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Terms & Phrases This glossary is a compilation of terms and phrases that you will find throughout our website and when  discussing your clock and watch repairs or maintenance. 

You might also find our FAQ of interest. 
Alarm : A timing device that will make a sound at a user defined pre-set time. Alarm functions can be found in both quartz and mechanical watches and clocks. 
Analog watch : A watch that consists of hands and a dial with typically 12 hour numbers or baton s to indicate the positions. 
Arbor: Shaft on which wheels and/or pinions are fixed. Pivots at the end of the Arbor run in plates or jewels. 
Arc of Vibration: The measure of rotational movement of a balance or pendulum from one extreme to the other. 
Automatic Watch: Also known as a self-winding watch, is a mechanical watch that has a device powered by the motion of the wearer to replenish power into the mainspring. 
Band: Also known as a strap, attached to the watch it holds the watch on the wearer’s wrist. It is attached to the case with spring bars which are fixed between the lugs with holes. Typically made from materials like: leather, fabric, rubber, and metal. 
Balance Spring: Also known as Hairspring. A spiral of special alloy metal attached to the balance that will try to return to the balance to its neutral position (recoil). When acted upon by a force, it acts as a resonant oscillator to ensure constant regular swings of a known frequency. 
Balance: The wheel that oscillates back and forth at a frequency governed by its mass and the restoring power of the balance spring. 
Barrel: A cylindrical hollow container with an arbor running through the middle that consists of a gear and teeth. It holds the mainspring of a mechanical watch, allowing winding of the mainspring via the arbor and powering the watch via the teeth round the circumference. 
Battery: A battery is a chemical reaction cell that produces direct current to power electrically driven watches. 
Bezel: A bezel is a ring located on the upper part of the watch body, it can be used to secure the crystal (glass) to the watch. Or a rotating bezel can be found outside of the crystal. A rotating bezel is to be able to begin timing an event at any given time. The three types of bezels are: Fixed bezel which cannot be turned; Uni-directional bezel which is turned in the counter clockwise direction; and Bi- directional turning bezel which can be turned both ways. 
Bob: The weight that is attached to a pendulum rod. The raising and lowering of the bob will change the effective length of the pendulum, therefore altering the rate of oscillation. 
Bow: A hoop at the top of a pocket watch that a pocket watch chain may be attached to. 
Bracelet: The bracelet is a flexible metal strap. The Bracelet may be made out of any metal or synthetic material; it is attached to the case with spring bars which are fixed between the lugs with holes. In most bracelets links can be removed to adjust the size for the wearer. 
Bracket Clock: A clock that is designed to be in a semi permanent position (not portable), spring driven and often larger than a mantel clock. 
Bridge: The Bridge is a shaped part fixed very precisely into the main plate. Consisting of holes, posts, pins and jewels. Its primary function is to keep the different parts in their correct positions while also allowing them to pivot. 
Bush: A bearing surface in clock or watch plate in which the pivots turn. Small cylinders of metal are often used to replace these, to correct wear from long use and provide a fresh bearing surface when broached to the correct size for the pivot. 
Calendar: A complication/function which indicates days of the month. There are 2 types of displays for indicating the date on a calendar watch: hands, and discs. With hands the day and the month are shown by hands on small dials. With discs the day of the week and names of the months appear on disks which revolve under the dial. 
Calibre: Can be the movements model number to uniquely identify that particular design. 
Cannon Pinion: The part of the watch / clock that carries the minute hand. Driven my the movement, but also has a friction device that allows the correction of the time by the user. 
Carriage Clock: Small portable spring driven clock, typically brass or metal framed with glass panels on four sides and a small carrying handle on the top. Platform escapements used in carriage clocks make them portable. 
Case: The metal component that houses the watch’s parts. There are many shapes and materials from which cases may be made. 
Carat: Carat is a term used to refer to the measure of weight for gemstones. 
Chiming clock: A clock that has a selection of bells or gongs of different pitches that will play a melody when struck in the correct order, often denoting the quarters of the hour. e.g. Westminster Chimes. 
Chronograph : A chronograph is a watch that has the ability to tell the time and independently measure time. It can be started, stopped and reset by the user. 
Chronometer: Denotes a timepiece which satisfies certain timekeeping accuracy standards. 
Clasp: The device used to connect the two ends of the watch bracelet around the wrist. 
Click: Device that is part of the winding mechanism that insures that the mainspring when wound is not able to unwind itself. 
Collet: A collar that is either spit or solid that is used to attach a wheel or other similar component to an arbor. 
