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Encyclopedia > Chronometer

A chronometer is a timekeeper precise enough to be used as a portable time standard, usually in order to determine longitude by means of celestial navigation. In the world of watches, the term is also often attached to those tested and certified to meet certain precision standards. In Switzerland, only timepieces certified by the COSC may use the word 'Chronometer' on them. A time scale specifies divisions of time. ... Longitude, sometimes denoted by the Greek letter λ (lambda),[1][2] describes the location of a place on Earth east or west of a north-south line called the Prime Meridian. ... Celestial Navigation is the 15th episode of The West Wing. ... A clock (from the Latin cloca, bell) is an instrument for measuring time. ... Contrôle Officiel Suisse des Chronomètres // Founded in its current structure in 1973, the COSC (Contrôle Officiel Suisse des Chronomètres) is the Swiss Official Chronometer Testing Institute. ...

Contents

History

Bréguet twin barrel box chronometer.
Bréguet twin barrel box chronometer.

Until the mid 1750s, navigation at sea was an unsolved problem due to the difficulty in calculating longitudinal position. Navigators could determine their latitude by measuring the sun's angle at noon. However, to find their longitude, they needed a portable time standard that would work aboard a ship. The purpose of a chronometer is to keep the time of a known fixed location, which can then serve as a reference point for determining the ship's position. Conceptually, by comparing local high noon to the chronometer's time, a navigator could use the time difference to determine the ship's present longitude. Since the Earth rotates 360 degrees every day(24 hours, 1440 minutes), the time difference between the two points reveals how many degrees separate them. With the degrees of difference in hand, locating the position on a map was a relatively simple matter of spherical trigonometry. (In modern practice, a navigational almanac and trigonometric sight-reduction tables permit navigators to measure the Sun, Moon, visible planets, or any of 57 navigational stars at any time that the horizon is visible). Image File history File links Download high-resolution version (1402x1406, 211 KB) Work by Rama File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Chronometer 1893 ... Image File history File links Download high-resolution version (1402x1406, 211 KB) Work by Rama File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Chronometer 1893 ... A Breguet Classique watch with tourbillon Breguet is a manufacturer of fine watches, founded by Abraham Louis Breguet in Paris in 1775. ... Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia. ... Sea as seen from jetty in Frankston, Australia Look up maritime in Wiktionary, the free dictionary. ... Latitude, usually denoted symbolically by the Greek letter phi, , gives the location of a place on Earth north or south of the equator. ... Longitude, sometimes denoted by the Greek letter λ (lambda),[1][2] describes the location of a place on Earth east or west of a north-south line called the Prime Meridian. ... Noon is the time exactly through the day, written 12:00 in the 24-hour clock and 12:00 noon in the 12-hour clock. ... Look up time in Wiktionary, the free dictionary. ... The Sun is the star at the center of the Solar System. ... Apparent magnitude: up to -12. ... The eight planets and three dwarf planets of the Solar System. ...


The problem of creating a seaworthy timepiece was difficult. Until the 20th century, the best timekeepers were pendulum clocks, and the rolling of a ship at sea rendered the ordinary, gravity-based pendulum useless. John Harrison, a Yorkshire carpenter, invented a clock based on a pair of counter-oscillating weighted beams connected by springs whose motion was not influenced by gravity or the motion of a ship. His first two sea timekeepers used this system, but he became rightly convinced that they had a fundamental sensitivity to centrifugal force, which meant that they could never be accurate enough at sea. His third machine replaced one headache with a bigger one, and he eventually abandoned the large machines altogether. Harrison finally solved the precision problems with his H4 chronometer, essentially a large five-inch (12 cm) diameter pocket watch, which he submitted for a £20,000 prize offered by the British government in the early 18th century. His design used a fast-beating balance controlled by a temperature-compensated spiral spring. This general layout remained in use until microchips reduced the cost of a quartz clock to the point that electronic chronometers became commonplace. A pendulum clock uses a pendulum as its time base. ... John Harrison John Harrison (March 24, 1693–March 24, 1776) was an English clockmaker, who designed and built the worlds first successful chronometer (maritime clock), one whose accuracy was great enough to allow the determination of longitude over long distances. ... Centrifugal force (from Latin centrum center and fugere to flee) is a term which may refer to two different forces which are related to rotation. ... Microchip can refer to: Microchip (or simply chip) is used rather loosely in electronics. ... A quartz clock A quartz clock is a timepiece that uses an electronic oscillator which is made up by a quartz crystal to keep precise time. ...


After Harrison's pioneering work proved the possibility of portable precision timekeepers, making them practical by perfecting simpler and more affordable designs stood as the next problem. Pierre Le Roy and Ferdinand Berthoud in France, and Thomas Mudge in England successfully produced marine timekeepers of their own designs. Although none of these great makers discovered a path to simplicity, they did encourage others to enter the field by proving that Harrison's design did not represent the only answer to the problem. The greatest strides toward practicality came at the hands of Thomas Earnshaw and John Arnold, who developed simplified, detached, "spring detent" escapements, moved the temperature compensation to the balance, and improved the design and manufacturing process of balance springs. This combination of technological innovations served as the basis of marine chronometers until the electronic era. Thomas Earnshaw (born on February 4, 1749 in in Ashton-under-Lyne - died March 1, 1829 in London) was an English watchmaker who first simplified the process of chronometer production, making them available to the general public. ... London watchmaker John Arnold (1736–99), was one of the true master clockmakers from what was unarguably England’s golden age of horology. ... A simple escapement. ...


