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that measure duration, elapsed time and intervals</span> </div> </a> <ul id="toc-Devices_that_measure_duration,_elapsed_time_and_intervals-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Water_clocks" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Water_clocks"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.3</span> <span>Water clocks</span> </div> </a> <ul id="toc-Water_clocks-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Mechanical_water_clocks" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Mechanical_water_clocks"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.4</span> <span>Mechanical water clocks</span> </div> </a> <ul id="toc-Mechanical_water_clocks-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Fully_mechanical" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Fully_mechanical"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.5</span> <span>Fully mechanical</span> </div> </a> <ul id="toc-Fully_mechanical-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Astronomical" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Astronomical"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.6</span> <span>Astronomical</span> </div> </a> <ul id="toc-Astronomical-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Spring-driven" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Spring-driven"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.7</span> <span>Spring-driven</span> </div> </a> <ul id="toc-Spring-driven-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Pendulum" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Pendulum"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.8</span> <span>Pendulum</span> </div> </a> <ul id="toc-Pendulum-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Hairspring" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Hairspring"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.9</span> <span>Hairspring</span> </div> </a> <ul id="toc-Hairspring-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Marine_chronometer" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Marine_chronometer"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.10</span> <span>Marine chronometer</span> </div> </a> <ul id="toc-Marine_chronometer-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Mass_production" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Mass_production"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.11</span> <span>Mass production</span> </div> </a> <ul id="toc-Mass_production-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Early_electric" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Early_electric"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.12</span> <span>Early electric</span> </div> </a> <ul id="toc-Early_electric-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Quartz" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Quartz"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.13</span> <span>Quartz</span> </div> </a> <ul id="toc-Quartz-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Atomic" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Atomic"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.14</span> <span>Atomic</span> </div> </a> <ul id="toc-Atomic-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Operation" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Operation"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Operation</span> </div> </a> <button aria-controls="toc-Operation-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 Operation subsection</span> </button> <ul id="toc-Operation-sublist" class="vector-toc-list"> <li id="toc-Power_source" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Power_source"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Power source</span> </div> </a> <ul id="toc-Power_source-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Oscillator" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Oscillator"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Oscillator</span> </div> </a> <ul id="toc-Oscillator-sublist" class="vector-toc-list"> <li id="toc-Synchronized_or_slave_clocks" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Synchronized_or_slave_clocks"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2.1</span> <span>Synchronized or slave clocks</span> </div> </a> <ul id="toc-Synchronized_or_slave_clocks-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Controller" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Controller"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3</span> <span>Controller</span> </div> </a> <ul id="toc-Controller-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Counter_chain" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Counter_chain"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.4</span> <span>Counter chain</span> </div> </a> <ul id="toc-Counter_chain-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Indicator" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Indicator"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5</span> <span>Indicator</span> </div> </a> <ul id="toc-Indicator-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Types" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Types"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Types</span> </div> </a> <button aria-controls="toc-Types-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 Types subsection</span> </button> <ul id="toc-Types-sublist" class="vector-toc-list"> <li id="toc-Time_display_methods" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Time_display_methods"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Time display methods</span> </div> </a> <ul id="toc-Time_display_methods-sublist" class="vector-toc-list"> <li id="toc-Analog" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Analog"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.1</span> <span>Analog</span> </div> </a> <ul id="toc-Analog-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Digital" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Digital"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.2</span> <span>Digital</span> </div> </a> <ul id="toc-Digital-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Hybrid_(analog-digital)" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Hybrid_(analog-digital)"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.3</span> <span>Hybrid (analog-digital)</span> </div> </a> <ul id="toc-Hybrid_(analog-digital)-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Auditory" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Auditory"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.4</span> <span>Auditory</span> </div> </a> <ul id="toc-Auditory-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Word" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Word"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.5</span> <span>Word</span> </div> </a> <ul id="toc-Word-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Projection" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Projection"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.6</span> <span>Projection</span> </div> </a> <ul id="toc-Projection-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Tactile" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Tactile"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.7</span> <span>Tactile</span> </div> </a> <ul id="toc-Tactile-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Multi-display" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Multi-display"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.8</span> <span>Multi-display</span> </div> </a> <ul id="toc-Multi-display-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> </ul> </li> <li id="toc-Purposes" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Purposes"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Purposes</span> </div> </a> <button aria-controls="toc-Purposes-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 Purposes subsection</span> </button> <ul id="toc-Purposes-sublist" class="vector-toc-list"> <li id="toc-Time_standards" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Time_standards"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Time standards</span> </div> </a> <ul id="toc-Time_standards-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Navigation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Navigation"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.2</span> <span>Navigation</span> </div> </a> <ul id="toc-Navigation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Sports_and_games" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Sports_and_games"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.3</span> <span>Sports and games</span> </div> </a> <ul id="toc-Sports_and_games-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Culture" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Culture"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Culture</span> </div> </a> <button aria-controls="toc-Culture-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 Culture subsection</span> </button> <ul id="toc-Culture-sublist" class="vector-toc-list"> <li id="toc-Folklore_and_superstition" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Folklore_and_superstition"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.1</span> <span>Folklore and superstition</span> </div> </a> <ul id="toc-Folklore_and_superstition-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Specific_types" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Specific_types"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Specific types</span> </div> </a> <ul id="toc-Specific_types-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Awards" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Awards"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>Awards</span> </div> </a> <ul id="toc-Awards-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Notes_and_references" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Notes_and_references"> <div class="vector-toc-text"> <span class="vector-toc-numb">10</span> <span>Notes and references</span> </div> </a> <ul id="toc-Notes_and_references-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Bibliography" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Bibliography"> <div class="vector-toc-text"> <span class="vector-toc-numb">11</span> <span>Bibliography</span> </div> </a> <ul id="toc-Bibliography-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">12</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div 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Available in 143 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-143" 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">143 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ady mw-list-item"><a href="https://ady.wikipedia.org/wiki/%D0%A1%D1%8B%D1%85%D1%8C%D0%B0%D1%82" title="Сыхьат – Adyghe" lang="ady" hreflang="ady" data-title="Сыхьат" data-language-autonym="Адыгабзэ" data-language-local-name="Adyghe" class="interlanguage-link-target"><span>Адыгабзэ</span></a></li><li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/Klokhorlosie" title="Klokhorlosie – Afrikaans" lang="af" hreflang="af" data-title="Klokhorlosie" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-als mw-list-item"><a href="https://als.wikipedia.org/wiki/Uhr" title="Uhr – Alemannic" lang="gsw" hreflang="gsw" data-title="Uhr" data-language-autonym="Alemannisch" data-language-local-name="Alemannic" class="interlanguage-link-target"><span>Alemannisch</span></a></li><li class="interlanguage-link interwiki-am mw-list-item"><a href="https://am.wikipedia.org/wiki/%E1%88%B0%E1%8A%A0%E1%89%B5_(%E1%88%98%E1%88%B3%E1%88%AA%E1%8B%AB)" title="ሰአት (መሳሪያ) – Amharic" lang="am" hreflang="am" data-title="ሰአት (መሳሪያ)" data-language-autonym="አማርኛ" data-language-local-name="Amharic" class="interlanguage-link-target"><span>አማርኛ</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%B3%D8%A7%D8%B9%D8%A9_(%D8%A2%D9%84%D8%A9)" title="ساعة (آلة) – Arabic" lang="ar" hreflang="ar" data-title="ساعة (آلة)" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-an mw-list-item"><a href="https://an.wikipedia.org/wiki/Reloch" title="Reloch – Aragonese" lang="an" hreflang="an" data-title="Reloch" data-language-autonym="Aragonés" data-language-local-name="Aragonese" class="interlanguage-link-target"><span>Aragonés</span></a></li><li class="interlanguage-link interwiki-as mw-list-item"><a href="https://as.wikipedia.org/wiki/%E0%A6%98%E0%A6%A1%E0%A6%BC%E0%A7%80" title="ঘড়ী – Assamese" lang="as" hreflang="as" data-title="ঘড়ী" data-language-autonym="অসমীয়া" data-language-local-name="Assamese" class="interlanguage-link-target"><span>অসমীয়া</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/Rel%C3%B3" title="Reló – Asturian" lang="ast" hreflang="ast" data-title="Reló" data-language-autonym="Asturianu" data-language-local-name="Asturian" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-atj mw-list-item"><a href="https://atj.wikipedia.org/wiki/Tipahipisimon" title="Tipahipisimon – Atikamekw" lang="atj" hreflang="atj" data-title="Tipahipisimon" data-language-autonym="Atikamekw" data-language-local-name="Atikamekw" class="interlanguage-link-target"><span>Atikamekw</span></a></li><li class="interlanguage-link interwiki-gn mw-list-item"><a href="https://gn.wikipedia.org/wiki/Aravopapaha" title="Aravopapaha – Guarani" lang="gn" hreflang="gn" data-title="Aravopapaha" data-language-autonym="Avañe'ẽ" data-language-local-name="Guarani" class="interlanguage-link-target"><span>Avañe'ẽ</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/Saat" title="Saat – Azerbaijani" lang="az" hreflang="az" data-title="Saat" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-azb mw-list-item"><a href="https://azb.wikipedia.org/wiki/%D8%B3%D8%A7%D8%B9%D8%A7%D8%AA" title="ساعات – South Azerbaijani" lang="azb" hreflang="azb" data-title="ساعات" data-language-autonym="تۆرکجه" data-language-local-name="South Azerbaijani" class="interlanguage-link-target"><span>تۆرکجه</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%98%E0%A6%A1%E0%A6%BC%E0%A6%BF" title="ঘড়ি – Bangla" lang="bn" hreflang="bn" data-title="ঘড়ি" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-zh-min-nan mw-list-item"><a href="https://zh-min-nan.wikipedia.org/wiki/S%C3%AE-cheng" title="Sî-cheng – Minnan" lang="nan" hreflang="nan" data-title="Sî-cheng" data-language-autonym="閩南語 / Bân-lâm-gú" data-language-local-name="Minnan" class="interlanguage-link-target"><span>閩南語 / Bân-lâm-gú</span></a></li><li class="interlanguage-link interwiki-ba mw-list-item"><a href="https://ba.wikipedia.org/wiki/%D0%A1%D3%99%D2%93%D3%99%D1%82" title="Сәғәт – Bashkir" lang="ba" hreflang="ba" data-title="Сәғәт" data-language-autonym="Башҡортса" data-language-local-name="Bashkir" class="interlanguage-link-target"><span>Башҡортса</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%93%D0%B0%D0%B4%D0%B7%D1%96%D0%BD%D0%BD%D1%96%D0%BA" title="Гадзіннік – Belarusian" lang="be" hreflang="be" data-title="Гадзіннік" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%93%D0%B0%D0%B4%D0%B7%D1%96%D0%BD%D1%8C%D0%BD%D1%96%D0%BA" title="Гадзіньнік – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Гадзіньнік" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%A7%D0%B0%D1%81%D0%BE%D0%B2%D0%BD%D0%B8%D0%BA" title="Часовник – Bulgarian" lang="bg" hreflang="bg" data-title="Часовник" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bar mw-list-item"><a href="https://bar.wikipedia.org/wiki/Uah" title="Uah – Bavarian" lang="bar" hreflang="bar" data-title="Uah" data-language-autonym="Boarisch" data-language-local-name="Bavarian" class="interlanguage-link-target"><span>Boarisch</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Sat_(instrument)" title="Sat (instrument) – Bosnian" lang="bs" hreflang="bs" data-title="Sat (instrument)" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-br mw-list-item"><a href="https://br.wikipedia.org/wiki/Horolaj" title="Horolaj – Breton" lang="br" hreflang="br" data-title="Horolaj" data-language-autonym="Brezhoneg" data-language-local-name="Breton" class="interlanguage-link-target"><span>Brezhoneg</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Rellotge" title="Rellotge – Catalan" lang="ca" hreflang="ca" data-title="Rellotge" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cv mw-list-item"><a href="https://cv.wikipedia.org/wiki/%D0%A1%D0%B5%D1%85%D0%B5%D1%82_(%D1%85%D0%B0%D1%82%C4%95%D1%80)" title="Сехет (хатĕр) – Chuvash" lang="cv" hreflang="cv" data-title="Сехет (хатĕр)" data-language-autonym="Чӑвашла" data-language-local-name="Chuvash" class="interlanguage-link-target"><span>Чӑвашла</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Hodiny" title="Hodiny – Czech" lang="cs" hreflang="cs" data-title="Hodiny" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-cy mw-list-item"><a href="https://cy.wikipedia.org/wiki/Cloc" title="Cloc – Welsh" lang="cy" hreflang="cy" data-title="Cloc" data-language-autonym="Cymraeg" data-language-local-name="Welsh" class="interlanguage-link-target"><span>Cymraeg</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Ur" title="Ur – Danish" lang="da" hreflang="da" data-title="Ur" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-ary mw-list-item"><a href="https://ary.wikipedia.org/wiki/%D8%B3%D8%A7%D8%B9%D8%A9_(%D8%AF%D9%88%D8%B2%D8%A7%D9%86)" title="ساعة (دوزان) – Moroccan Arabic" lang="ary" hreflang="ary" data-title="ساعة (دوزان)" 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/Uhr" title="Uhr – German" lang="de" hreflang="de" data-title="Uhr" 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/Kell" title="Kell – Estonian" lang="et" hreflang="et" data-title="Kell" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%A1%CE%BF%CE%BB%CF%8C%CE%B9" title="Ρολόι – Greek" lang="el" hreflang="el" data-title="Ρολόι" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-eml mw-list-item"><a href="https://eml.wikipedia.org/wiki/Arl%C3%B3i" title="Arlói – Emiliano-Romagnolo" lang="egl" hreflang="egl" data-title="Arlói" data-language-autonym="Emiliàn e rumagnòl" data-language-local-name="Emiliano-Romagnolo" class="interlanguage-link-target"><span>Emiliàn e rumagnòl</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Reloj" title="Reloj – Spanish" lang="es" hreflang="es" data-title="Reloj" 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/Horlo%C4%9Do" title="Horloĝo – Esperanto" lang="eo" hreflang="eo" data-title="Horloĝo" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Erloju" title="Erloju – Basque" lang="eu" hreflang="eu" data-title="Erloju" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%B3%D8%A7%D8%B9%D8%AA" title="ساعت – Persian" lang="fa" hreflang="fa" data-title="ساعت" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-hif mw-list-item"><a href="https://hif.wikipedia.org/wiki/Gharri" title="Gharri – Fiji Hindi" lang="hif" hreflang="hif" data-title="Gharri" data-language-autonym="Fiji Hindi" data-language-local-name="Fiji Hindi" class="interlanguage-link-target"><span>Fiji Hindi</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Horloge" title="Horloge – French" lang="fr" hreflang="fr" data-title="Horloge" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-fy