Complication: An additional function more than the basic movement timekeeping. These can include calendar, chronograph, power reserve, Tourbillion, minute repeater, quarter repeater. 
C.O.S.C.: Control Officile Suiss de Chronometers. The official chronometer testing organization in Switzerland. 
Crown: The knurled/textured button on the outside of the case, used to set the hands and date on all watches and to wind the mainspring on mechanical watches. 
Crutch: Link between the pendulum and the escapement. 
Crystal: The clear material on the top of the case covering the dial and hands. Three types of crystals are: synthetic (acrylic), natural, and sapphire crystals. Synthetic crystals are made of soft material and are easily scratched. Natural glass crystal may be scratched by very hard substances. Sapphire crystals can only be damaged by a diamond. 
Day/Date Watch: A watch with a complication that indicates the date and days of the week. 
Demagnetiser: A tool used by watch and clockmakers to remove any magnetism that a watch/clock may have developed over its life. Magnetised components can severely affect the timekeeping and can even stop a movement from running. 
Deployment Buckle: A clasp that folds under the strap of the watch. The buckle is expanded so that the watch can be slipped on and easily closed to fasten on the wrist. 
Dial: A flat brass disk known as the watch face that the numerals, indicators, and surface design/branding are applied to. 
Dial Clock: Circular large pendulum wall clock. Often known as School clock, office or kitchen dial. 
Digital Display: A type of display that shows information such as numbers, letters, signs, images, etc. which are provided by electronic signals. For example LCD or LED displays. 
Diver’s Watch: A watch designed for any underwater activity usually equipped with a rotating bezel, screw down crown, and thicker gaskets (‘O’ rings) designed to withstand higher pressures caused from being submerged at greater depths. 
Drop Dial Clock: Similar to the Dial Clock, with the exception that the case is extended below the dial to allow for a longer pendulum to be utilised, sometimes with a glass panel so that the pendulum can be seen swinging. 
Dual Time Watch: A watch that is capable of measuring current local time as well as at least one other time zone. 
Elapsed Time: A measurement of time from a start of a measurement to the last measurement. 
Engine Turning: A process to obtain a decorative finish to parts of a watch or clock. Engine Turning or Guilloche refers to delicate surface engraving onto watch or clock components including: cases, plates, dials, bezels, and movements. 
Escapement: The Escapement stops and starts the movement or the watch or clock gear train and is also an energy distributing unit. The purpose of the escapement is to unlock and lock the gear train in accordance with the oscillations of the balance wheel of a watch, or a pendulum of a clock, via the escapement, a small amount of energy (impulse) is provided to the balance or pendulum the keep the oscillations going. 
Face: The visible side of the watch or clock, also known as the dial. 
Friction Rest Escapement: Where the escape wheel is in constant contact with the balance e.g. Virgule escapements. Therefore there is always some friction present between the two components. 
Function: A term used to describe the different tasks that a watch can perform. e.g. Date/chronograph. 
Fusee: The spirally grooved pulley used to compensate the different forces produced at different states or winding of the mainspring. A fully wound mainspring has more force acting on the gear train then a partially wound mainspring. 
Gasket: A type of 'O' ring. A rubber or plastic ring that ensures a dust and water resistant seal between two separate parts, for instance, a crown and crown tube, or case and case back. 
Gilt: A gold coloured coating applied to base metals such as brass. 
Glass Crystal: Located on the topside of the case, covering and protecting the dial and hands. Natural glass crystal may be scratched by very hard substances. 
GMT time zone: Greenwich Mean Time, also known as Zulu Time, and Universal Time Coordinated (UTC). Greenwich, England is the place from where all time zones are measured. It is placed on the Prime Meridian or Zero Longitude, and was set as a standard by which all World Time is set. The World Time was agreed to at the 1884 International Meridian Conference at Washington DC, USA. 
Gold: A precious metal, a soft yellow corrosion-resistant element. Soft in it's pure form, often alloyed with other metals to make a more hard wearing material. 
Gold Plating: Applying a thin gold layer onto a base metal like silver, or copper to enhance, and give the metal a look of gold. Method of application can be by either electrolysis or chemical deposition. The thickness of gold plating is measured in microns. 
Guard pin: Part of the pallet fork, this is a safety device that prevents the pallet fork from moving to the incorrect side of the balance impulse pin if the watch was to receive a physical shock whilst being worn. 
Gut line: The line that is used to suspend weights in clocks and also that can be used to run from a mainspring barrel to a fusee. Synthetic gut is typically used, Historically the gut would have been derived from animal origins. 
