Watch Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

12-hour (24-hour) recorder (or register): A sub-dial on a chronograph (see chronograph) that can time periods of up to 12 or 24 hours

30-minute recorder (or register): A sub-dial on a chronograph (see "chronograph") that can time periods of up to 30 minutes.

A

Acrylic Crystal: Sometimes referred to as Hesolite or Hesalite, an acrylic crystal is basically plastic. Polymethylacrylate is often used. Benefits of an acrylic crystal are that is flexes rather than shatters on impact, it doesn't produce too much glare under bright light and it can be polished easily.

Alarm: Alarm functions may be fitted (most commonly) to battery powered quartz watches; the alarm with beep at the pre-set time. There are mechanical alarm watches featuring a hammer which produces the alarm sound at the pre-set time. Most noteworthy examples are perhaps the Revue Thommen Cricket and the Jaeger Le Coultre Memovox.

Amplitude: Sometimes used to describe the frequency of a mechanical movement, however seems more often used to describe the angle of oscillation of the balance wheel either side of its neutral position. This would therefore be measured in degrees, for example 'an amplitude of 270 degrees'.

Analogue: Analogue simply refers to the means of showing the time on a watch dial by means of hands which point to the hours, minutes and usually seconds.

Analogue: Digital display: A watch that shows the time by means of hour and minute hands (analog display) as well as by numbers (a digital display).

Anchor: The anchor, sometimes referred to as Swiss anchor helps perform the final part of the mechanical process in a mechanical watch in order to divide the seconds and provide accurate timekeeping. Moving side to side, the anchor allows the final wheel (escape wheel) to rotate one cog at a time. This process produces the ticking sound of a mechanical watch.

Anti-magnetic: The movement of a mechanical watch can be thrown off balance if it comes in contact with a strong magnetic field; Magnetism is common in loudspeakers, televisions, refrigerators, cars, etc. etc. and these days most watches claim to be anti-magnetic. This is achieved by using alloys for certain parts, among them the balance wheel and escape wheel. Electronic watches are not susceptible to magnetism

Aperture: Small opening. The dials of some watches (in French: montres à guichet) have apertures in which certain indications are given (e.g. the date, the hour, etc)

Apnea timing: A watch function which allows free divers to read instantly how much time has passed. A system of seven circles changes colours completely each minute.

Appliqué: Appliqué or applied chapters are numerals or symbols cut out of a sheet metal and stuck or riveted to a dial (face).

Assembling: Process of fitting together the components of a movement. This was formerly done entirely by hand, but the operations have now been largely automated. Nevertheless, the human element is still primordial, especially for inspection and testing.

Assortiment: French term for the parts used for making an escapement.

Automatic winding (or self-winding): This term refers to a watch with a mechanical movement (as opposed to a quartz or electrical movement). The watch is wound by the motion of the wearer's arm rather than through turning the winding crown. A rotor that turns in response to motion winds the mainspring. If an automatic watch is not worn for a day or two, it will wind down and need to be wound by hand a few turns to get it started again.

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B

Balance: Moving part, usually circular, oscillating about its axis of rotation. The hairspring coupled to it makes it swing to and fro, dividing time into exactly equal parts. Each of the to-and-fro movements of the balance ("tick-tock") is called an "oscillation". One oscillation is composed of two vibrations.

Barrel: Thin cylindrical box containing the mainspring of a watch. The toothed rim of the barrel drives the train.

Battery EOL: Battery End Of Life indicator. This function forewarns of impending battery failure in a quartz watch by means of the second hand jumping in two or sometimes four second intervals. The wearer usually has approximately two weeks before battery failure.

Bezel: The bezel is the topmost ring of the watch, surrounding the dial of the watch. A bezel may be fixed or in the case of a diver's watch, rotating. It can either be plain (usually fixed) or can be marked with, for example a 0-60 minute scale in the case of divers' watches. Older rotating bezels were usually bi-directional, modern diving watches are equipped with a unidirectional bezel.