mw-list-item"><a href="https://fy.wikipedia.org/wiki/Klok_(oerwurk)" title="Klok (oerwurk) – Western Frisian" lang="fy" hreflang="fy" data-title="Klok (oerwurk)" data-language-autonym="Frysk" data-language-local-name="Western Frisian" class="interlanguage-link-target"><span>Frysk</span></a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/Clog" title="Clog – Irish" lang="ga" hreflang="ga" data-title="Clog" data-language-autonym="Gaeilge" data-language-local-name="Irish" class="interlanguage-link-target"><span>Gaeilge</span></a></li><li class="interlanguage-link interwiki-gv mw-list-item"><a href="https://gv.wikipedia.org/wiki/Clag_(traa)" title="Clag (traa) – Manx" lang="gv" hreflang="gv" data-title="Clag (traa)" data-language-autonym="Gaelg" data-language-local-name="Manx" class="interlanguage-link-target"><span>Gaelg</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Reloxo" title="Reloxo – Galician" lang="gl" hreflang="gl" data-title="Reloxo" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-gan mw-list-item"><a href="https://gan.wikipedia.org/wiki/%E9%90%98" title="鐘 – Gan" lang="gan" hreflang="gan" data-title="鐘" data-language-autonym="贛語" data-language-local-name="Gan" class="interlanguage-link-target"><span>贛語</span></a></li><li class="interlanguage-link interwiki-glk mw-list-item"><a href="https://glk.wikipedia.org/wiki/%D8%B3%D8%A7%D8%B9%D8%AA" title="ساعت – Gilaki" lang="glk" hreflang="glk" data-title="ساعت" data-language-autonym="گیلکی" data-language-local-name="Gilaki" class="interlanguage-link-target"><span>گیلکی</span></a></li><li class="interlanguage-link interwiki-hak mw-list-item"><a href="https://hak.wikipedia.org/wiki/S%E1%B9%B3%CC%80-ch%C3%BBng-%C3%A9" title="Sṳ̀-chûng-é – Hakka Chinese" lang="hak" hreflang="hak" data-title="Sṳ̀-chûng-é" data-language-autonym="客家語 / Hak-kâ-ngî" data-language-local-name="Hakka Chinese" class="interlanguage-link-target"><span>客家語 / Hak-kâ-ngî</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%8B%9C%EA%B3%84" title="시계 – Korean" lang="ko" hreflang="ko" data-title="시계" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-ha mw-list-item"><a href="https://ha.wikipedia.org/wiki/Agogo" title="Agogo – Hausa" lang="ha" hreflang="ha" data-title="Agogo" data-language-autonym="Hausa" data-language-local-name="Hausa" class="interlanguage-link-target"><span>Hausa</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D4%BA%D5%A1%D5%B4%D5%A1%D6%81%D5%B8%D6%82%D5%B5%D6%81" title="Ժամացույց – Armenian" lang="hy" hreflang="hy" data-title="Ժամացույց" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Sat_(instrument)" title="Sat (instrument) – Croatian" lang="hr" hreflang="hr" data-title="Sat (instrument)" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-ilo mw-list-item"><a href="https://ilo.wikipedia.org/wiki/Pagorasan" title="Pagorasan – Iloko" lang="ilo" hreflang="ilo" data-title="Pagorasan" data-language-autonym="Ilokano" data-language-local-name="Iloko" class="interlanguage-link-target"><span>Ilokano</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Jam_(alat)" title="Jam (alat) – Indonesian" lang="id" hreflang="id" data-title="Jam (alat)" 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/Horologio" title="Horologio – Interlingua" lang="ia" hreflang="ia" data-title="Horologio" data-language-autonym="Interlingua" data-language-local-name="Interlingua" class="interlanguage-link-target"><span>Interlingua</span></a></li><li class="interlanguage-link interwiki-ie mw-list-item"><a href="https://ie.wikipedia.org/wiki/Horloge" title="Horloge – Interlingue" lang="ie" hreflang="ie" data-title="Horloge" data-language-autonym="Interlingue" data-language-local-name="Interlingue" class="interlanguage-link-target"><span>Interlingue</span></a></li><li class="interlanguage-link interwiki-zu mw-list-item"><a href="https://zu.wikipedia.org/wiki/Iwashi" title="Iwashi – Zulu" lang="zu" hreflang="zu" data-title="Iwashi" data-language-autonym="IsiZulu" data-language-local-name="Zulu" class="interlanguage-link-target"><span>IsiZulu</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Klukka" title="Klukka – Icelandic" lang="is" hreflang="is" data-title="Klukka" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Orologio" title="Orologio – Italian" lang="it" hreflang="it" data-title="Orologio" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A9%D7%A2%D7%95%D7%9F" title="שעון – Hebrew" lang="he" hreflang="he" data-title="שעון" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-kn mw-list-item"><a href="https://kn.wikipedia.org/wiki/%E0%B2%97%E0%B2%A1%E0%B2%BF%E0%B2%AF%E0%B2%BE%E0%B2%B0" title="ಗಡಿಯಾರ – Kannada" lang="kn" hreflang="kn" data-title="ಗಡಿಯಾರ" data-language-autonym="ಕನ್ನಡ" data-language-local-name="Kannada" class="interlanguage-link-target"><span>ಕನ್ನಡ</span></a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/%E1%83%A1%E1%83%90%E1%83%90%E1%83%97%E1%83%98" title="საათი – Georgian" lang="ka" hreflang="ka" data-title="საათი" data-language-autonym="ქართული" data-language-local-name="Georgian" class="interlanguage-link-target"><span>ქართული</span></a></li><li class="interlanguage-link interwiki-ks mw-list-item"><a href="https://ks.wikipedia.org/wiki/%DA%AF%D9%94%D8%B1" title="گٔر – Kashmiri" lang="ks" hreflang="ks" data-title="گٔر" data-language-autonym="कॉशुर / کٲشُر" data-language-local-name="Kashmiri" class="interlanguage-link-target"><span>कॉशुर / کٲشُر</span></a></li><li class="interlanguage-link interwiki-csb mw-list-item"><a href="https://csb.wikipedia.org/wiki/Z%C3%A9d%C5%BCer" title="Zédżer – Kashubian" lang="csb" hreflang="csb" data-title="Zédżer" data-language-autonym="Kaszëbsczi" data-language-local-name="Kashubian" class="interlanguage-link-target"><span>Kaszëbsczi</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%A1%D0%B0%D2%93%D0%B0%D1%82" title="Сағат – Kazakh" lang="kk" hreflang="kk" data-title="Сағат" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-kw mw-list-item"><a href="https://kw.wikipedia.org/wiki/Klock" title="Klock – Cornish" lang="kw" hreflang="kw" data-title="Klock" data-language-autonym="Kernowek" data-language-local-name="Cornish" class="interlanguage-link-target"><span>Kernowek</span></a></li><li class="interlanguage-link interwiki-sw mw-list-item"><a href="https://sw.wikipedia.org/wiki/Saa_(ala)" title="Saa (ala) – Swahili" lang="sw" hreflang="sw" data-title="Saa (ala)" data-language-autonym="Kiswahili" data-language-local-name="Swahili" class="interlanguage-link-target"><span>Kiswahili</span></a></li><li