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id="toc-Museums_and_libraries" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Museums_and_libraries"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Museums and libraries</span> </div> </a> <button aria-controls="toc-Museums_and_libraries-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Museums and libraries subsection</span> </button> <ul id="toc-Museums_and_libraries-sublist" class="vector-toc-list"> <li id="toc-Europe" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Europe"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Europe</span> </div> </a> <ul id="toc-Europe-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-North_America" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#North_America"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.2</span> <span>North America</span> </div> </a> <ul id="toc-North_America-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Organizations" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Organizations"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Organizations</span> </div> </a> <ul id="toc-Organizations-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Glossary" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Glossary"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Glossary</span> </div> </a> <ul id="toc-Glossary-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">8</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Notes" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Notes"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>Notes</span> </div> </a> <ul id="toc-Notes-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">10</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">11</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-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 " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" 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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-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Cronometria" title="Cronometria – Catalan" lang="ca" hreflang="ca" data-title="Cronometria" 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/M%C4%9B%C5%99en%C3%AD_%C4%8Dasu" title="Měření času – Czech" lang="cs" hreflang="cs" data-title="Měření času" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-ary mw-list-item"><a href="https://ary.wikipedia.org/wiki/%D8%B9%D8%A8%D8%A7%D8%B1_%D8%AF_%D8%A7%D9%84%D8%B2%D9%85%D8%A7%D9%86" title="عبار د الزمان – Moroccan Arabic" lang="ary" hreflang="ary" data-title="عبار د الزمان" data-language-autonym="الدارجة" data-language-local-name="Moroccan Arabic" class="interlanguage-link-target"><span>الدارجة</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Zeitmessung" title="Zeitmessung – German" lang="de" hreflang="de" data-title="Zeitmessung" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Aja_m%C3%B5%C3%B5tmine" title="Aja mõõtmine – Estonian" lang="et" hreflang="et" data-title="Aja mõõtmine" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Cronometr%C3%ADa" title="Cronometría – Spanish" lang="es" hreflang="es" data-title="Cronometría" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Tempomezurado" title="Tempomezurado – Esperanto" lang="eo" hreflang="eo" data-title="Tempomezurado" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%B2%D9%85%D8%A7%D9%86%E2%80%8C%D8%B3%D9%86%D8%AC%DB%8C" title="زمان‌سنجی – Persian" lang="fa" hreflang="fa" data-title="زمان‌سنجی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Chronom%C3%A9trie" title="Chronométrie – French" lang="fr" hreflang="fr" data-title="Chronométrie" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Kronometri" title="Kronometri – Indonesian" lang="id" hreflang="id" data-title="Kronometri" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-ia mw-list-item"><a href="https://ia.wikipedia.org/wiki/Chronometria" title="Chronometria – Interlingua" lang="ia" hreflang="ia" data-title="Chronometria" data-language-autonym="Interlingua" data-language-local-name="Interlingua" class="interlanguage-link-target"><span>Interlingua</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%9E%D7%93%D7%99%D7%93%D7%94_%D7%95%D7%A6%D7%99%D7%95%D7%9F_%D7%A9%D7%9C_%D7%96%D7%9E%D7%9F" title="מדידה וציון של זמן – Hebrew" lang="he" hreflang="he" data-title="מדידה וציון של זמן" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%A5%D1%80%D0%BE%D0%BD%D0%BE%D0%BC%D0%B5%D1%82%D1%80%D0%B8%D1%98%D0%B0" title="Хронометрија – Macedonian" lang="mk" hreflang="mk" data-title="Хронометрија" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%95%E0%B5%8D%E0%B4%B0%E0%B5%8B%E0%B4%A3%E0%B5%8B%E0%B4%AE%E0%B5%86%E0%B4%9F%E0%B5%8D%E0%B4%B0%E0%B4%BF" title="ക്രോണോമെട്രി – Malayalam" lang="ml" hreflang="ml" data-title="ക്രോണോമെട്രി" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Kronometri" title="Kronometri – Malay" lang="ms" hreflang="ms" data-title="Kronometri" 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-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Tijdmeting" title="Tijdmeting – Dutch" lang="nl" hreflang="nl" data-title="Tijdmeting" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Kronometri" title="Kronometri – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Kronometri" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Kronometri" title="Kronometri – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Kronometri" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Cronometragem" title="Cronometragem – Portuguese" lang="pt" hreflang="pt" data-title="Cronometragem" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Tidm%C3%A4tning" title="Tidmätning – Swedish" lang="sv" hreflang="sv" data-title="Tidmätning" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tt mw-list-item"><a href="https://tt.wikipedia.org/wiki/%D0%A5%D1%80%D0%BE%D0%BD%D0%BE%D0%BC%D0%B5%D1%82%D1%80%D0%B8%D1%8F" title="Хронометрия – Tatar" lang="tt" hreflang="tt" data-title="Хронометрия" data-language-autonym="Татарча / tatarça" data-language-local-name="Tatar" class="interlanguage-link-target"><span>Татарча / tatarça</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Zaman%C4%B1n_%C3%B6l%C3%A7%C3%BClmesi" title="Zamanın ölçülmesi – Turkish" lang="tr" hreflang="tr" data-title="Zamanın ölçülmesi" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E8%AE%A1%E6%97%B6%E5%AD%A6" title="计时学 – Chinese" lang="zh" hreflang="zh" data-title="计时学" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q186398#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div 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noexcerpt noprint searchaux" style="display:none">Specifying measures of time-measurement in clear reference units</div> <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">Not to be confused with <a href="/wiki/Chronology" title="Chronology">Chronology</a>.</div> <p class="mw-empty-elt"> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Wooden_hourglass_edit.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/5b/Wooden_hourglass_edit.jpg/140px-Wooden_hourglass_edit.jpg" decoding="async" width="140" height="303" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/5b/Wooden_hourglass_edit.jpg/210px-Wooden_hourglass_edit.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/5b/Wooden_hourglass_edit.jpg/280px-Wooden_hourglass_edit.jpg 2x" data-file-width="1134" data-file-height="2454" /></a><figcaption>The <a href="/wiki/Hourglass" title="Hourglass">hourglass</a> is often used as a symbol representing the passage of time</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Clocks;_a_watch-maker_seated_at_his_workbench_with_a_long-ca_Wellcome_V0023855.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Clocks%3B_a_watch-maker_seated_at_his_workbench_with_a_long-ca_Wellcome_V0023855.jpg/220px-Clocks%3B_a_watch-maker_seated_at_his_workbench_with_a_long-ca_Wellcome_V0023855.jpg" decoding="async" width="220" height="186" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Clocks%3B_a_watch-maker_seated_at_his_workbench_with_a_long-ca_Wellcome_V0023855.jpg/330px-Clocks%3B_a_watch-maker_seated_at_his_workbench_with_a_long-ca_Wellcome_V0023855.