This is a very old and simple trick, but it is none the less very effective oftentimes. It consists merely in arranging the twelve court cards in a horizontal row on the table, and then telling the company to reverse anyone of the cards while your back is turned, after which you will touch the card thus changed.
Close observation of the court cards reveals the fact that practically always the margin at one end of a card is somewhat wider than at the other end. When you lay the cards on the table, you must take care that all the cards have their wider and narrower margins in line. That is to say, that each of the cards in the row of twelve has its wide margin at the same end as has the card next to it, and similarly for all the others.
You direct that one or more of the cards shall be reversed, while your back is turned, or even while you are out of the room. After this has been done, a glance at the row shows which card or cards have been turned, and you name these.
You should note that sometimes the company agrees to reverse all of the cards, or none, and you should be alert against being puzzled by this maneuver.
It is better not to repeat the trick often. Nor should you, before doing the trick a second time, restore any changed cards to their first position, which would tend to give a clue to the manner of performing the trick. You must instead keep in memory the alterations made, and so be able to observe the reversing of these cards as well as of the others.