class="interlanguage-link interwiki-ku mw-list-item"><a href="https://ku.wikipedia.org/wiki/Saet_(yeke)" title="Saet (yeke) – Kurdish" lang="ku" hreflang="ku" data-title="Saet (yeke)" data-language-autonym="Kurdî" data-language-local-name="Kurdish" class="interlanguage-link-target"><span>Kurdî</span></a></li><li class="interlanguage-link interwiki-ky mw-list-item"><a href="https://ky.wikipedia.org/wiki/%D0%A1%D0%B0%D0%B0%D1%82" title="Саат – Kyrgyz" lang="ky" hreflang="ky" data-title="Саат" data-language-autonym="Кыргызча" data-language-local-name="Kyrgyz" class="interlanguage-link-target"><span>Кыргызча</span></a></li><li class="interlanguage-link interwiki-lo mw-list-item"><a href="https://lo.wikipedia.org/wiki/%E0%BB%82%E0%BA%A1%E0%BA%87" title="ໂມງ – Lao" lang="lo" hreflang="lo" data-title="ໂມງ" data-language-autonym="ລາວ" data-language-local-name="Lao" class="interlanguage-link-target"><span>ລາວ</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/Horologium" title="Horologium – Latin" lang="la" hreflang="la" data-title="Horologium" data-language-autonym="Latina" data-language-local-name="Latin" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Pulkstenis" title="Pulkstenis – Latvian" lang="lv" hreflang="lv" data-title="Pulkstenis" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-lb mw-list-item"><a href="https://lb.wikipedia.org/wiki/Auer" title="Auer – Luxembourgish" lang="lb" hreflang="lb" data-title="Auer" data-language-autonym="Lëtzebuergesch" data-language-local-name="Luxembourgish" class="interlanguage-link-target"><span>Lëtzebuergesch</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Laikrodis" title="Laikrodis – Lithuanian" lang="lt" hreflang="lt" data-title="Laikrodis" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-li mw-list-item"><a href="https://li.wikipedia.org/wiki/Kl%C3%B3k_(tied)" title="Klók (tied) – Limburgish" lang="li" hreflang="li" data-title="Klók (tied)" data-language-autonym="Limburgs" data-language-local-name="Limburgish" class="interlanguage-link-target"><span>Limburgs</span></a></li><li class="interlanguage-link interwiki-lmo mw-list-item"><a href="https://lmo.wikipedia.org/wiki/Orelogg" title="Orelogg – Lombard" lang="lmo" hreflang="lmo" data-title="Orelogg" data-language-autonym="Lombard" data-language-local-name="Lombard" class="interlanguage-link-target"><span>Lombard</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/%C3%93ra_(eszk%C3%B6z)" title="Óra (eszköz) – Hungarian" lang="hu" hreflang="hu" data-title="Óra (eszköz)" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%A7%D0%B0%D1%81%D0%BE%D0%B2%D0%BD%D0%B8%D0%BA" title="Часовник – Macedonian" lang="mk" hreflang="mk" data-title="Часовник" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-mg mw-list-item"><a href="https://mg.wikipedia.org/wiki/Famantaranandro" title="Famantaranandro – Malagasy" lang="mg" hreflang="mg" data-title="Famantaranandro" data-language-autonym="Malagasy" data-language-local-name="Malagasy" class="interlanguage-link-target"><span>Malagasy</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%98%E0%B4%9F%E0%B4%BF%E0%B4%95%E0%B4%BE%E0%B4%B0%E0%B4%82" title="ഘടികാരം – Malayalam" lang="ml" hreflang="ml" data-title="ഘടികാരം" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-mr mw-list-item"><a href="https://mr.wikipedia.org/wiki/%E0%A4%98%E0%A4%A1%E0%A5%8D%E0%A4%AF%E0%A4%BE%E0%A4%B3" title="घड्याळ – Marathi" lang="mr" hreflang="mr" data-title="घड्याळ" data-language-autonym="मराठी" data-language-local-name="Marathi" class="interlanguage-link-target"><span>मराठी</span></a></li><li class="interlanguage-link interwiki-arz mw-list-item"><a href="https://arz.wikipedia.org/wiki/%D8%B3%D8%A7%D8%B9%D9%87_(%D8%A7%D9%84%D9%87)" title="ساعه (اله) – Egyptian Arabic" lang="arz" hreflang="arz" data-title="ساعه (اله)" data-language-autonym="مصرى" data-language-local-name="Egyptian Arabic" class="interlanguage-link-target"><span>مصرى</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Jam_(alat)" title="Jam (alat) – Malay" lang="ms" hreflang="ms" data-title="Jam (alat)" 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-cdo mw-list-item"><a href="https://cdo.wikipedia.org/wiki/C%E1%B9%B3%CC%86ng" title="Cṳ̆ng – Mindong" lang="cdo" hreflang="cdo" data-title="Cṳ̆ng" data-language-autonym="閩東語 / Mìng-dĕ̤ng-ngṳ̄" data-language-local-name="Mindong" class="interlanguage-link-target"><span>閩東語 / Mìng-dĕ̤ng-ngṳ̄</span></a></li><li class="interlanguage-link interwiki-mwl mw-list-item"><a href="https://mwl.wikipedia.org/wiki/Reloijo" title="Reloijo – Mirandese" lang="mwl" hreflang="mwl" data-title="Reloijo" data-language-autonym="Mirandés" data-language-local-name="Mirandese" class="interlanguage-link-target"><span>Mirandés</span></a></li><li class="interlanguage-link interwiki-my mw-list-item"><a href="https://my.wikipedia.org/wiki/%E1%80%94%E1%80%AC%E1%80%9B%E1%80%AE" title="နာရီ – Burmese" lang="my" hreflang="my" data-title="နာရီ" data-language-autonym="မြန်မာဘာသာ" data-language-local-name="Burmese" class="interlanguage-link-target"><span>မြန်မာဘာသာ</span></a></li><li class="interlanguage-link interwiki-nah badge-Q70894304 mw-list-item" title=""><a href="https://nah.wikipedia.org/wiki/Tlapohualtepoztli" title="Tlapohualtepoztli – Nahuatl" lang="nah" hreflang="nah" data-title="Tlapohualtepoztli" data-language-autonym="Nāhuatl" data-language-local-name="Nahuatl" class="interlanguage-link-target"><span>Nāhuatl</span></a></li><li class="interlanguage-link interwiki-fj mw-list-item"><a href="https://fj.wikipedia.org/wiki/Kaloko" title="Kaloko – Fijian" lang="fj" hreflang="fj" data-title="Kaloko" data-language-autonym="Na Vosa Vakaviti" data-language-local-name="Fijian" class="interlanguage-link-target"><span>Na Vosa Vakaviti</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Klok_(tijd)" title="Klok (tijd) – Dutch" lang="nl" hreflang="nl" data-title="Klok (tijd)" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-new mw-list-item"><a href="https://new.wikipedia.org/wiki/%E0%A4%88%E0%A4%B2%E0%A4%9A%E0%A4%82" title="ईलचं – Newari" lang="new" hreflang="new" data-title="ईलचं" data-language-autonym="नेपाल भाषा" data-language-local-name="Newari" class="interlanguage-link-target"><span>नेपाल भाषा</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E6%99%82%E8%A8%88" title="時計 – Japanese" lang="ja" hreflang="ja" data-title="時計" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-ce mw-list-item"><a