Clocks Magazine Glossary
Beginners Guide to Clock Repair Collectable Pocket Watches 1750-1920 Clocks logo Beginners Guide to Pocket Watches horological gift idea

Glossary of horological terms

Acorn clockType of American shelf clock said to resemble an acorn in shape
Act of Parliament clocksee tavern clock
AnalemmaFigure-of-eight shape describing the Equation of Time
Anchor escapementsee escapement, anchor
Anniversary clockClock with torsion pendulum, which runs for over a year at one winding. Also known as 'four-hundred day clock'.
ArborSpindle or axle on which clock wheels, pinions etc are mounted.
Atmos clockClock which derives its motive power from variations in atmospheric pressure.
AutowinderMechanism based around an electric motor which winds a clock automatically.
Back cockSingle-foot bracket, usually of brass, which holds the rear pivot of the escape wheel
Back platesee movement plates
Balance (wheel)Non-toothed wheel of watch or chronometer movement, or platform escapement which spins alternately clockwise and anticlockwise, under the influence of the balance spring, moving a lever or detent on each pass. This lever or detent governs the rate at which power escapes from the train and thus the timekeeping of the mechanism.
Balance, floatingBalance suspended in position vertically by helical balance spring
Balance springCoiled spring which controls the back and forth spinning of the balance wheel
Balance staffArbor on which the balance wheel pivots
Balloon clockClock in the shape of a hot-air balloon, usually French
Banjo clockClock said to resemble a banjo, invented by American clockmaker Simon Willard, 1753-1848, of Roxbury, near Boston, Massachusetts.
BarrelShort cylinder of brass which contains the mainspring.
BarometerInstrument for measuring atmospheric pressure.
Beat (setting)The 'tick-tock' of the clock as the escapement operates. The 'tick' should be of equal length to the 'tock', beat-setting being the process of making sure this happens, after which the clock is said to be 'in beat'.
Black Forest clockClock from the Schwarzwald or Black Forest area of Germany, often with wooden movements manufactured on a cottage-industry basis.
Blu(e)ingThe process of heating steel until it changes colour to blue.
Bob The part of the pendulum at the far end of the rod from the suspension. The bob accounts for most of the weight of the pendulum
BodgingRepairing a clock badly, in a very amateurish manner.
Bornholm clocksClocks from the Danish island of Bornholm.
Bracket clockStyle of spring-driven British clock, once thought to have stood on a matching bracket attached to the wall.
Break-archThe arch which sits on top of an otherwise square dial, the base of the arch being somewhat narrower than the top of the square.
Broach(ing)The process of widening a hole, usually a pivot hole, using a tool of the same name
Bush(ing)The process of plugging elongated or misshapen holes in movement plates using small cylinders of brass (know as 'bushes' or 'buchons') so that pivots will run properly.
Caddy topTop moulding of a longcase clock or bracket clock featuring an S-shape, wider at the bottom than the top.
Cannon pinionPinion which drives the motionwork of a clock, part of which takes the form of a hollow cylinder (thought to resemble a cannon) on to which the minute hand fits
Carriage clockSmall travelling clock, usually in a brass or decorated brass case with a platform escapement and a carrying handle, often with an outer case finished in leather.
Cartel clockA highly decorative wall clock, usually French, sometimes English, made from ormolu.
Cartwheel dialLongcase clock dial with cut-outs behind the chapter ring giving a superficial resemblance to a cart wheel.
Centre arborArbor of centre wheel which revolves once every 12 hours to which the cannon pinion is attached
Centre wheelThe wheel, usually the third wheel of the time train, on the arbor of which the minute hand is mounted.
ChamplevéType of enamelling popular on carriage clocks, the enamel sitting in depressions engraved in brass.
Chain, fuseeFine bicycle-type chain which winds on to a clock barrel and connects it to a fusee allowing the power of the mainspring to be delivered evenly to the train
Chapter ringThe ring on a clock dial which shows the hours or 'chapters', showing religious derivation: the first clocks were in monasteries, reminding the various chapters of monks of the times of their religious duties.
ChimeShort tune played by clock on the hours and quarters.
ChinoiserieOriental style lacquer work used on clock cases.
ChronometerType of clock specially designed to keep accurate time at sea, usually held on gimbals in a wooden box.
click, clickspringThe click is a ratchet pawl used in winding springs, the clickspring being a small spring which keeps the click in engagement with the ratchet.
ColletCircular ring used to hold clock parts on arbors etc.
Comtoise clockStyle of clock made in the Franche Comté region of France, also known as Morez or Morbier clocks
Congreve clockClock devised by British inventor William Congreve, 1772-1828, in which the escapement features a ball running in a zig-zag channel on a brass plate.
