THE CLOCK OF THE LONG NOw - Long Now Foundation

Options considered as sources of timing for clock:
pendulum inaccurate
spring and mass inaccurate
water flow inaccurate and wet
solid material flow inaccurate
daily temperature cycle unreliable
seasonal temperature cycle imprecise
tidal forces difficult to measure
earth’s rotating inertial frame difficult to measure accurately
stellar alignment unreliable (clouds)
solar alignment unreliable (clouds)
atomic oscillator too high tech, difficult to maintain
piezoelectric oscillator too high tech, difficult to maintain
atomic decay difficult to measure precisely
wear and corrosion very inaccurate
marble roll very inaccurate
diffusion inaccurate
tectonic motion difficult to predict and measure
orbital dynamics difficult to scale
audio oscillator inaccurate and difficult to measure
pressure chamber cycle inaccurate
inertial governor inaccurate
human ritual too much dependence on humans
Conclusion: Since no single source does the job, use an unreliable timer to adjust an
inaccurate timer, creating a phase locked loop. My current favorite combination is to use
solar alignment to adjust a slow mechanical oscillator.