With occasional maintenance, the clock should reasonably be expected to display the correct time for the next 10,000 years.
The clock should be maintainable with bronze-age technology.
It should be possible to determine operational principles of the clock by close inspection.
It should be possible to improve the clock with time.
It should be possible to build working models of the clock from table-top to monumental size using the same design.
- Go slow
- Avoid sliding friction (gears)
- Avoid ticking
- Stay clean
- Stay dry
- Expect bad weather
- Expect earthquakes
- Expect non-malicious human interaction
- Dont tempt thieves
- Maintainability and transparency:
- Use familiar materials
- Allow inspection
- Rehearse motions
- Make it easy to build spare parts
- Expect restarts
- Include the manual
- Scalability and Evolvabilty:
- Make all parts similar size
- Separate functions
- Provide simple interfaces
Conclusion: My current favorite is human winding because it fits with goals of clock. Temperature change is also a viable alternative.
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.
Conclusion: Mechanical digital logic.
Conclusion: This is the one I have thought about the least. Note that there can be multiple displays, and that some display can have independent power sources.
The design principles for the clock were primarily the work of Daniel Hillis with additional thoughts brought about by discussion with the other founding board members.