Complications
Horological Complications Encyclopedia
Any function beyond the simple display of hours and minutes is a complication. Each record here covers definition, historical origin, how the mechanism actually works, its appearance in pocket watches, wristwatches and (where relevant) clocks, identification features and servicing notes.
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TimingSmall SecondsA subsidiary dial, usually below the centre, showing seconds independently of the main hour/minute display, driven directly off the fourth wheel of the going train.
TimingSweep (Centre) SecondsA seconds hand mounted concentrically on the centre arbor and sweeping the full dial, rather than occupying a small subsidiary dial.
TimingIndependent (Dead) Seconds — Foudroyante DistinguishedA seconds display driven by its own separate wheel train and detent, advancing in discrete jumps once per second rather than sweeping continuously, so it can be read to the exact second.See editorial status
TimingChronographA watch with an independent stopwatch function layered on top of ordinary timekeeping, started, stopped and reset by pushers, typically displaying elapsed seconds and minutes (and sometimes hours) on subsidiary dials.See editorial status
TimingFlyback ChronographA chronograph variant allowing the running hand to be reset to zero and instantly restarted with a single pusher action, without first stopping the timing function.See editorial status
TimingSplit-Seconds Chronograph (Rattrapante)A chronograph with two superimposed centre seconds hands that normally move together, allowing one to be stopped momentarily to read a split (intermediate) time while the other continues running, then snapped back into sync.See editorial status
TimingColumn Wheel (Chronograph Switching)A star-shaped, vertically pivoted wheel with raised columns used to coordinate the start, stop and reset levers of a chronograph in the correct sequence.
Calendar & astronomySimple (Date) CalendarA calendar mechanism showing the date (and often day and/or month) which requires manual correction at the end of short months, because it does not account for months of fewer than 31 days.
Calendar & astronomyAnnual CalendarA calendar complication that automatically accounts for months of 30 and 31 days, requiring correction only once a year at the end of February.See editorial status
Calendar & astronomyPerpetual CalendarA calendar complication that correctly tracks date, day, month and leap years without manual correction (other than for the rare centurial exceptions to the leap-year rule), for as long as the watch runs continuously.See editorial status
Calendar & astronomyDay-DateA calendar display combining a numerical date with a spelled-out day-of-the-week indication, typically shown side by side or in a double aperture at the top of the dial.See editorial status![Vacheron] How does this month indicator work? : r/Watches](/__l5e/assets-v1/3630b784-3061-4e64-a86c-30ab6fda3fb6/vacheron-how-does-this-month-indicator-work-r-watches.jpg)
Calendar & astronomyMonth IndicationA calendar display, usually a small subsidiary dial or aperture, showing the current month, generally as part of a triple (day-date-month) or perpetual calendar.
Calendar & astronomyMoon PhaseA display, usually a rotating disc showing two moons behind an aperture shaped like the sky, indicating the current phase of the moon across the synodic (lunar) month.
DisplayPower Reserve IndicationA dial display, usually an arc or subsidiary dial with a hand, showing how much running time remains before the mainspring fully unwinds.
DisplayUp-and-Down IndicatorAn early, chronometer-associated form of power reserve indication, showing the winding state of the mainspring as 'up' (fully wound) through 'down' (run down) on a graduated arc.See editorial status
Striking & chimingAlarmA mechanism that sounds an audible signal at a pre-set time, using a separate striking train and hammer independent of the main timekeeping train.See editorial status
Striking & chimingQuarter RepeaterA repeating watch that, on demand, strikes the current time to the nearest quarter hour: hours on one tone, quarters on a different tone or two-tone combination.See editorial status
Striking & chimingFive-Minute RepeaterA repeating watch striking hours, then the number of completed five-minute intervals since the hour, offering finer time resolution than a quarter repeater without the full complexity of a minute repeater.See editorial status
Striking & chimingMinute RepeaterThe most refined common repeating grade, striking hours, quarters, and then the exact number of minutes elapsed since the last quarter, giving the time to the minute on demand.See editorial status
Striking & chimingGrande SonnerieA striking complication that automatically sounds the full hours and quarters as they pass, in addition to being repeatable on demand — combining the functions of a clock-style striking watch and a minute or quarter repeater.See editorial status
Striking & chimingPetite SonnerieA striking complication closely related to the grande sonnerie, automatically sounding the hours at each hour and a single tone at each quarter, but without repeating the full hour count at every quarter.See editorial status
Striking & chimingCarillon (Repeater)A repeating or striking watch using three (or more) gongs and hammers to strike the quarters in a melodic, multi-tone sequence rather than the simple two-tone pattern of a standard quarter repeater.See editorial status
PrecisionTourbillonA rotating carriage housing the escapement and balance, typically completing one revolution per minute, designed to average out positional timekeeping errors caused by gravity acting differently on the balance in different vertical orientations.
