Story Seed · 3:15am Aug 15th, 2017
I won't call it a story prompt, or a story idea, as I don't think it's anywhere near fleshed out enough. It's a story i'd love to read, though, assuming someone writes it. (Who knows, maybe I will?)
So, the premise is that Earth is Equestria's distant past, and that somepony rediscovers an ancient artifact: one of the 10,000 year clocks that the Long Now Foundation is beginning to build, with the aid of funding from Jeff Bezos.
There's lots of things about it that would be interesting to the pony who explores it. For example, although it keeps accurate time for 10,000+ years, it doesn't advance the time display, which includes the date, and a year display. The time displayed when you enter that room is the time the last visitor powered the display. In order to get the current time, you have to turn a crank until it stops. How long will the pony find it has been? Will they have thought to note what its position was, before they give it a whirl?
Will it still be accurate as designed? It uses a special cam to mechanically encode the (pre-computed) changes in the motion of the solar system over the course of the millenia, and a mechanism powered by solar heating to synchronize the clock with the solar system if any drifting occurs (designed in such a way as to bring the clock back in true synchronization, not just correct time of day). This mechanism also winds the timekeeping mechanism, and will even, very slowly, wind the chimes, which are designed to normally be wound by visitors.
Imagine being there when it chimes for the first time in decades, not having any idea why the mountain is playing a melody.
It would probably be best as a one-shot, but then again, the clocks are going to have antechambers. There could be clues...
That does sound interesting! You should write it!