Although industrial production methods began revolutionizing watchmaking in the middle of the 19th century, chronometer manufacture remained craft-based for much longer. Around the turn of the 20th century, Swiss makers like Ulysse Nardin made great strides toward incorporating modern production methods, like fully interchangeable parts, but it was only with the onset of World War II that the American Hamilton Watch Company finally succeeded in fully harnessing mass production to produce chronometers in quantity for the US Navy. Despite Hamilton's success, chronometers made in the old way never disappeared from the marketplace during the era of mechanical timekeepers. Mercer, in St. Albans, England, for instance, continued to produce high-quality chronometers by traditional production methods well into the 1970s. Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... The Hamilton Watch Company was founded in Lancaster, Pennsylvania in 1892. ... Mass production is the production of large amounts of standardised products on production lines. ... The United States Navy (USN) is the branch of the United States armed forces responsible for naval operations. ...


The most complete international collection of marine chronometers, including Harrison's H1 to H4, is at the National Maritime Museum, Greenwich, England.


Mechanical chronometers

A chronometer mechanism diagrammed (text is in German). Note fusee to transform varying spring tension to a constant force

The crucial problem was to find a resonator that remained unaffected by the changing conditions met by a ship at sea. The balance wheel harnessed to a spring solved most of the problems associated with the ship's motion. Unfortunately, the elasticity of most balance spring materials changes relative to temperature. To compensate for ever-changing spring strength, the majority of chronometer balances used bi-metallic strips to move small weights toward and away from the center of oscillation, thus altering the period of the balance to match the changing force of the spring. Eventually, the balance spring problem was solved by the development of a nickel-steel named Elinvar for its invariable elasticity at normal temperatures. The inventor was Charles Edouard Guillaume, who won the Nobel Prize for physics in recognition for his metallurgical work (the only Nobel that has been granted for work related to horology). Image File history File links Size of this preview: 725 × 599 pixel Image in higher resolution (1355 × 1120 pixel, file size: 156 KB, MIME type: image/png) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Chronometer ... Image File history File links Size of this preview: 725 × 599 pixel Image in higher resolution (1355 × 1120 pixel, file size: 156 KB, MIME type: image/png) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Chronometer ... The spring-powered clock (invented in about 1510 by Peter Henlein of Nuremberg, Germany) did have its problems, that of slowing down when the mainspring unwound. ... Red arrows indicate the balance wheel on this movement. ... Elinvar is the name of a type of metallic alloy with a modulus of elasticity which does not vary with temperature; the name means elastically invariable. ... Charles Édouard Guillaume (February 15, 1861, Fleurier – June 13, 1938, Sèvres), was a French-Swiss Physicist that received the Nobel Prize in Physics in 1920 in recognition of the service he had rendered to precision measurements in Physics by his discovery of anomalies in nickel steel alloys. ... List of Nobel Prize laureates in Physics from 1901 to the present day. ... Horology is the study of the science and art of timekeeping devices. ...


The escapement serves two purposes. First, it allows the train to advance fractionally and record the balance's oscillations. At the same time, it supplies minute amounts of energy to counter tiny losses from friction, thus maintaining the equilibrium of the oscillating balance. The escapement is the part that ticks. Since the natural resonance of an oscillating balance serves as the heart of a chronometer, chronometer escapements are designed to interfere with the balance as little as possible. There are many constant force and detached escapement designs, but the most common by far are the spring detent and pivoted detent. In both of these, a small detent locks the escape wheel and allows the balance to swing completely free of interference except for a brief moment at the center of oscillation, when it is least susceptible to outside influences. At the center of oscillation, a roller on the balance staff momentarily displaces the detent, allowing one tooth of the escape wheel to pass. The escape wheel tooth then imparts its energy on a second roller on the balance staff. Since the escape wheel turns in only one direction, the balance receives impulse in only one direction. On the return oscillation, a passing spring on the tip of the detent allows the unlocking roller on the staff to move by without displacing the detent. A simple escapement. ...


Chronometers often included many other technological innovations designed to increase their efficiency and precision. Hard stones such as diamond, ruby, and sapphire were often use as jewel bearings to decrease friction and wear of the pivots and escapement parts that made repeated contact. Chronometer makers also took advantage of the physical properties of rare metals such as gold, platinum, and palladium. Until the end of mechanical chronometer production in the third quarter of the 20th century, makers continued to experiment with things like ball bearings and chrome-plated pivots. ruby jewel bearings used in an Omega mechanical watch movement A jewel bearing is a bearing which allows motion by running a shaft slightly off-center so that the shaft rolls inside of the bearing rather than sliding. ...