Bi-directional rotating bezel: A bezel that can be rotated either clockwise or counterclockwise. These are used for mathematical calculations such as average speed or distance (see "slide rule") or for keeping track of elapsed time (see "elapsed time rotating bezel").

Blued Screws: Traditionally, high quality movements were fitted with screws which were artificially blued, more for decoration than function.

Bridge: Complementary part fixed to the main plate to form the frame of a watch movement. The other parts are mounted inside the frame (part of the "ébauche").

Built-in illumination: Lighting on a watch dial that allows the wearer to read the time in the dark. Check out Seiko's Lumi-brite technology.

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C

Calendar: The calendar mechanism or function on a watch can consist of a date only showing in a window through to a triple calendar, showing the date, day and month. A combination of dial cut outs and pointer hands may be used. The most complicated calendar mechanisms may be mechanically programmed to show the year, and months including those with less that 31 days; leap years can also be mechanically allowed for. Sometimes referred to as perpetual calendars.

Calibre: Originally used to mean the size of a watch movement, this term now denotes a type of movement (men's calibre, automatic calibre, etc). When a calibre number is accompanied by the manufacturer's mark, it serves as an indication of origin.

Case materials: Materials range from inexpensive cast metal through moulded plastic to solid chunks of steel or gold from which the case is machined. In Great Britain, gold cases are usually 18k, but less expensive watches are 9k. In most other countries, 14k is preferred. Caratage indicates the gold content of metal, stated as the number of parts of gold in every 24 parts, i.e. 18k gold is 18 parts of gold alloyed with six parts of metal. Platinum is becoming increasingly popular, as is titanium for its lightness. Ceramic cases and bracelets -a scratch resistant space age material formed under great pressure and heat from powder -are used by some manufacturers. It does not bear any resemblance to the ceramics used in pottery. Some watches in the middle price ranges are gold plated over brass -9k or 18k plating usually. Vermeil is the term used to describe silver which has been gold plated

Centre seconds: Seconds indicated by a hand at the centre of the dial, along with the hour and minute hands.

Chapter ring: The ring on the watch dial bearing figures and minute marks. The hour figures are sometimes called chapterscases: The case of a watch must not only protect the mechanism and hold all the parts together but it must also look good -sometimes to the extent of making a timepiece into a piece of jewellery. A watch case is generally in 3 parts -the bezel, which holds the crystal, -the band or centrepart, which contains the movement, -and the back, either snapped or screwed on, in to which, sometimes, is fitted a crystal so that an intricate mechanical movement watch.

Chronograph: A watch that includes a built in stopwatch function - i.e., a timer that can be started and stopped to time an event. There are many variations on the chronograph. Some operate with a center seconds hand which keeps time on the watch's main dial. Others use sub-dials to time elapsed hours, minutes and seconds. Still others show elapsed time on a digital display on the watch face. Some chronographs can be used as a lap timer (see "flyback hand" and "split seconds hand"). The accuracy of the stopwatch function will commonly vary from 1/5th second to 1/100th second depending on the chronograph. Some chronographs will measure elapsed time up to 24 hours. Watches that include the chronograph function are themselves called "chronographs." When a chronograph is used in conjunction with specialized scales on the watch face it can perform many different functions, such as determining speed or distance (see "tachymeter" and "telemeter") Do not confuse the term "chronograph" with "chronometer." The latter refers to a timepiece, which may or may not have a chronograph function that has met certain high standards of accuracy set by an official watch institute in Switzerland.

Chronometer: Movements which meet specific timekeeping criteria laid down by the Swiss Official Chronometer Control are awarded a Chronometer Certificate. Movements are usually tested out of the case for 15 days and nights in various positions and at various temperatures.

Co-axial: Escapement invented by Dr G. Daniels and commercialized by Omega for high-precision watches. The escapement uses a low-friction energy transmission system.

Complications: One or more features added to a watch in addition to its usual time-telling functions, which normally not only include the hours, minutes and seconds but also date and often the day of the week as well. Complications such as; perpetual calendars, moonphase displays, alarms, repeating mechanisms, quarter strikes as well as stop/start chronograph functions. Power reserve indicators are also usually regarded as 'complications'

Corrector: Manual corrections function for a specific element.

