endeavour to make his questions amusing, and, as the powers of speech possessed by the glass are but limited, they must not be too severely taxed.
If a tumbler be suspended from the wand by means of a thread tied loosely round the wand and tightly round the glass, a sound will be emitted on twisting the wand ever so slightly. With practice this movement can be made almost imperceptible. If the onlookers begin to look at the hand and wand too much the display must cease at once.