Watchmaker Glossary

AT

First electronic watch controlled by a tuning fork, launched in 1960.

Indication of time and other data. The display can be done either by hands moving on a dial (analog display), or by figures appearing in one (or more) window(s) (digital or numerical display); these figures may be supplemented by alphabetical indications (alphanumeric display) or by any other sign. Example: 12.05 LU 12.3 = 12 hours, 5 minutes, Monday March 12. These displays can be produced by mechanical and/or electronic means.

Indicator organ made up of a piece of metal, generally thin and light, of very different shapes, which moves on a dial or a divided limb. Watches usually have three hands to indicate hours, minutes and seconds.

Name given to the teeth of a pinion.

Organ against which air friction moderates the speed of a moving object, such as the arm of a gravity escapement.

Movement of a pendulum or an oscillating member, limited by two consecutive extreme positions. The balance of a mechanical watch generally makes five vibrations per second, or 18,000 per hour. The oscillation ("tic-tac") has two alternations (the word oscillation is sometimes incorrectly used to designate the alternation).

Elastic bearing whose purpose, in the watch, is to absorb the shocks received by the pivots of the balance shaft.

Centerpiece of the escapement, in steel or brass, so named because of its shape, reminiscent of a ship's anchor.

Sundial adjustable according to the different latitudes.

First truly accurate quartz oscillator, used for observatory quartz clocks.

Standard designation granted to watches capable of withstanding an accidental fall from a height of 1 m onto a hard surface without adverse consequences, thus meeting criteria rigorously defined by ISO (International Organization for Standardization, founded in Geneva in 1947 ).

Hour numerals or signs cut from metal plates and then glued or riveted to the dial are called appliques.

Laminated spring used to transmit driving force in some American console clocks.

In watchmaking, term synonymous with axis (ex: barrel shaft): in general it is a cylindrical body on which is fixed a toothed wheel which it rotates.

Flexible steel or wooden rod that is used to stretch a gut cord or horsehair in order to move a part on the lathe.

Operation which consists in tensioning (arming) the mainspring of a barrel, and which is carried out either manually (using the crown or a key), or automatically (using the rotor).

Device which limits the winding of the barrel, by reducing its angular stroke. The best known of these mechanisms is the so-called "Maltese cross" stop.

Finish the profile of the gear teeth by milling.

Set of parts that make up the escapement (escapement wheel, lever, plate) and which transform the rotary movement of the gear train into the to-and-fro movement of the balance wheel or pendulum.

In antiquity, the most important instrument for astronomy, navigation and time measurement; he measured the height of the stars.

Animated character or miscellaneous object, such as a windmill or seesaw.

Watch whose spring is wound by the movement of the wearer. Many devices have been made since the end of the 18th century. Nevertheless it is the so-called "rotor" device, which since the 1940s has become widespread in wristwatches. The origin of this system can be found in a document from the French Academy of Sciences, dated December 23, 1778, which describes a part deposited by the Liège watchmaker Hubert Sarton. It is currently the oldest descriptive text of an automatic system listed.

Term synonymous with tree. Watchmakers are used to saying, for example, pendulum axis.

All axes are shafts, with the exception of the balance wheel, which is called an axis.

B

Mobile part, generally circular, which oscillates on its axis of rotation. The balance spring which is coupled to it gives it a to-and-fro movement, dividing time into strictly equal portions. Each of these round trips ("tick-tocks") is called an oscillation. The oscillation is divided into two alternations.

Originally a foliot, then a circle that regulates the speed of the escapement; associated with a spiral spring from 1675.

Oscillating bridge with a mass at each end, used in watches before the invention of the balance-spring.

Thin cylindrical box - inside which is housed the mainspring - whose toothed edge drives the train of the watch.

Barrel on which a rope, a rope or a coiled gut rope terminated by a weight drives the cogs of a clock.

Barrel containing a mainspring which transmits the driving force.

As opposed to the smooth barrel connected to the fusee by a chain or a gut cord, the toothed barrel is fixed on a wheel which meshes with the rest of the gear train.

Said of a toothed barrel fixed only in the movement by its upper part.

Small metal rod fixed between the horns of the case and on which the bracelet is fitted.

Textually, to turn a box to give it the shape of a "basin" by rounding the bottom of the box with a chisel.

Means, inside a watch case, the part on which the movement rests. In chiming watches, Julien Le Roy imagined removing this baton and replacing it with a small gold metal ring separating the dial from the front plate. The space thus created makes it possible to accommodate a large part of the parts of the striking mechanism. All the parts thus housed under the dial have, by extension of the term, been baptized "cadrature".

