Glossary of Watch Terms

Automatic Watch	Traditional mechanical watch with additional mechanism that performs the action of winding the mainspring usually by means of a oscillating weight, counter-moving with each movement of the wearers wrist.
Balance Wheel	A weighted wheel that rotates back and forth, being returned toward its center position by the hairspring. It is driven by the escapement, which transforms the rotating motion of the watch gear train into impulses delivered to the balance wheel. Each swing of the wheel (called a 'tick' or 'beat') allows the gear train to advance a set amount, moving the hands forward. The combination of the mass of the balance wheel and the elasticity of the spring keep the time between each oscillation or ‘tick’ very constant, accounting for its near universal use as the timekeeper in mechanical watches to the present. From its invention in the 14th century until quartz movements became available in the 1970s, virtually every portable timekeeping device used some form of balance wheel.
Case	The protective housing for the movement. Their construction materials include almost all metals, plastic, stone, and even wood. Once very fragile, but modern cases are at a minium dust proof and are frequently shock proof, or even water resistant to a depth rating normally shown on the dial.
Chronograph	(Chrono = Time, Graph = Recorder) Standard time watch with the addition of a time recording feature. Running durations from 15 to 30 minutes are the standard with some watches recording 1 to 12 hours are available. Not to be confused as a stopwatch.
Chronometer	A watch which is tested and certified to meet certain precision standards. In Switzerland, only timepieces certified by the COSC may use the word 'Chronometer' on them. Unfortunately the average quartz time piece will run more accurately than a chronometer rated watch.
Crown	The knob from which the watch functions are set. The crown turns the stem, which engages the setting gears. Crowns are screwed to the stem and must be tightened if loose. A Screw-down crown, screws to lock against a threaded tube at the case to offer a superior level of water resistance
Dial	The numbered gage from which the time is displayed.
Hairspring	A fine spiral or helical spring used in mechanical watches, marine chronometers, and other timekeeping mechanisms to control the rate of vibration of the balance wheel.
Hands	The pointers or indicators from which the time is read. Frequently their surface receive a luminous treatment to allow reading in low light conditions.
Lever Escapement	Invented by Thomas Mudge around 1757 and later refined by Breguet, and Massey, the lever escapement is a key component of the better quality balance wheel watches. It is a detached escapement, which means that the time- keeping element runs entirely free of interference from the escapement during a portion of the operating cycle.
Lugs	Attachment point for a wrist strap or band. Horn or post style are the most common, but others include articulated, hidden, ring-end, and T-bar.
Main Spring	The steel ribbon, which provides the power for a mechanical gear train. A main spring rarely breaks as a result of winding, but rather simply metal fatigue causes most failures.
Mechanical Watch	Spring driven gear train regulated with a balance wheel escapement.
Perpetual Calendar	A calendar that is perpetually correct regardless of the lengths of the various months, the best even can account for leap years with wheel that only rotates once in 4 years. The current day, date, and month are often shown. Some recently developed quartz movements now incorporate this feature.
Pocket Watch	Earliest forms of portable timekeeping. These watches were secured with a chain to the gentleman’s clothing (mostly to prevent pick-pockets from "lifting the watch") and kept in a pocket. Available as a open-face or the covered styles known as hunting cases.
Push Button	A spring loaded plunger used to activate features not addressed by the standard stem and crown.
Regulator	Lever used to adjust the rate of the timepiece by lengthening or shortening the balance hairspring or a pendulums suspension spring by affecting its oscillating period or frequency.
Quartz Watch	A consistent timing element. Electricity in induced into a piece of quartz crystal which vibrates at a specific frequency (32 KHz), these vibrations are "clipped and divided" to reach the mathematical increment needed to approximate a second duration, this duration it then pulsed to a stepping motor and the rest is just the gearing for the needed ratios.
Repeater	A audible striking feature allowing the time to be recalled by means of a pushbutton. Some times refereed as a "blind mans watch" This allowed one to get the time in the dead of night without having to fumble around for a candle. An hour repeater only repeats the last passed hour, a quarter repeater will repeat the last passed hour and quarter and a minute repeater can strike out the time to the last hour, quarter, and minute passed.
Spring Bar	Cylindrical pin with spring loaded, sliding end-tips. Available in several diameters and in a range of sizes from 6 mm to 24 mm lengths. Pins do wear and the springs can loose their tension with age. Replace pins when the band is replaced or with each service.
Tourbillon	Invented in 1795 by Swiss watchmaker Abraham-Louis Breguet, the tourbillion (french word for "whirlwind") is an addition to the mechanics of a watch escapement. Basically a mechanical means of countering the effects of gravity by mounting the escapement and balance wheel in a rotating cage, ostensibly in order to negate the effect of gravity when the timepiece (and thus the escapement) is rotated. Once a viable addition to the movement of certain watches or nautical timepieces, today’s use is simply a demonstration of watchmaking virtuosity.