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<li id="toc-First_examples" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#First_examples"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1</span> <span>First examples</span> </div> </a> <ul id="toc-First_examples-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_development" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Further_development"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.2</span> <span>Further development</span> </div> </a> <ul id="toc-Further_development-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Rationalizing_production_methods" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Rationalizing_production_methods"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.3</span> <span>Rationalizing production methods</span> </div> </a> <ul id="toc-Rationalizing_production_methods-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Historical_significance" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Historical_significance"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.4</span> <span>Historical significance</span> </div> </a> <ul id="toc-Historical_significance-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Characteristics" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Characteristics"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Characteristics</span> </div> </a> <ul id="toc-Characteristics-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Chronometer_rating" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Chronometer_rating"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Chronometer rating</span> </div> </a> <ul id="toc-Chronometer_rating-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Marine_chronometer_use_today" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Marine_chronometer_use_today"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Marine chronometer use today</span> </div> </a> <ul id="toc-Marine_chronometer_use_today-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " 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Available in 23 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-23" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">23 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-als mw-list-item"><a href="https://als.wikipedia.org/wiki/L%C3%A4ngenuhr" title="Längenuhr – Alemannic" lang="gsw" hreflang="gsw" data-title="Längenuhr" data-language-autonym="Alemannisch" data-language-local-name="Alemannic" class="interlanguage-link-target"><span>Alemannisch</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%85%D9%82%D9%8A%D8%A7%D8%B3_%D8%A7%D9%84%D8%B2%D9%85%D9%86_%D8%A7%D9%84%D8%A8%D8%AD%D8%B1%D9%8A" title="مقياس الزمن البحري – Arabic" lang="ar" hreflang="ar" data-title="مقياس الزمن البحري" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Cron%C3%B2metre_n%C3%A0utic" title="Cronòmetre nàutic – Catalan" lang="ca" hreflang="ca" data-title="Cronòmetre nàutic" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/N%C3%A1mo%C5%99n%C3%AD_chronometr" title="Námořní chronometr – Czech" lang="cs" hreflang="cs" data-title="Námořní chronometr" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/L%C3%A4ngenuhr" title="Längenuhr – German" lang="de" hreflang="de" data-title="Längenuhr" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Cron%C3%B3metro_marino" title="Cronómetro marino – Spanish" lang="es" hreflang="es" data-title="Cronómetro marino" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fo mw-list-item"><a href="https://fo.wikipedia.org/wiki/Skipskronometur" title="Skipskronometur – Faroese" lang="fo" hreflang="fo" data-title="Skipskronometur" data-language-autonym="Føroyskt" data-language-local-name="Faroese" class="interlanguage-link-target"><span>Føroyskt</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Chronom%C3%A8tre_de_marine" title="Chronomètre de marine – French" lang="fr" hreflang="fr" data-title="Chronomètre de marine" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%ED%95%B4%EC%83%81%EC%8B%9C%EA%B3%84" title="해상시계 – Korean" lang="ko" hreflang="ko" data-title="해상시계" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%95%E0%A4%BE%E0%A4%B2%E0%A4%AE%E0%A4%BE%E0%A4%AA%E0%A5%80" title="कालमापी – Hindi" lang="hi" hreflang="hi" data-title="कालमापी" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Hronometrs" title="Hronometrs – Latvian" lang="lv" hreflang="lv" data-title="Hronometrs" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Tenger%C3%A9szeti_kronom%C3%A9ter" title="Tengerészeti kronométer – Hungarian" lang="hu" hreflang="hu" data-title="Tengerészeti kronométer" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Kronometer_marin" title="Kronometer marin – Malay" lang="ms" hreflang="ms" data-title="Kronometer marin" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-my mw-list-item"><a href="https://my.wikipedia.org/wiki/%E1%80%81%E1%80%9B%E1%80%AD%E1%80%AF%E1%80%99%E1%80%AE%E1%80%90%E1%80%AC%E1%80%94%E1%80%AC%E1%80%9B%E1%80%AE" title="ခရိုမီတာနာရီ – Burmese" lang="my" hreflang="my" data-title="ခရိုမီတာနာရီ" data-language-autonym="မြန်မာဘာသာ" data-language-local-name="Burmese" class="interlanguage-link-target"><span>မြန်မာဘာသာ</span></a></li><li class="interlanguage-link interwiki-or mw-list-item"><a href="https://or.wikipedia.org/wiki/%E0%AC%B8%E0%AC%BE%E0%AC%AE%E0%AD%81%E0%AC%A6%E0%AD%8D%E0%AC%B0%E0%AC%BF%E0%AC%95_%E0%AC%95%E0%AD%8D%E0%AC%B0%E0%AD%8B%E0%AC%A8%E0%AD%8B%E0%AC%AE%E0%AC%BF%E0%AC%9F%E0%AC%B0" title="ସାମୁଦ୍ରିକ କ୍ରୋନୋମିଟର – Odia" lang="or" hreflang="or" data-title="ସାମୁଦ୍ରିକ କ୍ରୋନୋମିଟର" data-language-autonym="ଓଡ଼ିଆ" data-language-local-name="Odia" class="interlanguage-link-target"><span>ଓଡ଼ିଆ</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Cron%C3%B4metro_mar%C3%ADtimo" title="Cronômetro marítimo – Portuguese" lang="pt" hreflang="pt" data-title="Cronômetro marítimo" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9F%D0%B0%D0%BB%D1%83%D0%B1%D0%BD%D1%8B%D0%B5_%D1%87%D0%B0%D1%81%D1%8B" title="Палубные часы – Russian" lang="ru" hreflang="ru" data-title="Палубные часы" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Laivakronometri" title="Laivakronometri – Finnish" lang="fi" hreflang="fi" data-title="Laivakronometri" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%95%E0%AE%9F%E0%AE%B1%E0%AF%8D_%E0%AE%95%E0%AE%BE%E0%AE%B2%E0%AE%AE%E0%AE%BE%E0%AE%A9%E0%AE%BF" title="கடற் காலமானி – Tamil" lang="ta" hreflang="ta" data-title="கடற் காலமானி" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Deniz_kronometresi" title="Deniz kronometresi – Turkish" lang="tr" hreflang="tr" data-title="Deniz kronometresi" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9C%D0%BE%D1%80%D1%81%D1%8C%D0%BA%D0%B8%D0%B9_%D1%85%D1%80%D0%BE%D0%BD%D0%BE%D0%BC%D0%B5%D1%82%D1%80" title="Морський хронометр – Ukrainian" lang="uk" hreflang="uk" data-title="Морський хронометр" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%E8%A8%88%E6%99%82%E5%99%A8" title="計時器 – Cantonese" lang="yue" hreflang="yue" data-title="計時器" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target"><span>粵語</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E8%88%AA%E6%B5%B7%E9%90%98" title="航海鐘 – Chinese" lang="zh" hreflang="zh" data-title="航海鐘" data-language-autonym="中文" data-language-local-name="Chinese" 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id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Clock used on ships to aid in navigation</div> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox"><tbody><tr><th colspan="2" class="infobox-above">Marine chronometer</th></tr><tr><td colspan="2" class="infobox-image"><span class="mw-default-size" typeof="mw:File/Frameless"><a href="/wiki/File:Frodsham_chronometer_mechanism.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/ca/Frodsham_chronometer_mechanism.jpg/220px-Frodsham_chronometer_mechanism.jpg" decoding="async" width="220" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/ca/Frodsham_chronometer_mechanism.jpg/330px-Frodsham_chronometer_mechanism.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/ca/Frodsham_chronometer_mechanism.jpg/440px-Frodsham_chronometer_mechanism.jpg 2x" data-file-width="5184" data-file-height="3456" /></a></span><div class="infobox-caption">A marine chronometer by <a href="/wiki/Charles_Frodsham" title="Charles Frodsham">Charles Frodsham</a> of London, shown turned upside down to reveal the movement. Chronometer circa 1844-1860.</div></td></tr><tr><th scope="row" class="infobox-label">Classification</th><td class="infobox-data"><a href="/wiki/Clock" title="Clock">Clock</a></td></tr><tr><th scope="row" class="infobox-label">Industry</th><td class="infobox-data"><a href="/wiki/Transportation" class="mw-redirect" title="Transportation">Transportation</a></td></tr><tr><th scope="row" class="infobox-label">Application</th><td class="infobox-data">Timekeeping</td></tr><tr><th scope="row" class="infobox-label">Powered</th><td class="infobox-data">No</td></tr><tr><th scope="row" class="infobox-label">Inventor</th><td class="infobox-data"><a href="/wiki/John_Harrison" title="John Harrison">John Harrison</a></td></tr><tr><th scope="row" class="infobox-label">Invented</th><td class="infobox-data">1761</td></tr></tbody></table> <p>A <b>marine chronometer</b> is a precision <a href="/wiki/Timepiece" class="mw-redirect" title="Timepiece">timepiece</a> that is carried on a ship and employed in the determination of the ship's position by <a href="/wiki/Celestial_navigation" title="Celestial navigation">celestial navigation</a>. It is used to determine <a href="/wiki/Longitude" title="Longitude">longitude</a> by comparing <a href="/wiki/Greenwich_Mean_Time" title="Greenwich Mean Time">Greenwich Mean Time</a> (GMT), and the time at the current location found from observations of celestial bodies. When first developed in the 18th century, it was a major technical achievement, as accurate knowledge of the time over a long sea voyage was vital for effective <a href="/wiki/Navigation" title="Navigation">navigation</a>, lacking electronic or communications aids. The first true chronometer was the life work of one man, <a href="/wiki/John_Harrison" title="John Harrison">John Harrison</a>, spanning 31 years of persistent experimentation and testing that revolutionized naval (and later aerial) navigation. </p><p>The term <i><a href="https://en.wiktionary.org/wiki/chronometer" class="extiw" title="wikt:chronometer">chronometer</a></i> was coined from the Greek words <span title="Ancient Greek (to 1453)-language text"><span lang="grc"><a href="https://en.wiktionary.org/wiki/%CF%87%CF%81%CF%8C%CE%BD%CE%BF%CF%82" class="extiw" title="wikt:χρόνος">χρόνος</a></span></span> (<span title="Ancient Greek (to 1453)-language romanization"><i lang="grc-Latn">chronos</i></span>) (meaning time) and <span title="Ancient Greek (to 1453)-language romanization"><i lang="grc-Latn"><a href="/wiki/Meter" class="mw-redirect" title="Meter">meter</a></i></span> (meaning measure). The 1713 book <i>Physico-Theology</i> by the English cleric and scientist <a href="/wiki/William_Derham" title="William Derham">William Derham</a> includes one of the earliest theoretical descriptions of a marine chronometer.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> It has recently become more commonly used to describe <a href="/wiki/Chronometer_watch" title="Chronometer watch">watches tested and certified</a> to meet certain precision standards. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Marine_chronometer&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Chronometer_of_Jeremy_Thacker.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/92/Chronometer_of_Jeremy_Thacker.jpg/220px-Chronometer_of_Jeremy_Thacker.jpg" decoding="async" width="220" height="225" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/92/Chronometer_of_Jeremy_Thacker.jpg/330px-Chronometer_of_Jeremy_Thacker.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/92/Chronometer_of_Jeremy_Thacker.jpg/440px-Chronometer_of_Jeremy_Thacker.jpg 2x" data-file-width="686" data-file-height="703" /></a><figcaption>The marine "Chronometer" of <a href="/wiki/Jeremy_Thacker" title="Jeremy Thacker">Jeremy Thacker</a> used <a href="/wiki/Gimbal" title="Gimbal">gimbals</a> and a <a href="/wiki/Vacuum" title="Vacuum">vacuum</a> in a bell jar.</figcaption></figure> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/History_of_longitude" title="History of longitude">History of longitude</a></div> <p>To determine a position on the Earth's surface, it is necessary and sufficient to know the <a href="/wiki/Latitude" title="Latitude">latitude</a>, <a href="/wiki/Longitude" title="Longitude">longitude</a>, and <a href="/wiki/Altitude" title="Altitude">altitude</a>. Altitude considerations can naturally be ignored for vessels operating at <a href="/wiki/Sea_level" title="Sea level">sea level</a>. Until the mid-1750s, accurate <a href="/wiki/Navigation" title="Navigation">navigation</a> at <a href="/wiki/Sea" title="Sea">sea</a> out of sight of land was an unsolved problem due to the difficulty in calculating longitude. <a href="/wiki/Navigator" title="Navigator">Navigators</a> could determine their latitude by measuring the sun's angle at noon (i.e., when it reached its highest point in the sky, or <a href="/wiki/Culmination" title="Culmination">culmination</a>) or, in the Northern Hemisphere, by measuring the angle of Polaris (the North Star) from the horizon (usually during <a href="/wiki/Twilight" title="Twilight">twilight</a>). To find their <a href="/wiki/Longitude" title="Longitude">longitude</a>, however, they needed a time standard that would work aboard a ship. Observation of regular celestial motions, such as <a href="/wiki/Galileo_Galilei#Engineering" title="Galileo Galilei">Galileo's method</a> based on observing <a href="/wiki/Jupiter%27s_natural_satellites" class="mw-redirect" title="Jupiter's natural satellites">Jupiter's natural satellites</a>, was usually not possible at sea due to the ship's motion. The <a href="/wiki/Lunar_distance_(navigation)" title="Lunar distance (navigation)">lunar distances method</a>, initially proposed by <a href="/wiki/Johannes_Werner" title="Johannes Werner">Johannes Werner</a> in 1514, was developed in parallel with the marine chronometer. The Dutch scientist <a href="/wiki/Gemma_Frisius" title="Gemma Frisius">Gemma Frisius</a> was the first to propose the use of a chronometer to determine longitude in 1530. </p><p>The purpose of a chronometer is to measure accurately the time of a known fixed location. This is particularly important for navigation. As the Earth rotates at a regular predictable rate, the time difference between the chronometer and the ship's local time can be used to calculate the longitude of the ship relative to the <a href="/wiki/Greenwich_Meridian" class="mw-redirect" title="Greenwich Meridian">Prime Meridian (defined as 0°)</a> (or another starting point) if accurately enough known, using <a href="/wiki/Spherical_trigonometry" title="Spherical trigonometry">spherical trigonometry</a>. Practical <a href="/wiki/Celestial_navigation" title="Celestial navigation">celestial navigation</a> usually requires a marine chronometer to measure time, a <a href="/wiki/Sextant" title="Sextant">sextant</a> to measure the angles, an <a href="/wiki/Nautical_almanac" title="Nautical almanac">almanac</a><sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> giving schedules of the coordinates of celestial objects, a set of <a href="/wiki/Sight_reduction" title="Sight reduction">sight reduction tables</a> to help perform the height and <a href="/wiki/Azimuth" title="Azimuth">azimuth</a> computations, and a chart of the region. With sight reduction tables, the only calculations required are addition and subtraction. Most people can master simpler celestial navigation procedures after a day or two of instruction and practice, even using manual calculation methods. The use of a marine chronometer to determine <a href="/wiki/Longitude_by_chronometer" title="Longitude by chronometer">longitude by chronometer</a> permits <a href="/wiki/Navigator" title="Navigator">navigators</a> to obtain a reasonably accurate position fix.