The following mechanical card trick is easy to prepare and simple to perform:
First, procure a new deck, and divide it into two piles, one containing the red cards and the other the black ones, all cards facing the same way. Take the red cards, square up and place in a vise. Then, with a plane, plane off the upper right hand corner and lower left hand corner, as in Fig. 1, about 1/16 in.
Then take the black cards, square up, and plane off about 1/16 in. on the upper left hand corner and lower right hand corner, as in Fig. 2.
Next restore all the cards to one pack, taking care to have the first card red, the next black, and so on, every alternate card being the same color. Bend the pack so as to give some spring to the cards, and by holding one thumb on the upper left-hand corner all the cards will appear red to the audience; place thumb in the center at top of pack and they will appear mixed, red and black; with thumb on upper right-hand corner all cards appear black. You can display either color called for. --Contributed by Ralph Gingrich, Chicago.
Illustration: Card Trick