Clock of The Long Now - Design

Design

I want to build a clock that ticks once a year. The century hand advances once every one hundred years, and the cuckoo comes out on the millennium. I want the cuckoo to come out every millennium for the next 10,000 years. If I hurry I should finish the clock in time to see the cuckoo come out for the first time.

— Danny Hillis, The Millennium Clock, Wired Scenarios, 1995

The basic design principles and requirements for the clock are:

1. Longevity: The clock should be accurate even after 10,000 years, and must not contain valuable parts (such as jewels, expensive metals, or special alloys) that might be looted.
2. Maintainability: Future generations should be able to keep the clock working, if necessary, with nothing more advanced than Bronze Age tools and materials.
3. Transparency: The clock should be understandable without stopping or disassembling it; no functionality should be opaque.
4. Evolvability: It should be possible to improve the clock over time.
5. Scalability: To ensure that the final large clock will work properly, smaller prototypes must be built and tested.

No clock can have a guaranteed lifetime of 10,000 years, but some clocks are designed with guaranteed limits. (For example, a clock that shows a four-digit year date will not display the correct year after the year 9999.) With continued care and maintenance the Clock of the Long Now could reasonably be expected to display the correct time for 10,000 years.

Whether a clock would actually receive continued care and maintenance for such a long time is debatable. Hillis chose the 10,000-year goal to be just within the limits of plausibility. There are technological artifacts, such as fragments of pots and baskets, from 10,000 years in the past, so there is some precedent for human artifacts surviving this long, although very few human artifacts have been continuously tended for more than a few centuries.