href="https://ce.wikipedia.org/wiki/%D0%A1%D0%B0%D1%85%D1%8C%D1%82" title="Сахьт – Chechen" lang="ce" hreflang="ce" data-title="Сахьт" data-language-autonym="Нохчийн" data-language-local-name="Chechen" class="interlanguage-link-target"><span>Нохчийн</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Klokke_(ur)" title="Klokke (ur) – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Klokke (ur)" 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/Klokke" title="Klokke – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Klokke" 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-oc mw-list-item"><a href="https://oc.wikipedia.org/wiki/Rel%C3%B2tge" title="Relòtge – Occitan" lang="oc" hreflang="oc" data-title="Relòtge" data-language-autonym="Occitan" data-language-local-name="Occitan" class="interlanguage-link-target"><span>Occitan</span></a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/Soat_(asbob)" title="Soat (asbob) – Uzbek" lang="uz" hreflang="uz" data-title="Soat (asbob)" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="Uzbek" class="interlanguage-link-target"><span>Oʻzbekcha / ўзбекча</span></a></li><li class="interlanguage-link interwiki-pa mw-list-item"><a href="https://pa.wikipedia.org/wiki/%E0%A8%98%E0%A9%9C%E0%A9%80" title="ਘੜੀ – Punjabi" lang="pa" hreflang="pa" data-title="ਘੜੀ" data-language-autonym="ਪੰਜਾਬੀ" data-language-local-name="Punjabi" class="interlanguage-link-target"><span>ਪੰਜਾਬੀ</span></a></li><li class="interlanguage-link interwiki-pnb mw-list-item"><a href="https://pnb.wikipedia.org/wiki/%DA%AF%DA%BE%DA%91%DB%8C" title="گھڑی – Western Punjabi" lang="pnb" hreflang="pnb" data-title="گھڑی" data-language-autonym="پنجابی" data-language-local-name="Western Punjabi" class="interlanguage-link-target"><span>پنجابی</span></a></li><li class="interlanguage-link interwiki-ps mw-list-item"><a href="https://ps.wikipedia.org/wiki/%DA%AF%DA%93%D9%8A%D8%A7%D9%84" title="گړيال – Pashto" lang="ps" hreflang="ps" data-title="گړيال" data-language-autonym="پښتو" data-language-local-name="Pashto" class="interlanguage-link-target"><span>پښتو</span></a></li><li class="interlanguage-link interwiki-jam mw-list-item"><a href="https://jam.wikipedia.org/wiki/Klak" title="Klak – Jamaican Creole English" lang="jam" hreflang="jam" data-title="Klak" data-language-autonym="Patois" data-language-local-name="Jamaican Creole English" class="interlanguage-link-target"><span>Patois</span></a></li><li class="interlanguage-link interwiki-pwn mw-list-item"><a href="https://pwn.wikipedia.org/wiki/tuki" title="tuki – Paiwan" lang="pwn" hreflang="pwn" data-title="tuki" data-language-autonym="Pinayuanan" data-language-local-name="Paiwan" class="interlanguage-link-target"><span>Pinayuanan</span></a></li><li class="interlanguage-link interwiki-nds mw-list-item"><a href="https://nds.wikipedia.org/wiki/Klock_(Tiet)" title="Klock (Tiet) – Low German" lang="nds" hreflang="nds" data-title="Klock (Tiet)" data-language-autonym="Plattdüütsch" data-language-local-name="Low German" class="interlanguage-link-target"><span>Plattdüütsch</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Zegar" title="Zegar – Polish" lang="pl" hreflang="pl" data-title="Zegar" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Rel%C3%B3gio" title="Relógio – Portuguese" lang="pt" hreflang="pt" data-title="Relógio" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Ceas" title="Ceas – Romanian" lang="ro" hreflang="ro" data-title="Ceas" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-qu mw-list-item"><a href="https://qu.wikipedia.org/wiki/Pacha_tupuq" title="Pacha tupuq – Quechua" lang="qu" hreflang="qu" data-title="Pacha tupuq" data-language-autonym="Runa Simi" data-language-local-name="Quechua" class="interlanguage-link-target"><span>Runa Simi</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%A7%D0%B0%D1%81%D1%8B" title="Часы – Russian" lang="ru" hreflang="ru" data-title="Часы" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-szy mw-list-item"><a href="https://szy.wikipedia.org/wiki/tuki" title="tuki – Sakizaya" lang="szy" hreflang="szy" data-title="tuki" data-language-autonym="Sakizaya" data-language-local-name="Sakizaya" class="interlanguage-link-target"><span>Sakizaya</span></a></li><li class="interlanguage-link interwiki-sco mw-list-item"><a href="https://sco.wikipedia.org/wiki/Knock" title="Knock – Scots" lang="sco" hreflang="sco" data-title="Knock" data-language-autonym="Scots" data-language-local-name="Scots" class="interlanguage-link-target"><span>Scots</span></a></li><li class="interlanguage-link interwiki-sq mw-list-item"><a href="https://sq.wikipedia.org/wiki/Sahati" title="Sahati – Albanian" lang="sq" hreflang="sq" data-title="Sahati" data-language-autonym="Shqip" data-language-local-name="Albanian" class="interlanguage-link-target"><span>Shqip</span></a></li><li class="interlanguage-link interwiki-scn mw-list-item"><a href="https://scn.wikipedia.org/wiki/Rul%C3%B2ggiu" title="Rulòggiu – Sicilian" lang="scn" hreflang="scn" data-title="Rulòggiu" data-language-autonym="Sicilianu" data-language-local-name="Sicilian" class="interlanguage-link-target"><span>Sicilianu</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Clock" title="Clock – Simple English" lang="en-simple" hreflang="en-simple" data-title="Clock" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sd mw-list-item"><a href="https://sd.wikipedia.org/wiki/%DA%AF%DA%BE%DA%99%D9%8A%D8%A7%D9%84" title="گھڙيال – Sindhi" lang="sd" hreflang="sd" data-title="گھڙيال" data-language-autonym="سنڌي" data-language-local-name="Sindhi" class="interlanguage-link-target"><span>سنڌي</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Hodiny" title="Hodiny – Slovak" lang="sk" hreflang="sk" data-title="Hodiny" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Ura_(naprava)" title="Ura (naprava) – Slovenian" lang="sl" hreflang="sl" data-title="Ura (naprava)" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-szl mw-list-item"><a href="https://szl.wikipedia.org/wiki/Zyg%C5%8Fr" title="Zygŏr – Silesian" lang="szl" hreflang="szl" data-title="Zygŏr" data-language-autonym="Ślůnski" data-language-local-name="Silesian" class="interlanguage-link-target"><span>Ślůnski</span></a></li><li class="interlanguage-link interwiki-so mw-list-item"><a href="https://so.wikipedia.org/wiki/Goorsheegto" title="Goorsheegto – Somali" lang="so" hreflang="so" data-title="Goorsheegto" data-language-autonym="Soomaaliga" data-language-local-name="Somali" class="interlanguage-link-target"><span>Soomaaliga</span></a></li><li