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Clocks%3B_a_watch-maker_seated_at_his_workbench_with_a_long-ca_Wellcome_V0023855.jpg/440px-Clocks%3B_a_watch-maker_seated_at_his_workbench_with_a_long-ca_Wellcome_V0023855.jpg 2x" data-file-width="2888" data-file-height="2444" /></a><figcaption>Clocks; a watch-maker seated at his workbench</figcaption></figure> <p><b>Chronometry</b><sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup> or <b>horology</b><sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>b<span class="cite-bracket">]</span></a></sup> (<abbr style="font-size:85%" title="literal translation">lit.</abbr><span style="white-space: nowrap;"> </span><span class="gloss-quot">'</span><span class="gloss-text">the study of time</span><span class="gloss-quot">'</span>) is the science studying the measurement of <a href="/wiki/Time" title="Time">time</a> and <a href="/wiki/Timekeeping" class="mw-redirect" title="Timekeeping">timekeeping</a>.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Chronometry enables the establishment of standard measurements of time, which have applications in a broad range of social and scientific areas. <i>Horology</i> usually refers specifically to the study of mechanical timekeeping devices, while <i>chronometry</i> is broader in scope, also including biological behaviours with respect to time (biochronometry), as well as the dating of geological material (<a href="/wiki/Geochronometry" title="Geochronometry">geochronometry</a>). </p><p>Horology is commonly used specifically with reference to the mechanical instruments created to keep time: <a href="/wiki/Clock" title="Clock">clocks</a>, <a href="/wiki/Watches" class="mw-redirect" title="Watches">watches</a>, <a href="/wiki/Clockwork" title="Clockwork">clockwork</a>, <a href="/wiki/Sundial" title="Sundial">sundials</a>, <a href="/wiki/Hourglass" title="Hourglass">hourglasses</a>, <a href="/wiki/Water_clock" title="Water clock">clepsydras</a>, <a href="/wiki/Timer" title="Timer">timers</a>, <a href="/wiki/Time_recorder" class="mw-redirect" title="Time recorder">time recorders</a>, <a href="/wiki/Marine_chronometer" title="Marine chronometer">marine chronometers</a>, and <a href="/wiki/Atomic_clock" title="Atomic clock">atomic clocks</a> are all examples of <a href="/wiki/Measuring_instrument" class="mw-redirect" title="Measuring instrument">instruments</a> used to measure time. People interested in horology are called <i>horologists</i>. That term is used both by people who deal professionally with timekeeping apparatuses, as well as enthusiasts and scholars of horology. Horology and horologists have numerous organizations, both professional associations and more scholarly societies. The largest horological membership organisation globally is the NAWCC, the National Association of Watch and Clock Collectors, which is US based, but also has local chapters elsewhere. </p><p>Records of timekeeping are attested during the <a href="/wiki/Paleolithic" title="Paleolithic">Paleolithic</a>, in the form of inscriptions made to mark the passing of lunar cycles and measure years. Written calendars were then invented, followed by mechanical devices. The highest levels of precision are presently achieved by <a href="/wiki/Atomic_clock" title="Atomic clock">atomic clocks</a>, which are used to track the international standard second.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Etymology">Etymology</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=1" title="Edit section: Etymology"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Chronometry is derived from two root words, chronos and metron (χρόνος and μέτρον in <a href="/wiki/Ancient_Greek" title="Ancient Greek">Ancient Greek</a> respectively), with rough meanings of "time" and "measure".<sup id="cite_ref-:0_8-0" class="reference"><a href="#cite_note-:0-8"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> The combination of the two is taken to mean time measuring. </p><p>In the Ancient Greek lexicon, meanings and translations differ depending on the source. Chronos, used in relation to time when in definite periods, and linked to dates in time, chronological accuracy, and sometimes in rare cases, refers to a delay.<sup id="cite_ref-:1_9-0" class="reference"><a href="#cite_note-:1-9"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> The length of the time it refers ranges from seconds to seasons of the year to lifetimes, it can also concern periods of time wherein some specific event takes place, or persists, or is delayed.<sup id="cite_ref-:0_8-1" class="reference"><a href="#cite_note-:0-8"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:White_marble_sculpture_Chronos_-_stadsmuseum_Lokeren.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3d/White_marble_sculpture_Chronos_-_stadsmuseum_Lokeren.jpg/220px-White_marble_sculpture_Chronos_-_stadsmuseum_Lokeren.jpg" decoding="async" width="220" height="238" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/3d/White_marble_sculpture_Chronos_-_stadsmuseum_Lokeren.jpg/330px-White_marble_sculpture_Chronos_-_stadsmuseum_Lokeren.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/3d/White_marble_sculpture_Chronos_-_stadsmuseum_Lokeren.jpg/440px-White_marble_sculpture_Chronos_-_stadsmuseum_Lokeren.jpg 2x" data-file-width="2645" data-file-height="2858" /></a><figcaption>Chronos, the Greeks' personification of time</figcaption></figure> <p>The root word is correlated with the god <a href="/wiki/Chronos" title="Chronos">Chronos</a> in Ancient Greek mythology, who embodied the image of time, originated from out of the primordial chaos. Known as the one who spins the Zodiac Wheel, further evidence of his connection to the progression of time.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> However, Ancient Greek makes a distinction between two types of time, chronos, the static and continuing progress of present to future, time in a sequential and chronological sense, and <a href="/wiki/Kairos" title="Kairos">Kairos</a>, a concept based in a more abstract sense, representing the opportune moment for action or change to occur. </p><p>Kairos (καιρός) carries little emphasis on precise chronology, instead being used as a time specifically fit for something, or also a period of time characterised by some aspect of crisis, also relating to the endtime.<sup id="cite_ref-:0_8-2" class="reference"><a href="#cite_note-:0-8"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> It can as well be seen in the light of an advantage, profit, or fruit of a thing,<sup id="cite_ref-:1_9-1" class="reference"><a href="#cite_note-:1-9"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> but has also been represented in apocalyptic feeling, and likewise shown as variable between misfortune and success, being likened to a body part vulnerable due to a gap in armor for <a href="/wiki/Homer" title="Homer">Homer</a>,<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> benefit or calamity depending on the perspective. It is also referenced in <a href="/wiki/Christian_theology" title="Christian theology">Christian theology</a>, being used as implication of God's action and judgement in circumstances.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p><p>Because of the inherent relation between chronos and kairos, their function the Ancient Greek's portrayal and concept of time, understanding one means understanding the other in part. 