CADRATURE. Under-dial work, viz. repeating work.

CALIBRE. The size and type of design of a watch movement. The term was used by Sully in about 1715 to denote the dimensions and layout of a movement; more recently the term has been used to indicate the shape of the movement or even the designer's name - e.g. Lepine calibre (q.v.) - or the origin of the movement.

CAM. A part shaped with an irregular contour so as to give the requisite reciprocal irregular movement to a lever in contact with it.

CANISTER CASE. An early form of case, drum-shaped. Not dissimilar to a tambour case (q.v.), but not hinged.

CANNON PINION. A pinion, part of the motion work carrying the minute hand. Its hollow arbor, or pipe, is merely a friction fit on the centre wheel arbor, thus allowing the hand to be set.

CAP JEWEL. See END STONE.

CAPPED MOVEMENT. A movement provided with a dust cap (q.v.).

CARTOUCHE DIAL. Found on continental watches, French in particular. White enamel plaques with blue or black numerals, the plaques being fired on to the metal dial. On champlevé dials, the maker's name is usually engraved on a cartouche which has been polished in contrast to the matted centre of the dial.

CENTRE PINION. The pinion in the going train (see TRAIN), driven by the great wheel. Normally it is centrally placed in the movement.

CENTRE SECONDS. A seconds hand pivoted in the centre of the dial concentric with the hour and minute hands, and traversing the dial in one minute. Sometimes called a 'sweep seconds.' The hour and minute hands may be on a subsidiary dial.

CENTRE WHEEL. The wheel, centrally planted, the arbor of which carries the minute hand.

CHAFF-CUTTER. See ORMSKIRK and DEBAUFRE ESCAPEMENT.

CHAISE - WATCH. A large watch used for travelling. Not to be confused with a carriage clock.

CHAMPLEVÉ. An area of metal which has been hollowed out with a graver to take enamelling: champleve enamel. 'Champlevé dial' is a metal dial with portions removed to leave others standing proud of the main surface - i.e. the hour numerals and minute markings. The hollowed-out numerals are then filled with black or coloured wax, or pitch.

CHAPTER RING. The ring upon which the hours and minute graduations or half and quarter-hour divisions are engraved. An alternative name is 'the hour ring'.

CHASING. Engraving in relief.

CHÂTELAINE. A chain for suspending a lady's watch or piece of jewellery. In addition to the watch, the winding key, seals or other trinkets were often attached. Normally the decoration on the watch case is en suite with the decoration on the chatelaine. See also FOB CHAIN.

CHINESE DUPLEX. A form of duplex escapement invented by C. E. Jacot in 1830. It was commonly used for watches exported from Fleurier to China. The locking teeth are double, thus resembling a fork. After the first prong of the fork passes the roller, the escape wheel is immediately locked again, so that a second swing of the balance is necessary to unlock the whole tooth or 'fork' before impulse can be given. A second elapses between each complete unlocking, but the intermediate stage is detectable by a slight movement of the centre seconds hand: otherwise, the watch appears to beat seconds.

CHRONOGRAPH. A watch which, in addition to the time-of-day hands, has a centrally mounted seconds hand. This can be started, stopped and returned to zero by means of a push-piece or slide. A subsidiary dial is provided which records the number of revolutions (each of a minute) made by the centre seconds or chronograph hand. A more correct term would be 'chronoscope'. See also SPLIT-SECONDS.

CHRONOMETER. Among English watchmakers and collectors, a chronometer is understood to be a watch or portable clock (hence a ship's, marine or box chronometer) which has a detent escapement (q.v.), although the use of the word preceded the detent escapement. Of recent years there has been a tendency - regretted by many - to use the word in the French or Swiss sense to indicate a watch which has obtained an official rating certificate issued by the observatories at Geneva or Neuchatel. Etymologically, any instrument for measuring time.

CHRONOSCOPE. See WANDERING HOUR DIAL.

CLICK. A pawl or lever with a 'beak' which engages in the ratchet-shaped teeth of a wheel, it being under the tension of a spring, and pivoted. The usual purpose of a click, its spring and the ratchet wheel is to allow the wheel to turn in one direction only. On watches the ratchet wheel is fixed to the arbor of the mainspring barrel, thus enabling the mainspring to be wound; the tension of the mainspring is held up against the tensioned click.