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These spheres appear from time to time on eBay and tend to go for pretty high prices. They are said to be from an air force gyroscope: The sphere would be spinning at very high speed, suspended electrostatically. The markings on the surface allowed the system to track the orientation of the sphere as it was spinning. It's commonly claimed that they are extremely accurate spheres, within millionths of an inch of perfect. Or at least, they were until they inevitably crashed into the wall, got scratched or bent, and thus ended up on eBay. Here's what the seller had to say about this particular one:
This is a hollow beryllium Electrostatically Suspended Gyroscope (ESG) Sphere used in the Inertial Guidance System of the B52 and F117 bomber Aircraft.This is very similar to what other sellers say about similar spheres, and having to reason to doubt it, I think it's probably all true. See the next sample for a fascinating variation on the theme: A broken gyroscope sphere.
Source: eBay seller spatial-one
Contributor: Theodore Gray
Acquired: 29 February, 2004