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.sidebar-title-with-pretitle{background:transparent!important}html.skin-theme-clientpref-os .mw-parser-output .sidebar:not(.notheme) .sidebar-title-with-pretitle a{color:var(--color-progressive)!important}}@media print{body.ns-0 .mw-parser-output .sidebar{display:none!important}}</style><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><table class="sidebar sidebar-collapse nomobile nowraplinks"><tbody><tr><th class="sidebar-title" style="background:#ccccff;"><a href="/wiki/Time" title="Time">Time</a></th></tr><tr><td class="sidebar-image"><span typeof="mw:File"><a href="/wiki/File:MontreGousset001.jpg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/45/MontreGousset001.jpg/220px-MontreGousset001.jpg" decoding="async" width="220" height="192" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/45/MontreGousset001.jpg/330px-MontreGousset001.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/45/MontreGousset001.jpg/440px-MontreGousset001.jpg 2x" data-file-width="800" data-file-height="697" /></a></span></td></tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="background:#ddddff;background:#ddf;padding-bottom:0;color: var(--color-base)"><div class="sidebar-list-title-c">Major concepts</div></div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Past" title="Past">Past</a></li> <li><a href="/wiki/Present" title="Present">Present</a></li> <li><a href="/wiki/Future" title="Future">Future</a></li></ul> <ul><li><a href="/wiki/Eternity" title="Eternity">Eternity</a> <ul><li><a href="/wiki/Eternity_of_the_world" title="Eternity of the world">of the world</a></li></ul></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="background:#ddddff;background:#ddf;padding-bottom:0;color: var(--color-base)"><div class="sidebar-list-title-c">Fields of study</div></div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Archaeology" title="Archaeology">Archaeology</a></li> <li><a href="/wiki/Chronology" title="Chronology">Chronology</a></li> <li><a href="/wiki/History" title="History">History</a></li> <li><a href="/wiki/Horology" class="mw-redirect" title="Horology">Horology</a></li> <li><a href="/wiki/Time_metrology" class="mw-redirect" title="Time metrology">Metrology</a></li> <li><a href="/wiki/Paleontology" title="Paleontology">Paleontology</a></li> <li><a href="/wiki/Futures_studies" title="Futures studies">Futurology</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="background:#ddddff;background:#ddf;padding-bottom:0;color: var(--color-base)"><div class="sidebar-list-title-c"><a href="/wiki/Philosophy_of_space_and_time" title="Philosophy of space and time">Philosophy</a></div></div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Philosophical_presentism" title="Philosophical presentism">Presentism</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/Fatalism" title="Fatalism">Fatalism</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="background:#ddddff;background:#ddf;padding-bottom:0;color: var(--color-base)"><div class="sidebar-list-title-c"><div class="hlist nowrap"><ul><li><a href="/wiki/Category:Time_in_religion" title="Category:Time in religion">Religion</a></li><li>Mythology</li></ul></div></div></div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Creation_myth" title="Creation myth">Creation</a></li> <li><a href="/wiki/Eschatology" title="Eschatology">End time</a></li> <li><a href="/wiki/Last_Judgment" title="Last Judgment">Day of Judgement</a></li> <li><a href="/wiki/Immortality" title="Immortality">Immortality</a></li> <li><a href="/wiki/Afterlife" title="Afterlife">Afterlife</a></li> <li><a href="/wiki/Reincarnation" title="Reincarnation">Reincarnation</a></li> <li><a href="/wiki/Kalachakra" title="Kalachakra">Kalachakra</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="background:#ddddff;background:#ddf;padding-bottom:0;color: var(--color-base)"><div class="sidebar-list-title-c"><div class="hlist nowrap"><ul><li><a class="mw-selflink selflink">Measurement</a></li><li><a href="/wiki/Time_standard" title="Time standard">Standards</a></li></ul></div></div></div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/ISO_8601" title="ISO 8601">ISO 8601</a></li> <li><a href="/wiki/Metric_time" title="Metric time">Metric</a></li> <li><a href="/wiki/Hexadecimal_time" title="Hexadecimal time">Hexadecimal</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="background:#ddddff;background:#ddf;padding-bottom:0;color: var(--color-base)"><div class="sidebar-list-title-c"><div class="hlist nowrap"><ul><li>Science</li><li><a href="/wiki/Naturalism_(philosophy)" title="Naturalism (philosophy)">Naturalism</a></li></ul></div></div></div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Chronobiology" title="Chronobiology">Chronobiology</a></li> <li><a href="/wiki/Cosmogony" title="Cosmogony">Cosmogony</a></li> <li><a href="/wiki/Evolution" title="Evolution">Evolution</a></li> <li><a href="/wiki/Radiometric_dating" title="Radiometric dating">Radiometric dating</a></li> <li><a href="/wiki/Ultimate_fate_of_the_universe" title="Ultimate fate of the universe"><span class="wrap">Ultimate fate of the universe</span></a></li> <li><a href="/wiki/Time_in_physics" title="Time in physics">Time in physics</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="background:#ddddff;background:#ddf;padding-bottom:0;color: var(--color-base)"><div class="sidebar-list-title-c">Related topics</div></div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Motion" title="Motion">Motion</a></li> <li><a href="/wiki/Space" title="Space">Space</a></li> <li><a href="/wiki/Spacetime" title="Spacetime">Spacetime</a></li> <li><a href="/wiki/Time_travel" title="Time travel">Time travel</a></li></ul></div></div></td> </tr><tr><td class="sidebar-navbar"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .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_sidebar" title="Template:Time sidebar"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Time_sidebar" title="Template talk:Time sidebar"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Time_sidebar" title="Special:EditPage/Template:Time sidebar"><abbr title="Edit this template">e</abbr></a></li></ul></div></td></tr></tbody></table> <div class="mw-heading mw-heading3"><h3 id="Biochronometry">Biochronometry</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=3" title="Edit section: Biochronometry"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Biochronometry (also chronobiology or biological chronometry) is the study of biological behaviours and patterns seen in animals with factors based in time. It can be categorised into <a href="/wiki/Circadian_rhythm" title="Circadian rhythm">Circadian rhythms</a> and <a href="/wiki/Circannual_cycle" title="Circannual cycle">Circannual cycles</a>. Examples of these behaviours can be: the relation of daily and seasonal tidal cues to the activity of marine plants and animals,<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> the photosynthetic capacity and phototactic responsiveness in algae,<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> or metabolic temperature compensation in bacteria.<sup id="cite_ref-:2_16-0" class="reference"><a href="#cite_note-:2-16"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Biological_clock_human.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/30/Biological_clock_human.svg/220px-Biological_clock_human.svg.png" decoding="async" width="220" height="114" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/30/Biological_clock_human.svg/330px-Biological_clock_human.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/30/Biological_clock_human.svg/440px-Biological_clock_human.svg.png 2x" data-file-width="1200" data-file-height="620" /></a><figcaption>Features of the human circadian cycle</figcaption></figure> <p>Circadian rhythms of various species can be observed through their gross motor function throughout the course of a day. These patterns are more apparent with the day further categorised into activity and rest times. Investigation into a species is conducted through comparisons of free-running and entrained rhythms, where the former is attained from within the species' natural environment and the latter from a subject that has been taught certain behaviours. Circannual rhythms are alike but pertain to patterns within the scale of a year, patterns like migration, moulting, reproduction, and body weight are common examples, research and investigation are achieved with similar methods to circadian patterns.