COSC: Controle Officiel Suisse des Chronometres [Official Swiss Chronometer Testing Institute].

Cosmograph: The cosmograph differs to the chronograph in that the tachymeter is on the bezel rather than on the outer rim of the dial. This was invented by Rolex to create a more modern look to the watch.

Countdown timer: A function that lets the wearer keep track of how much of a pre-set period of time has elapsed. Some countdown timers sound a warning signal a few seconds before the time runs out. These are useful in events such as yacht races, where the sailor must maneuver the boat into position before the start of a race.

Crown: The crown, often referred to as the winding crown or winder is used for winding the watch in the case of a non-automatic, for setting the hands to the correct time and often for setting the date in the case of calendar equipped watches. On diving/sports models, the crown may be screw down whereby it screws onto a threaded tube which protrudes from the case of the watch. This often ensures superior water resistance.

Crystal: The crystal is the clear cover over the dial. Can be referred to as the glass. Various materials have been used over the years including acrylic, mineral (glass) and sapphire.

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D

Date: The day of the month, displayed in a window on a watch dial typically at the 3 o'clock or 6 o'clock position.

DATE JUMPER: Systems and concepts with an effect on the date change at midnight: Instantaneous: the date changes with a synchronized jump at midnight within a tolerance of 1/- 10 minutes. (Calibre. 1120) Semi-instantaneous: the date moves slowly from around 11.30pm, at midnight the date is still visible. The function concludes with a jump of the disc. Total duration is 45 to 60 min. (Calibres 1128, 1152, 1164) Dragging: slow function, the date changes slowly, starting at around 11pm, at midnight the date is still visible and the function continues without the disc jumping. Total duration is 120 min. (Calibres 1424, 1438, 1538 and quartz calibres with time zones).

Day-Date: Apertures which display both the day of the month (numerical) and the day of the week.

Decorated Movement: Some watch movements come highly decorated, for example with Geneva Stripes and blued screws. Whilst decoration may not improve function, it often indicates a degree of hand assembly/finishing and an attention to detail in the construction of a watch. Some watches show off the decorated movement through the use of a display back.

Depth alarm: An alarm on a divers' watch that sounds when the wearer exceeds a pre-set depth.

Depth sensor/depth meter: A device on a divers' watch that determines the wearer's depth by measuring water pressure. It shows the depth either by analog hands and a scale on the watch face or through a digital display.

Dial: The dial, often referred to as the face is usually marked with numbers or batons to which the hands point in order for the wearer to tell the correct time. Dials themselves can be very simple, sometimes with no markers at all or extremely complex as in the case of pilots' chronographs. Dials can be decorated with patterns or in some cases with precious stones.

Digital Display: As opposed to an analogue display, a digital display shows the time in numbers. Most often used with LCD displays in the case of a quartz watch, during the 1960's there were many mechanical digitals with rotating discs instead of hands. Cut outs in the dial would show the correct time. The first quartz digital watches came onto the market in the early/mid 1970s; for example the Pulsar Time Computer.

Digital watch: A watch that shows the time with digits rather than with a dial and hands (analog) display

Diver's Watch: Divers' watches traditionally are large, featuring a graduated rotating bezel and often a screw down winding crown. Water resistant to 200m as a minimum, the modern diver's watch must confirm to certain standards laid down for example by ISA in order to be classified as a Scuba Divers Watch.

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E

Ebauche: The ebauche refers to the basic movement. To this, a particular manufacturer may add complications, decorate the movement or refine the movement by adding higher grade components.

Elapsed time rotating bezel: A graduated rotating bezel (see rotating bezel") used to keep track of elapsed time. The bezel can be turned so the wearer can align the zero on the bezel with the watch's seconds or minutes hand. After a period of time passes, you can read the elapsed time off the bezel. This saves you having to perform the subtraction that would be necessary if you used the watch's regular dial.