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> For every four seconds that the time source is in error, the east–west position may be off by up to just over one nautical mile as <a href="/wiki/Earth%27s_rotation#Angular_speed" title="Earth's rotation">the angular speed of Earth</a> is latitude dependent.<sup id="cite_ref-Cox2000_4-0" class="reference"><a href="#cite_note-Cox2000-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>The creation of a timepiece which would work reliably at sea was difficult. Until the 20th century, the best timekeepers were <a href="/wiki/Pendulum_clock" title="Pendulum clock">pendulum clocks</a>, but both the rolling of a ship at sea and the up to 0.2% variations in the <a href="/wiki/Gravity_of_Earth" title="Gravity of Earth">gravity of Earth</a> made a simple gravity-based pendulum useless both in theory and in practice. </p> <div class="mw-heading mw-heading3"><h3 id="First_examples">First examples</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Marine_chronometer&action=edit&section=2" title="Edit section: First examples"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Henry_Sully_clock_with_escapement_and_suspension_mechanism.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Henry_Sully_clock_with_escapement_and_suspension_mechanism.jpg/220px-Henry_Sully_clock_with_escapement_and_suspension_mechanism.jpg" decoding="async" width="220" height="303" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Henry_Sully_clock_with_escapement_and_suspension_mechanism.jpg/330px-Henry_Sully_clock_with_escapement_and_suspension_mechanism.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Henry_Sully_clock_with_escapement_and_suspension_mechanism.jpg/440px-Henry_Sully_clock_with_escapement_and_suspension_mechanism.jpg 2x" data-file-width="610" data-file-height="840" /></a><figcaption><a href="/wiki/Henry_Sully" title="Henry Sully">Henry Sully</a> (1680-1729) presented a first marine chronometer in 1716</figcaption></figure> <p><a href="/wiki/Christiaan_Huygens" title="Christiaan Huygens">Christiaan Huygens</a>, following his invention of the <a href="/wiki/Pendulum_clock" title="Pendulum clock">pendulum clock</a> in 1656, made the first attempt at a marine chronometer in 1673 in <a href="/wiki/France" title="France">France</a>, under the sponsorship of <a href="/wiki/Jean-Baptiste_Colbert" title="Jean-Baptiste Colbert">Jean-Baptiste Colbert</a>.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> In 1675, Huygens, who was receiving a pension from <a href="/wiki/Louis_XIV" title="Louis XIV">Louis XIV</a>, invented a chronometer that employed a <a href="/wiki/Balance_wheel" title="Balance wheel">balance wheel</a> and a <a href="/wiki/Balance_spring" title="Balance spring">spiral spring</a> for regulation, instead of a pendulum, opening the way to marine chronometers and modern pocket watches and wristwatches. He obtained a <a href="/wiki/Patent" title="Patent">patent</a> for his invention from Colbert, but his clock remained imprecise at sea.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> Huygens' attempt in 1675 to obtain an English patent from <a href="/wiki/Charles_II_of_England" title="Charles II of England">Charles II</a> stimulated <a href="/wiki/Robert_Hooke" title="Robert Hooke">Robert Hooke</a>, who claimed to have conceived of a spring-driven clock years earlier, to attempt to produce one and patent it. During 1675 Huygens and Hooke each delivered two such devices to Charles, but none worked well and neither Huygens nor Hooke received an English patent. It was during this work that Hooke formulated <a href="/wiki/Hooke%27s_law" title="Hooke's law">Hooke's law</a>.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:H1_low_250.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/bf/H1_low_250.jpg/220px-H1_low_250.jpg" decoding="async" width="220" height="259" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/b/bf/H1_low_250.jpg 1.5x" data-file-width="250" data-file-height="294" /></a><figcaption><a href="/wiki/John_Harrison" title="John Harrison">John Harrison</a>'s H1 marine chronometer of 1735</figcaption></figure> <p>The first published use of the term <i>chronometer</i> was in 1684 in <span title="Latin-language text"><i lang="la">Arcanum Navarchicum</i></span>, a theoretical work by Kiel professor Matthias Wasmuth. This was followed by a further theoretical description of a chronometer in works published by English scientist <a href="/wiki/William_Derham" title="William Derham">William Derham</a> in 1713. Derham's principal work, <i>Physico-theology, or a demonstration of the being and attributes of God from his works of creation</i>, also proposed the use of vacuum sealing to ensure greater accuracy in the operation of clocks.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> Attempts to construct a working marine chronometer were begun by <a href="/wiki/Jeremy_Thacker" title="Jeremy Thacker">Jeremy Thacker</a> in England in 1714, and by <a href="/wiki/Henry_Sully" title="Henry Sully">Henry Sully</a> in France two years later. Sully published his work in 1726 with <span title="French-language text"><i lang="fr">Une Horloge inventée et executée par M. Sulli</i></span>, but neither his nor Thacker's models were able to resist the rolling of the seas and keep precise time while in shipboard conditions.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Harrison_H4_clock_in_The_principles_of_Mr_Harrison%27s_time-keeper_1767.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/91/Harrison_H4_clock_in_The_principles_of_Mr_Harrison%27s_time-keeper_1767.jpg/220px-Harrison_H4_clock_in_The_principles_of_Mr_Harrison%27s_time-keeper_1767.jpg" decoding="async" width="220" height="326" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/91/Harrison_H4_clock_in_The_principles_of_Mr_Harrison%27s_time-keeper_1767.jpg/330px-Harrison_H4_clock_in_The_principles_of_Mr_Harrison%27s_time-keeper_1767.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/91/Harrison_H4_clock_in_The_principles_of_Mr_Harrison%27s_time-keeper_1767.jpg/440px-Harrison_H4_clock_in_The_principles_of_Mr_Harrison%27s_time-keeper_1767.jpg 2x" data-file-width="595" data-file-height="881" /></a><figcaption>Drawings of Harrison's <a href="/wiki/H4_chronometer" class="mw-redirect" title="H4 chronometer">H4 chronometer</a> of 1761, published in <i>The principles of Mr Harrison's time-keeper</i>, 1767.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup></figcaption></figure> <p>In 1714, the British government offered a <a href="/wiki/Longitude_prize" class="mw-redirect" title="Longitude prize">longitude prize</a> for a method of determining longitude at sea, with the awards ranging from £10,000 to £20,000 (£2 million to £4 million in 2024 terms) depending on accuracy. <a href="/wiki/John_Harrison" title="John Harrison">John Harrison</a>, a Yorkshire carpenter, submitted a project in 1730, and in 1735 completed 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 timepieces H1 and H2 (completed in 1741) used this system, but he realised that they had a fundamental sensitivity to <a href="/wiki/Centrifugal_force" title="Centrifugal force">centrifugal force</a>, which meant that they could never be accurate enough at sea. Construction of his third machine, designated H3, in 1759 included novel circular balances and the invention of the <a href="/wiki/Bi-metallic_strip" class="mw-redirect" title="Bi-metallic strip">bi-metallic strip</a> and caged <a href="/wiki/Roller_bearing" class="mw-redirect" title="Roller bearing">roller bearings</a>, inventions which are still widely used. However, H3's circular balances still proved too inaccurate and he eventually abandoned the large machines.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Marine_watch_no_3-CnAM_1388-IMG_1522-black.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/34/Marine_watch_no_3-CnAM_1388-IMG_1522-black.jpg/220px-Marine_watch_no_3-CnAM_1388-IMG_1522-black.jpg" decoding="async" width="220" height="220" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/34/Marine_watch_no_3-CnAM_1388-IMG_1522-black.jpg/330px-Marine_watch_no_3-CnAM_1388-IMG_1522-black.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/34/Marine_watch_no_3-CnAM_1388-IMG_1522-black.jpg/440px-Marine_watch_no_3-CnAM_1388-IMG_1522-black.jpg 2x" data-file-width="4000" data-file-height="4000" /></a><figcaption><a href="/wiki/Ferdinand_Berthoud" title="Ferdinand Berthoud">Ferdinand Berthoud</a>'s marine chronometer no.3, 1763</figcaption></figure> <p>Harrison solved the precision problems with his much smaller <a href="/wiki/H4_chronometer" class="mw-redirect" title="H4 chronometer">H4 chronometer</a> design in 1761. H4 looked much like a large five-inch (12 cm) diameter pocket watch. In 1761, Harrison submitted H4 for the £20,000 longitude prize. His design used a fast-beating balance wheel controlled by a temperature-compensated spiral spring. These features remained in use until stable <a href="/wiki/Electronic_oscillator" title="Electronic oscillator">electronic oscillators</a> allowed very accurate portable timepieces to be made at affordable cost. In 1767, the <a href="/wiki/Board_of_Longitude" title="Board of Longitude">Board of Longitude</a> published a description of his work in <i>The Principles of Mr. Harrison's time-keeper</i>.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> A French expedition under <a href="/wiki/Charles-Fran%C3%A7ois-C%C3%A9sar_Le_Tellier_de_Montmirail" class="mw-redirect" title="Charles-François-César Le Tellier de Montmirail">Charles-François-César Le Tellier de Montmirail</a> performed the first measurement of longitude using marine chronometers aboard <a href="/wiki/French_corvette_Aurore_(1767)" title="French corvette Aurore (1767)"><i>Aurore</i></a> in 1767.<sup id="cite_ref-ancre_14-0" class="reference"><a href="#cite_note-ancre-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Further_development">Further development</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Marine_chronometer&action=edit&section=3" title="Edit section: Further development"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Pierre_Le_Roy_chronometer_1766.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Pierre_Le_Roy_chronometer_1766.jpg/220px-Pierre_Le_Roy_chronometer_1766.jpg" decoding="async" width="220" height="156" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Pierre_Le_Roy_chronometer_1766.jpg/330px-Pierre_Le_Roy_chronometer_1766.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Pierre_Le_Roy_chronometer_1766.jpg/440px-Pierre_Le_Roy_chronometer_1766.jpg 2x" data-file-width="1460" data-file-height="1036" /></a><figcaption><a href="/wiki/Pierre_Le_Roy" title="Pierre Le Roy">Pierre Le Roy</a> marine chronometer, 1766, photographed at the <a href="/wiki/Mus%C3%A9e_des_Arts_et_M%C3%A9tiers" title="Musée des Arts et Métiers">Musée des Arts et Métiers</a> in Paris</figcaption></figure> <p>In France, 1748, <a href="/wiki/Pierre_Le_Roy" title="Pierre Le Roy">Pierre Le Roy</a> invented the <a href="/wiki/Escapement#Detent_escapement" title="Escapement">detent escapement</a> characteristic of modern chronometers.<sup id="cite_ref-books.google.com_15-0" class="reference"><a href="#cite_note-books.google.com-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> In 1766, he created a revolutionary chronometer that incorporated a <a href="/wiki/Escapement" title="Escapement">detent escapement</a>, the <a href="/wiki/Balance_wheel" title="Balance wheel">temperature-compensated balance</a> and the <a href="/wiki/Balance_spring" title="Balance spring">isochronous balance spring</a>:<sup id="cite_ref-Macey_16-0" class="reference"><a href="#cite_note-Macey-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> Harrison showed the possibility of having a reliable chronometer at sea, but these developments by Le Roy are considered by <a href="/wiki/Rupert_Gould" title="Rupert Gould">Rupert Gould</a> to be the foundation of the modern chronometer.<sup id="cite_ref-Macey_16-1" class="reference"><a href="#cite_note-Macey-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> Le Roy's innovations made the chronometer a much more accurate piece than had been anticipated.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Harrison%27s_Chronometer_H5.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/14/Harrison%27s_Chronometer_H5.JPG/220px-Harrison%27s_Chronometer_H5.JPG" decoding="async" width="220" height="146" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/14/Harrison%27s_Chronometer_H5.JPG/330px-Harrison%27s_Chronometer_H5.