horology

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Measurement of the time dimension. In practice, horology is the search for a steady or repetitive action, and the design of an instrument to perform that action and to indicate (read out) a measure of the action. Until early in the twentieth century, horology dealt with mechanical instruments, with effort distributed between improving accuracy and decreasing size of timepieces. Increasingly, however, electronic instruments provided means for meeting these objectives. See also Chronometer; Clock; Quartz clock.

An advance in accurate measurement of time came by replacement of dynamic mechanical oscillators with quantum energy transitions. Two standards in common use are the cesium atomic beam clock and the rubidium gas cell. More recently, trapped ion clocks, which use quantum transitions in elements such as mercury, have been developed. A small cloud of ions is trapped in a quadrupole electric field. The ions' thermal motions are then reduced by a technique called laser cooling. The quantum transitions in these clouds can then be measured with high precision. See also Atomic clock; Laser cooling; Particle trap.

Radio astronomers require precise time for two areas of experimentation: very long-baseline interferometry (VLBI) and pulsars. Both areas have the capability of providing precise time information. Very long-baseline interferometry involves multiplying samples of an incident electric field that are recorded independently at telescopes situated around the globe while being trained on the same object in the sky. Solar time, or Coordinated Universal Time (UTC), is offset from International Atomic Time (TAI) to allow for the variable rotation of the Earth. The most precise measurement of Earth rotation comes from VLBI measurements. Pulsars are highly magnetized and rapidly rotating neutron stars that emit intense beams of radio emission. Astronomers keep track of the rotations of these stars by referencing pulse arrival times to TAI, but not even the TAI time scale is sufficiently accurate because of the relativistic effects, gravitational redshift, and time dilation that result from the motion of the Earth. A new time scale, Terrestrial Time (TT), is derived from TAI without the relativistic effects. Timing measurements of the fastest pulsars, which rotate more than 600 times per second, are now as precise as the best Earth clocks over durations of a year or more. Time, which in prehistory was reckoned solely by astronomical events, has again become the province of astronomical observations. See also Atomic time; Dynamical Time; Pulsar; Radio astronomy; Radio telescope.

• Measures and Standards of Time - horology: art or science of measuring time and making timepieces

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Horology (from Greek: ὥρα, "hour, time" and Greek: λόγος, logos, "study, speech"; lit. the study of time) is the art or science of measuring time. Clocks, watches, clockwork, sundials, clepsydras, timers, time recorders and marine chronometers are all examples of instruments used to measure time.

People interested in horology are called horologists. That term is used both by people who deal professionally with timekeeping apparatus (watchmakers, clockmakers), as well as aficionados and scholars of horology. Horology and horologists have numerous organizations, both professional associations and more scholarly societies.

Contents 1 Horological museums and libraries 2 Horological organizations 3 World Exhibitions 4 List of horological terms 5 See also 6 References 7 Further reading 8 External links

Horological museums and libraries

Horology has a long history^{[chronology citation needed]} and there are many museums and several specialized libraries devoted to the subject. An example is the Royal Greenwich Observatory, which is also the source of the Prime Meridian (longitude 0° 0' 0"), and the home of the first marine timekeepers accurate enough to determine longitude (made by John Harrison). Other horological museums in the London area include the Clockmakers' Museum, and the horological collections at the British Museum, the Science Museum (London) and at the Wallace Collection.

One of the more comprehensive museums dedicated to horology is the Musée international d'horlogerie in La Chaux-de-Fonds (Switzerland). The Musée d'Horlogerie du Locle is a bit smaller but located nearby. One of the better horological museums in Germany is the Deutsches Uhrenmuseum. The two leading specialised horological museums in North America are the National Watch and Clock Museum in Columbia, Pennsylvania, and the American Clock and Watch Museum in Bristol, Connecticut.

An example of a museum devoted to one particular type of clock is the Cuckooland Museum, in the U. K., which hosts the world's largest collection of antique cuckoo clocks.

