With cliffs for the lazy:
Part 1: Description of how
was designed and built. Cliffs: It's under 10mm across, and the frail delicate cage is machined from a solid block of aluminum.
part 2: The difference between clock time and solar time, why it's not linear, and how the wristwatch accurately tells you the difference... mechanically, without inputs.
Part 3: How it tells you the month and the day, accurately, including leap years, forever, mechanically.