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/14/Harrison%27s_Chronometer_H5.JPG/440px-Harrison%27s_Chronometer_H5.JPG 2x" data-file-width="3008" data-file-height="2000" /></a><figcaption>Harrison's Chronometer H5 of 1772, now on display at the <a href="/wiki/Science_Museum,_London" title="Science Museum, London">Science Museum, London</a></figcaption></figure> <p><a href="/wiki/Ferdinand_Berthoud" title="Ferdinand Berthoud">Ferdinand Berthoud</a> in France, as well as <a href="/wiki/Thomas_Mudge_(horologist)" title="Thomas Mudge (horologist)">Thomas Mudge</a> in Britain also successfully produced marine timekeepers.<sup id="cite_ref-books.google.com_15-1" class="reference"><a href="#cite_note-books.google.com-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> Although none were simple, they proved that Harrison's design was not the only answer to the problem. The greatest strides toward practicality came at the hands of <a href="/wiki/Thomas_Earnshaw" title="Thomas Earnshaw">Thomas Earnshaw</a> and <a href="/wiki/John_Arnold_(watchmaker)" title="John Arnold (watchmaker)">John Arnold</a>, who in 1780 developed and patented simplified, detached, "spring detent" <a href="/wiki/Escapement" title="Escapement">escapements</a>,<sup id="cite_ref-landes_18-0" class="reference"><a href="#cite_note-landes-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> moved the temperature compensation to the balance, and improved the design and manufacturing of <a href="/wiki/Balance_spring" title="Balance spring">balance springs</a>. This combination of innovations served as the basis of marine chronometers until the electronic era. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Berthoud_clock_24_p1040260.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Berthoud_clock_24_p1040260.jpg/220px-Berthoud_clock_24_p1040260.jpg" decoding="async" width="220" height="293" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Berthoud_clock_24_p1040260.jpg/330px-Berthoud_clock_24_p1040260.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/51/Berthoud_clock_24_p1040260.jpg/440px-Berthoud_clock_24_p1040260.jpg 2x" data-file-width="1920" data-file-height="2560" /></a><figcaption><a href="/wiki/Ferdinand_Berthoud" title="Ferdinand Berthoud">Ferdinand Berthoud</a> chronometer no. 24 (1782), on display at the <a href="/wiki/Mus%C3%A9e_des_Arts_et_M%C3%A9tiers" title="Musée des Arts et Métiers">Musée des Arts et Métiers</a>, Paris</figcaption></figure> <p>The new technology was initially so expensive that not all ships carried chronometers, as illustrated by the fateful last journey of the East Indiaman <a href="/wiki/Arniston_(ship)" class="mw-redirect" title="Arniston (ship)"><i>Arniston</i></a>, shipwrecked with the loss of 372 lives.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> However, by 1825, the <a href="/wiki/Royal_Navy" title="Royal Navy">Royal Navy</a> had begun routinely supplying its vessels with chronometers.<sup id="cite_ref-Watchmakers_and_their_Work,_pg_230_21-0" class="reference"><a href="#cite_note-Watchmakers_and_their_Work,_pg_230-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> </p><p>Beginning in 1820, the British Royal Observatory in Greenwich tested marine chronometers in an Admiralty instigated trial or "chronometer competition" program intended to encourage the improvement of chronometers. In 1840 a new series of trials in a different format was begun by the seventh Astronomer Royal <a href="/wiki/George_Biddell_Airy" title="George Biddell Airy">George Biddell Airy</a>. These trials continued in much the same format until the outbreak of World War I in 1914, at which point they were suspended. Although the formal trials ceased, the testing of chronometers for the Royal Navy did not.<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> </p><p>Marine chronometer makers looked to a phalanx of <a href="/wiki/Observatory" title="Observatory">astronomical observatories</a> located in Western Europe to conduct accuracy assessments of their timepieces. Once mechanical timepiece movements developed sufficient precision to allow for adequately accurate marine navigation, these third party independent assessments also developed into what became known as "chronometer competitions" at the astronomical observatories located in Western Europe. The <a href="/wiki/Neuch%C3%A2tel_Observatory" title="Neuchâtel Observatory">Neuchâtel Observatory</a>, <a href="/wiki/Geneva_Observatory" title="Geneva Observatory">Geneva Observatory</a>, <a href="/wiki/Besan%C3%A7on_Observatory" class="mw-redirect" title="Besançon Observatory">Besançon Observatory</a>, <a href="/wiki/Kew_Observatory" class="mw-redirect" title="Kew Observatory">Kew Observatory</a>, <a href="/wiki/Wilhelm_von_Freeden#North_German_Naval_Observatory" title="Wilhelm von Freeden">German Naval Observatory Hamburg</a> and <a href="/wiki/Glash%C3%BCtte" title="Glashütte">Glashütte</a> 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 the <a href="/wiki/COSC" title="COSC">Contrôle Officiel Suisse des Chronomètres (COSC)</a>. When a movement passed the observatory test, it became certified as an <a href="/wiki/Observatory_chronometer" title="Observatory chronometer">observatory chronometer</a> and received a Bulletin de Marche from the observatory, stipulating the performance of the movement. </p><p>It was common for ships at the time to observe a <a href="/wiki/Time_ball" title="Time ball">time ball</a>, such as the one at the <a href="/wiki/Royal_Observatory,_Greenwich" title="Royal Observatory, Greenwich">Royal Observatory, Greenwich</a>, to check their chronometers before departing on a long voyage. Every day, ships would anchor briefly in the <a href="/wiki/River_Thames" title="River Thames">River Thames</a> at Greenwich, waiting for the ball at the observatory to drop at precisely 1pm.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> This practice was in small part responsible for the subsequent adoption of <a href="/wiki/Greenwich_Mean_Time" title="Greenwich Mean Time">Greenwich Mean Time</a> as an international standard.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> (Time balls became redundant around 1920 with the introduction of <a href="/wiki/Time_signal" title="Time signal">radio time signals</a>, which have themselves largely been superseded by <a href="/wiki/GPS#Timekeeping" class="mw-redirect" title="GPS">GPS time</a>.) In addition to setting their time before departing on a voyage, ship chronometers were also routinely checked for accuracy while at sea by carrying out <a href="/wiki/Lunar_distance_(navigation)" title="Lunar distance (navigation)">lunar</a><sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> or solar observations.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> In typical use, the chronometer would be mounted in a sheltered location below decks to avoid damage and exposure to the elements. Mariners would use the chronometer to set a so-called <a href="/wiki/Hack_watch" title="Hack watch">hack watch</a>, which would be carried on deck to make the astronomical observations. Though much less accurate (and less expensive) than the chronometer, the hack watch would be satisfactory for a short period of time after setting it (i.e., long enough to make the observations). </p> <div class="mw-heading mw-heading3"><h3 id="Rationalizing_production_methods">Rationalizing production methods</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Marine_chronometer&action=edit&section=4" title="Edit section: Rationalizing production methods"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Russian_Ship_Chronometer.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Russian_Ship_Chronometer.jpg/220px-Russian_Ship_Chronometer.jpg" decoding="async" width="220" height="330" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Russian_Ship_Chronometer.jpg/330px-Russian_Ship_Chronometer.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Russian_Ship_Chronometer.jpg/440px-Russian_Ship_Chronometer.jpg 2x" data-file-width="3168" data-file-height="4752" /></a><figcaption><span title="German-language text"><i lang="de">Einheitschronometer</i></span> pattern MX6 marine chronometer mass-produced in the Soviet Union after World War II</figcaption></figure> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Hamilton_Marine_Chronometer_Model_21.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/16/Hamilton_Marine_Chronometer_Model_21.jpg/220px-Hamilton_Marine_Chronometer_Model_21.jpg" decoding="async" width="220" height="286" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/16/Hamilton_Marine_Chronometer_Model_21.jpg/330px-Hamilton_Marine_Chronometer_Model_21.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/16/Hamilton_Marine_Chronometer_Model_21.jpg/440px-Hamilton_Marine_Chronometer_Model_21.jpg 2x" data-file-width="1576" data-file-height="2046" /></a><figcaption>Inner working of the Hamilton Model 21 marine chronometer mass-produced in the United States during and after World War II</figcaption></figure> <p>Although industrial production methods began revolutionizing watchmaking in the middle of the 19th century, chronometer manufacture remained craft-based much longer and was dominated by British and Swiss manufacturers. Around the turn of the 20th century, Swiss makers such as <a href="/wiki/Ulysse_Nardin" title="Ulysse Nardin">Ulysse Nardin</a> made great strides toward incorporating modern production methods and using fully interchangeable parts, but it was only with the onset of <a href="/wiki/World_War_II" title="World War II">World War II</a> that the <a href="/wiki/Hamilton_Watch_Company" title="Hamilton Watch Company">Hamilton Watch Company</a> in the <a href="/wiki/United_States" title="United States">United States</a> perfected the process of <a href="/wiki/Mass_production" title="Mass production">mass production</a>, which enabled it to produce thousands of its <a href="/wiki/Hamilton_Watch_Company#Marine_chronometers" title="Hamilton Watch Company">Hamilton Model 21 and Model 22 chronometers</a> from 1942 onwards for the branches of the <a href="/wiki/United_States" title="United States">United States</a> military and merchant marine as well as other <a href="/wiki/Allies_of_World_War_II" title="Allies of World War II">Allied</a> forces during World War II. The Hamilton 21 Marine Chronometer had a <a href="/wiki/Fusee_(horology)" title="Fusee (horology)">chain drive fusee</a> and its second hand advanced in <style data-mw-deduplicate="TemplateStyles:r1154941027">.mw-parser-output .frac{white-space:nowrap}.mw-parser-output .frac .num,.mw-parser-output .frac .den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output .frac .den{vertical-align:sub}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}</style><span class="frac"><span class="num">1</span>⁄<span class="den">2</span></span>-second increments over a 60 seconds marked sub dial. In Germany, where marine chronometers were imported or used foreign key components, a <span title="German-language text"><i lang="de">Drei-Pfeiler Werk Einheitschronometer</i></span> (three-pillar movement unified chronometer) was developed by a collaboration between the Wempe Chronometerwerke and <a href="/wiki/A._Lange_%26_S%C3%B6hne" title="A. Lange & Söhne">A. Lange & Söhne</a> companies to make more efficient production possible. The development of a precise and inexpensive <span title="German-language text"><i lang="de">Einheitschronometer</i></span> was a 1939 German naval command and <a href="/wiki/Ministry_of_Aviation_(Nazi_Germany)" title="Ministry of Aviation (Nazi Germany)">Aviation ministry</a> driven initiative. Serial production began in 1942. All parts were made in Germany and interchangeable.<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> During the course of World War II modifications that became necessary when raw materials became scarce were applied and work was compulsory and sometimes voluntarily shared between various German manufacturers to speed up production. The production of German unified design chronometers with their harmonized components continued until long after World War II in Germany and the Soviet Union, who confiscated the original <span title="German-language text"><i lang="de">Einheitschronometer</i></span> technical drawings, and set up a production line in Moscow in 1949 that produced the first Soviet MX6 chronometers containing German made movements.<sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> From 1952 onwards until 1997 MX6 chronometers with minor <span title="Russian-language text"><span lang="ru">НИИ ЧАСПРОМ</span></span> (NII Chasprom — Horological institute of the Soviet era) devised alterations were produced from components all made in the Soviet Union.<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> The German <span title="German-language text"><i lang="de">Einheitschronometer</i></span> ultimately became the mechanical marine timekeeper design produced in the highest volume, with about 58,000 units produced. Of these, less than 3,000 were produced during World War II, about 5,000 after the war in West and East Germany and about 50,000 in the Soviet Union and later post-Soviet Russia.<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> Of the Hamilton 21 Marine Chronometer during and after World War II about 13,000 units were produced. Despite the <span title="German-language text"><i lang="de">Einheitschronometer</i></span> and Hamilton's success, chronometers made in the old way never disappeared from the marketplace during the era of mechanical timekeepers. <a href="/wiki/Thomas_Mercer_Chronometers" title="Thomas Mercer Chronometers">Thomas Mercer Chronometers</a> was among the companies that continued to make them. </p> <div class="mw-heading mw-heading3"><h3 id="Historical_significance">Historical significance</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Marine_chronometer&action=edit&section=5" title="Edit section: Historical significance"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Royal_time_chronometer_-_Flickr_-_Tatters_%E2%9D%80.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/82/Royal_time_chronometer_-_Flickr_-_Tatters_%E2%9D%80.jpg/310px-Royal_time_chronometer_-_Flickr_-_Tatters_%E2%9D%80.jpg" decoding="async" width="310" height="212" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/82/Royal_time_chronometer_-_Flickr_-_Tatters_%E2%9D%80.jpg/465px-Royal_time_chronometer_-_Flickr_-_Tatters_%E2%9D%80.