CountwheelStrike train wheel which determines the number of times the clock strikes at a given hour.
Crown wheelEscape wheel in verge escapement with teeth are at right angles to the plane of the wheel, resembling a crown.
Crown wheel escapement see escapement, verge.
CrutchLever which transmits impulse from escape wheel to pendulum and transmits the beat from the pendulum to the pallets
Cuckoo clockBlack Forest clock, often highly carved and shaped like a house, from which a carved cuckoo appears on the hour while the clock strikes with a 'cuckoo' sound.
Depthing Establishing the correct meshing of wheels and pinions in a clock train, often using a depthing tool
Detent Stop which holds the ratchet of the maintaining power in a chronometer
Dial Face of clock or watch against which hands show the time
Dial, brass Face of longcase clock made of brass, usually with silvered chapter ring
Dial, painted Face of longcase clock, post 1770s, which has the chapters, spandrels and other decoration painted on to an iron sheet, rather than being engraved and applied on to brass. Also known as a 'white' dial
Draw Part of the escapement action in which the pallet nib is drawn inwards by the tooth of the escape wheel against which it bears
Drop-trunk Also incorrectly known as 'drop-dial', the drop-trunk wall clock is a clock similar to an English dial clock but where the box which conceals the pendulum projects below the circumference of the dial
Drop Part of the escapement action in which the pallet nib is falls or 'drops' on to the tooth of the escape wheel
Engine-turning Type of decoration often used on the plates of American watches, also known as 'damascening' due to the similarity of the effect to damask
English dial clock Type of wall clock which originated in Britain in which only the dial is usually visible, the movement, pendulum etc being hidden behind it. These clocks were commonly used in public buildings such as schools, post-offices, government buildings etc
Equation of Time The difference between apparent time and mean time, which can differ by up to 15 minutes per day, mean time being the average or mean of the differing day lengths caused by wobble in the earth's orbit
Escapement The mechanism at the end of the wheel train which allows the power to escape in regular bursts, thus allowing the accurate display of the passage of time
Escapement, anchor Type of escapement popular with the makers of English longcase clocks, the pallets of which are similar in shape to a ship's anchor
Escapement, bent-strip Escapement used particularly by American clockmakers, the pallets of which are fashion out of a strip of metal bent to shape
Escapement, co-axial Escapement designed by George Daniel which compensates for the drying out of oil in watches
Escapement, cylinder Escapement in which part of the balance staff is formed into a cylinder on which the teeth of the escape wheel act to allow power to escape
Escapement, dead-beat Escapement without recoil, giving more accurate timekeeping than the anchor escapement
Escapement, duplex Watch escapement designed by George Daniel to compensate for the drying up of lubricants in the movement
Escapement, lever Type of escapement, common in watches, in which the pallets form part of a lever which is rocked back and forth by a pin on the balance wheel to release power in regular bursts
Escapement, platform Type of lever or cylinder escapement mounted on a platform to make it easily removable from the wheel train, often used in carriage clocks
Escapement, recoil see Escapement, anchor
Escapement, tic-tac Type of recoil escapement, the pallets of which embrace just one or two teeth of the escape wheel
Escapement, verge Primitive form of escapement in which a verge swinging back and forth under the influence of a balance or a pendulum interrups the revolution of a crown wheel, allowing the wheel to turn at a regular and predictable rate and thus the clock to keep time
Escape wheel Wheel on which the nibs of the pallets act to release power from the going train in a regulated manner
Falseplate Metal plate which attaches to the rear of the dial of a white or painted dial longcase and to which the movement in turn is attached
Finial Decoration used to 'top-off' part of the case of a clock. Finials are commonly found at the top corners of the case of a longcase or bracket clock and on the bellstand of a lantern clock
Fly Arbor carrying vanes, usually at the end of the strike train, which acts as an air-brake, slowing down the rate at which the train runs when striking takes place
Fly dial Dial of painted dial longcase clock with fly or bee painted on as decoration
Foliate Pertaining to foliage, often used in referring to engraving or decoration of clock cases
Foliot Bar carrying pallets, part of verge escapement
Four-glass clock Clock in case normally made of metal with four windows or glasses, one at the front, one at each side, and one at the top
Franklin three-wheeler Clock invented by American inventor Benjamin Franklin which has only three wheels in the going train. The dial layout is necessarily modified from the normal 12-hour layout to a four-hour layout, thus what would normally be the three o'clock position shows one o'clock, five o'clock and nine o'clock, six-o'clock shows two-o'clock, six o'clock and ten o'clock and so on
Fret Opening, usually highly decorative, in clock case to allow sound of bell to be heard. Also decoration above dial of lantern clock
Fusee Conical construction from which a chain or gutline is pulled by the spring barrel on, for example, a bracket clock, allowing the power of the mainspring to be released evenly
Gallery clock Clock designed to be mounted in the gallery of, for example, a church
Gathering pallet Pin on striking train which 'gathers' the rack teeth allowing the clock to strike the requisite number of hours
Girandole Type of banjo clock pioneered by Lemuel Curtis (dates) of (place) thought to resemble a girandole
Gong Bar of bell metal on which certain clocks chime and/or strike
Gnomon The part of a sundial which casts a shadow
Grand sonnerie see sonnerie
Gut (line) Gut or plastic cord which performs the same function as the fusee chain
Hairsping see balance spring
Half-quarter markers Markings on the dial of esp. single-handed longcase clocks half-way between the quarter hour markers, eg at seven and a half minutes past the hour etc
Heliochronometer Type of sundial which uses a lens to focus the sun's ray on a scale indicating time of day.