class="interlanguage-link interwiki-ckb mw-list-item"><a href="https://ckb.wikipedia.org/wiki/%DA%A9%D8%A7%D8%AA%DA%98%D9%85%DB%8E%D8%B1" title="کاتژمێر – Central Kurdish" lang="ckb" hreflang="ckb" data-title="کاتژمێر" data-language-autonym="کوردی" data-language-local-name="Central Kurdish" class="interlanguage-link-target"><span>کوردی</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%A7%D0%B0%D1%81%D0%BE%D0%B2%D0%BD%D0%B8%D0%BA" title="Часовник – Serbian" lang="sr" hreflang="sr" data-title="Часовник" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/%C4%8Casovnik" title="Časovnik – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Časovnik" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-su mw-list-item"><a href="https://su.wikipedia.org/wiki/Jam_t%C3%A9mbok" title="Jam témbok – Sundanese" lang="su" hreflang="su" data-title="Jam témbok" data-language-autonym="Sunda" data-language-local-name="Sundanese" class="interlanguage-link-target"><span>Sunda</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Kello" title="Kello – Finnish" lang="fi" hreflang="fi" data-title="Kello" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Ur" title="Ur – Swedish" lang="sv" hreflang="sv" data-title="Ur" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tl mw-list-item"><a href="https://tl.wikipedia.org/wiki/Orasan" title="Orasan – Tagalog" lang="tl" hreflang="tl" data-title="Orasan" data-language-autonym="Tagalog" data-language-local-name="Tagalog" class="interlanguage-link-target"><span>Tagalog</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%95%E0%AE%9F%E0%AE%BF%E0%AE%95%E0%AE%BE%E0%AE%B0%E0%AE%AE%E0%AF%8D" title="கடிகாரம் – Tamil" lang="ta" hreflang="ta" data-title="கடிகாரம்" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-tt mw-list-item"><a href="https://tt.wikipedia.org/wiki/%D0%A1%D3%99%D0%B3%D0%B0%D1%82%D1%8C_(%D0%BA%D0%BE%D1%80%D0%B0%D0%BB)" title="Сәгать (корал) – Tatar" lang="tt" hreflang="tt" data-title="Сәгать (корал)" 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-te mw-list-item"><a href="https://te.wikipedia.org/wiki/%E0%B0%95%E0%B1%8D%E0%B0%B2%E0%B0%BE%E0%B0%95%E0%B1%8D" title="క్లాక్ – Telugu" lang="te" hreflang="te" data-title="క్లాక్" data-language-autonym="తెలుగు" data-language-local-name="Telugu" class="interlanguage-link-target"><span>తెలుగు</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B8%99%E0%B8%B2%E0%B8%AC%E0%B8%B4%E0%B8%81%E0%B8%B2" title="นาฬิกา – Thai" lang="th" hreflang="th" data-title="นาฬิกา" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Saat" title="Saat – Turkish" lang="tr" hreflang="tr" data-title="Saat" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-kcg mw-list-item"><a href="https://kcg.wikipedia.org/wiki/A%CC%B1gogo" title="A̱gogo – Tyap" lang="kcg" hreflang="kcg" data-title="A̱gogo" data-language-autonym="Tyap" data-language-local-name="Tyap" class="interlanguage-link-target"><span>Tyap</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%93%D0%BE%D0%B4%D0%B8%D0%BD%D0%BD%D0%B8%D0%BA" title="Годинник – Ukrainian" lang="uk" hreflang="uk" data-title="Годинник" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%DA%AF%DA%BE%DA%91%D9%89" title="گھڑى – Urdu" lang="ur" hreflang="ur" data-title="گھڑى" data-language-autonym="اردو" data-language-local-name="Urdu" class="interlanguage-link-target"><span>اردو</span></a></li><li class="interlanguage-link interwiki-za mw-list-item"><a href="https://za.wikipedia.org/wiki/Cung" title="Cung – Zhuang" lang="za" hreflang="za" data-title="Cung" data-language-autonym="Vahcuengh" data-language-local-name="Zhuang" class="interlanguage-link-target"><span>Vahcuengh</span></a></li><li class="interlanguage-link interwiki-vec mw-list-item"><a href="https://vec.wikipedia.org/wiki/Re%C5%82ojo" title="Rełojo – Venetian" lang="vec" hreflang="vec" data-title="Rełojo" data-language-autonym="Vèneto" data-language-local-name="Venetian" class="interlanguage-link-target"><span>Vèneto</span></a></li><li class="interlanguage-link interwiki-vep mw-list-item"><a href="https://vep.wikipedia.org/wiki/%C4%8Casud" title="Časud – Veps" lang="vep" hreflang="vep" data-title="Časud" data-language-autonym="Vepsän kel’" data-language-local-name="Veps" class="interlanguage-link-target"><span>Vepsän kel’</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/%C4%90%E1%BB%93ng_h%E1%BB%93" title="Đồng hồ – Vietnamese" lang="vi" hreflang="vi" data-title="Đồng hồ" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-fiu-vro mw-list-item"><a href="https://fiu-vro.wikipedia.org/wiki/Kell" title="Kell – Võro" lang="vro" hreflang="vro" data-title="Kell" data-language-autonym="Võro" data-language-local-name="Võro" class="interlanguage-link-target"><span>Võro</span></a></li><li class="interlanguage-link interwiki-wa mw-list-item"><a href="https://wa.wikipedia.org/wiki/%C3%94rlodje" title="Ôrlodje – Walloon" lang="wa" hreflang="wa" data-title="Ôrlodje" data-language-autonym="Walon" data-language-local-name="Walloon" class="interlanguage-link-target"><span>Walon</span></a></li><li class="interlanguage-link interwiki-guc mw-list-item"><a href="https://guc.wikipedia.org/wiki/Ka%27iyaawatia" title="Ka'iyaawatia – Wayuu" lang="guc" hreflang="guc" data-title="Ka'iyaawatia" data-language-autonym="Wayuunaiki" data-language-local-name="Wayuu" class="interlanguage-link-target"><span>Wayuunaiki</span></a></li><li class="interlanguage-link interwiki-war mw-list-item"><a href="https://war.wikipedia.org/wiki/Relo" title="Relo – Waray" lang="war" hreflang="war" data-title="Relo" data-language-autonym="Winaray" data-language-local-name="Waray" class="interlanguage-link-target"><span>Winaray</span></a></li><li class="interlanguage-link interwiki-wuu mw-list-item"><a href="https://wuu.wikipedia.org/wiki/%E6%97%B6%E9%92%9F" title="时钟 – Wu" lang="wuu" hreflang="wuu" data-title="时钟" data-language-autonym="吴语" data-language-local-name="Wu" class="interlanguage-link-target"><span>吴语</span></a></li><li class="interlanguage-link interwiki-yi mw-list-item"><a href="https://yi.wikipedia.org/wiki/%D7%96%D7%99%D7%99%D7%92%D7%A2%D7%A8" title="זייגער – Yiddish" lang="yi" hreflang="yi" data-title="זייגער" data-language-autonym="ייִדיש" data-language-local-name="Yiddish" class="interlanguage-link-target"><span>ייִדיש</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%E9%90%98" title="鐘 – Cantonese" lang="yue" hreflang="yue" data-title="鐘" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target"><span>粵語</span></a></li><li class="interlanguage-link interwiki-diq mw-list-item"><a href="https://diq.wikipedia.org/wiki/Saete_(hacet)" title="Saete (hacet) – Zazaki" lang="diq" hreflang="diq" data-title="Saete (hacet)" data-language-autonym="Zazaki" data-language-local-name="Zazaki" class="interlanguage-link-target"><span>Zazaki</span></a></li><li class="interlanguage-link interwiki-bat-smg mw-list-item"><a href="https://bat-smg.wikipedia.org/wiki/Dzieguorios" title="Dzieguorios – Samogitian" lang="sgs" hreflang="sgs" data-title="Dzieguorios" data-language-autonym="Žemaitėška" data-language-local-name="Samogitian" 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srcset="//upload.wikimedia.org/wikipedia/en/thumb/1/1b/Semi-protection-shackle.svg/30px-Semi-protection-shackle.