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/82/Royal_time_chronometer_-_Flickr_-_Tatters_%E2%9D%80.jpg/620px-Royal_time_chronometer_-_Flickr_-_Tatters_%E2%9D%80.jpg 2x" data-file-width="1582" data-file-height="1080" /></a><figcaption>Mechanical boxed Marine Chronometer used on <a href="/wiki/Queen_Victoria" title="Queen Victoria">Queen Victoria</a>'s royal yacht <a href="/wiki/HMY_Victoria_and_Albert_(1899)" title="HMY Victoria and Albert (1899)">HMY <i>Victoria and Albert</i></a>, made about 1865</figcaption></figure> <p>Ship’s marine chronometers are the most exact portable mechanical timepieces ever produced and in a static environment were only trumped by non-portable precision <a href="/wiki/Pendulum_clocks" class="mw-redirect" title="Pendulum clocks">pendulum clocks</a> for observatories. They served, alongside the sextant, to determine the location of ships at sea. The seafaring nations invested richly in the development of these precision instruments, as pinpointing location at sea gave a decisive naval advantage. Without their accuracy and the accuracy of the feats of navigation that marine chronometers enabled, it is arguable that the ascendancy of the <a href="/wiki/Royal_Navy" title="Royal Navy">Royal Navy</a>, and by extension that of the <a href="/wiki/British_Empire" title="British Empire">British Empire</a>, might not have occurred so overwhelmingly; the formation of the empire by wars and conquests of colonies abroad took place in a period in which British vessels had reliable navigation due to the chronometer, while their Portuguese, Dutch, and French opponents did not.<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> For example: the French were well established in <a href="/wiki/India" title="India">India</a> and other places before Britain, but were defeated by naval forces in the <a href="/wiki/Seven_Years%27_War" title="Seven Years' War">Seven Years' War</a>. </p><p>Rating and maintaining marine chronometers was deemed important well into the 20th century, as after World War I the work of the British Royal Observatory’s Chronometer Department became largely confined to rating of chronometers and watches that the Admiralty already owned and providing acceptance testing.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> In 1937 a workshop was set up for the first time by the Time Department for the repair and adjustment of British armed forces issued chronometers and watches. These maintenance activities had previously been outsourced to commercial workshops.<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> </p><p>From about the 1960s onwards mechanical <a href="/wiki/Escapement#Detent_escapement" title="Escapement">spring detent</a> marine chronometers were gradually replaced and supplanted by chronometers based on electric engineering techniques and technologies.<sup id="cite_ref-36" class="reference"><a href="#cite_note-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> In 1985 the British Ministry of Defence invited bids by tender for the disposal of their mechanical Hamilton Model 21 Marine Chronometers. The US Navy kept their Hamilton Model 21 Marine Chronometers in service as backups to the <a href="/wiki/Loran-C" title="Loran-C">Loran-C</a> <a href="/wiki/Hyperbolic_navigation" title="Hyperbolic navigation">hyperbolic</a> <a href="/wiki/Radio_navigation" title="Radio navigation">radio navigation</a> system until 1988, when the GPS global navigation satellite system was approved as reliable. At the end of the 20th century the production of mechanical marine chronometers had declined to the point where only a few were being made to special order by the First Moscow Watch Factory 'Kirov' (<a href="/wiki/Poljot" title="Poljot">Poljot</a>) in Russia, Wempe in Germany and <a href="/wiki/Thomas_Mercer_Chronometers" title="Thomas Mercer Chronometers">Mercer</a> in England.<sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> </p><p>The most complete international collection of marine chronometers, including Harrison's H1 to H4, is at the <a href="/wiki/Royal_Observatory,_Greenwich" title="Royal Observatory, Greenwich">Royal Observatory, Greenwich</a>, in <a href="/wiki/London" title="London">London</a>, UK. </p> <div class="mw-heading mw-heading2"><h2 id="Characteristics">Characteristics</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Marine_chronometer&action=edit&section=6" title="Edit section: Characteristics"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:L-Cronometer.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/38/L-Cronometer.png/220px-L-Cronometer.png" decoding="async" width="220" height="182" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/38/L-Cronometer.png/330px-L-Cronometer.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/38/L-Cronometer.png/440px-L-Cronometer.png 2x" data-file-width="1355" data-file-height="1120" /></a><figcaption>A chronometer mechanism diagrammed (text is in <a href="/wiki/German_(language)" class="mw-redirect" title="German (language)">German</a>). Note <a href="/wiki/Fusee_(horology)" title="Fusee (horology)">fusee</a> to transform varying spring tension to a constant force</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Marine-Chronometer.A.Lange%26Soehne.1948.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/04/Marine-Chronometer.A.Lange%26Soehne.1948.jpg/220px-Marine-Chronometer.A.Lange%26Soehne.1948.jpg" decoding="async" width="220" height="168" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/04/Marine-Chronometer.A.Lange%26Soehne.1948.jpg/330px-Marine-Chronometer.A.Lange%26Soehne.1948.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/04/Marine-Chronometer.A.Lange%26Soehne.1948.jpg/440px-Marine-Chronometer.A.Lange%26Soehne.1948.jpg 2x" data-file-width="2482" data-file-height="1896" /></a><figcaption><span title="German-language text"><i lang="de">Einheitschronometer</i></span> pattern marine chronometer (A. Lange & Söhne, 1948) displaying its second hand advancing in <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1154941027"><span class="frac"><span class="num">1</span>⁄<span class="den">2</span></span>-second increments over a 60 seconds marked sub dial for optimal timing of celestial objects angle measurements at the <a href="/wiki/GFZ_German_Research_Centre_for_Geosciences" title="GFZ German Research Centre for Geosciences">GFZ</a></figcaption></figure> <p>The crucial problem was to find a resonator that remained unaffected by the changing conditions met by a ship at sea. The <a href="/wiki/Balance_wheel" title="Balance wheel">balance wheel</a>, 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 centre of oscillation, thus altering the period of the balance to match the changing force of the spring. The balance spring problem was solved with a nickel-steel alloy named <a href="/wiki/Elinvar" title="Elinvar">Elinvar</a> for its invariable elasticity at normal temperatures. The inventor was <a href="/wiki/Charles_%C3%89douard_Guillaume" title="Charles Édouard Guillaume">Charles Édouard Guillaume</a>, who won the 1920 <a href="/wiki/Nobel_Prize_for_physics" class="mw-redirect" title="Nobel Prize for physics">Nobel Prize for physics</a> in recognition for his metallurgical work. </p><p>The <a href="/wiki/Escapement" title="Escapement">escapement</a> 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 momentum 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 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 centre of oscillation, when it is least susceptible to outside influences. At the centre 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. The weakest link of any mechanical timekeeper is the escapement's lubrication. When the oil thickens through age or temperature or dissipates through <a href="/wiki/Humidity" title="Humidity">humidity</a> or evaporation, the rate will change, sometimes dramatically as the balance motion decreases through higher friction in the escapement. A <a href="/wiki/Escapement#Detent_escapement" title="Escapement">detent escapement</a> has a strong advantage over other escapements as it needs no lubrication. An impulse from the escape wheel to the impulse roller is nearly dead-beat, meaning little sliding action needing lubrication. Chronometer escape wheels and passing springs are typically gold due to the metal's lower slide friction over brass and steel. </p><p>Chronometers often included other innovations to increase their efficiency and precision. Hard stones such as ruby and sapphire were often used as <a href="/wiki/Jewel_bearing" title="Jewel bearing">jewel bearings</a> to decrease friction and wear of the pivots and escapement. Diamond was often used as the cap stone for the lower balance staff pivot to prevent wear from years of the heavy balance turning on the small pivot end. 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. </p><p>The timepieces were normally protected from the elements and kept below decks in a fixed position in a traditional box suspended in <a href="/wiki/Gimbal" title="Gimbal">gimbals</a> (a set of rings connected by bearings). This keeps the chronometer isolated in a horizontal "dial up" position to counter ship inclination (rocking) movements induced timing errors on the <a href="/wiki/Balance_wheel#Temperature-compensated_balance_wheels" title="Balance wheel">balance wheel</a>. </p><p>Marine chronometers always contain a <a href="/wiki/Maintaining_power" title="Maintaining power">maintaining power</a> which keeps the chronometer going while it is being wound, and a <a href="/wiki/Power_reserve" class="mw-redirect" title="Power reserve">power reserve</a> indicator to show how long the chronometer will continue to run without being wound. </p><p>These technical provisions usually yield timekeeping in mechanical marine chronometers accurate to within 0.5 second per day.<sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Chronometer_rating">Chronometer rating</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Marine_chronometer&action=edit&section=7" title="Edit section: Chronometer rating"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In strictly horological terms, "rating" a chronometer means that prior to the instrument entering service, the average rate of gaining or losing per day is observed and recorded on a rating certificate which accompanies the instrument. This daily rate is used in the field to correct the time indicated by the instrument to get an accurate time reading. Even the best-made chronometer with the finest temperature compensation etc. exhibits two types of error, (1) random and (2) consistent. The quality of design and manufacture of the instrument keeps the random errors small. In principle, the consistent errors should be amenable to elimination by adjustment, but in practice it is not possible to make the adjustment so precisely that this error is completely eliminated, so the technique of rating is used. The rate will also change while the instrument is in service due to e.g. thickening of the oil, so on long expeditions the instrument's rate would be periodically checked against accurate time determined by astronomical observations. </p> <div class="mw-heading mw-heading2"><h2 id="Marine_chronometer_use_today">Marine chronometer use today</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Marine_chronometer&action=edit&section=8" title="Edit section: Marine chronometer use today"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:OMC_ships_clock.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/90/OMC_ships_clock.jpg/240px-OMC_ships_clock.jpg" decoding="async" width="240" height="320" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/90/OMC_ships_clock.jpg/360px-OMC_ships_clock.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/90/OMC_ships_clock.jpg/480px-OMC_ships_clock.jpg 2x" data-file-width="3000" data-file-height="4000" /></a><figcaption>Omega 4.19 MHz (<span class="nowrap"><span data-sort-value="7006419430400000000♠"></span>4<span style="margin-left:.25em;">194</span><span style="margin-left:.25em;">304</span></span> = 2<sup>22</sup> high frequency quartz resonator) <a href="/wiki/Omega_Marine_Chronometer#4.19_MHz_Ships_Marine_Chronometer" title="Omega Marine Chronometer">Ships Marine Chronometer</a> giving an autonomous accuracy of less than ± 5 seconds per year, French Navy issued, 1980. The second hand can advance in <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1154941027"><span class="frac"><span class="num">1</span>⁄<span class="den">2</span></span>-second increments for optimal timing of celestial objects' angle measurements.</figcaption></figure> <p>Since the 1990s <a href="/wiki/Boat" title="Boat">boats</a> and <a href="/wiki/Ship" title="Ship">ships</a> can use several <a href="/wiki/Satellite_navigation" title="Satellite navigation">Global Navigation Satellite Systems</a> (GNSS) to navigate all the world's lakes, seas and oceans. Maritime GNSS units include functions useful on water, such as "man overboard" <a href="/wiki/Man_overboard#Technology" title="Man overboard">(MOB) functions</a> that allow instantly marking the location where a person has fallen overboard, which simplifies rescue efforts. GNSS may be connected to the ship's <a href="/wiki/Self-steering_gear" title="Self-steering gear">self-steering gear</a> and <a href="/wiki/Chartplotter" title="Chartplotter">Chartplotters</a> using the <a href="/wiki/NMEA_0183" title="NMEA 0183">NMEA 0183</a> interface, and can also improve the security of shipping traffic by enabling <a href="/wiki/Automatic_Identification_System" class="mw-redirect" title="Automatic Identification System">Automatic Identification Systems</a> (AIS). </p><p>Even with these convenient 21st-century technological tools, modern practical navigators usually use <a href="/wiki/Celestial_navigation" title="Celestial navigation">celestial navigation</a> using <a href="/wiki/Navigation#Marine_chronometer" title="Navigation">electric-powered time sources</a> in combination with satellite navigation.<sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> Small handheld computers, laptops, navigational calculators and even scientific calculators enable modern navigators to "reduce" sextant sights in minutes, by automating all the calculation and/or data lookup steps.<sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> Using multiple independent position fix methods without solely relying on subject-to-failure electronic systems helps the navigator detect errors. Professional mariners are still required to be proficient in traditional piloting and celestial navigation, which requires the use of a precisely adjusted and rated autonomous or periodically external time-signal corrected chronometer.