- 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