What is "chronometer watch"

Watch \Watch\ (w[o^]ch), n. [OE. wacche, AS. w[ae]cce, fr. wacian to wake; akin to D. wacht, waak, G. wacht, wache.

1. The act of watching; forbearance of sleep; vigil; wakeful, vigilant, or constantly observant attention; close observation; guard; preservative or preventive vigilance; formerly, a watching or guarding by night.

   Shepherds keeping watch by night.
   --Milton.

   All the long night their mournful watch they keep.
   --Addison.

   Note: Watch was formerly distinguished from ward, the former signifying a watching or guarding by night, and the latter a watching, guarding, or protecting by day Hence, they were not unfrequently used together, especially in the phrase to keep watch and ward, to denote continuous and uninterrupted vigilance or protection, or both watching and guarding. This distinction is now rarely recognized, watch being used to signify a watching or guarding both by night and by day, and ward, which is now rarely used, having simply the meaning of guard, or protection, without reference to time.

   Still, when she slept, he kept both watch and ward.
   --Spenser.

   Ward, guard, or custodia, is chiefly applied to the daytime, in order to apprehend rioters, and robbers on the highway . . . Watch, is properly applicable to the night only, . . . and it begins when ward ends, and ends when that begins.
   --Blackstone.

2. One who watches, or those who watch; a watchman, or a body of watchmen; a sentry; a guard.

   Pilate said unto them, Ye have a watch; go your way, make it as sure as ye can.
   --Matt. xxvii. 65.

3. The post or office of a watchman; also, the place where a watchman is posted, or where a guard is kept.

   He upbraids Iago, that he made him Brave me upon the watch.
   --Shak.

4. The period of the night during which a person does duty as a sentinel, or guard; the time from the placing of a sentinel till his relief; hence, a division of the night.

   I did stand my watch upon the hill.
   --Shak.

   Might we but hear . . . Or whistle from the lodge, or village cock Count the night watches to his feathery dames.
   --Milton.

5. A small timepiece, or chronometer, to be carried about the person, the machinery of which is moved by a spring.

   Note: Watches are often distinguished by the kind of escapement used, as an anchor watch, a lever watch, a chronometer watch, etc. (see the Note under Escapement, n., 3); also, by the kind of case, as a gold or silver watch, an open-faced watch, a hunting watch, or hunter, etc.

6. (Naut.)

   1. An allotted portion of time, usually four hour for standing watch, or being on deck ready for duty. Cf. Dogwatch.

   2. That part, usually one half, of the officers and crew, who together attend to the working of a vessel for an allotted time, usually four hours. The watches are designated as the port watch, and the starboard watch. Anchor watch (Naut.), a detail of one or more men who keep watch on deck when a vessel is at anchor. To be on the watch, to be looking steadily for some event. Watch and ward (Law), the charge or care of certain officers to keep a watch by night and a guard by day in towns, cities, and other districts, for the preservation of the public peace. --Wharton. --Burrill. Watch and watch (Naut.), the regular alternation in being on watch and off watch of the two watches into which a ship's crew is commonly divided. Watch barrel, the brass box in a watch, containing the mainspring. Watch bell (Naut.), a bell struck when the half-hour glass is run out, or at the end of each half hour. --Craig. Watch bill (Naut.), a list of the officers and crew of a ship as divided into watches, with their stations. --Totten. Watch case, the case, or outside covering, of a watch; also, a case for holding a watch, or in which it is kept. Watch chain. Same as watch guard, below. Watch clock, a watchman's clock; see under Watchman. Watch fire, a fire lighted at night, as a signal, or for the use of a watch or guard. Watch glass.

      1. A concavo-convex glass for covering the face, or dial, of a watch; -- also called watch crystal.

      2. (Naut.) A half-hour glass used to measure the time of a watch on deck.

         Watch guard, a chain or cord by which a watch is attached to the person.

         Watch gun (Naut.), a gun sometimes fired on shipboard at 8 p. m., when the night watch begins.

         Watch light, a low-burning lamp used by watchers at night; formerly, a candle having a rush wick.

         Watch night, The last night of the year; -- so called by the Methodists, Moravians, and others, who observe it by holding religious meetings lasting until after midnight.

         Watch paper, an old-fashioned ornament for the inside of a watch case, made of paper cut in some fanciful design, as a vase with flowers, etc.

         Watch tackle (Naut.), a small, handy purchase, consisting of a tailed double block, and a single block with a hook.

The term chronometer (From Greek: Χρονόμετρο) is a specific type of timepiece tested and certified to meet certain precision standards. In Switzerland, only timepieces certified by the Contrôle Officiel Suisse des Chronomètres (COSC) may use the word 'Chronometer' on them. Outside Switzerland, equivalent bodies (such as the Japan Chronometer Inspection Institute) have in the past certified timepieces to the same internationally recognised standards, although use of the term has not always been strictly controlled.

The term chronometer was coined by Jeremy Thacker of Beverley, England in 1714, referring to his invention of a clock ensconced in a vacuum chamber. The term chronometer is also used to describe a marine chronometer used for celestial navigation and determination of longitude. The marine chronometer was invented by John Harrison in 1730. This was the first of a series of chronometers that enabled accurate marine navigation. From then on, an accurate chronometer was essential to deep sea marine or air navigation out of sight of land. Early in the Twentieth Century the advent of radiotelegraphy time signals supplemented the onboard marine chronometer for marine and air navigation, and various radio navigation systems were invented, developed, and implemented during and following the Second World War (e.g., Gee, Sonne a.k.a. Consol, LORAN(-A and -C), Decca Navigator System and Omega Navigation System) that significantly reduced the need for positioning using the onboard marine chronometer. These culminated in the development and implementation of global satellite navigation systems (GSN- GPS) in the last half of the 20th century. The marine chronometer is no longer used as the primary means for navigation at sea, although it is still required as a backup, since radio systems and their associated electronics can fail for a variety of reasons.

Once mechanical timepiece movements developed sufficient precision to allow for accurate marine navigation, there eventually developed what became known as "chronometer competitions" at astronomical observatories located in Europe. The Neuchâtel Observatory, Geneva Observatory, Besancon Observatory, and Kew Observatory are prominent examples of observatories that certified the accuracy of mechanical timepieces. The observatory testing regime typically lasted for 30 to 50 days and contained accuracy standards that were far more stringent and difficult than modern standards such as those set by COSC. When a movement passed the Observatory, it became certified as an Observatory Chronometer and received a Bulletin de Marche from the Observatory, stipulating the performance of the movement. Because only very few movements were ever given the attention and manufacturing level necessary to pass the Observatory standards, there are very few Observatory Chronometers in existence. Most Observatory Chronometers had movements so specialized to accuracy that they could never withstand being used as wristwatches in normal usage. They were useful only for accuracy competitions, and so never were sold to the public for usage. However, in 1966 and 1967, Girard Perregaux manufactured approximately 670 wristwatches with the Calibre 32A movement, which became Observatory Chronometers certified by the Neuchatel Observatory, while in 1968, 1969 and 1970 Seiko had 226 wristwatches with its 4520 and 4580 Calibres certified. These Observatory Chronometers were then sold to the public for normal usage as wristwatches, and some examples may still be found today. The Observatory competitions ended with the advent of the quartz watch movement, in the late 1960s and early 1970s, which generally have superior accuracy at far lesser costs. In 2009, the Watch Museum of Le Locle would renew with this tradition and launch a new chronometry contest based on ISO 3159 certification.