<sup id="cite_ref-:2_16-1" class="reference"><a href="#cite_note-:2-16"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p><p>Circadian and circannual rhythms can be seen in all organisms, in both single and multi-celled organisms.<sup id="cite_ref-:3_17-0" class="reference"><a href="#cite_note-:3-17"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:4_18-0" class="reference"><a href="#cite_note-:4-18"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> A sub-branch of biochronometry is microbiochronometry (also chronomicrobiology or microbiological chronometry), and is the examination of behavioural sequences and cycles within micro-organisms. Adapting to circadian and circannual rhythms is an essential evolution for living organisms,<sup id="cite_ref-:3_17-1" class="reference"><a href="#cite_note-:3-17"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:4_18-1" class="reference"><a href="#cite_note-:4-18"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> these studies, as well as educating on the adaptations of organisms also bring to light certain factors affecting many of species' and organisms' responses, and can also be applied to further understand the overall physiology, this can be for humans as well, examples include: factors of human performance, sleep, metabolism, and disease development, which are all connected to biochronometrical cycles.<sup id="cite_ref-:4_18-2" class="reference"><a href="#cite_note-:4-18"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Mental_chronometry">Mental chronometry</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=4" title="Edit section: Mental chronometry"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Mental_chronometry" title="Mental chronometry">Mental chronometry</a> (also called cognitive chronometry) studies human information processing mechanisms, namely reaction time and <a href="/wiki/Perception" title="Perception">perception</a>. As well as a field of chronometry, it also forms a part of <a href="/wiki/Cognitive_psychology" title="Cognitive psychology">cognitive psychology</a> and its contemporary human information processing approach.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> Research comprises applications of the chronometric paradigms – many of which are related to classical reaction time paradigms from <a href="/wiki/Psychophysiology" title="Psychophysiology">psychophysiology</a><sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> – through measuring reaction times of subjects with varied methods, and contribute to studies in cognition and action.<sup id="cite_ref-:5_21-0" class="reference"><a href="#cite_note-:5-21"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> Reaction time models and the process of expressing the temporostructural organisation of human processing mechanisms have an innate computational essence to them. It has been argued that because of this, conceptual frameworks of cognitive psychology cannot be integrated in their typical fashions.<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> </p><p>One common method is the use of <a href="/wiki/Event-related_potential" title="Event-related potential">event-related potentials</a> (ERPs) in stimulus-response experiments. These are fluctuations of generated transient voltages in neural tissues that occur in response to a stimulus event either immediately before or after.<sup id="cite_ref-:5_21-1" class="reference"><a href="#cite_note-:5-21"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> This testing emphasises the mental events' time-course and nature and assists in determining the structural functions in human information processing.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Geochronometry">Geochronometry</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=5" title="Edit section: Geochronometry"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The dating of geological materials makes up the field of geochronometry, and falls within areas of <a href="/wiki/Geochronology" title="Geochronology">geochronology</a> and <a href="/wiki/Stratigraphy" title="Stratigraphy">stratigraphy</a>, while differing itself from <a href="/wiki/Chronostratigraphy" title="Chronostratigraphy">chronostratigraphy</a>. The geochronometric scale is periodic, its units working in powers of 1000, and is based in units of duration, contrasting with the chronostratigraphic scale. The distinctions between the two scales have caused some confusion – even among academic communities.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> </p><p>Geochronometry deals with calculating a precise date of rock sediments and other geological events, giving an idea as to what the history of various areas is, for example, volcanic and magmatic movements and occurrences can be easily recognised, as well as marine deposits, which can be indicators for marine events and even global environmental changes.<sup id="cite_ref-:6_25-0" class="reference"><a href="#cite_note-:6-25"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> This dating can be done in a number of ways. All dependable methods – barring the exceptions of <a href="/wiki/Thermoluminescence" title="Thermoluminescence">thermoluminescence</a>, <a href="/wiki/Radioluminescence" title="Radioluminescence">radioluminescence</a><sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> and <a href="/wiki/Esr_dating" class="mw-redirect" title="Esr dating">ESR</a> (electron spin resonance) dating – are based in <a href="/wiki/Radioactive_decay" title="Radioactive decay">radioactive decay</a>, focusing on the degradation of the radioactive parent nuclide and the corresponding daughter product's growth.<sup id="cite_ref-:6_25-1" class="reference"><a href="#cite_note-:6-25"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Geological_time_spiral.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/79/Geological_time_spiral.png/220px-Geological_time_spiral.png" decoding="async" width="220" height="195" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/79/Geological_time_spiral.png/330px-Geological_time_spiral.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/79/Geological_time_spiral.png/440px-Geological_time_spiral.png 2x" data-file-width="2424" data-file-height="2145" /></a><figcaption>An artistic illustration of the tracking of the earth's history through geology</figcaption></figure> <p>By measuring the daughter isotopes in a specific sample its age can be calculated. The preserved conformity of parent and daughter nuclides provides the basis for the radioactive dating of geochronometry, applying the Rutherford Soddy Law of Radioactivity, specifically using the concept of radioactive transformation in the growth of the daughter nuclide.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> </p><p>Thermoluminescence is an extremely useful concept to apply, being used in a diverse amount of areas in science,<sup id="cite_ref-:7_28-0" class="reference"><a href="#cite_note-:7-28"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> dating using thermoluminescence is a cheap and convenient method for geochronometry.<sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> Thermoluminescence is the production of light from a heated insulator and semi-conductor, it is occasionally confused with incandescent light emissions of a material, a different process despite the many similarities. However, this only occurs if the material has had previous exposure to and absorption of energy from radiation. Importantly, the light emissions of thermoluminescence cannot be repeated.<sup id="cite_ref-:7_28-1" class="reference"><a href="#cite_note-:7-28"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> The entire process, from the material's exposure to radiation would have to be repeated to generate another thermoluminescence emission. The age of a material can be determined by measuring the amount of light given off during the heating process, by means of a phototube, as the emission is proportional to the dose of radiation the material absorbed.