horology

1. The science of measuring time.
2. The art of making timepieces.

[Greek hōrā, hour, season + -LOGY.]

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.

Horology (from Greek ώρα, "hour, time"; and 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 See also 3.1 People (Horologists) 3.2 Literature 3.3 Horological Professions 3.4 Museums (dedicated to horology) 3.5 Museums (not specialized in horology, but displaying major horological collections) 3.6 Institutions 3.7 Newsgroup 3.8 Others 4 External links

Horological museums and libraries

Horology has a long history and there are many museums and several specialised 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.

Besides museums dedicated only to horology you will often find horological objects in major art museums (including the Metropolitan Museum in New York or the Getty Museum in Los Angeles) or in major museums dealing with the history of science or the history of technology (including the Deutsches Museum in Munich, the London Science Museum or the Musée des Arts et Métiers in Paris.)

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)

See also

Look up horology in Wiktionary, the free dictionary.

rounding up tool

People (Horologists)

• Abraham Louis Bréguet
• Joost Burgi
• Giovanni de Dondi
• Aaron Lufkin Dennison
• Rupert Gould
• John Harrison
• Nicolas Hayek
• Christiaan Huygens
• Jens Olsen
• Ernst Thomke
• Richard of Wallingford
• Simon Willard

Literature

• Revolution in Time, by David S. Landes, Harvard University: the history of the measure of time throughout the evolution of the civilisations

Horological Professions

• clockmaker
• timekeeper
• watchmaker

Museums (dedicated to horology)

• American Clock & Watch Museum, Bristol, Connecticut, USA
• Belmont House, near Faversham, Kent, UK
• British Horological Institute, Upton UK
• Clockmakers' Museum, London, UK
• Deutsches Uhrenmuseum, Furtwangen im Schwarzwald, Germany
• Dorf- und Uhrenmuseum Gütenbach, Gütenbach, Germany
• Museum fũr Uhren und Mechanische Musik, Oberhofen am Thunersee, Switzerland
• Musée d'Horlogerie du Locle, Le Locle, Switzerland
• Musée international d'horlogerie, La Chaux-de-Fonds, Switzerland
• van het NEDERLANDSE UURWERK, Zaandam, The Netherlands
• National Watch and Clock Museum, Columbia, Pennsylvania, USA
• Royal Observatory, Greenwich, UK
• Städtisches Uhrenmuseum, Schulhof Wien, Austria
• Schwäbisches Turmuhrenmuseum Mindelheim, Germany
• Timexpo Museum, Waterbury Connecticut USA
• Uhrenindustriemuseum, Villingen-Schwenningen, Germany
• Uhrenmuseum Beyer, Zurich, Switzerland
• Uhrenmuseum zum Rösli, zurich, Switzerland
• Willard House and Clock Museum, Grafton, Massachusetts, USA
• Irish Swiss Institute of Horology, Dublin

Museums (not specialized in horology, but displaying major horological collections)

• Bavarian National Museum, Munich, Germany
• Boerhaave Museum, Leiden, Netherlands
• British Museum, London, UK
• Deutsches Museum, Munchen, Germany
• Frick Collection, New York City, USA
• Metropolitan Museum, New York City, USA
• Musée des Arts et Métiers, Paris, France
• Museumslandschaft Hessen Kassel
• Science Museum (London), UK
• Wallace Collection, London, UK
• St Edmundsbury Heritage Service, Bury St Edmunds, UK

Institutions

• American Watchmakers-Clockmakers Institute, USA
• Antiquarian Horological Society, UK
• British Horological Institute, UK
• Chronometrophilia, Switzerland
• Deutsche Gesellschaft für Chronometrie, Germany
• NAWCC, USA
• National Watch and Clock Library, USA
• Federation of the Swiss Watch Industry FH, Switzerland
• Canadian Horological Society, Canada
• York Time Institute, USA

Newsgroup

• alt.horology

Others

• System time

External links

• American Watchmakers-Clockmakers Institute
• BHI - The British Horological Institute
• 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

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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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