Watch Glossary - C

C

C.O.S.C. - Controle Officiel Suisse de Chronometres

Cabochon – A precious stone, polished but not faceted. In French also used to name a relief decoration at the dial.

Cal. – Size or designation of a movement

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

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

Cannon-Pinion - A pinion which is a friction-fit on the arbor of the centre wheel and has a tubular extension (whose shape gives rise to the name) passing through the central hole in the dial, on which the minute-hand is fitted. On English key-wound watches the top of this extension is squared off to receive the key for setting the hands.

Cantilever Cock - This, I must confess, is not a recognized technical term but a coinage of my own for something which otherwise seems to have no specific name: the English type of cock which is secured to the dial at one point only, by means of a screw passing through a hole in the large wedge-shaped foot, and whose table is prevented from collapsing onto the balance-wheel only by its own rigidity.

Case - Container that protects the watch-movement from dust, damp and shocks. It also gives the watch as attractive an appearance as possible, subject to fashion and the taste of the public.

Casing (up) – A process of inserting and fixing a watch movement into its case.

CCW – counter clockwise

Centre Wheel - The second wheel of the train, driven (by means of a pinion which shares its arbor) from the great wheel. The arbor forms the spindle around which the hands revolve.

CEST – Central Europe summer time

CET – Central Europe time

CH - Confoederatio Helvetica

Chablon - French term for a watch movement (not including the dial and hands), of which all or part of the components are not assembled.

Champleve - This has two meanings: (1) A technique of enamel decoration used on very early watches. The metal body of the item to be so decorated is carved away, leaving its original surface only as a series of narrow walls between hollowed-out cells which are then filled with enamel — hence the French name (‘raised field’). (2) A type of dial much used in the eighteenth century in which each hour and minute numeral is surrounded by a narrow platform following its outline, the rest of the dial being recessed and (usually) textured or engraved. The numerals themselves are engraved within the platforms and then filled in, not with enamel but with black wax.

Chapter ring - The circle of hour numerals on a dial, or the part of the dial which contains these numerals.

Chr. - chromed

Chronograph (Chronoscope) - A chronograph is a mechanism for measuring short time spans independently of the normal timekeeping function. Many mechanical chronographs can measure up to 12 hours with indicators for seconds, minutes (usually to 30) and hours.

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

Chronoscop – A chronograph module

CIDH - Centre International de Documentation sur l'Horlogerie

CIHH - Comite International de la Haute Horlogerie

Click - A spring-loaded pawl or tongue used in conjunction with a wheel with angled teeth (in which the click engages) so that the wheel can be turned one way only. Most familiar association is one of the two large wheels usually visible in a stem-wound movement.

Clock-watch - A chiming watch, distinguished from a repeater in that it sounds the hours etc. automatically as the appropriate time arrives, whereas a repeater does so only when a plunger is pressed. Some of the earliest portable timekeepers are clock-watches.

COA - Clean, Oil and Adjust

Coaxial - Two or more forms share a common axis. A coaxial movement of the minute and hour hands round the same axis.

Cock, Bridge, Bar - The shaped bracket which supports the bottom bearing of the balance-wheel and to some extent protects the wheel itself. A cock consists of a ‘foot’ (or, on French, Swiss and some German and Dutch movements until the 1820s, two feet) screwed to the movement and a ‘table’ extending over the balance. Until about 1790 the table covered the entire wheel and was elaborately pierced and engraved; then, as compensated balances crept into use, the table was made narrower so as to give access to the timing-screws and piercing died out, although engraving of some kind persisted even into the 1900s.

Collet - A retaining-ring, usually of brass; especially the one which holds the inner end of the balance-spring on the staff.

Combo – A multifunctional watch with a double display – analogue and digital.

Compensated Balance - A balance-wheel constructed in such a way that its diameter (variations in which can affect its rate) remains constant at all temperatures, despite the tendency of its material to expand and contract with heat and cold. This is usually done by making the rim of the wheel out of two different metals (brass and steel) fused together so that their differing expansion rates cancel each other out. This rim is split at two points so that the resulting fluctuations cannot cause it to buckle. This kind of balance appeared shortly before 1800 but took nearly 100 years to penetrate throughout the market; the Americans were the first to adopt it more or less as standard (c. 1880). See next entry for an earlier form of compensation.

Compensation Curb - An early form of temperature-compensation, using a bimetallic strip with one end fixed to one of the plates and the other, which is free, carrying the curb-pins. The controlled expansion and contraction of the strip adjusts the position of the pins on the hairspring and so maintains its effective length. This device was first used in a watch designed by John Harrison in about 1755.

Complication - Strictly, any function in a clock or watch other than the recording and display of hours, minutes and seconds; e.g. calendars (the most common kind), week-day indicators and moon-phase indicators. The description is sometimes applied to an instrument which has only the normal functions but displays them on more dials than usual, e.g. by showing hours and minutes on two separate dials.

Cone - In a watch fitted with a fusee, the tapered, spiral-grooved drum onto which the chain is wound and whose parabolically-curved profile provides the progressive gearing effect. The cone incorporates the great wheel.

Consular Case - The standard pattern of case in 19th-century British watches. The body of the case consists of an open ring to which the back and bezel are both hinged; a third hinge carries the movement so that this can be swung out for inspection. Inside the back there is a fixed inner panel, the dome, usually pierced with a hole for the winding-key.

Contrate Wheel - A wheel with teeth standing upright on its rim, so that it resembles a comb bent into a circle. Most often found in verge watches, where the fourth wheel is of contrite form.

Controller - The oscillating component – balance-wheel, foliot, or in modern watches an electronic vibrator – which, in conjunction with the escape-wheel, meters out the motive power of the watch and makes it a timekeeper. Where there is a separate carrier for the pallets, as in the lever escapement, this can be considered as part of the controller.

Coqueret - A steel plate shaped like a keyhole, mounted on the cock of an 18th or early 19th-century French or Swiss watch. The circular end fits over the balance-staff and is pierced for the pivot; the other end is screwed to the cock. With the screw loosened the coqueret can be rotated, allowing for some adjustment of the staff.

Counter, timer, meter – Any device counting or measuring time intervals.

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

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

Curb Pin - The part of a regulator which controls the operative length of the balance-spring. Generally there are two such pins side by side, the spring passing between them so that they restrict its motion; they are mounted on an arm or quadrant which can be moved, so that they slide along the length of the spring and allow a greater or lesser proportion of its length to vibrate freely.

Cuvette - The hinged inner back cover of a 19th-century Swiss or French watch, pierced with holes for winding and setting (if the watch is key-wound) and often engraved with the maker's name, number, type of escapement and number of jewels. Some people also use the name for the removable dust-cap of an English watch.

CW – clockwise

Cylinder - A type of escapement, especially popular in Switzerland between about 1840 and 1890, in which the teeth of the escape-wheel interact with a cut-away cylinder which forms part of the balance-staff.