PrecisionKarruselA rotating-carriage escapement mechanism, similar in purpose to the tourbillon, that averages positional timekeeping errors but rotates the carriage at a different and typically slower rate driven from a different point in the train.
Time zonesWorld TimeA display showing the current time in every major time zone simultaneously, typically via a rotating 24-hour ring read against a fixed ring of city or time-zone names.See editorial status
Time zonesDual Time / GMTA complication showing the time in a second time zone in addition to local time, typically via an independently adjustable additional hour hand, a 24-hour hand referencing a rotating or fixed bezel, or a subsidiary dial.See editorial status
Calendar & astronomyEquation of TimeA display showing the difference between mean solar time (the constant time kept by clocks) and true (apparent) solar time (as read from a sundial), which varies through the year due to the Earth's elliptical orbit and axial tilt.
Calendar & astronomySidereal TimeA display of time measured against the fixed stars rather than the sun, running slightly faster than solar time (a sidereal day is about 3 minutes 56 seconds shorter than a mean solar day), used for astronomical observation.See editorial status
Calendar & astronomyAstronomical IndicationsA broad category of complications displaying astronomical phenomena beyond calendar and moon phase, including sunrise/sunset times, zodiacal position, planetary positions, star charts and celestial coordinates.See editorial status
DisplayJump HourA display in which the hour is shown in a numbered aperture (rather than by a conventional hand) and changes instantaneously — 'jumping' — from one hour to the next at the top of the hour, rather than creeping.See editorial status
DisplayRetrograde IndicationsA display in which a hand sweeps across a scale (rather than a full circle) and then jumps instantaneously back to its starting point once it reaches the end, used for dates, seconds, day or other indications.
PrecisionDeadbeat SecondsA seconds display that advances in a single, sharp, discrete step once per second, as opposed to the small tremor of an ordinary lever-escapement seconds hand or the smooth glide of a high-frequency escapement; historically associated with the deadbeat escapement used in precision pendulum clocks.
DisplayWandering HoursA display in which the current hour numeral itself travels along an arc of the dial, passing a fixed pointer or aperture that indicates the minutes, so that a single rotating hour numeral (rather than a hand) reads the time.See editorial status
TimingFoudroyante (Jumping Fractional Seconds)A hand that completes one full revolution of its own subsidiary dial per second, divided into fractions (commonly fifths, sixths or eighths of a second), jumping abruptly between each fraction rather than sweeping or ticking once per second like an ordinary seconds hand.See editorial status
Calendar & astronomyBig Date (Grand Date)A date display enlarged well beyond the size of a conventional single date window, typically achieved with two separate discs — one for each digit — rather than a single printed date ring, to improve legibility.See editorial statusCalendar & astronomyTriple CalendarA calendar complication displaying day, date and month simultaneously (often alongside moon phase), but without the perpetual calendar's automatic leap-year and month-length logic, so it requires manual correction after every short month.See editorial status
Calendar & astronomyZodiac CalendarAn astronomical calendar indication showing the sun's position against the twelve signs of the zodiac through the year, typically displayed as a rotating ring or disc printed with the zodiacal symbols and a fixed pointer marking the current sign.See editorial statusCalendar & astronomyLunar and Religious CalendarA calendar display tracking a lunar or lunisolar calendar system — such as the Islamic Hijri calendar or the Hebrew calendar — rather than, or alongside, the Gregorian civil calendar, typically used to indicate religious dates and observances.See editorial status
Calendar & astronomyTide IndicationA display showing the state of the tide — typically high, low, and the direction of change — for a given location, calculated from the relative positions of the sun and moon rather than from direct tidal measurement.See editorial status
Calendar & astronomySunrise/Sunset IndicationA display showing the times of sunrise and sunset for a given date and location, usually via two hands or discs read against a 24-hour scale, or a shaded day/night sector whose boundary shifts through the year.See editorial status
DisplayDay/Night IndicatorA subsidiary display, typically a rotating disc shaded to represent day and night (often with sun and moon or star motifs), that shows whether the main time display currently refers to the AM or PM half of the 24-hour day.
Calendar & astronomyPlanetarium / Orrery IndicationA display modelling the relative positions and orbital motion of the sun, moon, earth and other planets, in the manner of a mechanical orrery, miniaturised into a watch or clock dial rather than presented as a standalone scientific instrument.See editorial statusPrecisionLinear and Double Power ReserveVariants of the power-reserve indication that depart from the common semicircular fan-shaped gauge, including linear (straight-line) scales and displays tracking two independently wound barrels rather than a single mainspring's state of wind.
