Glossary

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- A -

Anglesite finish
Breaking the edges of the movement parts to create a 45° angle with perfectly constant width of the breaking edge.

Assembling
Process of fitting together the components of a movement. This was formerly done entirely by hand, but the operations have now been largely automated. Nevertheless, the human element is still primordial, especially for inspection and testing.

Automatic Watch
A watch whose mainspring is wound by the movements or accelerations of the wearer's arm. On the basis of the principle of terrestrial attraction, a rotor turns and transmits its energy to the spring by means of an appropriate mechanism. The system was invented in Switzerland by Abraham-Louis Perrelet in the 18th century.

- B -

Balance
Moving part, usually circular, oscillating about its axis of rotation. The hairspring coupled to it makes it swing to and fro, dividing time into exactly equal parts. Each of the to-and-fro movements of the balance ("tick-tack") is called an "oscillation". One oscillation is composed of two vibrations.

Barrel
Thin cylindrical box containing the mainspring of a watch. The toothed rim of the barrel drives the train.

Blued screws
Hardened steel screws which are stress-relieved by heating them to abbout 290°C whereby they assume a permanent deep blue color.

Breguet spring
Balance spring with terminal curve whose final curve is formed around the actual balance spring according to precise calculations. With this invention, Abraham-Louis Bréguet (1747-1823) was able ti considerably reduce the effects of the dynamic balance error of a flat Archimedean balance spring.

Bridge
Complementary part fixed to the main plate to form the frame of a watch movement. The other parts are mounted inside the frame (part of the "ébauche").

- C -

Calibre
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.

(Watch-) 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.

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

Chronograph
Watch or other apparatus with two independent time systems: one indicates the time of day, and the other measures brief intervals of time. Counters registering seconds, minutes and even hours can be started and stopped as desired. It is therefore possible to measure the exact duration of a phenomenon. Not to be confused with the timer, the stopwatch and the chronometer.

Chronometer
Watch which has undergone a series of precision tests in an official institute. The requirements are very severe: a few seconds per day in the most unfavourable temperature conditions (for mechanical watches) and positions that are ordinarily encountered.

Complication
Mechanism in addition to the time display. For various displays and functions: chronograph, perpetual calendar

Crown
Knurled knob located on the outside of a watch case and used for winding the mainspring. It is also used for setting the hands to the right time and for correcting thecalendar indications.