Kugel fountain

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 holder's sides into a reservoir.
(C) Water is pumped back in an endless loop.
(D) Pump.
(E) Ball easily be moved by hand.

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 fluid bearing that is nearly frictionless. The sphere can weigh thousands of pounds, but the efficient bearing allows it to be spun by the force of a hand.^[1] The sphere does not float, being denser than water; it is often made from granite.^[2] Ring sculptures that rotate on an axis are also built.^[3]

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]

Kugel fountains

• 
  Celestial globe, weighing nine tons, being spun by a child.
• 
  Lansdale station, Railroad Plaza, Lansdale, Pennsylvania

Locations of kugel fountains

^{[lower-alpha 1][lower-alpha 2][lower-alpha 3]}

See also

• Aquaplaning
• Fluid bearing
• Lubrication theory
• Petrosphere
• Stone spheres of Costa Rica

References

External links

Wikimedia Commons has media related to Floating stone spheres.

• Snoeijer, Jacco H.; der Weele, Ko van (November 2014). "Physics of the granite sphere fountain" (PDF). American Journal of Physics. 82 (11): 1029–1039. doi:10.1119/1.4886365.
• Kugel fountain FAQ
• Terracache dedicated to the kugel fountain.
• Waymarking list of large kugel fountains, with GPS coordinates and images.