On the table are two empty transparent glass. Omit one of them brightly colored small ball. Raise both glasses up and pretend non-existent pour water from a glass without bulb in a glass ball. Water actually no, but the ball rises in the glass higher and higher. Finally, the ball rises to the top of the glass. Lower the ball into the vacant glass and repeat all over again. Non-existent water again raise the ball up. Remove the bulb and glasses flip upside down. The water in the glasses there.
What's the point? The ball is connected to the suit by a thin thread. It does not interfere with the ball.
When you pour the non-existent water, you need hands a little push forward. Then the thread will be pulled. Is to promote hands a little forward, as a stretched string will raise the ball in the Cup up. It seems that the ball "floats" in the glass.