Watch glossary: A

ACRYLIC CRYSTAL
The inexpensive plastic crystal. It's not very hard and shallow scratches can be buffed out.
ALARM WATCH
A watch provided with a movement capable of releasing an acoustic sound at the time set. A second crown is dedicated to the winding, setting and release of the striking-work; an additional center hand indicates the time set. The section of the movement dedicated to the alarm device is made up by a series of wheels linked with the barrel, an escapement and a hammer striking a gong or bell. Works much like a normal alarm clock.
AMPLITUDE
Maximum angle by which a balance or pendulum wings from its rest position.
ANALOG or ANALOGUE
A watch displaying time indications by means of hands.
ANALOG QUARTZ
The most commonly-used term in referring to any analog timepiece that operates on a battery or on solar power and is regulated by a quartz crystal
ANNUAL CALENDAR, see calendar, annual
ANTIMAGNETIC
Said of a watch whose movement is not influenced by electromagnetic fields that could cause two or more windings of the balance-spring to stick to each other, consequently accelerating the rate of the watch. This effect is obtained by adopting metal alloys (e.g. Nivarox) resisting magnetization.
ANTIREFLECTION, ANTIREFLECTIVE
Superficial glass treatment assuring the dispersion of reflected light. Better results are obtained if both sides are treated, but in order to avoid scratches on the upper layer, the treatment of the inner surface is preferred.
ARBOR
Bearing element of a gear (s.) or balance, whose ends-called pivots - run in jewel holes or brass bushings.
ATMOSPHERE (ATM)
Unit of pressure used in watch making to indicate water-resistance
ATOMIC TIME STANDARD
Provided by the U.S. National Institute of Standards and Technology, Time and Frequency Division, Boulder, Colorado, atomic time is measured through vibrations of atoms in a metal isotope that resembles mercury. The result is extremely accurate time that can be measured on instruments. Radio waves transmit this exact time throughout North America and some "atomic" watches can receive them and correct to the exact time.
AUTOMATIC
A watch whose mechanical movement is wound automatically. A rotor makes short oscillations due to the movements of the wrist. Through a series of gears, oscillations transmit motion to the barrel, thus winding the mainspring progressively.
AUTOMATIC WINDING
A rotating weight, set into motion by moving the wrist, winds the going barrel via the gear train of a mechanical watch movement. Automatic winding was invented during the pocket watch era in 1770 by Abraham-louis Perrelet, who created a watch with a weight swinging to and fro (when carried in a vest pocket, a pocket watch usually makes vertical movements). The first automatic winding wristwatches, invented by John Harwood in the 1920s, utilized so-called hammer winding, whereby a weight swung in an arc between two banking pins. The breakthrough automatic winding movement via rotor began with the ball bearing Eterna-Matic in the late 1940s, and the workings of such a watch haven't changed fundamentally since. Today we speak of unidirectional winding and bi-directionally winding rotors, depending on the type of gear train used.
AUTOMATON
Figures, placed on the dial or case of watches, provided with parts of the body or other elements moving at the same time as the sonnerie strikes. The moving parts are linked, through an aperture on the dial or caseback, with the sonnerie hammers striking a gong.