Half Hunter: A style / feature of a watch case that has a small central aperture in the front lid to show a portion of the dial and hands. 
Hall Mark: Used as the official quality and grade control of gold and silver with markings that denote date, location of assay office and purity of the gold or silver. 
Hands: The indicators on the watch face that point to the hour/minute markers to allow the reading of the time. There are many different shapes / styles. The appearance of the hands give a watch a certain style. They can be made of brass, steel, gold, or aluminium. The quality of the hands is very important; they must remain firm on their central pivot if the watch is subjected to a violent shock so that the do not move to display the incorrect time. 
Hairspring: Also known as Balance spring. A spiral of special alloy metal attached to the balance that will try to return to the balance to its neutral position (recoil). When acted upon by a force, it acts as a resonant oscillator to ensure constant regular swings of a known frequency. 
Hand winding Watch: Also known as a Manual Winding watch. The watch movement is powered by the wearer winding the mainspring by hand, typically by turning the crown. It is desirable for a fully wound mainspring to power the watch for a minimum 24 hours, although there are some watches with a 7 day power reserve or longer. It all depends on the quality and price of the watch (36 hours running time from a full wind can be expected from a high grade watch). 
Horology: The study and art of manufacturing or repairing watches and clocks. The science of time measurement. 
Hunter: A style / feature of a watch case that has the face of a watch fully covered by a cover or lid that is easily opened by the wearer by depressing a button 
In Beat: A term used to signify that the action of the escapement of a watch or clock balance or pendulum has equal timing between each half swing of both sides of the neutral resting point' 
Incabloc: Is the trade name for a spring loaded shock resisting system that protects the delicate balance pivots from damage. The jewel holes and end stones of the balance have some give when the watch receives a jolt, once the shock is over, the spring returns the jewel holes back to the original position. 
Jewel: To reduce wear and friction in watch movements, jewels used. These are synthetic rubies, often with holes in the middle and a profile that allows for a very small amount of oil to sit in reserve. Jewels serve as bearings for the gear trains. A pivot which turns in a ruby bearing will encounter a minimum of friction and wear, ensuring long life and reliable performance compared to a pivot running in a metal pivot hole. 
Karat: Karat is a standard measurement of the purity of gold alloys. 24K refers to 100% pure gold, 18K refers to 18 parts of gold mixed with 6 parts of metal. 
Key: A tool that fits onto a squared extended part of the watch or clock to allow the user to wind the watch or clock. 
Also – as typical key that is designed to work with a lock on the casing of a clock. 
Keyless: Description of the operation and the design feature of more modern watches. This feature gives the wearer the ability to wind and set hands of a watch without a key usually refers to a watch where winding and hand setting can be performed using the crown in different positions. 
Key Wind: A watch of earlier type, prior to the invention of keyless work, that is wound and hands are set with a key. 
Kinetic: A kinetic watch dies not have a battery or need to be wound. The watch harnesses the motion from the human body to keeps the watch running. The watch movement has an Oscillating weights that create a magnetic charge and convert it to energy by the movement of the wearer’s wrist / arms. Instead of a battery/cell, they store the energy produced in an accumulator, often a capacitor. 
Lap Timer: A chronograph function that allows the wearer to measure continuous or interrupted periods of time, for example segments of a race with the overall time from the start still being measured. 
LCD Display: Liquid Crystal Display shows time electronically by means of a liquid held in segments a thin layer between two transparent plates. When a current is applied to a segment it turns opaque, the patterns of segments that are displayed will form numbers or symbols. 
Lever Escapement: Invented by Thomas Mudge in 1759 getting its name from one of the components which acts as a lever. 
Luminous: Luminous paint (Lume) is a material applied very accurately to the hands and dials of many modern watches. The purpose of the lume is to help the wear tell time in low light conditions. It stores energy from light sources in high light conditions (ultra violet light from the sun and florescent light bulbs). Then in low light conditions, this energy is converted back to visible light through florescence. 
Mainspring: The mainspring is the means by which a clock or watch stores power. It is a coiled metal strip with a rectangular cross-section. The driving force needed for the watch to run is produced by the uncoiling of the spring, which is wound around the core of the barrel arbor. 
Manual Winding Movement: Also known as a hand winding watch. The watch movement is powered by the wearer winding the mainspring by hand, typically by turning the crown. It is desirable for a fully wound mainspring to power the watch for a minimum 24 hours, although there are some watches with a 7 day power reserve or longer. It all depends on the quality and price of the watch (36 hours running time from a full wind can be expected from a high grade watch). 