Striking & chimingSonnerie au Passage (Passing Strike)A striking mode in which the watch or clock sounds the hours (and sometimes quarters) automatically as each one passes, without being triggered on demand, distinguishing it from a repeater, which strikes only when activated by the wearer.
TimingMonopusher (Single-Button) ChronographA chronograph in which start, stop and reset of the timing function are all controlled by a single pusher (often integrated into or beside the winding crown) rather than the two separate pushers used on most modern chronographs.
TimingChronograph Scales — Tachymeter, Telemeter and PulsometerGraduated scales printed on a chronograph dial or bezel that convert an elapsed-time reading directly into a rate, distance or pulse-rate figure, without requiring the wearer to do the arithmetic themselves.
TimingDoctor's (Pulsation) ChronographA chronograph fitted with a pulsometer scale and marketed specifically as a clinical instrument for taking a patient's pulse rate quickly at the bedside, a specialised application of the pulsometer scale rather than a mechanically distinct complication.See editorial status
Striking & chimingDumb Repeater (Silent Repeater)A repeating mechanism that performs the full repeating action — hammers striking against their usual targets — but without gongs or bells tuned to sound audibly, so the time can be felt as a pattern of taps rather than heard as chimes.
PrecisionConstant-Force RemontoireA supplementary mechanism, interposed between the mainspring and the escapement, that periodically rewinds a small local spring or weight so the escapement always receives an almost constant driving force, independent of the mainspring's varying torque as it unwinds.See editorial status
DisplayDepth Gauge (Diving Watch Complication)A mechanical indication, distinct from an ordinary rotating dive bezel, that measures and displays the wearer's actual current depth underwater, typically via a pressure-sensitive membrane or capsule linked to a dial hand or scale.See editorial status
TimingRegatta (Yacht Timer) CountdownA specialised chronograph subsidiary display, usually a rotating disc or additional hand, that counts down the final minutes before a sailing race start, rather than counting elapsed time upward as an ordinary chronograph does.See editorial status
DisplayThermometer IndicationA subsidiary display showing ambient temperature, most often driven by a bimetallic strip or spiral coiled inside the case and coupled to a hand, added as an auxiliary instrument function alongside a watch's or clock's timekeeping.See editorial status
DisplayDigital (Disc) Time DisplayA dial layout in which both the hour and the minute are shown by numerals on rotating discs viewed through apertures, rather than by hands, giving a fully 'digital' reading of the time from an entirely mechanical movement.See editorial status
Calendar & astronomyLeap-Year IndicatorA small subsidiary display, typically a four-position disc or hand, showing where the watch currently sits within the four-year leap-year cycle, generally offered as a visible companion to a perpetual calendar's internal leap-year logic rather than as a standalone complication.
DisplayRegulator DialA dial layout that separates the hour, minute and seconds indications into distinct subsidiary displays of differing size (most often a large central minute hand with small subsidiary hour and seconds dials), historically adopted to maximise the reading precision of the minute hand.Striking & chimingRéveil (Alarm) à TocA miniature single-hammer alarm mechanism, striking directly against the case or a small stud rather than a tuned gong, giving a soft, discreet tapping signal rather than a loud buzzing or ringing alarm.See editorial statusStriking & chimingJaquemart Automaton Striking FiguresMechanical figures (jaquemarts) that strike a bell or gong with a hammer to mark the hours or quarters, functioning as an animated, decorative substitute for or accompaniment to an ordinary striking train's hammer.See editorial status
Striking & chimingShip's Bell StrikeA striking pattern that marks the successive half-hour watches of a nautical day using the traditional ship's bell code (one to eight strokes in a paired rhythm) rather than the ordinary hour/quarter count used by domestic clocks.See editorial status
Striking & chimingMusical Movement (Carillon-en-Musique / Musical Box Movement)A movement incorporating a tuned steel comb plucked by pins on a rotating cylinder or disc to play a melody, distinct from a chiming or carillon mechanism that strikes bells or gongs to mark the time.See editorial status
DisplayBarometric IndicationA subsidiary dial or hand showing atmospheric pressure, typically driven by an aneroid capsule linked to a pointer, incorporated into a clock (rarely a watch) alongside ordinary timekeeping.See editorial status
PrecisionPendule SympathiqueA paired mantel clock and pocket watch system in which the watch, docked in a purpose-built cradle atop or within the clock case overnight, is automatically wound, set to precise time, and (in some versions) regulated by the clock via a mechanical linkage engaged only while docked.See editorial status
Calendar & astronomyAstrolabe IndicationA rotating dial or set of dials reproducing the function of a classical astrolabe — plotting the position of the sun and selected stars against the local horizon and displaying related data such as sunrise/sunset or the ecliptic — built into a clock or watch movement rather than as a standalone hand instrument.See editorial status
Striking & chimingCount-Wheel (Locking-Plate) StrikingAn early and mechanically simple striking-control system in which a notched wheel (the count wheel or locking plate) determines how many blows are struck at each hour by the spacing of its notches, rather than by counting against the position of the hands.
