The Ten Duplicates.
Select any twenty cards; let any person shuffle them; lay them by pairs on the board, without looking at them. You next desire several persons, (as many persons as there are pairs on the table,) each to look at different pairs and remember what cards compose them. You then take up all the cards in the order they lay, and replace them with their faces uppermost on the table, according to the order of the letters in the following words:
M U T U S
1 2 3 4 5
D E D I T
6 7 8 9 10
N O M E N
11 12 13 14 15
C O C I S
16 17 18 19 20
(These words convey no meaning.)—You will observe, that they contain ten letters repeated, or two of each sort. You therefore ask each person which row or rows the cards he looked at are in; if he say the first, you know they must be the second and fourth, there being two letters of a sort (two U's) in that row; if he say the second and fourth, they must be the ninth and nineteenth, (two I's,) and so of the rest. This amusement, which is very simple, and requires very little practice, will be found to excite, in those who are unacquainted with the key, the greatest astonishment.
The readiest way is to have a fac-simile of the key drawn on a card, to which you refer.
To tell how many Cards a Person takes out of a Pack, and to specify each Card.
To perform this, you must so dispose a PIQUET pack of cards, that you can easily remember the order in which they are placed. Suppose, for instance, they are placed according to the words in the following line,
Seven Aces, Eight Kings, Nine Queens, and Ten Knaves;
and that every card be of a different suite, following each other in this order: spades, clubs, hearts, and diamonds. Then the eight first cards will be the seven of spades, ace of clubs, eight of hearts, king of diamonds, nine of spades, queen of clubs, ten of hearts, and knave of diamonds, and so of the rest.