[LEAPSECS] Time on time

[Hal Murray]

> Speaking of time, what sort of time is the Long Now clock keeping,  anyway?

> Solar, atomic, or something else entirely? 


Solar.  It's all mechanical.  No electronics.


>From http://en.wikipedia.org/wiki/Clock_of_the_Long_Now



> Hillis concluded that no single source of timing could meet the

> requirements. As a compromise the clock will use an unreliable but accurate

> timer to adjust an inaccurate but reliable timer, creating a phase-locked

> loop.



> In the current design, a slow mechanical oscillator, based on a torsional

> pendulum, keeps time inaccurately, but reliably. At noon the light from the

> Sun, a timer that is accurate but (due to weather) unreliable, is

> concentrated on a segment of metal through a lens. The metal buckles and the

> buckling force resets the clock to noon. The combination can, in principle,

> provide both reliability and long-term accuracy.




-- 
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