Electronic (quartz) watch: A watch, usually battery-powered, which uses an electric current to cause a quartz oscillator to vibrate, normally 32,768 Hz per second but sometimes at much higher frequencies. These vibrations are processed by an integrated circuit which transforms the current into impulses. These are fed into a stepping motor which drives a train of gears to move the hands. Some quartz watches have solar cells which take light from any soul, natural or artificial, and transform them into electrical energy. Another form is the Seiko Kinetic (See Kinetic).

Escapement: The escapement in a mechanical watch refers to a combination of parts including the anchor, pallets and balance wheel amongst others which translate the power of the mechanism into regular timekeeping. The escapement is responsible for the familiar ticking sound of a mechanical watch.

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F

Factory, works: In the Swiss watch industry, the term manufacture is used of a factory in which watches are manufactured almost completely, as distinct from an "atelier de terminage", which is concerned only with assembling, timing, fitting the hands and casing.

Flyback: This phrase is often used to describe two different functions of a chronograph watch. Some use it to describe the function of depressing a chronograph button which returns the seconds hand to zero but immediately starts the timing again. This can be used to time laps or to determine finishing times for several competitors in a race. To record a lap time or finishing time, stop the flyback hand.  After recording the time, push a button and the hand will "fly back" to catch up with the constantly moving elapsed-time hand. Repeat the process to record as many lap times or finishing times as needed. Also (probably wrongly) used to describe the split seconds chronograph which has two seconds hands sitting atop one another. On depression of a third chronograph button (most have two), the flyback hand will stop in order to measure say, a lap time; repressing this button with cause the flyback hand to flyback(!) to the other seconds hand which has remained in motion

Frequency: Amplitude, in the case of mechanical watches refers to how many times an hour the watch goes tick for a given time period! It is often referred to as half-swings per hour or beats per hour (BPH). Thus a watch beating at amplitude of 28,800 per hour ticks 8 times per second.

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G

Gear Train: The gears used in a mechanical watch which run from the mainspring which powers the watch through to the escapement which translates that power into timekeeping.

Geneva Stripes: A form of decoration in higher grade watch movements which look like stripes on the movement plates. These used to be applied by hand; in many cases in modern times, they are very simply applied by machine.

Gold plated: A layer of gold electroplated to a base metal.

Grande complications: The most complex of mechanical watches featuring an abundance of complications. The term is normally restricted to mechanical watches. Quartz watches with additional features are usually described as 'multi-functional'

Guilloche: A form of decoration for watch dials, giving the dial great depth. Often applied to silver or silvered dials.

Glass, Crystal: Thin plate of glass or transparent synthetic material, for protecting the dials of watches, clocks, etc

GMT: Greenwich Mean Time. Average time from zone 0, introduced on 01.11.1884, known scientifically as UTC (Universal Time Co-ordinated) and used as universal standard time.

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H

Hack/Hacking: Describes the feature of a movement whereby the seconds hand can be stopped for exact setting of the time. Originally a military term for this feature.

Handwind/Handwound: Simply describes a watch with a mechanical movement which needs to be wound by the wearer using the winding crown. This winds the mainspring up which then releases its energy to power the watch.

Helium escape valve: Decompression system which allows helium to escape from inside the watch when the watch is worn for professional use in pressure chambers. (Long-term underwater work, crude oil exploration)

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I

Incabloc: Incabloc is a trade name for a type of shock absorbing device/spring used to protect the delicate parts of the mechanical watch escapement. Mentioned here as it is probably the most widely used and some watch manufacturers used to draw attention to it by referring to it on the watch dial itself.

Index/Indices: Usually refers to the markings on the dial of a watch showing hours and minutes. Can however refer to the markings on the regulator of a watch movement to aid precision adjustment for accurate timekeeping.

Inhibition: Electronic process for adjusting a quartz watch without modifying the frequency of the quartz. The precision is obtained by adjusting the rhythm of the motor (moment of impulse) periodically, usually every 60 seconds, allowing the accuracy of the time displayed by the hands to be maintained.