Complications

In horology terms, a complication in a mechanical watch is a special feature that causes the design of the watch movement to become more complicated. Examples of complications include: In horology terms, a complication in a mechanical timepiece is any feature beyond that of a simple hours, minutes, and seconds movement. ...

18th century tourbillon by Bréguet Girard-Perregauxs Tourbillon sous trois ponts dor, the quintescance of the tourbillon as a display of mastery in luxury watch-making A tourbillon (IPA: , French for whirlwind) is a type of mechanical clock or watch escapement invented in 1795 by Abraham-Louis... A perpetual calendar is a calendar which is good for a span of many years, such as the Runic calendar. ... The minute repeater is a complication found in a mechanical watch, in which the time is struck to the nearest minute. ... During the course of the year, the time as read from a sundial can run ahead of clock time by as much as 16 min 33 s (around October 31–November 1) or fall behind by as much as 14 min 6 s (around February 11–12). ... Types of power reserve indicator Power Reserve Indicator - originally called French: - is a function of the watch, which is meant to show how long the watch is going to work until the next winding. ... Lunar phase refers to the appearance of the illuminated portion of the Moon as seen by an observer, usually on Earth. ... Double chronograph Double chronograph is a watch that includes two separate stopwatch mechanisms in order to estimate two separate events of different durations. ...

Today

Quartz clocks and atomic clocks have made mechanical clock-chronometers obsolete for time standards used scientifically and/or industrially, although some custom watchmakers can still produce them. The techniques used to mass-produce mechanical chronometers are now lost. A quartz clock A quartz clock is a timepiece that uses an electronic oscillator which is made up by a quartz crystal to keep precise time. ... Atomic clock Chip-Scale Atomic Clock Unveiled by NIST An atomic clock is a type of clock that uses an atomic resonance frequency standard to feed its counter. ...


Officially Certified Chronometers

Over 1,000,000 Officially Certified Chronometer certificates, mostly for mechanical wrist-chronometers (wristwatches) with sprung balance oscillators, are being delivered each year, after passing the COSC's most severe tests and being singly identified by an officially recorded individual serial number. According to COSC, a chronometer is a high-precision watch capable of displaying the seconds and housing a movement that has been tested over several days, in different positions, and at different temperatures, by an official, neutral body (COSC). Each movement is individually tested for several consecutive days, in five positions and at three temperatures. Each movement is individually measured. Any watch with the denomination "chronometer" is provided with a certified movement. For the Unix command, see Watch (Unix). ... Contrôle Officiel Suisse des Chronomètres // Founded in its current structure in 1973, the COSC (Contrôle Officiel Suisse des Chronomètres) is the Swiss Official Chronometer Testing Institute. ... A serial number is a unique number that is one of a series assigned for identification which varies from its successor or predecessor by a fixed discrete integer value. ...


See also

A clock (from the Latin cloca, bell) is an instrument for measuring time. ... A clockmaker is an artisan who makes and repairs clocks. ... Contrôle Officiel Suisse des Chronomètres // Founded in its current structure in 1973, the COSC (Contrôle Officiel Suisse des Chronomètres) is the Swiss Official Chronometer Testing Institute. ... Horology is the study of the science and art of timekeeping devices. ... ruby jewel bearings used in an Omega mechanical watch movement A jewel bearing is a bearing which allows motion by running a shaft slightly off-center so that the shaft rolls inside of the bearing rather than sliding. ... Railroad chronometers (railroaders watches) were critical to the safe and correct operation of trains in the United States. ... For the Unix command, see Watch (Unix). ... A watchmaker is an artisan who makes and repairs watches. ... Webb C. Ball was born in Fredericktown, Ohio, on October 6, 1847 and became a jeweller & watchmaker. ... A stopwatch is a timepiece designed to measure the amount of time elapsed from a particular time when activated and when the piece is deactivated. ...

External links


  Results from FactBites:
 
Evolution of a Design: Ulysse Nardin Marine Chronometer (1099 words)
In spite of the widespread enthusiasm, with which the community of watch lovers greeted the new "Marine", there are also some voices, criticizing the design as being too "modern", too far away from the classic naval precision clocks, even hampered by a mix of different styles in hands and numerals.
This is problematic, since at bad light (and at sea, the marine chronometer were normally stored well protected in a corner of the rudder house/map room, where it was rather dark), the legibility was seriously compromised.
At the end of the 19th century, most "legible" watches used exactly this type of hands, as opposed to the highly ornamental Louis XV and XVI style hands, or the elegant so-called "Breguet"-hands (Breguet did not invent this hand design, but was among the first to use it consequently).
Checking the Chronometer (405 words)
If it had not, it is understandable that the captains felt it imperative to discover the chronometer's error and rate of loss or gain.
It didn't matter if the chronometer stopped or ran erratically most of the time provided it ran uniformly between two Equal Altitudes observations a day or, perhaps, two apart during which a Lunar Distance observation was made.
The uncertainty about the chronometer's error on Local Time for September 30 and its rate of loss between September 30 and October 3 produces some uncertainty about any longitude calculated from that day's Lunar observations, but there are ways around this problem.
  More results at FactBites »

 
 

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