Horology

Horology (via Latin horologium from Greek ὡρολόγιον, from hṓra "hour; time" and -o- interfix and suffix -logy; literally "the study of time") is the art and/or science of measuring time. Clocks, watches, clockwork, sundials, hourglasses, clepsydras, timers, time recorders, marine chronometers and atomic clocks are all examples of instruments used to measure time. In current usage, horology refers mainly to the study of mechanical time-keeping devices, while chronometry more broadly includes electronic devices that have largely supplanted mechanical clocks for the best accuracy and precision in time-keeping.

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.

There are many horology museums and several specialized libraries devoted to the subject. One 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, which re-opened at the Science Museum in October 2015, and the horological collections at the British Museum, the Science Museum (London) and at the Wallace Collection.

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