Integrated bracelet: A watch bracelet that is incorporated into the design of the case.

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J

Jewels: In the mechanical watch and some quartz watches, jewels (usually made from synthetic ruby) are used as bearings for those parts of the movement subject to constant motion. They are not valuable at all in the monetary sense but they are valuable in aiding the precise running of a watch over a long period and reducing wear. It is a fallacy that the more jewels the better the watch. A basic handwound mechanical usually comprises 17 jewels which in the main is the optimum count. Automatics may require more for the winding mechanism itself. In the 1960s there appeared to be a competition to see who could fit the most jewels in a watch movement, manufacturers proudly referred to 100 Jewels on the dial; opening the watch usually revealed that up to 80% of these jewels had no purpose and were simply mounted here and there on the movement to up the jewel count!

Jumping Hour: System of timekeeping whereby the seconds and minutes are shown by traditional hands but the hour is shown in a dial cutout (often at 12), on the minutes hand reaching 59 minutes, the hour disc under the dial will jump to the next hour.

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K

Kif: A trade name for a shock absorbing system; in a similar vein to Incabloc above.

Kinetic: Refers to the Seiko line of Kinetic watches. This innovative technology has a quartz movement that does not use a battery. Movement of your wrist charges a very efficient capacitor which powers the quartz movement. Once the capacitor is fully charged, men's models will store energy for 7-14 days without being worn. Ladies models store energy for 3-7 days. Of course, if the watch is worn every day, the capacitor is continually recharged. The watch alerts you to a low capacitor charge when the seconds hand starts to move in two second intervals. For more information, click to go to Seiko's Internet Site.

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L

Lap timer: A chronograph function that lets the wearer time segments of a race. At the end of a lap, he stops the timer, which then returns to zero to begin timing the next lap.

LCD Display: Or Liquid Crystal Display; used for the display on most modern digital watches. Followed from the earlier LED or Light Emitting Diode display of the first quartz digital watches. The LCD was preferred as it used vastly less power than the LED thus the time could be shown constantly as opposed to having to press a button for time display.

Limited Edition: A series of watches whose production run is determined in advance of production and limited to a set number.

Lugs: Protrusions on the case of a watch to which the bracelet or strap is fitted. Various types of lugs can be found such as rounded lugs, teardrop lugs and hidden lugs.

Luminescence: Luminous dials first appeared during the Great War when soldiers needed to tell the time in the dark. Early forms used Zinc Sulphide compound agitated by a radioactive salt. It was painted on hands and was potentially dangerous to those applying it. Its use was banned in the 50's, since Tritium, a substance with a low radio activity, replaced it. Other methods have been devised. Timex's 'Indiglo' uses electronic luminescence; a button on the side of the case causes a tiny current from the battery to the electrodes and gives off energy in the form of light. Seiko uses fluorescent material on the dial, activated by any exposure to light.

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M

Main Plate: Base plate on which all the other parts of a watch movement are mounted (part of the "ébauche").

Mainspring: The driving spring of a watch, contained in the barrel.

Manufacture d'horlogerie: French term for a watch factory which itself produces the components (particularly the "ébauches") needed for the manufacture of its products (watches, alarm and desk clocks, etc).

Marine Chronometer: Highly accurate mechanical or electronic timekeeper enclosed in a box (hence the term box chronometer). Marine chronometers with mechanical movements are mounted on gimbals so that they remain in the horizontal position which is necessary for their precision.

Measurement conversion: A feature, usually consisting of a graduated scale on the watch's bezel, that lets the wearer translate one type of measurement into another-miles into kilometers, for instance, or pounds into kilograms

Mechanical movement: A movement powered by a mainspring, working in conjunction with a balance wheel. Most watches today have electronically controlled quartz movements and are powered by a battery (or cell). However, mechanical watches are currently enjoying a resurgence in popularity.

Mineral Crystal: Watch crystal made from what is essentially a form of glass. More scratch resistant than acrylic, a mineral crystal will however scratch and is extremely difficult, if not impossible to polish.