Number of ticks obtained in a given time. A longcase clock "beats the second", that is, once every second.

Ring of various shapes used to suspend the watch.

Blade made of two metals with different coefficients of expansion, used in the manufacture of compensated balance wheels.

See Draft

Movement in working order, ready to receive finishing work (ironing, adjustment, adjustment) and finishing (gilding, signature).

Box used to protect the watch movement against dust, humidity and shocks. It still makes the watch look as attractive as possible influenced by the fashion and taste of the buyers.

Signal used in the past to indicate the time using a ball which slid along a mast planted at the top of a tower.

Radius of a circular pendulum.

Small pliers that allow the watchmaker to handle delicate parts.

Pivot polishing process.

Polishing file used to give shine to metals, such as steel or copper.

Official document drawn up by various astronomical and chronometric observatories and giving the name of "chronometer" to a watch which has successfully undergone a series of very severe tests relating to its precision (diurnal rate, thermal coefficient, etc.).

Fixed component intended to limit the travel of a moving component. The angular movements of the anchor are limited by stops.

Large-format medieval bell tower and belfry clocks were wound using a capstan or spoked wheel attached to one end of the barrel.

Small metal cover used to protect the movement of watches at the time when it was easy, by tilting them, to take them out of their box.

Indicating device, metal or other part which bears various indications, the hours, the minutes and the seconds for the usual watches and clocks. The indications are given by numbers, divisions or signs (indexes) of various shapes.

dial made up of 12 enamelled cartridges bearing the hour numerals arranged around a thirteenth central piece, also enamelled and often decorated.

Special dial giving indications on the calendar, such as day of the week, date, month, year and religious holidays.

Sundial indicating, according to the length of the shadow cast by the gnomon, the height of the sun in the sky.

Fixed sundial with horizontal graduation, for example, ordinary garden sundial.

Sundial bearing vertical graduations.

Term designating all of the mechanisms (striking, dates, minute track) placed between the dial and the front plate.

According to the definition given by JC Nicolet, "the cage is the frame or chassis inside which are housed all the parts of the watch movement. The clock cage is made up of 2 plates while that of watches is made up a plate and several elements screwed onto it, called bridges".

Originally synonymous with dimension for a watch movement. Today, designates a type of movement (caliber for men, automatic caliber). Followed by the manufacturer's mark, designates the provenance.

Watch movement in which all the wheels are under a cock or bridges.

Time signal given by the detonation of a cannon.

Designates in watchmaking the end of a square section stem. In general the squares are used for reassembly. There are 2 kinds: male squares, filed on a cylindrical piece, female squares, formed in a hole.

Middle part of the watch case in which the movement is placed.

Rotating device analogous to the tourbillon, but more robust.

High-precision installation (most often today an electronic quartz clock or an atomic clock), which delivers pulses to a series of secondary clocks and sometimes controls a system itself distribution audience of the hour.

Watch movement (dial and hands not included) of which all or part of the spare parts are not assembled.

Small chain, similar in miniature to a bicycle chain which replaced the gut cord used in primitive watches to connect the rocket to the barrel.

Said of a surface dug with a chisel in the field of a metal plate, to receive the enamel.

Wheel whose profile, made up of alternating hollows and bumps, regulates the striking of the hours.

This term refers to invisible hinges for watch cases. Lépine was the first to make watch cases with "lost hinges".

"Chasing" a stone, in watchmaking, means pressing it into its housing. Because of its ease of execution, driving in has replaced crimping.

Friction pinion driving the timer and supporting the minute hand.

Horizontal frame of a modern steeple clock.

Metal ring in which is fixed the drilled ruby ​​which serves as a bearing for the pivot.

Part thanks to which certain oscillators receive their impulses.

Device that allows the watchmaker to quickly test the rate of a watch.

Watch or device comprising two independent time systems: one gives the time, the other records short times. Seconds, minutes and even hours counters are started and stopped on command. They thus make it possible to directly measure the precise duration of a phenomenon. Not to be confused with counter or stopwatch.

Watch having passed - in official offices - a control on its accuracy. The requirements are very high: a few seconds a day in the most difficult temperature conditions (for mechanical chronometers) and positions usually encountered.

High-precision timepiece (mechanical or electronic) enclosed in a box, used on ships to determine longitude. Marine chronometers with mechanical movements are mounted on gimbals to ensure the horizontal position necessary for their accuracy.

Water clock.

Small lever in the shape of a beak or comma which, under the action of a spring, penetrates the toothing of a wheel, so as to prevent it from rolling back.

Sundial which, oriented north-south, indicates, according to the angle formed by the shadow of the gnomon, the position of the sun in the sky.