Mechanical Movement: A movement powered purely by kinetic forces without the need of an outside electrical source. The movement is comprised of many components that allow the mainspring to slowly unwind, releasing energy to move the gears that drive the watch or clock. 
Minute Repeater: A type of complication to give an audible approximation of the time, it is a complex mechanism that is activated by the operator using a slide or a push-button. A minute repeater can chime the time down to the minute using different tones for hours, quarter hours and minutes. 
Moon Phase: An visual indicator that keeps track of the duration of a lunar cycle, ordinarily a rotating disc which bears two images of the moon one of which will be partially obscured. One lunar cycle is 29 days, 12 hours, 44 minutes, and 2.8 seconds. 
Mother of Pearl: An iridescent milky interior shell of the freshwater mollusc that can be used to decorate watch dials. Its colours vary and can have a milky white lustre, and is also available in an array of colours such as pink, blue, grey, yellow, and more. 
Movement: The internal mechanism of a watch or clock. It is the assembly of components that keeps time, and performs all available functions. There are 3 types of movements: Mechanical (Automatic, Manual-Wind), Quartz, and Kinetic. Mechanical movements rely on the mainspring to drive the watch. Quartz watches rely on a battery to give the movement power. Kinetic watches are powered by the motion of the wearer while worn which allows an oscillating weight to create a magnetic charge and convert it to energy that powers the watch. 
Open Face: Refers to a watch not fitted with a cover. 
O-Ring: Also known as a gasket, A rubber or plastic ring that ensures a dust and water resistant seal between two separate parts, for instance, a crown and crown tube, or case and case back. 
Pair Case: Two watch cases where the movement is fitted into one case then is fitted into an outer case. 
Pendant: A part of the watch case that has the Bow fitted. 
Perpetual Calendar: A complication that indicates day of the week, date, month, and can include the phases of the moon. A complex mechanism, it automatically adjusts for months of varying lengths (28, 29, 30, 31) days. 
Platinum: One of the rarest and most durable of precious metals. Because Platinum is wear and tarnish-resistant, it is well suited for making fine jewellery. 
Push-piece: Also known as a Push Button, a device for the wearer to activate and control functions on a chronograph watch. 
Quartz Movement: An electronic watch movement powered by a battery, which uses vibrations of a small shaped quartz crystal that vibrates at a known frequency to maintain timing accuracy. The crystals are made up of silicon and oxygen that crystallize in a hexagonal pattern. 
Rack Lever Escapement: Also known as rack and pinion escapement. A lever escapement using a toothed rack in place of the table roller and impulse jewel where the lever is in permanent engagement with the balance. 
Railway Time: Greenwich Mean Time. 
Repeater: Description of a complication that can on demand signify the time audibly. A repeater will typically sound the number of the most recently passed hour. The Minute-Repeater is a highly complex mechanism used to tell time to the nearest minute on demand, this is indicated by the sound of two hummers hitting two gongs of different pitches. 
Retrograde: A watch or clock that displays time in a linear manner instead of showing time in a circular fashion. Such that the hands are not moving around in a circle; they travel along an arc. When they get to the end, they jump back to the beginning. 
Rhodium Plating: A procedure by which a metal surface is coated with a thin layer of Rhodium. The main reasons for plating metal are: to enhance its appearance, and provide protection against corrosion. 
Rotating Bezel: A ring with indicators on it located on the upper part of the watch body. The rotating bezel is typically found on watches described as dive watches, this provides a countdown timer for diving. 
Rotor: Another term for the Oscillating weight found in automatic watches. Its function is to wind the watch. The rotor is a flat piece of metal usually shaped like a semicircle, which swivels on a pivot under the influence of gravity and the motion on the wearer. 
Sapphire Crystal: A type of material. Located on the topside of the case covering the dial and hands. This is the highest quality and most scratch resistant transparent crystal, made of synthetic sapphire that is shatter-resistant and scratch- resistant. Sapphire crystals can only be damaged by a diamond. 
Screw Down Crown: A design feature that gives a greater degree of water resistance to a watch. A Screw-Down crown is an essential feature for any watch intended to use with any water activity. The crown has a gasket that forms a seal with the gasket in the crown tube. The seal is achieved by the matching of a threaded tube on the case with the crowns internal threads which is locked into its place by turning the crown clockwise compressing the gasket to make a better seal. 
Self-winding: Another word for Automatic watch. It is a mechanical watch whose mainspring is wound automatically by the of motion on the wearer. 
