Watch Historian / Complications
The mechanisms
What each complication does, how it does it, and the watches that did it first.
AlarmA second mainspring driving a hammer against the case or a gong, released when a setting disc reaches the hour.Automatic windingA pivoted weight that winds the mainspring from the wearer’s own movement, through a reduction train to the barrel.Balance springA fine spiral spring that gives the balance wheel a natural rhythm of its own.ChronographAn independent seconds train that can be started, stopped and returned to zero without interrupting the running of the watch.DateA ring of thirty-one numerals advanced once every twenty-four hours, read through an aperture or by a pointer.Day-dateA calendar showing the day of the week alongside the date, the day usually spelled out in full through a second aperture.Electric driveA movement powered by a battery rather than a mainspring, keeping a mechanical resonator and gear train.Flyback chronographA chronograph that can be reset and restarted from zero with a single press while it is still running.MoonphaseA display of the illuminated fraction of the Moon, usually a rotating disc bearing two moons read through an arched aperture.Perpetual calendarA calendar that stores the length of every month and the four-year leap cycle, and needs no correction until 2100.QuartzA watch regulated by a vibrating quartz crystal whose frequency is divided electronically to one pulse per second.Split-seconds chronographA chronograph with two superimposed seconds hands, one of which can be halted to read an intermediate time and then caught up to the other.TourbillonThe balance and escapement mounted in a turning cage, so that gravity’s effect on the rate averages out.Water resistanceThe sealing of a case against water and dust through gaskets, threaded closures and a screw-down crown, rated by static pressure test.World timeA rotating twenty-four-hour ring read against a fixed ring of city names, showing every time zone at once.