In watchmaking, it is a generic term for chronographs.

Device generally made using two metals that expand differently, intended to correct the effects of temperature on the rate of watches and clocks.

A device added to the compensated pendulums of chronometers to correct for secondary error, i.e. the effects of changes at temperatures intermediate those actually compensated.

Layer of enamel deposited on the back of an enamelled piece, for example, on the back of a watch or clock dial, or inside a case with an enamelled back.

Watch balance bridge.

Crafted balance bridge attached to the lower plate of a watch and serving as a bearing for the balance shaft.

Metal washer used by French watchmakers instead of the counter-pivot stone.

In some clocks, cord which, once pulled, triggers the ringing of the elapsed hour, or even that of the quarters.

Ends of the hairspring curved towards the center to improve isochronism. Invented by Breguet and perfected by Phillips. By extension, we often speak of the "Phillips curve" or the "Breguet" hairspring.

Knurled button located outside the case of the watch and used as much for winding the mainspring as for setting the time of the watch or updating the date of the calendar if it has one.

Pivot hole made directly in the brass plate, where a steel pivot of the wheelset or the escapement moves, which was not without friction problems in the past, which were only solved by Nicols Fatio , who had the idea of ​​using rubies as cushions.

Correct an effect that is a source of error, such as that of temperature differences, on the rate of watches.

Instrument used to record time intervals (durations, short times), without indicating the time.

Undrilled precious stone used as a bearing and against which abuts the pivot of the balance shaft.

Knurled button located on the outside of the watch and used to wind the mainspring. Also used for setting the time and updating the calendar.

Straight or curved arm fitted with teeth.

In a watch case, the double bottom is called cuvette, often engraved with inscriptions or the signature.

Small springs invented by Huygens, intended to improve the isochronism of the oscillations of the pendulum.

In a lever escapement, a small metal pin that prevents accidental movement of the fork.

System instituted by a decree of the Convention of 1792 according to which the day was divided into two times 5 hours of one hundred minutes each lasting 100 seconds.

Generic term that refers to all turning, drilling, tapping and milling operations, whether carried out by hand or on automatic or semi-automatic machines.

Lever which maintains then triggers a mechanism and which, consequently, regulates its movement.

Some triggers are mounted on pivots, others are on the contrary on a leaf spring.

Rate variation of a timepiece.

Small metal part with two branches whose vibrations, maintained by an electromagnet, activate a pawl which pushes, tooth by tooth, 300 to 720 times per second, the first wheel of the cog.

Dotted light source used for displaying numbers on electronic digital watches.

It works on call by a push button.

Machine tool accessory intended to divide the circumference of the wheels and cut the number of teeth required.

Application on a metal support of a gold amalgam, followed by light heating to remove the mercury. Process now supplanted by electrolysis gilding.

Groove made in the bezel of a watch case to fix the crystal.

Specialized box turner who worked on a "Dubail" pantograph lathe allowing the same shapes of boxes to be reproduced in series.

Set of unassembled parts of the movement (plate, bridges, gear train, winding and time-setting mechanism, adjustment rack) and marketed in this form. The following are not part of the outline, however: the regulating organs, the escapement, the mainspring.

* at friction rest = cylinder, pendular balance, …

Watch escapement that gives excellent results and is reminiscent of the recoil anchor escapement, with the difference that it is free.

Regulating mechanism of pendulum clocks, invented around 1670, which greatly improved the keeping of time. In Europe, the fork stick was called recoil anchor because of its shape.

Lever escapement used in watches or clocks and in which round or D-shaped steel or ruby ​​pallets receive the impulse from the teeth of the escapement wheel. In modestly priced watches, ruby ​​pallets are replaced by hardened steel pegs.

Escapement in which a tooth of the escapement wheel is constantly in contact with the balance wheel, as in the cylinder escapement. This exhaust is not free.

Exhaust in which the ticking is faster than normal.

Escapement in which the balance shaft is part of a cylinder actuated by the toothing of the escapement wheel.

Free escapement that uses a detent to cause the escape wheel to stop.

Escapement in which the impulse is provided by a lever, generally under the action of gravity, in the form of a crown.

Elaborate flywheel escapement in which two vertical balance wheels oscillate in opposite directions and intersect.

Escapement without recoil where the escapement wheel acts, through the tips of its teeth, on the inclined beaks of the anchor.

Escapement used in the first mechanical clocks and which persisted for a very long time. It consists of the meeting wheel and a shaft (the rod) which carries the foliot and two pallets.

Exhaust provided with two escape wheels. Its name is taken from Ormskirk, in Lancashire where it was invented.