<sup id="cite_ref-:6_25-2" class="reference"><a href="#cite_note-:6-25"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Time_metrology">Time metrology</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=6" title="Edit section: Time metrology"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><b>Time metrology</b> or <b>time and frequency metrology</b> is the application of <a href="/wiki/Metrology" title="Metrology">metrology</a> for timekeeping, including <a href="/wiki/Frequency_stability" class="mw-redirect" title="Frequency stability">frequency stability</a>.<sup id="cite_ref-Arias_pp._2289–2305_30-0" class="reference"><a href="#cite_note-Arias_pp._2289–2305-30"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Levine_1999_pp._2567–2596_31-0" class="reference"><a href="#cite_note-Levine_1999_pp._2567–2596-31"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> Its main tasks are the realization of the <a href="/wiki/Second" title="Second">second</a> as the <a href="/wiki/International_System_of_Units" title="International System of Units">SI unit of measurement</a> for time and the establishment of <a href="/wiki/Time_standards" class="mw-redirect" title="Time standards">time standards</a> and <a href="/wiki/Frequency_standards" class="mw-redirect" title="Frequency standards">frequency standards</a> as well as their <a href="/wiki/Time_transfer" class="mw-redirect" title="Time transfer">dissemination</a>.<sup id="cite_ref-BIPM_32-0" class="reference"><a href="#cite_note-BIPM-32"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p> <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=Chronometry&action=edit&section=7" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/History_of_timekeeping_devices" title="History of timekeeping devices">History of timekeeping devices</a></div> <p>Early humans would have used their basic senses to perceive the time of day, and relied on their biological sense of time to discern the seasons in order to act accordingly. Their physiological and behavioural seasonal cycles mainly being influenced by a <a href="/wiki/Melatonin" title="Melatonin">melatonin</a> based photoperiod time measurement biological system – which measures the change in daylight within the annual cycle, giving a sense of the time in the year – and their circannual rhythms, providing an anticipation of environmental events months beforehand to increase chances of survival.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> </p><p>There is debate over when the earliest use of lunar calendars was, and over whether some findings constituted as a lunar calendar.<sup id="cite_ref-:8_34-0" class="reference"><a href="#cite_note-:8-34"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> Most related findings and materials from the palaeolithic era are fashioned from bones and stone, with various markings from tools. These markings are thought to not have been the result of marks to represent the lunar cycles but non-notational and irregular engravings, a pattern of latter subsidiary marks that disregard the previous design is indicative of the markings being the use of motifs and ritual marking instead.<sup id="cite_ref-:8_34-1" class="reference"><a href="#cite_note-:8-34"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> </p><p>However, as humans' focus turned to farming the importance and reliance on understanding the rhythms and cycle of the seasons grew, and the unreliability of lunar phases became problematic. An early human accustomed to the phases of the moon would use them as a rule of thumb, and the potential for weather to interfere with reading the cycle further degraded the reliability.<sup id="cite_ref-:8_34-2" class="reference"><a href="#cite_note-:8-34"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:9_36-0" class="reference"><a href="#cite_note-:9-36"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> The length of a moon is on average less than our current month, not acting as a dependable alternate, so as years progress the room of error between would grow until some other indicator would give indication.<sup id="cite_ref-:9_36-1" class="reference"><a href="#cite_note-:9-36"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:L_Ancient-egyptian-sundial.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/56/L_Ancient-egyptian-sundial.jpg/220px-L_Ancient-egyptian-sundial.jpg" decoding="async" width="220" height="241" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/5/56/L_Ancient-egyptian-sundial.jpg 1.5x" data-file-width="256" data-file-height="280" /></a><figcaption>Ancient Egyptian sundial splitting daytime into 12 parts</figcaption></figure> <p>The Ancient Egyptian calendars were among the first calendars made, and <a href="/wiki/Egyptian_calendar" title="Egyptian calendar">the civil calendar</a> even endured for a long period afterwards, surviving past even its culture's collapse and through the early Christian era. It has been assumed to have been invented near 4231 BC by some, but accurate and exact dating is difficult in its era and the invention has been attributed to 3200 BC, when the first historical king of Egypt, <a href="/wiki/Menes" title="Menes">Menes</a>, united <a href="/wiki/Upper_and_Lower_Egypt" title="Upper and Lower Egypt">Upper and Lower Egypt</a>.<sup id="cite_ref-:9_36-2" class="reference"><a href="#cite_note-:9-36"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> It was originally based on cycles and phases of the moon, however, Egyptians later realised the calendar was flawed upon noticing the star <a href="/wiki/Sirius" title="Sirius">Sirius</a> rose before sunrise every 365 days, a year as we know it now, and was remade to consist of twelve months of thirty days, with five epagomenal days.<sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:10_38-0" class="reference"><a href="#cite_note-:10-38"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> The former is referred to as the Ancient Egyptians' lunar calendar, and the latter the civil calendar. </p><p>Early calendars often hold an element of their respective culture's traditions and values, for example, the five day intercalary month of the Ancient Egyptian's civil calendar representing the birthdays of the gods <a href="/wiki/Horus_(god)" class="mw-redirect" title="Horus (god)">Horus</a>, <a href="/wiki/Isis_(goddess)" class="mw-redirect" title="Isis (goddess)">Isis</a>, <a href="/wiki/Set_(god)" class="mw-redirect" title="Set (god)">Set</a>, <a href="/wiki/Osiris_(god)" class="mw-redirect" title="Osiris (god)">Osiris</a> and <a href="/wiki/Nephthys" title="Nephthys">Nephthys</a>.<sup id="cite_ref-:9_36-3" class="reference"><a href="#cite_note-:9-36"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:10_38-1" class="reference"><a href="#cite_note-:10-38"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Maya_civilization" title="Maya civilization">Maya</a> use of a zero date as well as the <a href="/wiki/Tzolk%CA%BCin" title="Tzolkʼin">Tzolkʼin</a>'s connection to their thirteen layers of heaven (the product of it and all the human digits, twenty, making the 260-day year of the year) and the length of time between conception and birth in pregnancy.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Museums_and_libraries">Museums and libraries</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=8" title="Edit section: Museums and libraries"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-More_citations_needed_section plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/Chronometry" title="Special:EditPage/Chronometry">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed.</span> <span class="date-container"><i>(<span class="date">December 2009</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:RelojUniversal.