Minute repeater: A watch which can additionally tell the time, at the push of a button or move of a small slide on the side of the case, by striking the hours, quarter hours and minutes since the last quarter hour on small goings inside the watch. Such complex watches are never inexpensive.

Moonphase display: A graphic display by means of a specially shaped aperture in the dial to indicate the phase of the moon, i.e. full, new or somewhere in between. Very popular in the 90's but losing favour in the second half of the century.

Movement: The inner mechanism of a watch that keeps time and moves the watch's hands, calendar, etc. Movements are either mechanical or quartz.

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N

Nivarox/Nivaflex: Trade names for the metal alloy used for many Swiss watch mainsprings and hairsprings. These materials self compensate for the effects of temperature (e.g. expansion and contraction), are extremely strong and corrosion resistant.

Numbered edition: A watch series each of whose pieces is numbered sequentially in the order it is produced.

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O

O-Ring: O rings are used to seal the backs of watches which feature either a press-in back or a screw on back. They ensure water resistance. Usually also used on the winding stems of watches and in the winding crowns to protect against the ingestion of water and dust. Normally made from a rubber/plastic compound.

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P

Perpetual calendar: Memory function that respects all date changes, including 29th February in leap years (until 28/02/2100).

Power reserve: Period during which a watch or instrument can function on its own energy reserves (spring, battery etc.)

Power reserve indicator: A feature that shows when the watch will soon need a new battery or winding. A battery (or cell) reserve indicator on a quartz watch informs the wearer when the battery is low. Often this is indicated by the seconds hand moving at two or three-second intervals. Seiko's Kinetic watches are quartz watches that do not have a battery (see Kinetic). When a Seiko Kinetic needs to be wound, the seconds hand will also move in two second intervals.

Pulsometer: A watch with a scale to measure the number of heartbeats per minute.

Pushers or push pieces: Push buttons are on the case of the chronographs and some complicated watches. Most are used to stop and start a stopwatch but sometimes serve other functions.

PVD -physical vapour deposition: A coating of titanium nitrate applied in a vacuum and then covered by a coating of 22k gold to obtain a gold coloured finish.

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Q

Quartz: Used to describe a watch powered by an oscillating quartz crystal which draws its power from a small battery. Oscillating 32,768 times per second, an electronic circuit divides this oscillation into precise increments of 1 second or less. Used in both digital and analogue watches. Whilst derided by many purists as disposable and of little soul, the quartz watch is nonetheless extremely accurate. Watches have been made super-accurate by using a much higher frequency (e.g. 4.2 million cycles per second) or by using two oscillators and by using temperature compensation.

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R

Rapid date corrector: Function for correcting the date (months of 28, 29 or 30 days) without altering or stopping the watch's operation.

Rattrapante: used to describe the split seconds chronograph (see Flyback) which has two seconds hands sitting atop one another. On depression of a third chronograph button (most have two), the flyback hand will stop in order to measure say, a lap time; repressing this button with cause the flyback hand to flyback(!) to the other seconds hand which has remained in motion.

Regatta timing: A watch function which allows the easy reading of the critical regatta time intervals at glance.

Register: Another name for a sub-dial; this is usually a dial within the main dial of a watch. The best example is possibly a chronograph where there may be registers for the chronograph minutes and hours. Some watches have registers with pointers showing the day and date.

Regulating Elements: Set of parts comprising the regulating system (sprung balance) and the escapement (escape wheel, lever and roller).

Repeater: Watch that strikes the hours by means of a mechanism operated by a push-piece or bolt. There are various types of repeaters. Quarter-repeater: sounding a low note for the hours and a "ding-dong" for each of the quarters; Five-minute repeater: striking the hours, quarters and five-minute periods after the quarter; Minute-repeater: striking the hours, quarters and minutes; Grande sonnerie (grand strike): striking the hours and quarters automatically and repeating when a push-piece is pressed down; Chiming repeater: in which the quarters are struck on three or four gongs of different pitch.