Escapement in which the escapement wheel has a double row of teeth, or provided with two escapement wheels. Originally used for high precision watches, then cheaper models.

Another term used for cylinder escapement.

Escapement that has no contact with the balance wheel or pendulum except during release and impulse, for example in anchor and detent escapements.

Escapement in which the oscillator and the escape wheel are connected by a magnetic device.

Ingenious exhaust that required no oiling, invented by John Harrison.

Apparent motion of the Sun around the Earth.

In electronic digital watches, screen on which the time can be permanently read, indicated by dark digits or letters standing out against a light background (or vice versa).

Screen imitating the movement of a natural timepiece, such as that of the Sun, and reminiscent of a classic clock dial with moving hands.

Screen on which the time is indicated in figures: 07 16 42

Nut which, mounted under the lens of a pendulum, allows this component to be raised or lowered to adjust the period of the pendulum.

Art of painting a decorative pattern on the back of a clock sleeve glass panel.

Alloy with practically zero thermo-elastic coefficient within normal temperature limits and used to compensate for the effects of temperature on hairsprings.

Action of inserting and fixing the movement in its case

Set of clockwork stones used in the pivot holes to reduce friction. A normal setting includes 15 to 19 rubies.

Said of a wheel whose teeth penetrate the wings of a pinion to make it move.

Difference between true time (recorded on a sundial) and mean time (recorded on a clock).

Tool used by the watchmaker to wind and insert the mainspring into its barrel.

Method of manufacturing the watch and/or the movement consisting in assembling the various constituent elements. It generally includes the following operations: reception, control and storage of blanks, regulating parts, as well as other movement and clothing supplies; reassembly; setting; fitting the dial and the hands; casing; final check, before packing and shipping.

Hardened steel die that gives shape to a part or a hole.

Which does not allow water to enter. Waterproof box, whose joints, closures, are built to prevent the introduction of moisture.

This name designates the purely decorative plate on which the dials of clocks and watches were once fixed. Thereafter we continued to call false plate, the sheet on which the dials of pendulum are often fixed.

Set of operations that transform the blank (spare parts) into rolling blank (movement in working order).

Sculpted ornament that completes a column crown or any other part of a movement or the sheath of a clock.

This function has its origins in the field of aviation. By simple action of a pusher, the "Return in flight" function brings the chronograph second hand back to zero. It then resumes its course instantly for a new count.

Oscillating beam, each arm of which supports a mass, used in the first mechanical clocks as a regulating organ.

We call "function" any information delivered by a timepiece. A watch which gives the hour, the minute and the second, the day, the date and the month will be said to have 6 functions. The so-called "complicated" watches multiply the additional indications.

Thin layer of transparent enamel deposited on the surface of dials and enamels.

Small rod, carried by a special gear train, the end of which is engaged in the wings of the escapement pinion; released every second, the whip makes a full turn and communicates its movement to the seconds hand, which thus advances one step per second.

In watches as in pendulums, part of the lever which ensures the connection between the escapement and the stem of the pendulum or the balance wheel.

Detached pieces. These are the constituent parts intended either for the production of the watch or for its repair. In the latter case, we speak of "recovery supply".

One of the first instruments for cutting wheels and pinions, used in watchmaking factories, and resembling the fruit of the same name.

Unit of measurement which translates the number of oscillations or vibrations per second and which is expressed in Hertz; it is generally supplemented, for clocks and balance-spring watches, by indicating the number of vibrations per hour (eg: 2.5 Hz = 18,000 vibrations per hour = 9,000 oscillations per hour).

Conical piece, connected to the barrel by a hose or by a chain, and intended to regulate the force of the spring.

In watches equipped with a fusee, it is a small lever which, lifted by the chain, blocks the fusee at the end of winding. The chain guard is a stopper.

This designation, recently reserved for high-precision instruments used for the measurement and "conservation" of time, used to apply to any time instrument, such as clepsydra, hourglass, sundial, etc.

Thin sheet of glass or a transparent synthetic product, which protects the dial of the watch, clocks, etc.

Style whose shadow is projected on a sundial.

In chiming watches, these are metal blades, usually steel, arranged around the movement and on which the hammers strike. Gongs replaced gongs in chiming watches at the end of the 19th century, which made it possible to produce flatter watches.

Automatically strikes the hours and quarters.

In watchmaking, it is a device for correcting the effects of temperature, applied to clocks, more rarely to watches. It is made of rods, some of which are made of steel, others of brass, bronze or zinc.

Small opening. Aperture watch, in which the dial is provided with openings under which various indications appear: dates, hours, etc.

