First of all, the conjurer says that the base of the glass is wet. He takes out a clean handkerchief to dry it and in so doing wipes away the celluloid disc and puts it into his pocket. He pours a little of the water out of the glass, which should not be more than about half full, especially during the first rehearsals!
The feat consists in looping the loop with the glass, by swinging it right round with the hand, without spilling the water. It is as well to rehearse the feat in the garden!
Pick up the glass by holding the back of the hand towards the table and getting the stem of the glass between the second and third fingers. Extend the arm and then, with a quick semicircular sweep of the arm, which should be held stiffly, bring the glass right round and deposit it on the other side of the table. You want a little nerve, and the feat is not difficult, but it appears to be.
Fig. 5
Japanese performers present a very spectacular feat of this kind in which they use two large buckets tied to the ends of a rope. The buckets are swung about at an alarming pace and in "impossible" positions without a drop of water being spilled; centrifugal force explains the mystery.
The Floating Pin
This is a "quieter" trick. Give someone a bowl of water and ask them to lay a pin on the surface of the water and leave it there. The pin naturally sinks to the bottom of the bowl, whereupon you complain that your directions have not been carried out properly; they are not likely to be unless the person to whom you hand the pin happens to know the secret of the trick.
Lay a cigarette paper gently on the top of the water and put the pin on the paper. In a few moments the paper will sink, leaving the pin floating on the surface of the water.