On a workbench in Athens, a corroded lump from the Antikythera shipwreck split open to reveal bronze gears the size of coins. Turn a side crank on the Antikythera Mechanism and a calendar hand walks through the Greek zodiac, as if time were a machine you could wind. A pin‑and‑slot gear inside adds a wobble that matches the Moon’s uneven speed, a trick linked to Hipparchus’s lunar tables.