Engraving patterns on a watch case using a machine called a "guilloche lathe".

Set of spare parts (case, dial, hands, glass, crown, etc.) which, by covering the movement, contribute to giving the watch its definitive and utilitarian appearance.

Sundial showing mean time, i.e. the same time as a clock.

Unit of frequency equal to one cycle per second. A royal or seconds pendulum oscillates for example at 0.5 Hz, its period is 2 seconds.

Hour indicated by a sundial and corrected by the equation of time so that the hours have an equal duration.

Hour indicated by a sundial without correction by the equation of time.

Division of the light period of a day into a given number of hours and that of darkness into an equal number of hours. System commonly adopted before the introduction of the mechanical clock.

Generic term attributed to any time instrument (gnomon, clepsydra, sundial, hourglass, mechanical clock) and which common usage today reserves for a non-portable time mechanism often equipped with a chime (pendulum or grandfather clock) , operating only in a fixed position. In a time distribution system, we usually speak of a master clock (the central mechanism which delivers the pulses) and a secondary clock (the one which receives them and which only serves to indicate the time).

Clock which, driven by its own weight, slides along a rectilinear rack.

Monumental public clock also called belfry clock.

Clock that remotely operates other clocks or sub-dials.

Term used until the 19th century to designate marine chronometers.

Science of keeping time.

Cavity made in the bearings to deposit a drop of oil.

Motion communicated for a fraction of the time to keep the oscillator moving.

Most frequently used form of shock absorber in motors today.

Iron-nickel alloy which, having a very low coefficient of expansion, does not change length according to temperature variations. It is used for the stems of precision pendulums...

Which occurs at equal time intervals. The oscillations of a pendulum or a balance-spring are isochronous when their duration is independent of the amplitude.

Jaquemarts, "hammering" automatons operated by a ringer, then by a mechanism connected to a clock, striking a bell, Origin: Orient (time of the Crusades), After the 18th century: decline of the show giving way to the usefulness of public clocks (dial visible from afar) and indoor clocks, Statistics (in France): number: around 20, Characters: generally in oak, polychrome, sometimes covered with tinplate, some in copper (Dijon) or bronze (thin wall , Cambrai), Sizes: Romans-sur-Isère 2.60 m, Cambrai 2.50 m, Thann 1.18 m, Auffay 1 m, Lyon 40 cm, Number of statuettes: Auffay, Feurs, Molsheim, Thann, Cambrai 2 ; Aigueperse, Clermont-Ferrand, Compiegne, Lambese, Montbard, Befeld 3; Avignon, Lyon, Mondidier, Moulins, Dijon 4. Types: Avignon, Beaumont-le-Roger, Benfeld, Besançon, Lavaur, Moulins, etc. : "man-at-arms"; Molsheim: "wife and cherub child": Lyon: "Guignol and Gnafron"; Clermont-Ferrand: "Mars", "Time", "Fauna": Cambrai; "Moor": Benfeld, Thann: "Death"; Dijon: "Jacquemart, Jaquette, Jacquelinet, Jacquelinette": St-Omer: "Mathurin": Graveson: "Beluguet",

Mass attached to the end of the pendulum rod.

Part of the lever against which the escapement wheel abuts in order to obtain the momentum necessary to maintain the oscillations. A distinction is made between the entry lift and the exit lift.

opposes the stop lever, designed on the contrary to stop it when all the shots have been struck.

Said of an escapement which is only in contact with the balance wheel at the time of the impulse and release. The additional oscillation of the balance is therefore free.

Old unit of measurement still often used in watchmaking. The line is 2.256 mm.

Spiral-shaped cam with notches that regulate the strike of the hours, quarters and halves.

Ring fitted to the middle and carrying the glass.

In the Swiss watchmaking industry, this name designates the factories which make the watch almost entirely, as opposed to the finishing workshops in which only the winding, adjustment, fitting of the hands and casing are done.

Functioning of a timepiece, evaluated according to its regularity. We call diurnal walking the advance or the delay that it takes in 24 hours compared to a reference time standard.

Small metal parts placed on the rim of the balance wheel and used to adjust the advance and the delay when there is no adjustment wheel, in particular for chronometers.

Great imaginary circle passing through the two terrestrial poles.

It is very precisely, according to René Béguin, an auxiliary mechanism establishing the speed ratio between the minute hand and the hour hand and composed of 3 elements: the roadway, the timer wheel with its pinion and the wheel hours.

Pre-tensioning of the spring housed in the barrel connected to a rocket.

In watchmaking, the term movement refers to the mechanism of watches and clocks.