Hood Top section of the case of a longcase clock, usually removable, which surrounds the dial
Hooded (wall) clock Weight-driven wall clock in wooden case which resembles the hood of a longcase clock
Hour wheel Part of the motionwork to which the hour hand his fitted
Hunter Pocket watch cover over crystal. Also 'half-hunter', in which the metal cover has a lenticle to allow time to be viewed while the cover is closed
Huygens loop Where the rope which carries the weight which drives a longcase clock is formed into a loop, or endless rope, and arranged in such a way as to provide maintaining power for the clock
Impulse Part of the action of the escapement in which the tooth of the escape wheel gives a slight 'push' to the pallet in order to keep the pendulum, balance etc in motion
Jacot tool Tool used for polishing and burnishing clock pivots
Japanning Oriental lacquerwork found on cases of, for example, longcase clocks
Jewelling The process of inserting a doughnut-shaped jewel, usually an industrial ruby, into the pivot holes of a watch, chronometers or regulator escapement, in order to eliminate or minimise wear in the pivot hole
Joker Type of small Black Forest carriage clock
lancet (top) clock American clock with a pointed-top case, similar in shape to a lancet
lantern clock The first truly British domestic clock, made of brass and iron, the shape thought to resemble a lantern
lantern pinion Type of pinion with wire pins - trundles - instead of leaves
Leaf (leaves) The name given by horologists to the teeth of a pinion
Lock Part of the action of the escapement in which the pallets are 'locked' by the escapewheel
Loupe Watchmaker's eyeglass
Longcase clock Floor-standing, or 'grandfather' clock
Lunar cycle Period of 29 and a half days, approximating to the time taken for the moon to go round the earth
Mainspring Coiled flat spring which powers spring-driven clock movements, often contained in a barrel
Maintaining power Mechanism which keeps the clock hands moving while the clock is being wound up
Mantel clock Small clock designed to sit on a mantelpiece
Marquetry Highly ornate inlaying technique used to decorate clock cases
Mass dial Dial scratched into the wall of an ecclesiastical building to show times at which mass is celebrated, also known as a 'scratch dial'
Master clock Electrical clock which sends out signals to slaves to allow them to display the time
Matting Process or effect of finishing brass, esp centres of clock dials, with matt or stippled surface
Meccano Constructor set with metal pieces which can be bolted together to form larger constructions such as clocks, originally a child's educational toy. 'Erector' is the American equivalent
Minute wheel 12:1 wheel and pinion arrangment which converts the hourly revolution of the cannon pinion (and minute hand) into the 12 hourly revolution of the hour wheel (and hour hand)
moonphase System for showing age of moon on clock or watch dial
Morbier clock see Comtoise clock
Morez clock see Comtoise clock
Motionwork Gearing which converts the hourly rotation of the cannon pinion into 12-hourly rotation of the hour wheel
Movement The clock (or watch) mechanism
Musical clock Clock able to play tunes, usually on the hour
Mystery clock Clock with a hidden movement or no apparent connection between the movement and hands, so that it is not clear to the viewer what turns the hands
Napoleon's hat clock Style of mantel clock first produced in Britain in the 1930s, its wooden case thought to resemble the type of hat worn by Napoleon Bonaparte
Nib Part of the pallet which engages with the teeth of the escape wheel
Nightwatchman’s clock Type of clock used by a night watchman which records where he was on the premises at particular times of night
Norfolk clock Wall clock similar in style to a longcase clock with a long drop trunk
novelty clock Clock which exhibits some unusual feature often not associated with timekeeping. The mystery clock is a form of novelty clock
OG clock see ogee clock
Ogee clock American shelf clock in rectangular case with dial at top and reverse painted tablet below, with S-shaped or 'ogee' moulding round the edge
Oil sink Hemispherical depression in movement plate at pivot hole to retain oil which lubricates pivot
Orrery Mechanism which models the movements of the planets, named after the Duke of Orrery who had one made
Painted dial Dial developed in the 1770s in which the chapters and decorations were painted, usually on to a white ground, rather than being engraved on to brass
pallets Part of the escapement of a clock or watch which interferes with the movement of the escape wheel allowing power to escape from the going train at a regular rate
Pendulum Mechanism consisting of a bob, rod and suspension which, swinging back and forth, is part of the escapement of many clocks
Pendulum, Royal The so-called 'long' pendulum used in traditional longcase clocks which beats seconds, 39.14 inches in length
Pillars Cylindrical pegs which hold apart the plates of movements
Pinion Small clock gear, usually paired with a wheel on the going, striking or chiming train of a clock
Plates Parts of the movement between which the wheels run. The plates carry the pivot holes which carry the pivots of the arbors, plus the motionwork and, on striking and chiming clocks, a variety of levers.
