A Steady Hand
If any of your friends boast of a steady hand, you can easily give their pride a fall by wagering that not one of them can move a glass of water from one table to another without spilling every drop it contains.
Fill a tumbler with water to the very brim. Place a piece of perfectly flat, stout paper on the top of it, as shown in [Fig. 40], and the palm of the hand on the top of that. Now turn the glass upside down very quickly and carefully, and place it upon a flat part of the table, having done which slide the piece of paper from beneath it. As the air cannot enter none of the water escapes, but it will be absolutely impossible to move the glass without spilling the water.
Fig. 40.—A water trick.