Kugel fountain

A kugel fountain (also called a "floating" sphere fountain or by the pleonasmic name kugel ball) is a water feature or sculpture where a sphere sits in a fitted hollow in a pedestal, and is supported by aquaplaning on a thin film of water. Pressurized water flows between the sphere and socket, creating a mechanical hydrostatic bearing that is nearly frictionless. The sphere can weigh thousands of kilograms, but the efficient bearing allows it to be spun by the force of a hand. The sphere does not float, being denser than water; it is often made from granite.[1] The hydraulics of the fountain can be controlled so that the axis of rotation of the sphere changes continually.[2] Ring sculptures that rotate on an axis are also built.[2][3]

Principle of operation of a Kugel fountain
(A) Water flowing between the sphere and its shaped holder lifts the ball slightly.
(B) Water flows over the sides into a reservoir.
(C) Water is pumped back in an endless loop.
(D) Pump.
(E) Ball can easily be moved by hand.

Kugel fountains can be found all over the world. Many are at popular tourist destinations, such as science museums,[4] shopping centers, lobbies, and gardens.

The term kugel is from the German word Kugel for ball or sphere.[5]