Retrograde: Used to describe a pointer hand on a watch dial (often a sub-dial) which returns to zero at the end of a prescribed period. For example a watch may have retrograde date - in this case the hand moves up a scale a day at a time, pointing to the current date - when it reaches 31 it will spring back to 1

Rotating bezel: A bezel (the ring surrounding the watch face) that can be turned. Different types of rotating bezels perform different timekeeping and mathematical functions (see elapsed time rotating bezel," "unidirectional rotating bezel," "bi-directional rotating bezel" and "slide rule.")

Rotor: The oscillating mass which winds an automatic movement. A rotor most commonly is free to rotate in a full 360 degrees and may wind the watch when it is rotating in one direction only or indeed may wind in both directions through the use of reverser wheels and gears.

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S

Sapphire Crystal: Synthetic sapphire formed for use as the crystal of a watch. Extremely scratch resistant (9 on the Moh scale), a sapphire crystal is the material of choice for many watch collectors. The downsides are that sapphire can chip at the edges if they protrude and can shatter.

Screw-lock Crown: A watch winding crown which screws tightly to the case of the watch on a tube; the purpose is to ensure extreme water resistance.

Second time-zone indicator: An additional dial that can be set to the time in another time zone. It lets the wearer keep track of local time and the time in another state or country simultaneously.

Semi-perpetual calendar: Memory function that respects all date changes except for 29th February in leap years (manual correction).

Shock resistance: As defined by U.S. government regulation, a watch's ability to withstand an impact equal to that of being dropped onto a wood floor from a height of 3 feet.

Skeleton watch: A watch with no dial and only a chapter ring. As much metal is removed as possible and all the remaining parts are decorated with elaborate engravings.

Slide rule: A device, consisting of logarithmic or other scales on the outer edge of the watch face, that can be used to do mathematical calculations. One of the scales is marked on a rotating bezel, which can be slid against the stationary scale to make the calculations. Some watches have slide rules that allow specific calculations, such as for fuel consumption by an airplane or fuel weight.

Small seconds: A hand on a sub-dial which tracks seconds; typically it completes a full rotation in one minute.

Solar powered: A watch that uses solar energy (from any light source) to power the quartz movement. The Citizen >Solar-Tech< models use this technology and provide a 180 day power reserve, so they are able to run continuously. For more information, click here to go to Citizens Internet Site.

Spring bars (or pins) : Spring-loaded bars between the lugs on the case, used to attach a strap or metal bracelet to the case.

Split-seconds (rattrapante): In appearance a split-seconds chronograph is only slightly different from a standard chronograph. Its special feature is the additional device which drives a second center-sweep seconds hand called the split-seconds hand. When the chronograph mechanism is activated the two superimposed hands rotate around the dial. If the split-seconds pusher is pressed the split-seconds hand will stop, allowing the user to read the intermediate time. Meanwhile the chronograph seconds hand continues to turn. If the same pusher is pressed again, the split-seconds hand will catch up with the chronograph hand and continue to rotate in perfect unison with it. This operation can be repeated as many times as desired.

Stepping motor: The part of a quartz movement that moves the gear train, which in turn moves the watch's hands.

Stopwatch: A watch with a seconds hand that measures intervals of time. When a stopwatch is incorporated into a standard watch, both the stopwatch function and the timepiece are referred to as a chronograph.

Stop seconds (function): A braking system on the balance-spring which stops the seconds hand when the crown is pulled. This allows the seconds hand to be synchronized with an external time signal when setting the time (crown in position 3).

Striking-Mechanism: In a watch or clock, automatic or hand-operated mechanism that strikes the hours, etc, or rings an alarm-bell (v. repeater 

Sub-dial: A small dial on a watch face used for any of several purposes, such as keeping track of elapsed minutes or hours on a chronograph or indicating the date.

Swiss made: As a part of a move towards greater consumer protection and in order to combat fakes in the Far East that claim to be swiss made, the Swiss federal council in 1993 laid down the rule that a watch has to satisfy before it could be described as swiss made. The movement must be of Swiss origin, and must contain at least 50% swiss parts. The watch must be cased in Switzerland and pass its final inspection in that country.

