The Clock of the Long Now has a gear machined to match the earth's 26k year precession cycle: http://longnow.org/clock/prototype1/ http://longnow.org/clock/prot

The Clock of the Long Now has a gear machined to match the earth's 26k year precession cycle: http://longnow.org/clock/prototype1/ http://longnow.org/clock/prototype1/