<sup id="cite_ref-42" class="reference"><a href="#cite_note-42"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> These abilities are still a requirement for certain international <a href="/wiki/Licensed_mariner" title="Licensed mariner">mariner certifications</a> such as Officer in Charge of Navigational Watch, and <a href="/wiki/Licensed_mariner#Deck_officers" title="Licensed mariner">Master and Chief Mate</a> deck officers,<sup id="cite_ref-43" class="reference"><a href="#cite_note-43"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-44" class="reference"><a href="#cite_note-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> and supplements offshore yachtmasters on long-distance private cruising yachts.<sup id="cite_ref-45" class="reference"><a href="#cite_note-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> </p><p>Modern marine chronometers can be based on <a href="/wiki/Quartz_clock" title="Quartz clock">quartz clocks</a> that are corrected periodically by <a href="/wiki/Atomic_clock#Global_navigation_satellite_systems" title="Atomic clock">satellite time signals</a> or radio <a href="/wiki/Time_signal" title="Time signal">time signals</a> (see <a href="/wiki/Radio_clock" title="Radio clock">radio clock</a>). These quartz chronometers are not always the most accurate quartz clocks when no signal is received, and their signals can be lost or blocked. However, there are autonomous quartz movements, even in wrist watches, that are accurate to within 5 or 20 seconds per year.<sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup> At least one quartz chronometer made for advanced navigation utilizes multiple quartz crystals which are corrected by a computer using an average value, in addition to <a href="/wiki/GPS" class="mw-redirect" title="GPS">GPS</a> time signal corrections.<sup id="cite_ref-47" class="reference"><a href="#cite_note-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-48" class="reference"><a href="#cite_note-48"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Marine_chronometer&action=edit&section=9" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Celestial_navigation" title="Celestial navigation">Celestial navigation</a></li> <li><a href="/wiki/Sextant" title="Sextant">Sextant</a></li> <li><a href="/wiki/Clockmaker" title="Clockmaker">Clockmaker</a></li> <li><a href="/wiki/Thomas_Earnshaw" title="Thomas Earnshaw">Thomas Earnshaw</a>, inventor of the standard chronometer escapement</li> <li><a href="/wiki/Larcum_Kendall" title="Larcum Kendall">Larcum Kendall</a></li> <li><a href="/wiki/Noon_Gun" title="Noon Gun">Noon Gun</a></li> <li><a href="/wiki/Time_ball" title="Time ball">Time ball</a></li> <li><a href="/wiki/Time_signal" title="Time signal">Time signal</a></li> <li><a href="/wiki/Railroad_chronometer" title="Railroad chronometer">Railroad chronometer</a></li> <li><a href="/wiki/Rupert_Gould" title="Rupert Gould">Rupert Gould</a>, author of an important history of the marine chronometer</li> <li><a href="/wiki/Watch#Radio-controlled_movements" title="Watch">Radio-controlled watch</a></li> <li><a href="/wiki/Watchmaker" title="Watchmaker">Watchmaker</a></li> <li><a href="/wiki/Timeline_of_historic_inventions#18th_century" title="Timeline of historic inventions">Timeline of invention</a></li> <li><a href="/wiki/Longitude_(book)" title="Longitude (book)"><i>Longitude</i> (book)</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Marine_chronometer&action=edit&section=10" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFKoberer2016" class="citation journal cs1">Koberer, Wolfgang (May 2016). "Notes: On the First Use of the Term "Chronometer"=". <i>The Mariner's Mirror</i>. <b>102</b> (2). United Kingdom: Society for Nautical Research: 203–205. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1080%2F00253359.2016.1167400">10.1080/00253359.2016.1167400</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:164165009">164165009</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Mariner%27s+Mirror&rft.atitle=Notes%3A+On+the+First+Use+of+the+Term+%22Chronometer%22%3D&rft.volume=102&rft.issue=2&rft.pages=203-205&rft.date=2016-05&rft_id=info%3Adoi%2F10.1080%2F00253359.2016.1167400&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A164165009%23id-name%3DS2CID&rft.aulast=Koberer&rft.aufirst=Wolfgang&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.thenauticalalmanac.com">The free online Nautical Almanac in PDF format</a></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://casualnavigation.com/how-accurate-is-celestial-navigation-compared-to-gps/">How Accurate Is Celestial Navigation Compared To GPS?</a></span> </li> <li id="cite_note-Cox2000-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-Cox2000_4-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFArthur_N._Cox2000" class="citation book cs1">Arthur N. Cox, ed. (2000). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=w8PK2XFLLH8C&pg=PA244"><i>Allen's Astrophysical Quantities</i></a> (4th ed.). New York: AIP Press. p. 244. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-387-98746-0" title="Special:BookSources/978-0-387-98746-0"><bdi>978-0-387-98746-0</bdi></a><span class="reference-accessdate">. Retrieved <span class="nowrap">17 August</span> 2010</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Allen%27s+Astrophysical+Quantities&rft.place=New+York&rft.pages=244&rft.edition=4th&rft.pub=AIP+Press&rft.date=2000&rft.isbn=978-0-387-98746-0&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3Dw8PK2XFLLH8C%26pg%3DPA244&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHeath2018" class="citation book cs1">Heath, Byron (19 March 2018). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=yOWLaNm6c7sC&pg=PA167"><i>Great South Land</i></a>. Rosenberg. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9781877058318" title="Special:BookSources/9781877058318"><bdi>9781877058318</bdi></a><span class="reference-accessdate">. Retrieved <span class="nowrap">19 March</span> 2018</span> – via Google Books.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Great+South+Land&rft.pub=Rosenberg&rft.date=2018-03-19&rft.isbn=9781877058318&rft.aulast=Heath&rft.aufirst=Byron&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DyOWLaNm6c7sC%26pg%3DPA167&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><i>The maze of ingenuity: ideas and idealism in the development of technology</i> Arnold Pacey New p.133<i>ff</i> <a rel="nofollow" class="external autonumber" href="https://books.google.com/books?id=bwCkkLZI1JUC&pg=PA133">[1]</a></span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMatthews2000" class="citation book cs1">Matthews, Michael R. (31 October 2000). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=vCtYnEuW7TIC&pg=PA152"><i>Time for Science Education: How Teaching the History and Philosophy of Pendulum Motion Can Contribute to Science Literacy</i></a>. Springer Science & Business Media. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780306458804" title="Special:BookSources/9780306458804"><bdi>9780306458804</bdi></a><span class="reference-accessdate">. Retrieved <span class="nowrap">19 March</span> 2018</span> – via Google Books.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Time+for+Science+Education%3A+How+Teaching+the+History+and+Philosophy+of+Pendulum+Motion+Can+Contribute+to+Science+Literacy&rft.pub=Springer+Science+%26+Business+Media&rft.date=2000-10-31&rft.isbn=9780306458804&rft.aulast=Matthews&rft.aufirst=Michael+R.&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DvCtYnEuW7TIC%26pg%3DPA152&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://books.google.com/books?isbn=0330532189">"isbn:0330532189 - Google Search"</a>. <i>books.google.com</i><span class="reference-accessdate">. Retrieved <span class="nowrap">19 March</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=books.google.com&rft.atitle=isbn%3A0330532189+-+Google+Search&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fisbn%3D0330532189&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKoberer2016" class="citation journal cs1">Koberer, Wolfgang (May 2016). "Notes: On the First Use of the Term "Chronometer"<span class="cs1-kern-right"></span>". <i>The Mariner's Mirror</i>. <b>102</b> (2). United Kingdom: Society for Nautical Research: 203–205. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1080%2F00253359.2016.1167400">10.1080/00253359.2016.1167400</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:164165009">164165009</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Mariner%27s+Mirror&rft.atitle=Notes%3A+On+the+First+Use+of+the+Term+%22Chronometer%22&rft.volume=102&rft.issue=2&rft.pages=203-205&rft.date=2016-05&rft_id=info%3Adoi%2F10.1080%2F00253359.2016.1167400&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A164165009%23id-name%3DS2CID&rft.aulast=Koberer&rft.aufirst=Wolfgang&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.anthonygrayclocks.com/horological-timeline.htm">A Chronology of Clocks</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140325173508/http://www.anthonygrayclocks.com/horological-timeline.htm">Archived</a> 2014-03-25 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></span> </li> <li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><i><a rel="nofollow" class="external text" href="https://books.google.com/books?id=aB8OAAAAQAAJ">The principles of Mr Harrison's time-keeper</a></i></span> </li> <li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><i>A description concerning such mechanism as will afford a nice, or true, mensuration of time</i> John Harrison, 1775, p.14 "..no ponderosity in a pendulum or a balance, can rightly or ever make up the want of velocity; and indeed velocity was very much wanting in my three large machines.."</span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHarrisonMaskelyneGreat_Britain._Commissioners_of_Longitude1767" class="citation web cs1">Harrison, John; Maskelyne, Nevil; Great Britain. Commissioners of Longitude (19 March 1767). <a rel="nofollow" class="external text" href="https://archive.org/details/principlesmrhar00unkngoog">"The principles of Mr. Harrison's time-keeper; with plates of the same"</a>. London, Printed by W. Richardson and S. Clark and sold by J. Nourse<span class="reference-accessdate">. Retrieved <span class="nowrap">19 March</span> 2018</span> – via Internet Archive.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+principles+of+Mr.+Harrison%27s+time-keeper%3B+with+plates+of+the+same&rft.pub=London%2C+Printed+by+W.+Richardson+and+S.+Clark+and+sold+by+J.+Nourse&rft.date=1767-03-19&rft.aulast=Harrison&rft.aufirst=John&rft.au=Maskelyne%2C+Nevil&rft.au=Great+Britain.+Commissioners+of+Longitude&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fprinciplesmrhar00unkngoog&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-ancre-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-ancre_14-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://ancre.fr/en/monograph/64-monographie-de-l-aurore-corvette-1766.html">"MONOGRAPHIE DE L'AURORE - Corvette -1766"</a>. <i>Ancre</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2019-12-05</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Ancre&rft.atitle=MONOGRAPHIE+DE+L%27AURORE+-+Corvette+-1766&rft_id=https%3A%2F%2Fancre.fr%2Fen%2Fmonograph%2F64-monographie-de-l-aurore-corvette-1766.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-books.google.com-15"><span class="mw-cite-backlink">^ <a href="#cite_ref-books.google.com_15-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-books.google.com_15-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><i>Britten's Watch & Clock Makers' Handbook Dictionary & Guide Fifteenth Edition</i> p.122 <a rel="nofollow" class="external autonumber" href="https://books.google.com/books?id=s-cOAAAAQAAJ&pg=PA122">[2]</a></span> </li> <li id="cite_note-Macey-16"><span class="mw-cite-backlink">^ <a href="#cite_ref-Macey_16-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Macey_16-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMacey1994" class="citation book cs1">Macey, Samuel L. (19 March 1994). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=F7wNQk219KMC&pg=PA348"><i>Encyclopedia of Time</i></a>. Taylor & Francis. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780815306153" title="Special:BookSources/9780815306153"><bdi>9780815306153</bdi></a><span class="reference-accessdate">. Retrieved <span class="nowrap">19 March</span> 2018</span> – via Google Books.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Encyclopedia+of+Time&rft.pub=Taylor+%26+Francis&rft.date=1994-03-19&rft.isbn=9780815306153&rft.aulast=Macey&rft.aufirst=Samuel+L.&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DF7wNQk219KMC%26pg%3DPA348&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFUsher2018" class="citation book cs1">Usher, Abbott Payson (19 March 2018). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=xuDDqqa8FlwC&pg=PA330"><i>A History of Mechanical Inventions</i></a>. Courier Corporation. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780486255934" title="Special:BookSources/9780486255934"><bdi>9780486255934</bdi></a><span class="reference-accessdate">. Retrieved <span class="nowrap">19 March</span> 2018</span> – via Google Books.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+History+of+Mechanical+Inventions&rft.pub=Courier+Corporation&rft.date=2018-03-19&rft.isbn=9780486255934&rft.aulast=Usher&rft.aufirst=Abbott+Payson&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DxuDDqqa8FlwC%26pg%3DPA330&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-landes-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-landes_18-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLandes1983" class="citation book cs1">Landes, David S. (1983). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/revolutionintime00land_1/page/165"><i>Revolution in Time</i></a></span>. Cambridge, Massachusetts: Belknap Press of Harvard University Press. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/revolutionintime00land_1/page/165">165</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-674-76800-0" title="Special:BookSources/0-674-76800-0"><bdi>0-674-76800-0</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Revolution+in+Time&rft.place=Cambridge%2C+Massachusetts&rft.pages=165&rft.pub=Belknap+Press+of+Harvard+University+Press&rft.date=1983&rft.isbn=0-674-76800-0&rft.aulast=Landes&rft.aufirst=David+S.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Frevolutionintime00land_1%2Fpage%2F165&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span> Pierre Le Roy had developed the detached spring detent escapement around 1748, but abandoned the concept.