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/RelojUniversal.JPG/220px-RelojUniversal.JPG" decoding="async" width="220" height="329" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/RelojUniversal.JPG/330px-RelojUniversal.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4b/RelojUniversal.JPG/440px-RelojUniversal.JPG 2x" data-file-width="2592" data-file-height="3872" /></a><figcaption>"Universal Clock" at the Clock Museum in <a href="/wiki/Zacatl%C3%A1n" title="Zacatlán">Zacatlán</a>, <a href="/wiki/Sierra_Norte_de_Puebla" title="Sierra Norte de Puebla">Puebla</a>, Mexico</figcaption></figure> <div class="mw-heading mw-heading3"><h3 id="Europe">Europe</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=9" title="Edit section: Europe"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/History_of_clockmaking_in_Besan%C3%A7on" title="History of clockmaking in Besançon">History of clockmaking in Besançon</a></div> <p>There are many horology museums and several specialized libraries devoted to the subject. One example is the <a href="/wiki/Royal_Greenwich_Observatory" class="mw-redirect" title="Royal Greenwich Observatory">Royal Greenwich Observatory</a>, which is also the source of the <a href="/wiki/Prime_Meridian" class="mw-redirect" title="Prime Meridian">Prime Meridian</a> and the home of the first marine timekeepers accurate enough to determine longitude (made by <a href="/wiki/John_Harrison" title="John Harrison">John Harrison</a>). Other horological museums in the London area include the <a href="/wiki/Clockmakers%27_Museum" title="Clockmakers' Museum">Clockmakers' Museum</a>, which re-opened at the Science Museum in October 2015, the horological collections at the <a href="/wiki/British_Museum" title="British Museum">British Museum</a>, the <a href="/wiki/Science_Museum_(London)" class="mw-redirect" title="Science Museum (London)">Science Museum (London)</a>, and the <a href="/wiki/Wallace_Collection" title="Wallace Collection">Wallace Collection</a>. The <a href="/wiki/Guildhall_Library" title="Guildhall Library">Guildhall Library</a> in London contains an extensive public collection on horology. In Upton, also in the United Kingdom, at the headquarters of the <a href="/wiki/British_Horological_Institute" title="British Horological Institute">British Horological Institute</a>, there is the Museum of Timekeeping. A more specialised museum of horology in the United Kingdom is the <a href="/wiki/Cuckooland_Museum" title="Cuckooland Museum">Cuckooland Museum</a> in <a href="/wiki/Cheshire" title="Cheshire">Cheshire</a>, which hosts the world's largest collection of antique <a href="/wiki/Cuckoo_clock" title="Cuckoo clock">cuckoo clocks</a>. </p><p>One of the more comprehensive museums dedicated to horology is the <a href="/wiki/Mus%C3%A9e_international_d%27horlogerie" class="mw-redirect" title="Musée international d'horlogerie">Musée international d'horlogerie</a>, in <a href="/wiki/La_Chaux-de-fonds" class="mw-redirect" title="La Chaux-de-fonds">La Chaux-de-Fonds</a> in Switzerland, which contains a public library of horology. The <a href="/wiki/Mus%C3%A9e_d%27Horlogerie_du_Locle" class="mw-redirect" title="Musée d'Horlogerie du Locle">Musée d'Horlogerie du Locle</a> is smaller but located nearby. Other good horological libraries providing public access are at the <a href="/wiki/Mus%C3%A9e_international_d%27horlogerie" class="mw-redirect" title="Musée international d'horlogerie">Musée international d'horlogerie</a> in Switzerland, at <a href="/wiki/La_Chaux-de-Fonds" title="La Chaux-de-Fonds">La Chaux-de-Fonds</a>, and at <a href="/wiki/Le_Locle" title="Le Locle">Le Locle</a>. </p><p>In France, <a href="/wiki/Besan%C3%A7on" title="Besançon">Besançon</a> has the Musée du Temps (Museum of Time) in the historic Palais Grenvelle. In <a href="/wiki/Serpa" title="Serpa">Serpa</a> and <a href="/wiki/%C3%89vora" title="Évora">Évora</a>, in <a href="/wiki/Portugal" title="Portugal">Portugal</a>, there is the Museu do Relógio. In Germany, there is the <a href="/wiki/Deutsches_Uhrenmuseum" class="mw-redirect" title="Deutsches Uhrenmuseum">Deutsches Uhrenmuseum</a> in <a href="/wiki/Furtwangen_im_Schwarzwald" title="Furtwangen im Schwarzwald">Furtwangen im Schwarzwald</a>, in the <a href="/wiki/Black_Forest" title="Black Forest">Black Forest</a>, which contains a public library of horology. </p> <div class="mw-heading mw-heading3"><h3 id="North_America">North America</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=10" title="Edit section: North America"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The two leading specialised horological museums in North America are the <a href="/wiki/National_Watch_and_Clock_Museum" title="National Watch and Clock Museum">National Watch and Clock Museum</a> in <a href="/wiki/Columbia,_Pennsylvania" title="Columbia, Pennsylvania">Columbia, Pennsylvania</a>, and the <a href="/wiki/American_Clock_and_Watch_Museum" class="mw-redirect" title="American Clock and Watch Museum">American Clock and Watch Museum</a> in <a href="/wiki/Bristol,_Connecticut" title="Bristol, Connecticut">Bristol, Connecticut</a>. Another museum dedicated to clocks is the <a href="/wiki/Willard_House_and_Clock_Museum" title="Willard House and Clock Museum">Willard House and Clock Museum</a> in <a href="/wiki/Grafton,_Massachusetts" title="Grafton, Massachusetts">Grafton, Massachusetts</a>. One of the most comprehensive horological libraries open to the public is the <a href="/wiki/National_Watch_and_Clock_Library" title="National Watch and Clock Library">National Watch and Clock Library</a> in <a href="/wiki/Columbia,_Pennsylvania" title="Columbia, Pennsylvania">Columbia, Pennsylvania</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Organizations">Organizations</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=11" title="Edit section: Organizations"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Notable scholarly horological organizations include: </p> <ul><li><a href="/wiki/American_Watchmakers-Clockmakers_Institute" title="American Watchmakers-Clockmakers Institute">American Watchmakers-Clockmakers Institute</a> – AWCI (United States of America)</li> <li><a href="/wiki/Antiquarian_Horological_Society" title="Antiquarian Horological Society">Antiquarian Horological Society</a> – AHS (United Kingdom)</li> <li><a href="/wiki/British_Horological_Institute" title="British Horological Institute">British Horological Institute</a> – BHI (United Kingdom)</li> <li><a href="/wiki/Chronometrophilia" title="Chronometrophilia">Chronometrophilia</a> (Switzerland)</li> <li><a href="/wiki/Deutsche_Gesellschaft_f%C3%BCr_Chronometrie" title="Deutsche Gesellschaft für Chronometrie">Deutsche Gesellschaft für Chronometrie</a> – DGC (Germany)</li> <li><a href="/wiki/Horological_Society_of_New_York" title="Horological Society of New York">Horological Society of New York</a> – HSNY (United States of America)</li> <li><a href="/wiki/National_Association_of_Watch_and_Clock_Collectors" title="National Association of Watch and Clock Collectors">National Association of Watch and Clock Collectors</a> – NAWCC (United States of America)</li> <li><a rel="nofollow" class="external text" href="https://www.ukhorology.com/">UK Horology</a> - UK Clock & Watch Company based in Bristol</li></ul> <div class="mw-heading mw-heading2"><h2 id="Glossary">Glossary</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=12" title="Edit section: Glossary"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <table class="wikitable"> <tbody><tr> <th>Term</th> <th>Explanation </th></tr> <tr> <td>Chablon </td> <td>French term for a <a href="/wiki/Movement_(clockwork)" title="Movement (clockwork)">watch movement</a> (not including the dial and hands), that is not completely assembled. </td></tr> <tr> <td><a href="/wiki/%C3%89bauche" title="Ébauche">Ébauche</a> </td> <td>French term (commonly used in English-speaking countries) for a movement blank, i.e., an incomplete watch movement sold as a set of loose parts—comprising the main plate, bridges, train, winding and setting mechanism, and regulator. The timing system, escapement, and