[kazinator]

That wall clock would need to handle different month lengths somehow because the month ring can be 28, 29, 30 or 31 days, and provide for a way to add years to the outer ring.

Probably regarding months, it would likely do what a lot of mechanical watches do: go to 31, and require manual intervention to set the day of month.

That's kind of ugly because you have to rotate that wheel exactly to retain the fractional part of the day, which is hard to accurately other than at midnight.

[ahmedfromtunis]

With some 'smart' circuitry this can be handled automatically: the month ring should have 31 days. But if the month is shorter, the clock would jump automatically to the next month.

[nickpinkston]

Though I love the idea of doing it mechanically like the Long Now clock:

https://longnow.org/artifacts/equation-of-time-cam

[timbit42]

This is because our calendar sucks. The Enoch calendar would be easier to implement.