</span> </li> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMacey1994" class="citation book cs1">Macey, Samuel L. (19 March 1994). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=F7wNQk219KMC&pg=PA349"><i>Encyclopedia of Time</i></a>. Taylor & Francis. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780815306153" title="Special:BookSources/9780815306153"><bdi>9780815306153</bdi></a><span class="reference-accessdate">. Retrieved <span class="nowrap">19 March</span> 2018</span> – via Google Books.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Encyclopedia+of+Time&rft.pub=Taylor+%26+Francis&rft.date=1994-03-19&rft.isbn=9780815306153&rft.aulast=Macey&rft.aufirst=Samuel+L.&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DF7wNQk219KMC%26pg%3DPA349&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-20">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHall,_Basil1862" class="citation book cs1"><a href="/wiki/Basil_Hall" title="Basil Hall">Hall, Basil</a> (1862). "Chapter XIV. Doubling the cape (from "Fragments of voyages and travels", 2nd series, vol. 2 (1832))". <a rel="nofollow" class="external text" href="https://www.gutenberg.org/ebooks/17032"><i>The Lieutenant and Commander</i></a>. London: <a href="/wiki/George_Bell_%26_Sons" title="George Bell & Sons">Bell and Daldy</a> (via <a href="/wiki/Project_Gutenberg" title="Project Gutenberg">Project Gutenberg</a>). <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/9305276">9305276</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2007-11-09</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Chapter+XIV.+Doubling+the+cape+%28from+%22Fragments+of+voyages+and+travels%22%2C+2nd+series%2C+vol.+2+%281832%29%29&rft.btitle=The+Lieutenant+and+Commander&rft.place=London&rft.pub=Bell+and+Daldy+%28via+Project+Gutenberg%29&rft.date=1862&rft_id=info%3Aoclcnum%2F9305276&rft.au=Hall%2C+Basil&rft_id=https%3A%2F%2Fwww.gutenberg.org%2Febooks%2F17032&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-Watchmakers_and_their_Work,_pg_230-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-Watchmakers_and_their_Work,_pg_230_21-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBritten1894" class="citation book cs1">Britten, Frederick James (1894). <a rel="nofollow" class="external text" href="https://archive.org/details/formerclockwatc00britgoog"><i>Former Clock & Watchmakers and Their Work</i></a>. New York: Spon & Chamberlain. p. <a rel="nofollow" class="external text" href="https://archive.org/details/formerclockwatc00britgoog/page/n242">230</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2007-08-08</span></span>. <q>Chronometers were not regularly supplied to the Royal Navy until about 1825</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Former+Clock+%26+Watchmakers+and+Their+Work&rft.place=New+York&rft.pages=230&rft.pub=Spon+%26+Chamberlain&rft.date=1894&rft.aulast=Britten&rft.aufirst=Frederick+James&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fformerclockwatc00britgoog&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.royalobservatorygreenwich.org/articles.php?article=1040">Rates of chronometers and watches on trial at the Observatory, 1766–1915</a></span> </li> <li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.royalobservatorygreenwich.org/articles.php?article=1246">Chronometer Section: 1914–1981 by William Roseman</a></span> </li> <li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGolding_Bird1867" class="citation book cs1"><a href="/wiki/Golding_Bird" title="Golding Bird">Golding Bird</a> (1867). <a rel="nofollow" class="external text" href="https://archive.org/details/elementsnatural00broogoog"><i>The Elements of Natural Philosophy; Or, An Introduction to the Study of the Physical Sciences</i></a>. J. Churchill and Sons. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/elementsnatural00broogoog/page/n582">545</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2008-09-24</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Elements+of+Natural+Philosophy%3B+Or%2C+An+Introduction+to+the+Study+of+the+Physical+Sciences&rft.pages=545&rft.pub=J.+Churchill+and+Sons&rft.date=1867&rft.au=Golding+Bird&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Felementsnatural00broogoog&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFTony_Jones2000" class="citation book cs1">Tony Jones (2000). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=krZBQbnHTY0C"><i>Splitting the Second</i></a>. CRC Press. p. 121. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0750306408" title="Special:BookSources/0750306408"><bdi>0750306408</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Splitting+the+Second&rft.pages=121&rft.pub=CRC+Press&rft.date=2000&rft.isbn=0750306408&rft.au=Tony+Jones&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DkrZBQbnHTY0C&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFNathaniel_Bowditch,_Jonathan_Ingersoll_Bowditch1826" class="citation book cs1">Nathaniel Bowditch, Jonathan Ingersoll Bowditch (1826). <a rel="nofollow" class="external text" href="https://archive.org/details/newamericanprac01bowdgoog"><i>The New American Practical Navigator</i></a>. E. M. Blunt. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/newamericanprac01bowdgoog/page/n219">179</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+New+American+Practical+Navigator&rft.pages=179&rft.pub=E.+M.+Blunt&rft.date=1826&rft.au=Nathaniel+Bowditch%2C+Jonathan+Ingersoll+Bowditch&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fnewamericanprac01bowdgoog&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFNorie,_J._W.1816" class="citation journal cs1">Norie, J. W. (1816). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150907223430/http://library.mysticseaport.org/initiative/ImPage.cfm?BibID=13617&ChapterId=32">"To Find The Longitude of Chronometers or Time-Keepers"</a>. <i>New and Complete Epitome of Practical Navigation</i>. Archived from <a rel="nofollow" class="external text" href="https://library.mysticseaport.org/initiative/ImPage.cfm?BibID=13617&ChapterId=32">the original</a> on 2015-09-07.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=New+and+Complete+Epitome+of+Practical+Navigation&rft.atitle=To+Find+The+Longitude+of+Chronometers+or+Time-Keepers&rft.date=1816&rft.au=Norie%2C+J.+W.&rft_id=https%3A%2F%2Flibrary.mysticseaport.org%2Finitiative%2FImPage.cfm%3FBibID%3D13617%26ChapterId%3D32&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.wempe-maritim.de/the-unified-chronometer">The unified Chronometer - how it all began</a></span> </li> <li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.dsm.museum/zas/21-das-einheitschronometer.5059.de.html">THE STANDARDIZED CHRONOMETER</a></span> </li> <li id="cite_note-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-30">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.dg-chrono.de/uhrenwissen/russische-uhren/schiffe-und-uhren/1945-2000/marinechronometer/geburt-des-6mx/">Geburt des „6 MX“</a></span> </li> <li id="cite_note-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-31">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.dg-chrono.de/uhrenwissen/russische-uhren/schiffe-und-uhren/1945-2000/marinechronometer/leben-des-6mx/">Marine-Chronometer - Leben des „6 MX“</a></span> </li> <li id="cite_note-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-32">^</a></b></span> <span class="reference-text"><a href="/wiki/Alfred_T._Mahan" class="mw-redirect" title="Alfred T. Mahan">Alfred T. Mahan</a>, The Influence of Sea Power on History:</span> </li> <li id="cite_note-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-33">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.royalobservatorygreenwich.org/articles.php?article=1040">Rates of chronometers and watches on trial at the Observatory, 1766–1915</a></span> </li> <li id="cite_note-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-34">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.royalobservatorygreenwich.org/articles.php?article=1246">Chronometer Section: 1914–1981 by William Roseman</a></span> </li> <li id="cite_note-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-35">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.royalobservatorygreenwich.org/articles.php?article=1248">A brief history of Chronometer testing and repair at the Royal Observatory</a></span> </li> <li id="cite_note-36"><span class="mw-cite-backlink"><b><a href="#cite_ref-36">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.dsm.museum/zas/23-quarz-uhren.5063.de.html">QUARTZ TIMEPIECES</a></span> </li> <li id="cite_note-37"><span class="mw-cite-backlink"><b><a href="#cite_ref-37">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://clockdoc.org/gs/handler/getmedia.ashx?moid=57430&dt=3&g=1">The marine chronometer in the age of electricity by David Read, September 2015</a></span> </li> <li id="cite_note-38"><span class="mw-cite-backlink"><b><a href="#cite_ref-38">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.britannica.com/technology/chronometer">chronometer timekeeping device</a></span> </li> <li id="cite_note-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-39">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.dg-chrono.de/uhrenwissen/russische-uhren/schiffe-und-uhren/1945-2000/marinechronometer/bilder-zum-6mx/">Attestat/Pasport of some Russian made MX6 marine chronometers</a></span> </li> <li id="cite_note-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-40">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://fer3.com/arc/imgx/Bowditch-American-Practical-Navigator-2002-(2004).pdf">THE AMERICAN PRACTICAL NAVIGATORAN EPITOME OF NAVIGATION 2002 p. 269</a></span> </li> <li id="cite_note-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-41">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://fer3.com/arc/imgx/Bowditch-American-Practical-Navigator-2002-(2004).pdf">THE AMERICAN PRACTICAL NAVIGATORAN EPITOME OF NAVIGATION 2002 p. 270</a></span> </li> <li id="cite_note-42"><span class="mw-cite-backlink"><b><a href="#cite_ref-42">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://thenauticalalmanac.com/2019_Bowditch-_American_Practical_Navigator/Volume-_1/2019%20Bowditch_Vol_1.pdf">THE AMERICAN PRACTICAL NAVIGATORAN EPITOME OF NAVIGATION 2019 p. 280</a></span> </li> <li id="cite_note-43"><span class="mw-cite-backlink"><b><a href="#cite_ref-43">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.admiraltylawguide.com/conven/stcw1978.html">"International Convention on Standards of Training, Certification and Watchkeeping for Seafarers, 1978"</a>. Admiralty and Maritime Law Guide, International Conventions<span class="reference-accessdate">. Retrieved <span class="nowrap">2007-09-22</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=International+Convention+on+Standards+of+Training%2C+Certification+and+Watchkeeping+for+Seafarers%2C+1978&rft.pub=Admiralty+and+Maritime+Law+Guide%2C+International+Conventions&rft_id=http%3A%2F%2Fwww.admiraltylawguide.com%2Fconven%2Fstcw1978.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-44"><span class="mw-cite-backlink"><b><a href="#cite_ref-44">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20070703133024/http://www.imo.org/Conventions/contents.asp?doc_id=651&topic_id=257">"International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (with amendments)"</a>. International Maritime Organization. Archived from <a rel="nofollow" class="external text" href="http://www.imo.org/Conventions/contents.asp?doc_id=651&topic_id=257">the original</a> on 2007-07-03<span class="reference-accessdate">. Retrieved <span class="nowrap">2007-09-22</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=International+Convention+on+Standards+of+Training%2C+Certification+and+Watchkeeping+for+Seafarers+%28with+amendments%29&rft.pub=International+Maritime+Organization&rft_id=http%3A%2F%2Fwww.imo.org%2FConventions%2Fcontents.asp%3Fdoc_id%3D651%26topic_id%3D257&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-45"><span class="mw-cite-backlink"><b><a href="#cite_ref-45">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20110226011139/http://www.muehle-glashuette.de/en/nautical-instruments/yacht-and-marine-chronometer.html">Yachting Chronometer and Sextant</a>, Accessed 25 May 2013, publisher=Nautische Instrumente</span> </li> <li id="cite_note-46"><span class="mw-cite-backlink"><b><a href="#cite_ref-46">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRead" class="citation web cs1">Read, Alexander. <a rel="nofollow" class="external text" href="http://80calcs.pagesperso-orange.fr/Navigation/Chronometer.html">"High accuracy timepieces that could be used as marine chronometer"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2007-09-22</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=High+accuracy+timepieces+that+could+be+used+as+marine+chronometer&rft.aulast=Read&rft.aufirst=Alexander&rft_id=http%3A%2F%2F80calcs.pagesperso-orange.fr%2FNavigation%2FChronometer.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-47"><span class="mw-cite-backlink"><b><a href="#cite_ref-47">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMontgomery" class="citation web cs1">Montgomery, Bruce G. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110609125114/http://www.cotsjournalonline.com/articles/view/100409">"Keeping Precision Time When GPS Signals Stop"</a>. Cotts Journal Online. Archived from <a rel="nofollow" class="external text" href="http://www.cotsjournalonline.com/articles/view/100409">the original</a> on 2011-06-09<span class="reference-accessdate">. Retrieved <span class="nowrap">2007-09-22</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Keeping+Precision+Time+When+GPS+Signals+Stop&rft.pub=Cotts+Journal+Online&rft.aulast=Montgomery&rft.aufirst=Bruce+G.&rft_id=http%3A%2F%2Fwww.cotsjournalonline.com%2Farticles%2Fview%2F100409&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> <li id="cite_note-48"><span class="mw-cite-backlink"><b><a href="#cite_ref-48">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20101231055940/http://www.dodtechmatch.com/DOD/SuccessStories/View.aspx?id=60141">"Precise Time and Frequency for Navy Applications: The PICO Advanced Clock"</a>. DoD TechMatch, West Virginia High Technology Consortium Foundation. Archived from <a rel="nofollow" class="external text" href="http://www.dodtechmatch.com/DOD/SuccessStories/View.aspx?id=60141">the original</a> on December 31, 2010<span class="reference-accessdate">. Retrieved <span class="nowrap">2007-09-22</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Precise+Time+and+Frequency+for+Navy+Applications%3A+The+PICO+Advanced+Clock&rft.pub=DoD+TechMatch%2C+West+Virginia+High+Technology+Consortium+Foundation.