One of the most comprehensive horological libraries open to the public is the National Watch and Clock Library in Columbia, PA (USA). Other good horological libraries providing public access are at the Musée international d'horlogerie in Switzerland, at the Deutsches Uhrenmuseum in Germany, and at the Guildhall Library in London.

Horological organizations

The leading scholarly horological organizations are:

• American Watchmakers-Clockmakers Institute - AWCI (United States of America)
• Antiquarian Horological Society - AHS (United Kingdom)
• Association Française des Amateurs d'Horlogerie Ancienne - AFAHA (France)
• British Horological Institute - BHI (United Kingdom)
• Chronometrophilia (Switzerland)
• Deutsche Gesellschaft für Chronometrie - DGC (Germany)
• HORA Associazione Italiana Cultori di Orologeria Antica (Italy)
• National Association of Watch and Clock Collectors - NAWCC (United States of America)
• American Watch Guild - AWG

World Exhibitions

• BaselWorld
• Geneva Time Exhibition ^[1]
• Salon International de la Haute Horlogerie (SIHH) ^[2]

List of horological terms

Term	Explanation
Chablon	French term for a watch movement (not including the dial and hands), of which all or part of the components are not assembled.
Ébauche	French term (but commonly used in English-speaking countries) for a movement blank, i.e. an incomplete watch movement which is sold as a set of loose parts, comprising the main plate, the bridges, the train, the winding and setting mechanism and the regulator. The timing system, the escapement and the mainspring, however, are not parts of the "ébauche"
Établissage	French term for the method of manufacturing watches and/or movements by assembling their various components. It generally includes the following operations: receipt, inspection and stocking of the "ébauche", the regulating elements and the other parts of the movement and of the make-up; assembling; springing and timing; fitting the dial and hands; casing; final inspection before packing and dispatching.
Établisseur	French term for a watch factory which is engaged only in assembling watches, without itself producing the components, which it buys from specialist suppliers.
Factory, works	In the Swiss watch industry, the term manufacture is used of a factory in which watches are manufactured almost completely, as distinct from an "atelier de terminage", which is concerned only with assembling, timing, fitting the hands and casing.
Manufacture d'horlogerie	French term for a watch factory which itself produces the components (particularly the "ébauche") needed for the manufacture of its products (watches, alarm and desk clocks, etc.).
Terminage	French term denoting the process of assembling watch parts for the account of a producer.
Termineur	French term for an independent watchmaker (or workshop) engaged in assembling watches, either wholly or in part, for the account of an "établisseur" or a "manufacture", who supply the necessary loose parts. See "atelier de terminage" above.

See also

• Hora (astrology)
• List of clock manufacturers
• System time
• WatchTime Magazine

References

1. ^ Geneva Time Exposition - official website
2. ^ Salon International de la Haute Horlogerie - official website

Further reading

• Berner, G.A., Illustrated Professional Dictionary of Horology, Federation of the Swiss Watch Industry FH 1961 - 2012

External links

Look up horology in Wiktionary, the free dictionary.

• American Watchmakers-Clockmakers Institute
• BHI - The British Horological Institute
• Tendance Horlogerie: Watches Portal in french and english versions
• Horological Portal
• Federation of the Swiss Watch Industry FH
• Musée d'horlogerie du Locle (Château des Monts)
• Musée International d'Horlogerie
• NAWCC: National Association of Watch & Clocks Collectors (USA)
• Horology Patents
• A Rudimentary Treatise on Clocks, Watches and Bells by Edmund Beckett, 1st Baron Grimthorpe, 1903, from project Gutenberg
• Application horlogère