Platform escapement see escapement, platform
Public clock Clock intended to be viewed by the public, usually outside, often on a church or public building
Pull repeat Type of repeat work activated by pulling a cord
Rack Toothed lever used in rack striking for counting off the hours
Recoil Part of the action of, for example, the anchor escapement in which the escape wheel turns momentarily backwards
Regulator Highly accurate clock. Workshop regulators were used to time other clocks by
Repeat, repeat-work Mechanism which allows a clock to strike the hours (and occasionally quarters) after they have been struck on the hour
Rod The part of the pendulum between the bob and the suspension
Royal pendulum see pendulum, royal
Schild dial Dial in the shape of shield, as used on some Black Forest clocks
Scratch dial see mass dial
Seatboard Wooden board on which the movement of a longcase clock sits
Shelf clock A clock which is designed to sit on a shelf, cf mantel clock
Singing bird clock Musical clock featuring a bird which appears to sing, often opening and closing its beak as it does so
Skeleton clock Clock with plates which are fretted out to allow the movement to be seen
Slave Electrical clock controlled by a master clock
Sonnerie, Grand Clock, generally a carriage clock, which strikes the hour and quarter at each quarter as well as on the hour
Sonnerie, Petite Clock, generally a carriage clock, which strikes the quarter but not the hour at each quarter
Strike The act of sounding the hours (and often quarters) on a bell or gong
Strike/silent Mechanism, usually with a hand in a subsidiary dial above the main dial, which allows the strike to be turned on or off
Strut clock Clock propped up on a strut behind
Sundial Instrument for measuring time by means of the position of the sun in the sky
Subsidiary dial Small dial on main dial of a clock which allows other features such as seconds, date etc to be shown
Suspension, suspension spring System by which the pendulum is suspended from the back cock by a spring or, occasionally, a silk thread or on a knife-edge
Swan neck Decoration at the top centre of the hood of some longcase clocks thought to resemble the neck of a swan
Synchronous clock Mains electric clock which derives its timekeeping ability from the frequency of the alternating current
Tablet Glass panel on some American clocks, often reverse painted or mirrored
Tavern clock Wall clock, often in an octagonal case with a drop-trunk, formerly used for showing the time in taverns and other public places
Ticket clock Early digital clock in which the time is shown on plastic cards which flip over when the time changes
time ball Mechanism by which a large ball is lifted to the top of a pole to be dropped at a particular time, used to allow ships at sea to check their chronometers
Time recorder Clock used to record arrival and departure of people, usually employees in a factory
Ting-tang striking Striking system in which two bells or gongs are struck on the quarters
Torsion pendulum Pendulum which spins in one direction and then the other. Anniversary clocks have torsion pendulums
Tourbillon, tourbillion Carriage carrying the escapement of a clock or, more often a watch, which rotates to compensate for positional changes
Train, going, striking, chiming Sequence of wheels and pinions which carry power from the weight or spring to the escapement (going train) or the strikework (striking train) or the chiming mechanism (chime train)
Trundle The pin used instead of teeth on a lantern pinion
Turret clock see Public clock
Ultrasonic cleaner Cleaning machine which uses ultrasonic sound waves in the cleaning of watch or clock parts
Verge see Escapement, verge
Vienna (-style) clock and regulator Type of wall clock with highly accurate escapement developed in Austro-Hungary
Wagon-spring clock American clock developed by Joseph Ives which used a leaf-spring for the motive force
Wheels The large gears used in clockwork (cf pinions)
White dial see painted dial

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