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Chronograph and Timepiece Glossary

Glossary of watch terms used in this web-site

Automatic winding
Aperture
Balance
Caliber
Chronograph (Chronographe)
Chronometer (Chronometre)
Crown
Ekegren
Escapement
Gaskets
Glucydur
Hair spring
Hardness Definitions (Moh, Vicker, Knoop)
Incabloc Shock absorbtion
Jewels
Main spring
Manual wind
Moon phase
Movement
Perlage
Pulsometer
Sapphire Crystal (more about sapphire crystals here)
Tachymetre or Tachymeter
Telemeter
Vibrations per hour (vph)


Automatic winding:  A rotating weight (rotor) which is set into motion by the arm of the wearer. The motion causes this weight to wind the main-spring barrel in a mechanical watch, thereby keeping the watch wound when worn on the wrist. Automatic winding can occur uni-directionally (meaning the weight only winds the watch in one direction) or bi-directional winding (meaning the rotor will wind the watch regardless of which direction it spins).
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Aperture:  A small opening on the dial of a watch. Usually for the indication of the day, date, month, or moon-phase.
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Balance (or balance wheel):  The heart of a mechanical watch movement. Using the energy in the main-spring, this small wheel oscillates back and forth allowing a mechanical watch to run. The balance contains a spiral shaped balance spring (hair-spring) which sets the rythm of oscillation due to its vibrating frequency. Today balances are usually made of one piece of anti-magnetic glucydur, which expands very little when it is exposed to heat.
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Caliber:  A term, similar to type or model, which refers to different watch movements.
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Chronograph (Chronographe):  From the Greek word chronos ("time") and graphein ("to write"). Originally a chronograph literally wrote the elapsed time on a piece of paper with the aid of a pencil attached to a hand. Today, this term is used for watches that show not only the time of day, but also certain time intervals via the independent hand that may be started and stopped at will. A stop watch is different than a chronograph because it only shows elapsed time and does not display the time of day. Chronograph should not be confused with Chronometer.
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Chronometer (Chronometre):  Literally, "measure of time". As used today, chronometer denotes an especially accurate watch (one with a deviation of no more than 6 seconds per day for a mechanical watch). Chronometers are usually supplied with an official certificate from an independent office such as the C.O.S.C.

Click here to see the C.O.S.C. Chronometre Certificate.

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Crown:  The winding button. Usually with coin ridge edge for grip. Also generally located at 3 o'clock on the side of the case.
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Ekegren:  Waldan International's watch line as marketed and sold in Europe. The name Ekegren comes from Henri Robert Ekegren (1823-1896) who was one of the most skilled watchmakers of the second half of the 19th century.
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Escapement:  The combined mechanism of balance, lever, and escape wheel, which divides the impulses coming from the going barrel into small, accurately portioned doses.
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Gaskets:  Rubber O-rings located on the case back of watches, in the pushers and crown and are there to provide a seal to keep water out of the watch.
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Glucydur:  An anti-magnetic alloy that expands very little when exposed to heat. This quality makes glucydur useful in making balances.
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Hair spring:  Also known as balance spring, this is the small spiral spring that is attached to the balance wheel. The quality of this spring can affect the regularity and accuracy of a movement.
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Incabloc:  A patented shock absorbing device which permits the end stone of the balance to give when the watch is subjected to an impact or jolt.
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Jewels:  A synthetic ruby which is used to minimize friction and hold in oil.
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Mainspring:  A flat spring coiled or wound to supply power to the watch. The non-magnetic mainspring was introduced in 1947.
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Manual wind:  A manual wind watch has no means of getting wound other than by the user through the winding crown.
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Moon-phase:  A complication that represents the waxing and waning of the moon as it circles the earth. It is intended to represent the phase of the moon.
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Movement:  The fully functioning assembly of all the main timekeeping organs of a watch.
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Perlage:  Also known as circular graining, perlage is a surface decoration comprising of an even pattern of partially overlapping dots applied with a quickly rotating plastic or wooden peg.
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Pulsometer:  Scale on the dial or bezel of a watch which - in conjunction with the second hand of the chronograph - may be used to measure the pulse rate. A pulsometer is always marked with a reference number. For example, if it is marked "gradué pour 15 pulsations" then an operator counts 15 beats of a pulse. At the last beat of the pulse, the seconds hand shows on the pulsometer scale what the pulse rate is in beats per minute. See uses of a chronograph in the Instructions section of this web-site for an example.
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Sapphire Crystal:  Scratch resistant glass with a hardness of 9 on the moh's scale of hardness. The only thing harder is diamond. Sapphire crystals are usually synthetic (made in a lab).
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Tachymetre or Tachometer:  A scale on the dial or bezel of a chronograph that - in conjunction with the second hand of the chronograph - may be used to measure the speed of a moving object. A tachymetre takes a value determined in less than a minute and converts it into miles per hour. See uses of a chronograph in the Instructions section of this web-site for an example.
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Telemeter:  A scale on the dial or bezel of a chronograph that - in conjunction with the second hand of the chronograph - may be used to measure the distance of an object from its observer by measuring how long it takes sound to travel that distance. One application of a telemeter would be determining the distance of a storm from its observer. See uses of a chronograph in the Instructions section of this web-site for an example.
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Vibrations per hour (vph) Vibration Frequency:  The ring shaped balance swings around its own axis and acts as the ruling organ of the movement's escapement. The amplitude is restricted by the very thin balance spring, which also provides for the reversing of the direction of rotation. The frequency of the alternating vibrations is measured in Hertz (HZ) or in the more usual vibrations per hour (vph), which is also sometimes written as A/h, the A standing for the French alternance ("change"). Most of today's wristwatches tick at frequencies of 28,800vph (4Hz) or 21,600vph (3Hz). Less usual, but still used in certain models, are vibration frequencies of 18,000 vph (2.5Hz) and 36,000 vph (5Hz).
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