&rft_id=http%3A%2F%2Fwww.dodtechmatch.com%2FDOD%2FSuccessStories%2FView.aspx%3Fid%3D60141&rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarine+chronometer" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Marine_chronometer&action=edit&section=11" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png" decoding="async" width="30" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/45px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/59px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></span></span></div> <div class="side-box-text plainlist">Wikimedia Commons has media related to <span style="font-weight: bold; font-style: italic;"><a href="https://commons.wikimedia.org/wiki/Category:Marine_chronometers" class="extiw" title="commons:Category:Marine chronometers">Marine chronometers</a></span>.</div></div> </div> <ul><li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20111212075532/http://www.nmm.ac.uk/">National Maritime Museum, Greenwich</a></li> <li><a rel="nofollow" class="external text" href="http://pagesperso-orange.fr/fredouille/chronometre.html">Henri MOTEL n°258 Chronomètre de Marine 40 heures</a><sup class="noprint Inline-Template"><span style="white-space: nowrap;">[<i><a href="/wiki/Wikipedia:Link_rot" title="Wikipedia:Link rot"><span title=" Dead link tagged March 2020">permanent dead link</span></a></i><span style="visibility:hidden; color:transparent; padding-left:2px">‍</span>]</span></sup> <span class="languageicon">(in French)</span></li> <li><a rel="nofollow" class="external text" href="http://www.glashuetteuhren.de/kaliberuebersichten-modelle/a-lange-soehne/marinechronometer-kaliber-100/">Marine Chronometer Kaliber 100</a> - Presentation of marine chronometers of "Glashütter Uhrenbetriebe VEB" with picture and explanation <span class="languageicon">(in German)</span></li> <li><a rel="nofollow" class="external text" href="http://www.nma.gov.au/collections/collection_interactives/european_voyages_to_the_australian_continent/navigation/a_never_failing_guide/a_working_chronometer">A working chronometer, National Museum of Australia</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20111028033232/http://www.nma.gov.au/collections/collection_interactives/european_voyages_to_the_australian_continent/navigation/a_never_failing_guide/a_working_chronometer">Archived</a> 2011-10-28 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>. Short MPEG film showing an 1825 Barraud chronometer in action. (link is outdated)</li> <li><a href="https://en.wiktionary.org/wiki/marine_chronometer" class="extiw" title="wiktionary:marine chronometer">Marine chronometer</a> meaning at Wiktionary</li> <li><a rel="nofollow" class="external text" href="https://chronometre-online.fr">Web chronometer</a></li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output 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.navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Time_topics" title="Template:Time topics"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Time_topics" title="Template talk:Time topics"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a 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style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/Chronometry" title="Chronometry">Chronometry</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time">UTC</a></li> <li><a href="/wiki/Universal_Time" title="Universal Time">UT</a></li> <li><a href="/wiki/International_Atomic_Time" title="International Atomic Time">TAI</a></li> <li><a href="/wiki/Unit_of_time" title="Unit of time">Unit of time</a></li> <li><a href="/wiki/Orders_of_magnitude_(time)" title="Orders of magnitude (time)">Orders of magnitude (time)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/System_of_measurement" class="mw-redirect" title="System of measurement">Measurement<br />systems</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Italian_six-hour_clock" title="Italian six-hour clock">Italian six-hour clock</a></li> <li><a href="/wiki/Thai_six-hour_clock" title="Thai six-hour clock">Thai six-hour clock</a></li> <li><a href="/wiki/12-hour_clock" title="12-hour clock">12-hour clock</a></li> <li><a href="/wiki/24-hour_clock" title="24-hour clock">24-hour clock</a></li> <li><a href="/wiki/Relative_hour" title="Relative hour">Relative hour</a></li> <li><a href="/wiki/Daylight_saving_time" title="Daylight saving time">Daylight saving time</a></li> <li><a href="/wiki/Traditional_Chinese_timekeeping" title="Traditional Chinese timekeeping">Chinese</a></li> <li><a href="/wiki/Decimal_time" title="Decimal time">Decimal</a></li> <li><a href="/wiki/Hexadecimal_time" title="Hexadecimal time">Hexadecimal</a></li> <li><a href="/wiki/Hindu_units_of_time" title="Hindu units of time">Hindu</a></li> <li><a href="/wiki/Metric_time" title="Metric time">Metric</a></li> <li><a href="/wiki/Roman_timekeeping" title="Roman timekeeping">Roman</a></li> <li><a href="/wiki/Sidereal_time" title="Sidereal time">Sidereal</a></li> <li><a href="/wiki/Solar_time" title="Solar time">Solar</a></li> <li><a href="/wiki/Time_zone" title="Time zone">Time zone</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/Calendar" title="Calendar">Calendars</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Calendar#Systems" title="Calendar">Main types</a> <ul><li><a href="/wiki/Solar_calendar" title="Solar calendar">Solar</a></li> <li><a href="/wiki/Lunar_calendar" title="Lunar calendar">Lunar</a></li> <li><a href="/wiki/Lunisolar_calendar" title="Lunisolar calendar">Lunisolar</a></li></ul></li> <li><a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian</a></li> <li><a href="/wiki/Julian_calendar" title="Julian calendar">Julian</a></li> <li><a href="/wiki/Hebrew_calendar" title="Hebrew calendar">Hebrew</a></li> <li><a href="/wiki/Islamic_calendar" title="Islamic calendar">Islamic</a></li> <li><a href="/wiki/Solar_Hijri_calendar" title="Solar Hijri calendar">Solar Hijri</a></li> <li><a href="/wiki/Chinese_calendar" title="Chinese calendar">Chinese</a></li> <li><a href="/wiki/Hindu_calendar" title="Hindu calendar">Hindu Panchang</a></li> <li><a href="/wiki/Maya_calendar" title="Maya calendar">Maya</a></li> <li><i><a href="/wiki/List_of_calendars" title="List of calendars">List</a></i></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/Clock" title="Clock">Clocks</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Clock#Types" title="Clock">Main types</a> <ul><li><a href="/wiki/Astronomical_clock" title="Astronomical clock">astronomical</a> <ul><li><a href="/wiki/Astrarium" title="Astrarium">astrarium</a></li></ul></li> <li><a href="/wiki/Atomic_clock" title="Atomic clock">atomic</a> <ul><li><a href="/wiki/Quantum_clock" class="mw-redirect" title="Quantum clock">quantum</a></li></ul></li> <li><a href="/wiki/Hourglass" title="Hourglass">hourglass</a></li> <li><a class="mw-selflink selflink">marine</a></li> <li><a href="/wiki/Sundial" title="Sundial">sundial</a></li> <li><a href="/wiki/Watch" title="Watch">watch</a> <ul><li><a href="/wiki/Mechanical_watch" title="Mechanical watch">mechanical</a></li> <li><a href="/wiki/Stopwatch" title="Stopwatch">stopwatch</a></li></ul></li> <li><a href="/wiki/Water_clock" title="Water clock">water-based</a></li></ul></li> <li><a href="/wiki/Cuckoo_clock" title="Cuckoo clock">Cuckoo clock</a></li> <li><a href="/wiki/Digital_clock" title="Digital clock">Digital clock</a></li> <li><a href="/wiki/Grandfather_clock" title="Grandfather clock">Grandfather clock</a></li> <li><i><a href="/wiki/History_of_timekeeping_devices" title="History of timekeeping devices">History</a></i> <ul><li><i><a href="/wiki/Timeline_of_time_measurement_inventions" title="Timeline of time measurement inventions">Timeline</a></i></li></ul></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div class="hlist"><ul><li><a href="/wiki/Chronology" title="Chronology">Chronology</a></li><li><a href="/wiki/History" title="History">History</a></li></ul></div></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Astronomical_chronology" title="Astronomical chronology">Astronomical chronology</a></li> <li><a href="/wiki/Big_History" title="Big History">Big History</a></li> <li><a href="/wiki/Calendar_era" title="Calendar era">Calendar era</a></li> <li><a href="/wiki/Deep_time" title="Deep time">Deep time</a></li> <li><a href="/wiki/Periodization" title="Periodization">Periodization</a></li> <li><a href="/wiki/Regnal_year" title="Regnal year">Regnal year</a></li> <li><a href="/wiki/Timeline" title="Timeline">Timeline</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Philosophy_of_space_and_time" title="Philosophy of space and time">Philosophy of time</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/A_series_and_B_series" title="A series and B series">A series and B series</a></li> <li><a href="/wiki/B-theory_of_time" title="B-theory of time">B-theory of time</a></li> <li><a href="/wiki/Chronocentrism" title="Chronocentrism">Chronocentrism</a></li> <li><a href="/wiki/Duration_(philosophy)" title="Duration (philosophy)">Duration</a></li> <li><a href="/wiki/Endurantism" title="Endurantism">Endurantism</a></li> <li><a href="/wiki/Eternal_return" title="Eternal return">Eternal return</a></li> <li><a href="/wiki/Eternalism_(philosophy_of_time)" title="Eternalism (philosophy of time)">Eternalism</a></li> <li><a href="/wiki/Event_(philosophy)" title="Event (philosophy)">Event</a></li> <li><a href="/wiki/Perdurantism" title="Perdurantism">Perdurantism</a></li> <li><a href="/wiki/Philosophical_presentism" title="Philosophical presentism">Presentism</a></li> <li><a href="/wiki/Temporal_finitism" title="Temporal finitism">Temporal finitism</a></li> <li><a href="/wiki/Temporal_parts" title="Temporal parts">Temporal parts</a></li> <li><i><a href="/wiki/The_Unreality_of_Time" title="The Unreality of Time">The Unreality of Time</a></i></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div class="hlist"><ul><li><a href="/wiki/Category:Time_in_religion" title="Category:Time in religion">Religion</a></li><li><a href="/wiki/Template:Time_in_religion_and_mythology" title="Template:Time in religion and mythology">Mythology</a></li></ul></div></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ages_of_Man" title="Ages of Man">Ages of Man</a></li> <li><a href="/wiki/Destiny" title="Destiny">Destiny</a></li> <li><a href="/wiki/Immortality" title="Immortality">Immortality</a></li> <li><a href="/wiki/The_Dreaming" title="The Dreaming">Dreamtime</a></li> <li><a href="/wiki/K%C4%81la" title="Kāla">Kāla</a></li> <li><a href="/wiki/Time_and_fate_deities" title="Time and fate deities">Time and fate deities</a> <ul><li><a href="/wiki/Father_Time" title="Father Time">Father Time</a></li></ul></li> <li><a href="/wiki/Wheel_of_time" title="Wheel of time">Wheel of time</a> <ul><li><a href="/wiki/Kalachakra" title="Kalachakra">Kalachakra</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Time_perception" title="Time perception">Human experience</a><br />and <a href="/wiki/Time-use_research" title="Time-use research">use of time</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronemics" title="Chronemics">Chronemics</a></li> <li><a href="/wiki/Generation_time" title="Generation time">Generation time</a></li> <li><a href="/wiki/Mental_chronometry" title="Mental chronometry">Mental chronometry</a></li> <li><a href="/wiki/Duration_(music)" title="Duration (music)">Music</a> <ul><li><a href="/wiki/Tempo" title="Tempo">tempo</a></li> <li><a href="/wiki/Time_signature" title="Time signature">time signature</a></li></ul></li> <li><a href="/wiki/Rosy_retrospection" title="Rosy retrospection">Rosy retrospection</a></li> <li><a href="/wiki/Tense%E2%80%93aspect%E2%80%93mood" title="Tense–aspect–mood">Tense–aspect–mood</a></li> <li><a href="/wiki/Time_management" title="Time management">Time management</a></li> <li><a href="/wiki/Yesterday_(time)" title="Yesterday (time)">Yesterday</a> – <a href="/wiki/Present" title="Present">Today</a> – <a href="/wiki/Tomorrow_(time)" title="Tomorrow (time)">Tomorrow</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Time in <a href="/wiki/Science" title="Science">science</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/Geology" title="Geology">Geology</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Geologic_time_scale" title="Geologic time scale">Geological time</a> <ul><li><a href="/wiki/Age_(geology)" class="mw-redirect" title="Age (geology)">age</a></li> <li><a href="/wiki/Chronozone" title="Chronozone">chron</a></li> <li><a href="/wiki/Eon_(geology)" class="mw-redirect" title="Eon (geology)">eon</a></li> <li><a href="/wiki/Epoch_(geology)" class="mw-redirect" title="Epoch (geology)">epoch</a></li> <li><a href="/wiki/Era_(geology)" class="mw-redirect" title="Era (geology)">era</a></li> <li><a href="/wiki/Geological_period" class="mw-redirect" title="Geological period">period</a></li></ul></li> <li><a href="/wiki/Geochronology" title="Geochronology">Geochronology</a></li> <li><a href="/wiki/Geological_history_of_Earth" title="Geological history of Earth">Geological history of Earth</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/Time_in_physics" title="Time in physics">Physics</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Absolute_space_and_time" title="Absolute space and time">Absolute space and time</a></li> <li><a href="/wiki/Arrow_of_time" title="Arrow of time">Arrow of time</a></li> <li><a href="/wiki/Chronon" title="Chronon">Chronon</a></li> <li><a href="/wiki/Coordinate_time" title="Coordinate time">Coordinate time</a></li> <li><a href="/wiki/Instant" title="Instant">Instant</a></li> <li><a href="/wiki/Proper_time" title="Proper time">Proper time</a></li> <li><a href="/wiki/Spacetime" title="Spacetime">Spacetime</a></li> <li><a href="/wiki/Theory_of_relativity" title="Theory of relativity">Theory of relativity</a></li> <li><a href="/wiki/Time_domain" title="Time domain">Time domain</a></li> <li><a href="/wiki/Time_translation_symmetry" class="mw-redirect" title="Time translation symmetry">Time translation symmetry</a></li> <li><a href="/wiki/T-symmetry" title="T-symmetry">Time reversal symmetry</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;">Other fields</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronological_dating" title="Chronological dating">Chronological dating</a></li> <li><a