THE CARDS IN THE OPERA-GLASS.
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.