Device which slows down, which regulates. In watch and clock chimes, it is necessary to moderate the speed of certain cogs. This is done with finned flywheels, ball or centrifugal force regulators, or even escapements: anchor for certain bells (Julien Le Roy's invention in 1755) rod for alarm bells.

Before being used in electronic watchmaking, where it designates the entire movement, the module originally constituted, in mechanical watchmaking, an easily interchangeable sub-assembly (display, gear train, motor, etc.).

Mechanical watch which uses the principle of terrestrial attraction to wind itself by the movements of the arm alone, which turn a rotor which transmits the energy thus accumulated to the mainspring.

Watch in which a hammer strikes inside the case and allows the time to be known by touch. Imagined around 1750 by Julien Le Roy.

Watch whose case adopts a given shape, that of a beetle, a violin, a cross...

First commercial automatic watch, invented by Breguet.

Electric motor that rotates in synchronization with the mains frequency.

Duly assembled assembly of the main organs and mechanisms that make up the watch, namely: the winding and time-setting mechanism, the mainspring, the gear train, the escapement and the regulating organ or regulating organs (balance-spring) . "Anatomically", the movement is made up of the blank, the regulating parts and the other supplies (spring, stones, pivots, pinions, screws, shock absorbers, etc.). The watch is said to be "complete" when the movement has been covered with clothing.

Specifically French movement, with two bodies, cylindrical in shape, suitable for cartels and mantel clocks.

Hand-held protractor that allows you to determine the time at night by observing the position of the Big Dipper.

Belly watch, similar to an onion, produced in the 18th century by French watchmakers.

Name given to the planetary, mechanism representing the movement of the planets, after Charles, fourth Earl of Orrery.

The balance wheel and the hairspring constitute the regulating organs of the mechanical watch. These elements perform time counting. In a clock, the regulating organ is the pendulum. In electronic watches, it can be a balance-motor, a sound resonator or a quartz crystal.

Device which, like the pendulum or the pendulum, generates the oscillations which divide time into equal units.

Regulating organ of a quartz clock or watch.

It may just as well be the two levers of the rod against which the counter wheel abuts, thus maintaining the oscillations of the foliot, or the parts of the anchor (steel, ruby ​​or sapphire) which come into contact with the escape wheel.

Based on "a simple set of levers proportioned so that one end of the system reproduces exactly the movements of the other end by reducing or amplifying them", the pantograph is defined, according to JC Nicolet, as a machine allowing "to make shaped hollows in watch plates, by reproducing a model called the "patronne". The "Dubail" copy lathe is just an industrial version.

First watch shock absorber, invented by Breguet.

Set of parts comprising the regulating organs (balance-spring) and the escapement.

Part of the pocket watch that receives the winding crown and the ring that allows it to be hung; the invention of the pendant crown, which eliminated the separate winding key, was the work of Thomas Perst in 1820 and was improved by Louis Audemars in 1838, but it is Adrien Philippe who is responsible for the current system of winding, perfected in 1842.

This name, formerly reserved for timepieces regulated by a pendulum, now applies, whatever the particularities of the clockwork mechanism, to any large-volume timepiece intended to be placed or hung.

Pendulum made up of several rods of different metals (steel and brass) whose thermal coefficient of expansion keeps the length of the oscillator constant despite variations in temperature.

Pendulum in which a hollow cylinder containing mercury serves as a lens and compensates for the effects of temperature variations.

Pendulum fitted with a magnetic lens oscillating in a metal coil, invented by M. Favre Bulle around 1920.

Pendulum about one meter long beating the second, invented after about 1670.

Very large circular pendulum used in some early electric clocks.

Clock that sets the time and adjusts a special watch invented by Breguet during the night.

This oscillator, used in medium-sized clocks, has properties analogous to those of the pendulum proper, from which it differs in fact only by its period, which is much longer. It consists of a mass suspended from a metal wire or ribbon, around which the system rotates alternately in one direction and the other. It notably equips the so-called "400-day" clocks.

Time interval determined by the regular and repetitive return of a phenomenon.

Old term, used by Bréguet to designate a self-winding watch.

Indicates the state of the moon: new, waxing, waning or full

Small steel cog, usually driven by a larger brass wheel.

Pinion whose teeth are formed by small cylinders or spindles, used instead of the toothed pinion.

Each of the 4 columns that connect the two plates of a clock, together forming the cage.

Bearing, counter-pivot, paddle, used to reduce friction. Generally made of synthetic material, with the exception of precious or semi-precious stones (ruby, sapphire, garnet) which can be fitted to the movements of luxury watches.