mainspring, however, are not parts of the ébauche. </td></tr> <tr> <td>Établissage </td> <td>French term for the method of manufacturing watches or movements by assembling their various components. It generally includes the following operations: receipt, inspection and stocking of the "ébauche", the regulating elements and the other parts of the movement and of the make-up; assembling; springing and timing; fitting the dial and hands; casing; final inspection before packing and dispatching. </td></tr> <tr> <td>Établisseur </td> <td>French term for a watch factory that assembles watches from components it buys from other suppliers. </td></tr> <tr> <td>Factory, works </td> <td>In the Swiss watch industry, the term manufacture is used of a factory that manufacturers watches almost completely, as distinct from an <i>atelier de terminage</i>, which only assembles, times, and fits hands and casing. </td></tr> <tr> <td>Manufacture d'horlogerie </td> <td>French term for a watch factory that produces components (particularly the "ébauche") for its products (watches, alarm and desk clocks, etc.). </td></tr> <tr> <td><a href="/wiki/Remontoire" title="Remontoire">Remontoire</a> </td> <td>French term for a small secondary source of power, typically a weight or spring, which runs the timekeeping mechanism and is itself periodically rewound by the timepiece's main power source, such as a <a href="/wiki/Mainspring" title="Mainspring">mainspring</a>. </td></tr> <tr> <td>Terminage </td> <td>French term denoting the process of assembling watch parts for the account of a producer. </td></tr> <tr> <td>Termineur </td> <td>French term for an independent watchmaker (or workshop) engaged in assembling watches, either wholly or in part, for the account of an "établisseur" or a "manufacture", who supply the necessary loose parts. See "atelier de terminage" above. </td></tr></tbody></table> <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=Chronometry&action=edit&section=13" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">For a topical guide, see <a href="/wiki/Outline_of_metrology_and_measurement" title="Outline of metrology and measurement">Outline of metrology and measurement</a>.</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/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/40px-Wiktionary-logo-en-v2.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/60px-Wiktionary-logo-en-v2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/80px-Wiktionary-logo-en-v2.svg.png 2x" data-file-width="512" data-file-height="512" /></span></span></div> <div class="side-box-text plainlist">Look up <i><b><a href="https://en.wiktionary.org/wiki/chronometry" class="extiw" title="wiktionary:chronometry">chronometry</a></b></i> in Wiktionary, the free dictionary.</div></div> </div> <ul><li><a href="/wiki/Complication_(horology)" title="Complication (horology)">Complication (horology)</a></li> <li><a href="/wiki/Hora_(astrology)" title="Hora (astrology)">Hora (astrology)</a></li> <li><a href="/wiki/List_of_clock_manufacturers" title="List of clock manufacturers">List of clock manufacturers</a></li> <li><a href="/wiki/List_of_watch_manufacturers" title="List of watch manufacturers">List of watch manufacturers</a></li> <li><a href="/wiki/Winthrop_Kellogg_Edey" title="Winthrop Kellogg Edey">Winthrop Kellogg Edey</a></li> <li><a href="/wiki/Allan_variance" title="Allan variance">Allan variance</a></li> <li><a href="/wiki/Clock_drift" title="Clock drift">Clock drift</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/Time_and_Frequency_Standards_Laboratory" title="Time and Frequency Standards Laboratory">Time and Frequency Standards Laboratory</a></li> <li><a href="/wiki/Time_deviation" title="Time deviation">Time deviation</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=14" title="Edit section: Notes"><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-lower-alpha"> <div class="mw-references-wrap"><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">(from <a href="/wiki/Ancient_Greek_language" class="mw-redirect" title="Ancient Greek language">Ancient Greek</a> <i> </i><span lang="grc"><a href="https://en.wiktionary.org/wiki/%CF%87%CF%81%CF%8C%CE%BD%CE%BF%CF%82#Ancient_Greek" class="extiw" title="wikt:χρόνος">χρόνος</a></span><i> (<span title="Ancient Greek transliteration" lang="grc-Latn"><i><a href="/wiki/Chronos" title="Chronos">khrónos</a></i></span>)</i> 'time' and <i> </i><span lang="grc"><a href="https://en.wiktionary.org/wiki/%CE%BC%CE%AD%CF%84%CF%81%CE%BF%CE%BD#Ancient_Greek" class="extiw" title="wikt:μέτρον">μέτρον</a></span><i> (<span title="Ancient Greek transliteration" lang="grc-Latn"><i>métron</i></span>)</i> 'measure')</span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text">Related to <a href="/wiki/Latin" title="Latin">Latin</a> <i lang="la"><a href="https://en.wiktionary.org/wiki/horologium#Latin" class="extiw" title="wikt:horologium">horologium</a></i>; from <a href="/wiki/Ancient_Greek_language" class="mw-redirect" title="Ancient Greek language">Ancient Greek</a> <i> </i><span lang="grc"><a href="https://en.wiktionary.org/wiki/%E1%BD%A1%CF%81%CE%BF%CE%BB%CF%8C%CE%B3%CE%B9%CE%BF%CE%BD#Ancient_Greek" class="extiw" title="wikt:ὡρολόγιον">ὡρολόγιον</a></span><i> (<span title="Ancient Greek transliteration" lang="grc-Latn"><i>hōrológion</i></span>)</i> 'instrument for telling the hour'; from <i> </i><span lang="grc"><a href="https://en.wiktionary.org/wiki/%E1%BD%A5%CF%81%CE%B1#Ancient_Greek" class="extiw" title="wikt:ὥρα">ὥρα</a></span><i> (<span title="Ancient Greek transliteration" lang="grc-Latn"><i>hṓra</i></span>)</i> 'hour, time', <a href="/wiki/Interfix" title="Interfix">interfix</a> <i>-o-</i>, and suffix <i><a href="/wiki/-logy" title="-logy">-logy</a></i>)<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></span> </li> </ol></div></div> <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=Chronometry&action=edit&section=15" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626"><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</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 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AIP Publishing: 2567–2596. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1999RScI...70.2567L">1999RScI...70.2567L</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1063%2F1.1149844">10.1063/1.1149844</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0034-6748">0034-6748</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Review+of+Scientific+Instruments&rft.atitle=Introduction+to+time+and+frequency+metrology&rft.volume=70&rft.issue=6&rft.pages=2567-2596&rft.date=1999&rft.issn=0034-6748&rft_id=info%3Adoi%2F10.1063%2F1.1149844&rft_id=info%3Abibcode%2F1999RScI...70.2567L&rft.aulast=Levine&rft.aufirst=Judah&rfr_id=info%3Asid%2Fen.wikipedia.org%3AChronometry" class="Z3988"></span></span> </li> <li id="cite_note-BIPM-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-BIPM_32-0">^</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://www.bipm.org/metrology/time-frequency/">"time and frequency"</a>. <i>BIPM</i><span class="reference-accessdate">. Retrieved <span class="nowrap">26 January</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=BIPM&rft.atitle=time+and+frequency&rft_id=https%3A%2F%2Fwww.bipm.org%2Fmetrology%2Ftime-frequency%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AChronometry" class="Z3988"></span></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">Lincoln, GA, Andersson, H & Loudon A. (2003). Clock genes in calendar cells as the basis for annual timekeeping in mammals. BioScientifica.</span> </li> <li id="cite_note-:8-34"><span class="mw-cite-backlink">^ <a href="#cite_ref-:8_34-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:8_34-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-:8_34-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">Marshack, A. (1989). Current Anthropology: On Wishful Thinking and Lunar "Calendars", Vol 30(4), p.491-500. University of Chicago Press.