The Great Mysto Presents
THE SECRETS OF MAGIC
X-Ray Vision
The magician hands out an empty box and cover along with three wooden slabs and a cord. While the magician is out of the room, one of the members of the audience places one of the slabs in the box, replaces the cover and ties the cord around it. When the magician re-enters the room, he can tell which slab is inside the box without touching it.
The Secret:
The secret lies in the fact that the blocks are weighted as indicated by the dotted lines. Note that the slabs can fit in the box only one way. The cord, which is used to tie the cover in place, really acts as a pivot.
The magician can tell which slab is inside by the direction the box tips. Alternately, if using a thin string instead of a cord, the magician can pick up the box by the knot and see which way it tips.
This has been another magic trick you can build yourself, courtesy of the Great Mysto!