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From ‘alarm watch’ to ‘zodiac’…

The following pages are a glossary of terms associated with horology, watches and watchmaking.




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U


Uni-directional Rotating Bezel


A rotating bezel, often found on divers’ watches, that moves only in a counterclockwise direction and makes it easy to measure elapsed time. It is particularly useful for divers so they cannot accidentally rotate it in the wrong direction, which could cause them to miscalculate their dive times. Because the bezel moves in only one direction, the diver can err only on the side of safety when timing his dive. Many divers’ watches are ratcheted, so that they lock into place for greater safety.


 
Universal Time


The mean solar time of the Greenwich meridian, counted from noon to noon, often confused with the mean time notion.


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V


Variation


In horology the term is usually referred to the variation of the daily rate, i.e. the difference between two daily rates specified by a time interval.


 
Vibration Frequency (VPH)


The ring-shaped balance swings around its own axis and acts as the ruling organ of the movement’s escapement. Its amplitude (normally about 300 degrees) is restricted by the very thin balance spring, which also provides for the reversing of its direction of rotation. The frequency of the alternating vibrations is measured in Hertz (Hz) or in the more usual vibrations per hour (vph).

The most common frequency for modern mechanical wristwatch movements is 28,800 vph (or 4 Hz) like our own Malvern Automatic). A watch ticking at 4Hz makes 4 oscillations per second, or 8 semi-oscillations (or vibrations) per second. There are 60 seconds in a minute, so this watch would tick at 480 semi-oscillations (or vibrations) per minute. Multiplying the 480 vibrations per minute by the 60 minutes in an hour yields the 28,800 vph figure. Since this watch ticks 8 times per second, a chronograph in a 28,800 vph watch can time events to the nearest 1/8 of a second.


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W


Water Resistant or Waterproof


The ability to withstand contact with water without suffering damage. Watches have various degrees of water resistance. Usually measured in increments of one atmosphere (ATM or bar, equal to 10 metres of water pressure) or metres and is often noted on the dial or case back.

A water resistance level of 30 metres means the watch can withstand splashes of water. A level of 50 metres means that it can be worn for swimming in shallow depths. A level of 100 metres means it can be worn snorkelling and a level of 300 metres or more means it can be worn scuba diving. The water resistance record is held by The Hydromax by Bell & Ross which was developed for professional deep sea diving and is resistant to 11,100 metres!


 
Wheel


A circular component, mostly toothed, combines with an arbor and a pinion to make up a gear. The wheel rotates around an axis and its function is to transmit power or motion. Wheels are normally made of brass, while arbors and pinions are made of steel. The wheels between barrel and escapement make up the so-called train.


 
Winding Stem


Element transmitting motion from the crown to the gears governing manual winding and setting.


 
Window


Aperture in the dial, that allows reading the underlying indication, mainly the date, but also indications concerning a second zone’s time or jumping hour


 
World Time


Additional feature of watches provided with a GMT function, displaying the 24 time zones on the dial or bezel, each zone referenced by a city name, providing instantaneous reading of the time of any country


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Z


Zone


Small additional dial or indicator that may be positioned, or placed off-centre on the main dial, used for the display of various functions (e.g. second counters).


 
Zodiac


Circular belt with the ecliptic in the middle containing the twelve constellations through which the sun seems to pass in the course of a year.


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