In watchmaking, the term pirouette indicates that a gear has been placed between the escapement and the balance wheel. This device makes it possible to increase the extent of the arcs of the balance wheel, in other words its amplitude. Huygens' first verge escapement fitted with a hairspring was a pirouette, as was that of Sully.

End of a rotating shaft in the bearing which serves as its support.

Safety device which, in the lever escapement, limits the movement of the fork.

Basic part on which all the other parts of the movement are assembled (part of the blank).

These are weights used as a driving force, example: weight clocks.

Complementary part which is fixed on the plate forming the frame or cage of the movement; the other parts are assembled inside the cage (part of the blank).

Protrusion of a watch case which, by its pulsations, makes it possible to know the time on demand and silently.

Order number of each day in the month: February 10. Date watch: watch which indicates the date, the month, sometimes the year and the phases of the moon in apertures. Perpetual calendar: watch which indicates, in addition to the date, the leap years.

This designates watches and clocks whose calendar of the month passes automatically at the end of the month, whether the months have 28,29,31,31 days, taking leap years into account.

Toothed sector used in certain passing striking mechanisms which do not include a counting wheel (chaperone).

Device allowing the display of several successive times measured from the same origin, the reading time being able to be caught up without disturbing the measurement. Equivalent term: intermediate time.

Adjusting device which allows the diurnal rate of the watch to be corrected by adjusting the length of the hairspring.

Set of operations tending to ensure that the watch runs smoothly. There are several kinds of settings depending on the desired precision (setting in different positions, setting at temperatures).

Precision grandfather clock, usually fitted with a special dial whose hands are not coaxial.

Installation of the various organs that make up the movement. Operations (formerly entirely manual) are now highly automated. The human element, mainly for controls, is however always paramount.

Mechanism which transmits via the input and output pallets, a constant force to the pendulum or the pendulum.

Automatic winding of the mainspring of a wristwatch via a flywheel which rotates according to the movements of the wearer's arm.

Mechanism used to keep a timepiece running during the winding operation.

Device allowing, by means of a main spring, to arm a secondary spring or to raise a weight at regular and relatively close time intervals. Thanks to this device, it is possible to use as driving force the section of a mainspring which delivers a practically constant force to the train of a watch or a clock. The remontoire also makes it possible to use weights as the driving force of a mantel clock or a desk regulator. Since the weights are raised at regular intervals by the main spring, it is no longer necessary to have a great length for their stroke.

Striking watch, which indicates the hours by a chime when a pusher or a lock is activated. There are several kinds of repeats: quarter repeat, which sounds a low stroke for the hours and two strokes for each quarter, one low and the other high; five-minute repeater, which strikes the hours, quarters and five minutes in addition to a quarter; minute repeater, which strikes the hours, quarters and minutes; Grande Sonnerie, which strikes the hours and quarters in passing (automatically) and repeats the entire strike by the action of a pusher; chime repetition, where the quarters are sounded on three or four gongs giving different tones.

Moment during which the escape wheel no longer transmits energy to the regulating organ.

Display on the dial to visually know &endash; in hours or days &endash; the winding condition of the watch.

Contact used in some electric pendulum clocks to regulate the amplitudes of the pendulum's oscillations.

A spiral wound spring inside the barrel, used to produce the driving force instead of a weight.

Spring whose function is to bring an organ back to a determined position; it is for example used to prevent the hammer of a bell from resting on the gong.

Hairspring attached by its ends to the circular balance wheel and to the cock.

Action and result of re-dressing, that is to say of repairing a watch, of restoring it to working order.

Watchmaker specializing in the repair of watches.

Toothed wheel that a ratchet forces to turn in one direction only.

Half-disc of heavy metal that the energy coming from each movement of the arm rotates freely inside the case of the automatic watch. Its weight tends to always put it back upright. Geared up by an ad hoc device, its rotations continually wind the spring.

Set of cogwheels and pinions of the watch.

Set of wheels and pinions that activate the bell.

Drive wheel riveted to a pinion. The same shaft is connected to a large number of wheels and sprockets.

See "chaperone".

Toothed wheel of a timepiece whose rate is regulated by the escapement.

Wheel whose toothing is cut perpendicular to the side, as in angle wheels.

Escape wheel of an escape wheel and verge escapement, with pointed teeth on one side, and parallel to a shaft (called the verge).

Toothed wheel whose shaft turns the minute hand.

Main driving wheel of a clock.

Wheel whose teeth are inclined like those of a ratchet. Wolf tooth wheels were used by Lépine for some of his watches. Some of the winding wheels of the first pendant-wound watches were wolf-toothed.