</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">D'Errico, F. (1989). Current Anthropology: Palaeolithic Lunar Calendars: A Case of Wishful Thinking?. Vol 30(1), p.117-118. University of Chicago Press.</span> </li> <li id="cite_note-:9-36"><span class="mw-cite-backlink">^ <a href="#cite_ref-:9_36-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:9_36-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-:9_36-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-:9_36-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text">Winlock, H.E. (1940). Proceedings of the American Philosophical Society: The Origin of the Ancient Egyptian Calendar, Vol 83, p.447-464. American Philosophical Society.</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">Jones, A. (1997). On the Reconstructed Macedonian and Egyptian Lunar Calendars. Dr. Rudolf Habelt GmbH.</span> </li> <li id="cite_note-:10-38"><span class="mw-cite-backlink">^ <a href="#cite_ref-:10_38-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:10_38-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Spalinger, A. (1995). Journal of Near Eastern Studies: Some Remarks on the Epagomenal Days in Ancient Egypt, Vol 54(1), p.33-47. Chicago University Press.</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">Kinsella, J., & Bradley, A. (1934). The Mathematics Teacher: The Mayan Calendar. Vol 27(7), p.340-343. National Council of Teachers of Mathematics.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Chronometry&action=edit&section=16" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1235681985"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1237033735"><div class="side-box side-box-right plainlinks sistersitebox"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1126788409"> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/40px-Wiktionary-logo-en-v2.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/60px-Wiktionary-logo-en-v2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/80px-Wiktionary-logo-en-v2.svg.png 2x" data-file-width="512" data-file-height="512" /></span></span></div> <div class="side-box-text plainlist">Look up <i><b><a href="https://en.wiktionary.org/wiki/horology" class="extiw" title="wiktionary:horology">horology</a></b></i> in Wiktionary, the free dictionary.</div></div> </div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1235681985"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1237033735"><div class="side-box side-box-right plainlinks sistersitebox"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1126788409"> <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:Timekeeping" class="extiw" title="commons:Category:Timekeeping">Timekeeping</a></span>.</div></div> </div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPerman2013" class="citation book cs1">Perman, Stacy (2013). <i>A grand complication: the race to build the world's most legendary watch</i>. New York: Atria. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-439-19008-1" title="Special:BookSources/978-1-439-19008-1"><bdi>978-1-439-19008-1</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+grand+complication%3A+the+race+to+build+the+world%27s+most+legendary+watch&rft.place=New+York&rft.pub=Atria&rft.date=2013&rft.isbn=978-1-439-19008-1&rft.aulast=Perman&rft.aufirst=Stacy&rfr_id=info%3Asid%2Fen.wikipedia.org%3AChronometry" class="Z3988"></span></li> <li>Berner, G.A., <a rel="nofollow" class="external text" href="http://www.fhs.ch/berner/?l=en"><i>Illustrated Professional Dictionary of Horology</i></a>, <a href="/wiki/Federation_of_the_Swiss_Watch_Industry" title="Federation of the Swiss Watch Industry">Federation of the Swiss Watch Industry</a> FH 1961 - 2012</li> <li>Daniels, George, <a rel="nofollow" class="external text" href="https://books.google.com/books?id=ZWq8c0xvGxsC"><i>Watchmaking</i></a>, London: Philip Wilson Publishers, 1981 (reprinted June 15, 2011)</li> <li><a href="/wiki/Edmund_Beckett,_1st_Baron_Grimthorpe" title="Edmund Beckett, 1st Baron Grimthorpe">Beckett, Edmund</a>, <a rel="nofollow" class="external text" href="https://www.gutenberg.org/ebooks/17576"><i>A Rudimentary Treatise on Clocks, Watches and Bells</i></a>, 1903, from <a href="/wiki/Project_Gutenberg" title="Project Gutenberg">Project Gutenberg</a></li> <li>Grafton, Edward, <a rel="nofollow" class="external text" href="https://books.google.com/books?id=GlIEAAAAQAAJ"><i>Horology, a popular sketch of clock and watch making</i></a>, London: Aylett and Jones, 1849</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFIEEE" class="citation cs2"><i>IEEE Guide for Measurement of Environmental Sensitivities of Standard Frequency Generators (Revision of IEEE Std 1193 - 1994)</i>, Piscataway, NJ: IEEE, <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2Fieeestd.2004.94440">10.1109/ieeestd.2004.94440</a>, <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-738-13711-1" title="Special:BookSources/0-738-13711-1"><bdi>0-738-13711-1</bdi></a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=IEEE+Guide+for+Measurement+of+Environmental+Sensitivities+of+Standard+Frequency+Generators+%28Revision+of+IEEE+Std+1193+-+1994%29&rft.place=Piscataway%2C+NJ&rft.pub=IEEE&rft_id=info%3Adoi%2F10.1109%2Fieeestd.2004.94440&rft.isbn=0-738-13711-1&rfr_id=info%3Asid%2Fen.wikipedia.org%3AChronometry" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFIEEE" class="citation cs2"><i>IEEE Standard Definitions of Physical Quantities for Fundamental Frequency and Time Metrology—Random Instabilities</i>, Piscataway, NJ: IEEE, <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2Fieeestd.2008.4797525">10.1109/ieeestd.2008.4797525</a>, <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-738-16855-5" title="Special:BookSources/978-0-738-16855-5"><bdi>978-0-738-16855-5</bdi></a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=IEEE+Standard+Definitions+of+Physical+Quantities+for+Fundamental+Frequency+and+Time+Metrology%E2%80%94Random+Instabilities&rft.place=Piscataway%2C+NJ&rft.pub=IEEE&rft_id=info%3Adoi%2F10.1109%2Fieeestd.2008.4797525&rft.isbn=978-0-738-16855-5&rfr_id=info%3Asid%2Fen.wikipedia.org%3AChronometry" class="Z3988"></span></li></ul> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output 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style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><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_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 href="/wiki/Special:EditPage/Template:Time_topics" title="Special:EditPage/Template:Time topics"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Time" style="font-size:114%;margin:0 4em"><a href="/wiki/Time" title="Time">Time</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Key concepts</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/Past" title="Past">Past</a></li> <li><a href="/wiki/Present" title="Present">Present</a></li> <li><a href="/wiki/Future" title="Future">Future</a></li> <li><a href="/wiki/Eternity" title="Eternity">Eternity</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">Measurement</a><br />and <a href="/wiki/Time_standard" title="Time standard">standards</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 class="mw-selflink selflink">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 href="/wiki/Marine_chronometer" title="Marine chronometer">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 class="mw-selflink selflink">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 href="/wiki/Marine_chronometer" title="Marine chronometer">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" href="mw-data:TemplateStyles:r1236075235"><style data-mw-deduplicate="TemplateStyles:r1038841319">.mw-parser-output .tooltip-dotted{border-bottom:1px dotted;cursor:help}</style><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1038841319"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1038841319"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1038841319"><link 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