href="/wiki/Chronobiology" title="Chronobiology">Chronobiology</a> <ul><li><a href="/wiki/Circadian_rhythm" title="Circadian rhythm">Circadian rhythms</a></li></ul></li> <li><a href="/wiki/Chemical_clock" title="Chemical clock">Clock reaction</a></li> <li><a href="/wiki/Glottochronology" title="Glottochronology">Glottochronology</a></li> <li><a href="/wiki/Time_geography" title="Time geography">Time geography</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Leap_year" title="Leap year">Leap year</a></li> <li><a href="/wiki/Memory" title="Memory">Memory</a></li> <li><a href="/wiki/Moment_(unit)" title="Moment (unit)">Moment</a></li> <li><a href="/wiki/Space" title="Space">Space</a></li> <li><a href="/wiki/System_time" title="System time">System time</a></li> <li><i><a href="/wiki/Tempus_fugit" title="Tempus fugit">Tempus fugit</a></i></li> <li><a href="/wiki/Time_capsule" title="Time capsule">Time capsule</a></li> <li><a href="/wiki/Time_immemorial" title="Time immemorial">Time immemorial</a></li> <li><a href="/wiki/Time_travel" title="Time travel">Time travel</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <a href="/wiki/Category:Time" title="Category:Time">Category</a></li> <li><span class="noviewer" typeof="mw:File"><span title="Commons page"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/12px-Commons-logo.svg.png" decoding="async" width="12" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/18px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/24px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></span></span> <a href="https://commons.wikimedia.org/wiki/Category:Time" class="extiw" title="commons:Category:Time">Commons</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Time_measurement_and_standards" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="3"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Time_measurement_and_standards" title="Template:Time measurement and standards"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Time_measurement_and_standards" title="Template talk:Time measurement and standards"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Time_measurement_and_standards" title="Special:EditPage/Template:Time measurement and standards"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Time_measurement_and_standards" style="font-size:114%;margin:0 4em"><a href="/wiki/Time" title="Time">Time measurement</a> and <a href="/wiki/Time_standard" title="Time standard">standards</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="3"><div> <ul><li><a href="/wiki/Chronometry" title="Chronometry">Chronometry</a></li> <li><a href="/wiki/Orders_of_magnitude_(time)" title="Orders of magnitude (time)">Orders of magnitude</a></li> <li><a href="/wiki/Time_metrology" class="mw-redirect" title="Time metrology">Metrology</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">International standards</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time">Coordinated Universal Time</a> <ul><li><a href="/wiki/UTC_offset" title="UTC offset">offset</a></li></ul></li> <li><a href="/wiki/Universal_Time" title="Universal Time">UT</a></li> <li><a href="/wiki/%CE%94T_(timekeeping)" title="ΔT (timekeeping)">ΔT</a></li> <li><a href="/wiki/DUT1" title="DUT1">DUT1</a></li> <li><a href="/wiki/International_Earth_Rotation_and_Reference_Systems_Service" title="International Earth Rotation and Reference Systems Service">International Earth Rotation and Reference Systems Service</a></li> <li><a href="/wiki/ISO_31-1" title="ISO 31-1">ISO 31-1</a></li> <li><a href="/wiki/ISO_8601" title="ISO 8601">ISO 8601</a></li> <li><a href="/wiki/International_Atomic_Time" title="International Atomic Time">International Atomic Time</a></li> <li><a href="/wiki/12-hour_clock" title="12-hour clock">12-hour clock</a></li> <li><a href="/wiki/24-hour_clock" title="24-hour clock">24-hour clock</a></li> <li><a href="/wiki/Barycentric_Coordinate_Time" title="Barycentric Coordinate Time">Barycentric Coordinate Time</a></li> <li><a href="/wiki/Barycentric_Dynamical_Time" title="Barycentric Dynamical Time">Barycentric Dynamical Time</a></li> <li><a href="/wiki/Civil_time" title="Civil time">Civil time</a></li> <li><a href="/wiki/Daylight_saving_time" title="Daylight saving time">Daylight saving time</a></li> <li><a href="/wiki/Geocentric_Coordinate_Time" title="Geocentric Coordinate Time">Geocentric Coordinate Time</a></li> <li><a href="/wiki/International_Date_Line" title="International Date Line">International Date Line</a></li> <li><a href="/wiki/IERS_Reference_Meridian" title="IERS Reference Meridian">IERS Reference Meridian</a></li> <li><a href="/wiki/Leap_second" title="Leap second">Leap second</a></li> <li><a href="/wiki/Solar_time" title="Solar time">Solar time</a></li> <li><a href="/wiki/Terrestrial_Time" title="Terrestrial Time">Terrestrial Time</a></li> <li><a href="/wiki/Time_zone" title="Time zone">Time zone</a></li> <li><a href="/wiki/180th_meridian" title="180th meridian">180th meridian</a></li></ul> </div></td><td class="noviewer navbox-image" rowspan="9" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"><a href="/wiki/Hourglass" title="Hourglass"><img alt="template illustration" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Marine_sandglass_MMM.jpg/75px-Marine_sandglass_MMM.jpg" decoding="async" width="75" height="175" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Marine_sandglass_MMM.jpg/113px-Marine_sandglass_MMM.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/70/Marine_sandglass_MMM.jpg/150px-Marine_sandglass_MMM.jpg 2x" data-file-width="1637" data-file-height="3819" /></a></span><br /><span typeof="mw:File"><a href="/wiki/Time_zone" title="Time zone"><img alt="template illustration" src="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png/75px-Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png" decoding="async" width="75" height="152" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png/113px-Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/63/Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png/150px-Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png 2x" data-file-width="496" data-file-height="1007" /></a></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Obsolete standards</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ephemeris_time" title="Ephemeris time">Ephemeris time</a></li> <li><a href="/wiki/Greenwich_Mean_Time" title="Greenwich Mean Time">Greenwich Mean Time</a></li> <li><a href="/wiki/Prime_meridian" title="Prime meridian">Prime meridian</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Time_in_physics" title="Time in physics">Time in physics</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Absolute_space_and_time" title="Absolute space and time">Absolute space and time</a></li> <li><a href="/wiki/Spacetime" title="Spacetime">Spacetime</a></li> <li><a href="/wiki/Chronon" title="Chronon">Chronon</a></li> <li><a href="/wiki/Continuous_signal" class="mw-redirect" title="Continuous signal">Continuous signal</a></li> <li><a href="/wiki/Coordinate_time" title="Coordinate time">Coordinate time</a></li> <li><a href="/wiki/Cosmological_decade" title="Cosmological decade">Cosmological decade</a></li> <li><a href="/wiki/Discrete_time_and_continuous_time" title="Discrete time and continuous time">Discrete time and continuous time</a></li> <li><a href="/wiki/Proper_time" title="Proper time">Proper time</a></li> <li><a href="/wiki/Theory_of_relativity" title="Theory of relativity">Theory of relativity</a></li> <li><a href="/wiki/Time_dilation" title="Time dilation">Time dilation</a></li> <li><a href="/wiki/Gravitational_time_dilation" title="Gravitational time dilation">Gravitational time dilation</a></li> <li><a href="/wiki/Time_domain" title="Time domain">Time domain</a></li> <li><a href="/wiki/Time-translation_symmetry" title="Time-translation symmetry">Time-translation symmetry</a></li> <li><a href="/wiki/T-symmetry" title="T-symmetry">T-symmetry</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Horology" class="mw-redirect" title="Horology">Horology</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Clock" title="Clock">Clock</a></li> <li><a href="/wiki/Astrarium" title="Astrarium">Astrarium</a></li> <li><a href="/wiki/Atomic_clock" title="Atomic clock">Atomic clock</a></li> <li><a href="/wiki/Complication_(horology)" title="Complication (horology)">Complication</a></li> <li><a href="/wiki/History_of_timekeeping_devices" title="History of timekeeping devices">History of timekeeping devices</a></li> <li><a href="/wiki/Hourglass" title="Hourglass">Hourglass</a></li> <li><a class="mw-selflink selflink">Marine chronometer</a></li> <li><a href="/wiki/Marine_sandglass" title="Marine sandglass">Marine sandglass</a></li> <li><a href="/wiki/Radio_clock" title="Radio clock">Radio clock</a></li> <li><a href="/wiki/Watch" title="Watch">Watch</a> <ul><li><a href="/wiki/Stopwatch" title="Stopwatch">stopwatch</a></li></ul></li> <li><a href="/wiki/Water_clock" title="Water clock">Water clock</a></li> <li><a href="/wiki/Sundial" title="Sundial">Sundial</a></li> <li><a href="/wiki/Dialing_scales" title="Dialing scales">Dialing scales</a></li> <li><a href="/wiki/Equation_of_time" title="Equation of time">Equation of time</a></li> <li><a href="/wiki/History_of_sundials" title="History of sundials">History of sundials</a></li> <li><a href="/wiki/Schema_for_horizontal_dials" title="Schema for horizontal dials">Sundial markup schema</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Calendar" title="Calendar">Calendar</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian</a></li> <li><a href="/wiki/Hebrew_calendar" title="Hebrew calendar">Hebrew</a></li> <li><a href="/wiki/Hindu_calendar" title="Hindu calendar">Hindu</a></li> <li><a href="/wiki/Holocene_calendar" title="Holocene calendar">Holocene</a></li> <li><a href="/wiki/Islamic_calendar" title="Islamic calendar">Islamic</a> (lunar Hijri)</li> <li><a href="/wiki/Julian_calendar" title="Julian calendar">Julian</a></li> <li><a href="/wiki/Solar_Hijri_calendar" title="Solar Hijri calendar">Solar Hijri</a></li> <li><a href="/wiki/Astronomical_year_numbering" title="Astronomical year numbering">Astronomical</a></li> <li><a href="/wiki/Dominical_letter" title="Dominical letter">Dominical letter</a></li> <li><a href="/wiki/Epact" title="Epact">Epact</a></li> <li><a href="/wiki/Equinox" title="Equinox">Equinox</a></li> <li><a href="/wiki/Intercalation_(timekeeping)" title="Intercalation (timekeeping)">Intercalation</a></li> <li><a href="/wiki/Julian_day" title="Julian day">Julian day</a></li> <li><a href="/wiki/Leap_year" title="Leap year">Leap year</a></li> <li><a href="/wiki/Lunar_calendar" title="Lunar calendar">Lunar</a></li> <li><a href="/wiki/Lunisolar_calendar" title="Lunisolar calendar">Lunisolar</a></li> <li><a href="/wiki/Solar_calendar" title="Solar calendar">Solar</a></li> <li><a href="/wiki/Solstice" title="Solstice">Solstice</a></li> <li><a href="/wiki/Tropical_year" title="Tropical year">Tropical year</a></li> <li><a href="/wiki/Determination_of_the_day_of_the_week" title="Determination of the day of the week">Weekday determination</a></li> <li><a href="/wiki/Names_of_the_days_of_the_week" title="Names of the days of the week">Weekday names</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Archaeology and geology</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronological_dating" title="Chronological dating">Chronological dating</a></li> <li><a href="/wiki/Geologic_time_scale" title="Geologic time scale">Geologic time scale</a></li> <li><a href="/wiki/International_Commission_on_Stratigraphy" title="International Commission on Stratigraphy">International Commission on Stratigraphy</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Astronomical_chronology" title="Astronomical chronology">Astronomical chronology</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Galactic_year" title="Galactic year">Galactic year</a></li> <li><a href="/wiki/Nuclear_timescale" title="Nuclear timescale">Nuclear timescale</a></li> <li><a href="/wiki/Precession" title="Precession">Precession</a></li> <li><a href="/wiki/Sidereal_time" title="Sidereal time">Sidereal time</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other <a href="/wiki/Unit_of_time" title="Unit of time">units of time</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Instant" title="Instant">Instant</a></li> <li><a href="/wiki/Flick_(time)" title="Flick (time)">Flick</a></li> <li><a href="/wiki/Shake_(unit)" title="Shake (unit)">Shake</a></li> <li><a href="/wiki/Jiffy_(time)" title="Jiffy (time)">Jiffy</a></li> <li><a href="/wiki/Second" title="Second">Second</a></li> <li><a href="/wiki/Minute" title="Minute">Minute</a></li> <li><a href="/wiki/Moment_(unit)" title="Moment (unit)">Moment</a></li> <li><a href="/wiki/Hour" title="Hour">Hour</a></li> <li><a href="/wiki/Day" title="Day">Day</a></li> <li><a href="/wiki/Week" title="Week">Week</a></li> <li><a href="/wiki/Fortnight" title="Fortnight">Fortnight</a></li> <li><a href="/wiki/Month" title="Month">Month</a></li> <li><a href="/wiki/Year" title="Year">Year</a></li> <li><a href="/wiki/Olympiad" title="Olympiad">Olympiad</a></li> <li><a href="/wiki/Lustrum" title="Lustrum">Lustrum</a></li> <li><a href="/wiki/Decade" title="Decade">Decade</a></li> <li><a href="/wiki/Century" title="Century">Century</a></li> <li><a href="/wiki/Saeculum" title="Saeculum">Saeculum</a></li> <li><a href="/wiki/Millennium" title="Millennium">Millennium</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related topics</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronology" title="Chronology">Chronology</a></li> <li><a href="/wiki/Duration_(philosophy)" title="Duration (philosophy)">Duration</a> <ul><li><a href="/wiki/Duration_(music)" title="Duration (music)">music</a></li></ul></li> <li><a href="/wiki/Mental_chronometry" title="Mental chronometry">Mental chronometry</a></li> <li><a href="/wiki/Decimal_time" title="Decimal time">Decimal time</a></li> <li><a href="/wiki/Metric_time" title="Metric time">Metric time</a></li> <li><a href="/wiki/System_time" title="System time">System time</a></li> <li><a href="/wiki/Time_metrology" class="mw-redirect" title="Time metrology">Time metrology</a></li> <li><a href="/wiki/Time_value_of_money" title="Time value of money">Time value of money</a></li> <li><a href="/wiki/Timekeeper" title="Timekeeper">Timekeeper</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" 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