I spent a very happy pre-Copernican half-hour earlier today down at Oxford’s Museum of the History of Science having the mysteries of the astrolabe explained in a very informative talk. So I think I can now tell the time at night armed only with an astrolabe, the correct latitude plate, and a visible star. That’s probably a skill worth having.
They also have on display in the entrance gallery a very fine 1798 French armillary sphere, which is not (alas) keyed to the French Revolutionary Calendar, but which is (pleasingly) organised around the ten-hour day.
More on astrolabes at astrolabes.org (of course).