Photos: The 10,000 Year Clock

A 22-pound sphere of Tungsten, an incredibly dense and tough material, will be used for the pendulums of the clock. Because of its dense nature, a large mass can be formed into a small space, minimizing air drag and reducing energy loss. The high density of the Tugnsten is also important because it will prevent minute timing variation that may be caused by changes in the temperature, water vapor, and barometric pressure in other materials.

Photo by James Martin/CNET