Wind off a ball of cotton cord (piping) upon a tin tube six inches long,
and of the diameter of a half-crown or florin, or rather a trifle wider.
Borrow a coin which you have had marked, and change it by means of the
magic salver.
[Illustration: Fig. 10.]
Pass the marked coin off the stage to your confederate, who puts it down
the tube into the ball of cotton, and leaves it there in the centre; on
withdrawing the tube the hole can be completely covered up by pressing
the cord around it.
Thus prepared, the ball is brought to you in a glass cup, having a hole
in the rim through which you pass one end of the cotton. Fasten this to
a winding-off wheel (broad-tired), and as your assistant winds off the
cord, you pretend to throw the coin into the ball. Immediately, the
marked piece falls into the bottom of the vessel, in which it is taken
to the owner.
[Illustration: Fig. 11.—The Owner of the Coin.]