Shock Resistant: The watch’s ability to withstand impact, for instance the dropping of the watch or knocking into door frames. 
Skeleton Watch: A watch in which the case and various sections are either cut away or are of transparent material, thus allowing visibility of the watch’s internal components as they work. 
Solar Technology Powered: A feature found on some quartz watches. Similar in operation as a kinetic watch, an accumulator (capacitor) is charged / recharged by a solar panel embedded in or behind the watch dial. 
Stainless Steel: Material used in manufacture of watch cases/An extremely durable metal alloy that is virtually rustproof, and resistant to corrosion and discolouration, can be polished to a high shine. 
Stem: The winding shaft of a keyless wind watch, this connects the crown to the movement. 
Stopwatch / Timer: A handheld timepiece designed to measure intervals of time. Function found on chronograph watches. 
Strap: A watch band that holds the watch on the wearer’s wrist. It can be made out of cloth, rubber, or leather and designed into many different sizes and shapes. 
Striking Clock: A clock that has an extra gear train that is linked to the time gear train, it it triggered when the turn to the next hour and sounds the number of hours on a gong or bell. 
Swiss A.O.S.C. (Appellation d'Origine Suisse Certifiée): A certificate of origin. A mark identifying a watch that is assembled in Switzerland and has components of Swiss origin. 
Tachometer: A scale located on the bezel, or printed on the outer diameter of the dial. Tachometer can be used to measure speed over a predefined distance in mph or km/h. 
Tachymeter Chronograph: Has a calibrated dial so that miles per hour can be seen. Alternatively it can be used to measure an interval of a unit operation and shown the number of operations that would happen in an hour. 
Tank Watch: A rectangular timepiece created by Louis Cartier. Tank watch is equipped with heavier bars on either side of the watch. This design was inspired by the tank tracks of World War I. Often now used as a term to describe the shape of a watch case. 
Timepiece: A device that has a single function to tell the time, not a striking or chiming mechanism. 
Timer: Instrument used to measure and register intervals of time, without any indication of the time of day. 
Ting tang clock: A clock that sounds out the quarter and half past hours on two differently toned bells. Typically a high pitched 'Ting' and a lower pitched 'Tang'. 
Titanium: A “Space Age” metal, recognized for its high strength and light weight. Titanium is 30% stronger and nearly 50% lighter than steel. It is resistant to salt water corrosion and discolouration, therefore makes it a perfect material for Dive watches or lightweight watches. 
Tourbillion: Tourbillion is an additional mechanism of a mechanical watch that reduces the effects of gravity, and compensates for the difference in rate caused by different positions. The Tourbillion device comprises the escapement, balance wheel, hairspring, and the pallet fork. All of those parts are mounted in a cage; the entire cage assembly rotates around their common axis in order to average out the effects of gravity in different positions. This mechanism is highly complex and is an extremely difficult to achieve. Specialised literature must be studied in order to become familiar with the Tourbillion complication. 
Train: Also known as gear train. The succession of wheels (gears and pinions) driving a watch. 
Uni-directional Rotating Bezel: A bezel located on the upper part of the watch body, found around the crystal. Uni-Directional bezel can only be turned in the counter clockwise direction. It is used for timing sport events, and marking elapsed and remaining time while diving. For safety when diving, if the bezel were to be knocked it would only move in one direction, this direction would only give the impression of a shorter time remaining. A critical safety feature for dive watches. 
Verge: Also know as crown wheel escapement. An early recoil escapement (dated from 13th Century Europe) with a crown escape wheel and pallets on a rod (Verge) set at right angles to the axis of the escape wheel. 
Water Resistance: A very important feature in modern watches that protects the vital parts against water, dust, and humidity, this extends the life of the watch and reduces service intervals. Different watches can withstand protection against water to certain extents. Please refer to the watch manual, or see the water resistance section for a description of different levels of water resistance. 
Winding Crown: The button on the right side of the watch case, used to wind the mainspring, and set the time and date on the mechanical watches. Used to set the time on quartz watches. Winding crown may be decorated with a cabochon stone, or a decorative cap of a precious metal. 
Winding: An adding of power to the mainspring in a watch. This can be done manually by turning the crown clockwise or automatically by an oscillating weight (rotor) which is made to swing by the natural movement of the wearer. 
World Timer: A disk on the outer edge of the watch dial which represents 24 different time zones. The World timer can display the current time in any part of the world. The names of the cities are printed on the disk. The hour in a particular time zone can be read by looking at the scale next to the city that the hour hand is pointing to. 
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