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Tachymeter: A scale used to measure units per hour. Commonly found on the bezels of chronograph watches, an event is timed by using the chronograph seconds hand. The hand is stopped when the event ends and the hand will point to the number of units per hour that could be achieved.

Tank watch: A rectangular watch designed by Louis Cartier. The bars along the sides of the watch were inspired by the tanks used in World War 1.

Telemeter: ("tel EH meh ter"): A telemeter determines the distance of an object from the observer by measuring how long it takes sound to travel that distance. Like a tachymeter (see "tachymeter"), it consists of a stopwatch, or chronograph, and a special scale, usually on the outermost edge of the watch face.

Termocompensation: Electronic procedure for fine adjusting a quartz watch (comparable to inhibition), using a thermal sensor which allows better compensation of differences in rate resulting from temperature fluctuations experienced by the watch in use. Degree of precision: better than 1 second per month.

Terminage: French term denoting the process of assembling watch parts for the account of a producer.

Termineur: French term for an independent watchmaker (or workshop) engaged in assembling watches, either wholly or in part, for the account of an "établisseur" or a "manufacture", who supply the necessary loose parts.

Time zone (Function): Display of regional time (or universal time) by an independent movement of the hour hand, without affecting the watch's precision (minutes and seconds).

Timer: Instrument used for registering intervals of time (durations, brief times), without any indication of the time of day

Titanium: A metal that is used for some watch cases and bracelets. Titanium is much stronger and lighter than stainless steel. Titanium is also hypo-allergenic.

Tonneau watch: A watch shaped like a barrel, with two convex sides.

Tourbillon: A complex piece of micro-engineering which results in the escapement of a watch rotating on its own axis; the object of the exercise is to cancel out the variations in running regularity which can be caused by the watch being in different positions; (a watch may gain in one position yet lose in another).

Transparent case back: A transparent case back - frequently made of sapphire - makes it possible to see the movement inside the watch.

Tritium: An isotope of hydrogen used in the luminous compounds which give watch dials and hands their glow in the dark capabilities. Many watch dials will show a small T at the bottom, indicating the use of tritium. The half life of tritium is 12.5 years thus it will lose its ability to provide illumination as time passes. Now largely superseded by non-radioactive organic compounds such as the trade name Luminova.

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U

Unidirectional rotating bezel: An elapsed time rotating bezel (see "elapsed time rotating bezel"), often found on divers' watches that moves only in a counterclockwise direction. It is designed to prevent a diver who has unwittingly knocked the bezel off its original position from overestimating his remaining air supply. Because the bezel moves in only one direction, the diver can err only on the side of safety when timing his dive. Many divers' watches are ratcheted, so that they lock into place for greater safety.

UTC: Universal Time Co-ordinated. A universal time based on the Greenwich Meridian used by the military and in aviation. Greenwich Mean Time (GMT) can be considered approximately equivalent to Universal Time Co-ordinated(UTC).. GMT as such is now obsolete however, being replaced by UTC. Using this time zone/standard avoids errors and problems associated with different time zones and summer times operational in different countries.

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V

W

Water Resist/WR: Watches have varying degrees of water resistance, ranging from WR30 Meters to some specialist watches having a capability of withstanding water to 10000 Meters. The usual for a diver's watch is 200m whilst 100m would be suitable for everyday swimming.

Winder/Winding Crown: Same as Crown, above. Used for winding the watch and setting time/date.

World time dial: A dial, usually on the outer edge of the watch face, that tells the time in up to 24 time zones around the world. The time zones are represented by the names of cities printed on the bezel or dial. The wearer reads the hour in a particular time zone by looking at the scale next to the city that the hour hand is pointing to. The minutes are read as normal. Watches with this feature are called "world timers."

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X

Y

Yacht timer: A countdown timer (see "countdown timer") that sounds warning signals during the countdown to a boat race

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Z.