All pivot pins subject to friction are fitted with stones, usually rubies made of synthetic material, which protect them against excessive wear.

allows the clock to run eight times longer

Device that measures time intervals by the flow of sand from one bulb to another.

Pocket watch whose case has bottoms on each side. The one that covers the dial is operated by a spring mechanism called "secret".

Who jumps. Watch with jumping hours: watch whose hours appear in an aperture of the dial; the time change is done abruptly, by a jump.

Small lever held down by a spring, designed to keep a wheel in the same position between two movements.

Primitive graduated sundial inside a hollowed-out globe.

Rudimentary vertical sundial inscribed on the southern porch of a church several centuries ago, indicating the times of religious services. Sometimes called "Ground dial".

Pendulum, clock or dial operated by a master clock.

Base unit of time corresponding to the 86,400th part of the mean solar day. This is given by the duration of rotation on itself of an ideal Earth, describing a circle around the sun in one year, at constant speed and in the plane of the equator. After the Second World War, the atomic clocks became so precise that they were able to highlight the irregularities, however infinitesimal (a few hundredths of a second per year), of the duration of the rotation of the Earth on itself. It was then decided to redefine the reference standard, which the Thirteenth General Conference on Weights and Measures did in 1967, in the following terms: "The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom". Conventionally, the second is notably subdivided into tenths, hundredths, thousandths (milli-), millionths (micro-), billionths (nano-) and trillionths (pico-seconds).

When the seconds hand is in the center.

This is sometimes called the second hand.

When the seconds hand remains stationary between two seconds. It is also said to "beat the second". Bréguet used the term "second at a stroke".

Invention of Moïse Pouzait, when the mechanism activating the deadbeat seconds hand is independent of the movement of the watch itself.

This designates the annular part of the balance wheel of a watch or a chronometer.

Technique which consists in housing a pierced stone at the exact place of the pivot hole of a mobile and which, because of its difficulty of execution, was abandoned from 1935 in favor of "hunting".

Device that rings on demand or automatically to mark the hours or to wake up at a certain time (see repetition).

Ringing controlled by a curved rake which falls on a cochlea. This ringtone does not count down.

Small spring wound in a spiral and constituting with the balance wheel the regulating organ of the mechanical watch. It brings the balance wheel back to its starting position at the end of each alternation.

Hairspring whose outer coil is wound concentrically and raised relative to the rest of the spring. Sometimes referred to as the "Breguet hairspring". It allowed the spring to develop steadily while expanding and concentrating.

Replica of Ptolemy's universe, with the earth placed in the center. Assembly of circles and rings (armilles) used to represent the celestial equator, the tropics, the ecliptic...

Skeleton watch, watch whose case and various parts of the movement are made of transparent material, revealing the organs of the watch.

Mechanism imagined in Germany to equalize the driving force of the mainspring armed more or less strongly.

Another term used to refer to the gnomon.

Spring or silk thread … of a given length, used to suspend a pendulum.

Commutator fixed to a slave pendulum which one wishes to operate in synchronism with the free pendulum of a master clock.

Instrument for measuring speeds. In watchmaking, sports counter or chronograph equipped with a divided dial which allows the speed to be read in km/h or another unit.

Operation which consists of assembling and checking all the parts of the watch.

Independent workshop or independent watchmaker reassembling all or part of the watch on behalf of an estab- lisher or a manufacturer who gives it the spare parts to be assembled.

Term used to refer to the bells in watches and chiming clocks.

Safety device which, in a lever escapement, prevents the escape wheel from galloping.

Term used to designate chiming watches which do not have gongs or gongs, whose hammers strike directly on the case.

See "Pantograph".

Ordinary lathe equipped with a crank or a pedal.

Dial bearing the sequence of hours.

Machine that allowed the can turner to mass-produce the same shapes from one part to another.

Series of hours inscribed on a dial.

Device designed to cancel deviations in walking in vertical positions. It comprises a mobile cage which carries all the escapement organs and, in its centre, the regulating organ. The escape pinion rotates around the seconds wheel, which is fixed. The cage makes one revolution per minute, it cancels by turning the deviations in the vertical positions.

Rotary device invented by Breguet to improve time keeping.

Qualifies the seconds hand when it advances in small jumps.

In watchmaking, we designate under the name of holes, the bearings in which the pivots rotate. Example, ruby ​​holes refer to drilled rubies.

These terms refer to pivot holes that are not drilled through; it is the bottom of the hole that serves as a counter-pivot.

Set of advances and delays of a timepiece observed in relation to a reference time standard.

Screws fixed in the rim of the first balance wheels to modify their rate.

Speed ​​governor used in ringing mechanisms to control the speed of the cog.