Select twelve cards of any suit, ace to ten and king and queen; arrange
them in a circle to represent the figures on the face of a clock, the
king as twelve and the queen as eleven (Fig. 3), and request a member of
the company to think of one of the numbers. You then explain you will
tap the cards with a pencil and he is to mentally add your first tap to
the number he thought of and count your succeeding taps until twenty is
reached, when he is to call "Stop," and your pencil will then rest upon
his number. For instance, we will suppose he thinks of twelve; he must
count your first tap as thirteen and continue counting mentally until
twenty is reached.
[Illustration]
Fig. 3.
EXPLANATION.--Touch the cards at random during the first seven taps and
allow your pencil, on its eighth tap, to rest on the king (twelve).
Eight and twelve being twenty he will of course say "Stop." Supposing he
thought of a lower figure--seven, for instance. Tap at random as before
until your eighth tap, which must always be on twelve; then touch the
cards in rotation, making the queen your ninth tap, the ten your tenth
tap, nine your eleventh, and so on until you reach seven, which will be
your thirteenth tap, which number added to seven, the number thought of,
will make twenty, and your friend will say "Stop."
Another effective trick can be worked with the card dial, but it
requires the assistance of a confederate. Having previously instructed
him what to do, you tell the company that any one is at liberty to touch
one of the cards during your absence from the room, and on returning you
will indicate the card he has touched. Upon your returning hand a pencil
to your confederate and request him to touch the cards in rotation until
you say "Stop," when the pencil will rest on the right card. Your
confederate must hold the pencil in his right hand with his forefinger
resting on top. When he touches the right card he must raise that finger
slightly. It is a signal no one would notice, and the trick always
creates a great deal of wonder.