Turnstile

Not everyone knows that in every pack there are many cards whose small numbers in the corners (4, 5, 6) are printed unevenly as to margins-at one end of the card the number is closer to the side edge than at the other end.

Pick out four or five cards whose margins are noticeably different, and lay them face-up side by side on the table-being careful to make all narrow margins the left-side of the cards.

Say now to someone, "While my back is turned and my eyes are closed, turn one of those cards around, so the top of it will be where the bottom is now. I will tell you which card you moved."

When you turn back and open your eyes, you can tell instantly, for you will see one of the cards with its narrow-margin on the right. To mystify him further, you can take four more cards and tell by the way the pips are pointed. In most of the Hearts, Clubs, and Spades, it is very easy to tell one end of a card from another by the way the pips are printed, some pointing up and some down.

Then take four more cards whose pips are exactly alike top and bottom (any Diamond except the 7; or the 2,4, 10, and face-cards in the other suits) and tell again by the margins. But, be sure there is enough difference in the side margin for you to detect the change!