v t e Time Major concepts Time Eternity Arguments for eternity Immortality History Past Present Future Futures studies Deep time Time Portal Measurement and standards Chronometry UTC UT TAI Second Minute Hour Sidereal time Solar time Time zone Metric time Decimal time Hexadecimal time Clock Astrarium History of timekeeping devices Horology Marine chronometer Sundial Water clock Calendar Day Week Month Year Tropical year Gregorian Islamic Julian Intercalation Leap second Leap year Chronology Astronomical chronology Calendar era Chronicle Dating methodologies Geochronology Geologic Time Geological history Periodization Regnal year Timeline Religion and mythology Dreamtime Kāla Kalachakra Prophecy Time and fate deities Wheel of time Philosophy A-series and B-series B-Theory of time Causality Endurantism Eternal return Eternalism Event Perdurantism Presentism Temporal finitism Temporal parts The Unreality of Time Physical sciences Time in physics Absolute time and space Arrow of time Chronon Coordinate time Planck epoch Planck time Proper time Spacetime Theory of relativity Time dilation Gravitational time dilation Time domain T-symmetry Biology Chronobiology Circadian rhythms Psychology Mental chronometry Sense of time Specious present Sociology and anthropology Long Now Foundation Time discipline Time use research Economics Time value of money Time-based currency Time Banking Related topics Carpe diem Duration Space System time Tempus fugit Time capsule Time signature Time travel

v t e Time measurement and standards Major subjects Time · Chronometry · Orders of magnitude · Metrology International standards UTC · UTC offset · UT · ΔT · DUT1 · IERS · ISO 31-1 · ISO 8601 · TAI · 12-hour clock · 24-hour clock · Barycentric Coordinate Time · Civil time · Daylight saving time · Geocentric Coordinate Time · International Date Line · Leap second · Solar time · Terrestrial Time · Time zone Obsolete standards Barycentric Dynamical Time · Ephemeris time · Greenwich Mean Time · Prime Meridian Time in physics Absolute time and space · Spacetime · Chronon · Continuous time · Coordinate time · Cosmological decade · Discrete time · Planck epoch · Planck time · Proper time · Theory of relativity · Time dilation · Gravitational time dilation · Time domain · T-symmetry Horology Clock · Astrarium · Atomic clock · Complication · Equation of time · History of timekeeping devices · Hourglass · Marine chronometer · Marine sandglass · Radio clock · Sundial · Watch · Water clock Calendar Astronomical · Dominical letter · Epact · Equinox · Gregorian · Hebrew · Intercalation · Islamic · Julian · Leap year · Lunar · Lunisolar · Seven-day week · Solar · Solstice · Tropical year · Weekday determination · Weekday names Archaeology & geology Dating methodologies · Geologic time scale · International Commission on Stratigraphy Astronomical chronology Galactic year · Nuclear time scale · Precession · Sidereal time Units of time Century · Day · Decade · Fortnight · Hour · Jiffy · Lustrum · Millennium · Minute · Month · Saeculum · Second · Shake · Tide · Week · Year Related topics Chronology · Duration · Mental chronometry · Metric time · System time · Time value of money · Timekeeper

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Dansk (Danish)
n. - urmagerkunst

Nederlands (Dutch)
tijdmeting, het horlogemaken

Français (French)
n. - horlogerie, chronométrie

Deutsch (German)
n. - Lehre von der Zeitmessung, Uhrmacherkunst

Ελληνική (Greek)
n. - χρονομετρία

Italiano (Italian)
orologeria

Português (Portuguese)
n. - arte (f) de medir o tempo, arte (f) de fabricar relógios

Русский (Russian)
измерение времени, часовая башня, часослов

Español (Spanish)
n. - horología, arte de hacer relojes

Svenska (Swedish)
n. - urmakeri

中文（简体）(Chinese (Simplified))
钟表学, 测时法, 钟表制造术

中文（繁體）(Chinese (Traditional))
n. - 鐘錶學, 測時法, 鐘錶製造術

한국어 (Korean)
n. - 시계학, 시계제작법, 측시법

日本語 (Japanese)
n. - 時計学, 時計製作法

العربيه (Arabic)
‏(الاسم) علم قياس, الوقت, فن صنع الساعات‏

עברית (Hebrew)
n. - ‮שענות‬

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