Provide an opera-glass about two inches and a half long, the tube of which is to be of ivory, and so thin that the light may pass through it. In this tube place a lens of two inches and a quarter focus, so that a card of about three quarters of an inch long may appear of the size of a common card. At the bottom of the tube there is to be a circle of black pasteboard, to which must be fastened a small card with figures on both sides, by two threads of silk, in such manner that by turning the tube either side of the card may be visible.
You then offer two cards in a pack to two persons, which they are to draw, and which are the same as those in the glass. After which you show each of them the card he has drawn, in the glass, by turning it to the proper position.
The better to induce the parties to draw the two cards, place them first on the top of the pack, and then, by making the pass, bring them to the middle. When you can make the pass in a dextrous manner, it is preferable, on many occasions, to the long card, which obliges you to change the pack frequently; for otherwise it would be observed that the same card is always drawn, and doubtless suspicion arise.
TO TELL THE CARDS BY THEIR WEIGHT.
Ask a person to cut the pack as often as he likes, undertaking by weighing each card for a moment on your finger, not only to tell the colour, but the suit and number of spots, and, if a court card, whether it is king, queen, or knave.
Have two packs of cards exactly alike: one pack to be constantly in use during the evening in performing your other tricks; the second, or prepared pack, in your pocket, which take an opportunity of exchanging, so that it may be believed that the pack of cards of which you tell the names is the same as that you have been doing your other tricks with, and which they must know have been well shuffled.
The manner of preparing your pack (which must be done previously) is by the following line, which you commit to memory, the words in italics forming the key:
Eight Kings threa-tened to save nine fair Ladies for one sick Knave.
Eight King three ten two seven nine five Queen four ace six Knave.
The initial letter of the words in the line and the names of the cards are identical. The word “threatened” is divided into two words, in order that it may answer for the three and ten; pay attention to this, or you may forget the ten altogether, which would set you entirely wrong. You should likewise commit to memory the order in which the suits come, viz. hearts—spades—diamonds—clubs.