Complication (horology)
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In horology, a complication is any feature of a timepiece beyond the display of hours, minutes and seconds. A timepiece indicating only hours, minutes and seconds is known as a simple movement. Common
Three complications on a Gallet MultiChron Navigator (1943): a crown-controlled synchronizable second hand, a direction-finding 24-hour hand, and a 45-minute recording chronograph
Тhe Breguet No. 160 grand complication
Smartwatch with the following complications: Heart rate with sparkline; Moon phase; date; weather; sunrise/sunset.
Marine sandglass MMM
Perpetual calendar
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A perpetual calendar is a calendar valid for many years, usually designed to look up the day of the week for a given date in the past or future.
Illustration from 1881 U.S. Patent 248872, for a perpetual calendar paperweight. The upper section is rotated to reveal one of seven lists of years (splitting leap years) for which the seven calendars below apply.
A 50-year "pocket calendar" that is adjusted by turning the dial to place the name of the month under the current year. One can then deduce the day of the week or the date.
Breguet classique Grand complication perpetual calendar
Perpetual calendar wristwatch by Patek Philippe