Striking & chimingRack StrikingA striking-control system using a pivoted, toothed rack that falls onto a stepped cam (the snail) mounted on the hour wheel, so the number of teeth the rack is allowed to fall past — and hence the number of blows struck — is read directly from the current hour position, making the system self-correcting.See editorial status
Striking & chimingNight Silence (Silence en Veille) MechanismA selectable feature allowing the owner to disable a clock's or repeater's audible striking for a chosen period (typically overnight), without altering the going train or the underlying strike-count mechanism.See editorial status
Calendar & astronomyEaster Computus (Ecclesiastical Calendar) IndicatorA calendar display computing and indicating the date of Easter and related movable ecclesiastical feast days for the current year, based on the traditional computus (the lunisolar calculation fixing Easter to the first Sunday after the first full moon on or after the spring equinox).See editorial status
DisplayPulsometer ScaleA dial scale converting a counted number of pulse beats into a rate per minute.See editorial statusDisplayAsthmometer ScaleA scale converting counted breaths into a respiration rate.See editorial status
Calendar & astronomyStar Chart DisplayA rotating chart showing the visible night sky for a given latitude.See editorial status
DisplayCompass IndicationA magnetic or electronic compass built into a watch: a needle on the dial or in the pendant, a separate compass capsule inside the case, or a compass mode shown by the hands or display.See editorial status
DisplayPortable SundialA portable instrument telling time from the sun's position.See editorial status
Calendar & astronomySecular Perpetual CalendarA calendar complication that accounts for the century-year exceptions in the Gregorian calendar.See editorial status
PrecisionMulti-Axial TourbillonA tourbillon that rotates around two or more axes.See editorial status
PrecisionInclined TourbillonA tourbillon where the balance is set at an angle (usually 25 or 30 degrees) to the movement.See editorial statusPrecisionOrbital Carousel TourbillonA tourbillon or carousel that orbits the entire dial once per hour.See editorial status
PrecisionConstant Force EscapementAn escapement that delivers a consistent amount of energy to the balance regardless of mainspring tension.See editorial status
Striking & chimingDecimal RepeaterA repeater that strikes ten-minute intervals instead of quarters.See editorial status
DisplayMystery DialA display where the hands appear to float in mid-air without connection to the movement.See editorial status
Calendar & astronomyTelluriumA complication showing the relative positions and motions of the Earth, Sun, and Moon.See editorial status
Calendar & astronomyLunar Cycle RegisterA complication tracking the long-term cycle of the moon, including nodes or apogee/perigee.See editorial status
DisplayAltimeterA complication that indicates altitude above sea level based on atmospheric pressure.See editorial status
DisplayTorque IndicatorA display showing the quality of energy delivery (torque) from the mainspring.See editorial status
DisplayWinding State IndicatorA simple indicator showing whether a watch is being wound or is in its running state.See editorial status
DisplayService IndicatorA complication that alerts the wearer when the watch is due for professional servicing.See editorial status
PrecisionOverload ProtectionA mechanism that prevents the mainspring from being over-wound or damaged by excessive force.See editorial status
DisplayHumidity IndicatorA capsule containing a desiccant that changes color in the presence of moisture.See editorial status
Time zonesTime Zone SelectorA mechanism allowing for the rapid switching between different pre-set time zones.See editorial status
Timing1/100th Second ChronographA chronograph capable of measuring and displaying intervals as small as one-hundredth of a second.See editorial status
Timing1/1000th Second ChronographA mechanical chronograph capable of 1/1000th second resolution.See editorial status
TimingVertical Clutch ChronographA method of engaging the chronograph train using vertical friction instead of lateral gears.See editorial statusTimingIndependent WindingA movement with two separate barrels and trains, one for timekeeping and one for complications.See editorial status
PrecisionDouble Escapement with DifferentialA movement using two separate balances and escapements linked by a differential gear.See editorial statusCalendar & astronomyFly-back (Retrograde) DateA date shown by a hand that steps along an arc from the 1st to the last day of the month and then flies back instantly to the 1st, instead of turning a full circle.See editorial status