The term chronometer ( mainly, colloquially also male, from Ancient Greek χρόνος chronos "time" and μέτρον métron " measure, scale " ) denotes an especially accurate watch, such as the ones needed most at the time of determination and navigation of ships and aircraft.
The development of accurate clocks has been initiated by the carpenter and self-taught watchmaker John Harrison. The British Government had in 1714 a high price for the solution of the problem exposed length - a method for accurately determining the longitude at sea. Harrison's solution, a precise mechanical clock, angry contemporary astronomers and scientists who instead find other solutions (Moon distance of stars, Earth's magnetic field ) for the problem studied. Harrison was ultimately successful, his model but too expensive. One of the developments of the fourth and final model Harrisons created in 1778 the watchmaker John Arnold ( 1736-1799 ), who in 1780 coined the term chronometer in order to apply his instrument.
Marine chronometers were widespread until the end of World War II and were then further used in the field of navies. The decline of the mechanical chronometer began around 1960 with the invention of the quartz watch whose accuracy was better just around 2-3 orders of magnitude - see also quartz crisis. For the classical chronometer as a navigational instruments so hardly need was present. Today, ships navigate though mainly with the Global Positioning System ( GPS), which is also based on high-precision time measurement, but are for the emergency continues instruments of celestial navigation and related tables must be carried.
The necessary for determining the length standard or universal time is everywhere today by accurate quartz clocks or time signals, which are in turn controlled by a global network of atomic clocks.
Even today chronometers are made for collectors and enthusiasts. Colloquially, the term chronometer is often commonly used for high quality and precise timepieces. Officially a device but can only be described as a chronometer when it was tested by an observatory or an official passage control point in a standardized measurement method.
Several observatories offered chronometer tests. The observatory in Paris (1671-1891) began with tests, followed by Greenwich (1675-1886), Liverpool (1843, with certification standards from 1893), Hamburg ( 1877), Yale (1879 ), Kew - Teddington (1883 ), Leipzig (1883 ) and Besançon ( 1885).
Chronometer test in Switzerland
As the official chronometer, a clock may only call when their Swiss watch one test has passed ( according to NIH 95-11 / ISO 3159 ) of the independent Swiss Observatory Contrôle officiel suisse Chronometer ( COSC). Maintains the work of a clock, the COSC certificate, the manufacturer provides the clock usually with the word chronometer. After passing the examination, the factory receives a certificate attesting to its accuracy. It contains the following information:
With quartz movements the exam lasts 11 days and apply the following values:
Chronometer test in Germany
Since September 2006, exists in the observatory Wempe Chronometerwerke Glashütte i / SA, a German laboratory for chronometer, which is operated by the jewelry and watch dealer Wempe KG. She was certified in cooperation with the State Agency for Metrology and Verification beings Thuringia and the Saxon State Office for the measurement and calibration system of the Physikalisch-Technische Bundesanstalt ( PTB) as a calibration laboratory and field office for chronometer testing of the German Calibration Service ( DKD). The limit values for mechanical watches correspond (according to DIN 8319-1 ) the above-mentioned Swiss values. Differences to the Swiss Auditing there for quartz watches, in which the following criteria apply:
In contrast to the Swiss Auditing fully assembled watches are tested here. The tested quantities are much lower compared to COSC.
International chronometry competitions
From 1872 to 1968 Chronometriewettbewerbe individual, usually additionally regulated watches were carried out in the Neuchâtel Observatory. The contests were however then set based on the quartz crisis. Since 2009, the Watch Museum of Le Locle organized jointly with the town of Le Locle biennial Chronometriewettbewerb, its implementation by the COSC, the Haute Ecole ARC and the Observatoire de Besançon is organized.