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/1/1b/Semi-protection-shackle.svg/40px-Semi-protection-shackle.svg.png 2x" data-file-width="512" data-file-height="512" /></a></span></div></div> <div id="mw-indicator-spoken-icon" class="mw-indicator"><div class="mw-parser-output"><span typeof="mw:File"><a href="/wiki/File:Clock.ogg" title="Listen to this article"><img alt="Listen to this article" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/47/Sound-icon.svg/20px-Sound-icon.svg.png" decoding="async" width="20" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/47/Sound-icon.svg/30px-Sound-icon.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/47/Sound-icon.svg/40px-Sound-icon.svg.png 2x" data-file-width="128" data-file-height="96" /></a></span></div></div> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Instrument for measuring, keeping or indicating time</div> <p class="mw-empty-elt"> </p> <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">"Timepiece" redirects here. For other uses, see <a href="/wiki/Clock_(disambiguation)" class="mw-disambig" title="Clock (disambiguation)">Clock (disambiguation)</a> and <a href="/wiki/Timepiece_(disambiguation)" class="mw-disambig" title="Timepiece (disambiguation)">Timepiece (disambiguation)</a>.</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">"Clocks" redirects here. For song by Coldplay, see <a href="/wiki/Clocks_(song)" title="Clocks (song)">Clocks (song)</a>.</div> <p class="mw-empty-elt"> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Pendulum_clock_by_Jacob_Kock,_antique_furniture_photography,_IMG_0931_edit.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/cf/Pendulum_clock_by_Jacob_Kock%2C_antique_furniture_photography%2C_IMG_0931_edit.jpg/220px-Pendulum_clock_by_Jacob_Kock%2C_antique_furniture_photography%2C_IMG_0931_edit.jpg" decoding="async" width="220" height="301" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/cf/Pendulum_clock_by_Jacob_Kock%2C_antique_furniture_photography%2C_IMG_0931_edit.jpg/330px-Pendulum_clock_by_Jacob_Kock%2C_antique_furniture_photography%2C_IMG_0931_edit.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/cf/Pendulum_clock_by_Jacob_Kock%2C_antique_furniture_photography%2C_IMG_0931_edit.jpg/440px-Pendulum_clock_by_Jacob_Kock%2C_antique_furniture_photography%2C_IMG_0931_edit.jpg 2x" data-file-width="3378" data-file-height="4622" /></a><figcaption>An analog <a href="/wiki/Pendulum_clock" title="Pendulum clock">pendulum clock</a> made around 18th century</figcaption></figure> <p>A <b>clock</b> or <b>chronometer</b> is a device that measures and displays <a href="/wiki/Time" title="Time">time</a>. The clock is one of the oldest <a href="/wiki/Invention" title="Invention">human inventions</a>, meeting the need to measure intervals of time shorter than the natural units such as the <a href="/wiki/Day" title="Day">day</a>, the <a href="/wiki/Lunar_month" title="Lunar month">lunar month</a>, and the <a href="/wiki/Year" title="Year">year</a>. Devices operating on several physical processes have been used over the <a href="/wiki/Millennium" title="Millennium">millennia</a>. </p><p>Some predecessors to the modern clock may be considered "clocks" that are based on movement in nature: A <a href="/wiki/Sundial" title="Sundial">sundial</a> shows the time by displaying the position of a shadow on a flat surface. There is a range of duration timers, a well-known example being the <a href="/wiki/Hourglass" title="Hourglass">hourglass</a>. <a href="/wiki/Water_clock" title="Water clock">Water clocks</a>, along with sundials, are possibly the oldest time-measuring instruments. A major advance occurred with the invention of the <a href="/wiki/Verge_escapement" title="Verge escapement">verge escapement</a>, which made possible the first mechanical clocks around 1300 in Europe, which kept time with oscillating timekeepers like <a href="/wiki/Balance_wheel" title="Balance wheel">balance wheels</a>.<sup id="cite_ref-Dohrn_1-0" class="reference"><a href="#cite_note-Dohrn-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Marrison_2-0" class="reference"><a href="#cite_note-Marrison-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Cipolla_3-0" class="reference"><a href="#cite_note-Cipolla-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-White_4-0" class="reference"><a href="#cite_note-White-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Traditionally, in <a href="/wiki/Horology" class="mw-redirect" title="Horology">horology</a> (the study of timekeeping), the term <i>clock</i> was used for a <a href="/wiki/Striking_clock" title="Striking clock">striking clock</a>, while a clock that did not strike the hours audibly was called a <b>timepiece</b>. This distinction is not generally made any longer. <a href="/wiki/Watch" title="Watch">Watches</a> and other timepieces that can be carried on one's person are usually not referred to as clocks.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Spring-driven clocks appeared during the 15th century. During the 15th and 16th centuries, <a href="/wiki/Clockmaking" class="mw-redirect" title="Clockmaking">clockmaking</a> flourished. The next development in accuracy occurred after 1656 with the invention of the <a href="/wiki/Pendulum_clock" title="Pendulum clock">pendulum clock</a> by <a href="/wiki/Christiaan_Huygens" title="Christiaan Huygens">Christiaan Huygens</a>. A major stimulus to improving the accuracy and reliability of clocks was the importance of precise time-keeping for navigation. The mechanism of a timepiece with a series of gears driven by a spring or weights is referred to as <a href="/wiki/Clockwork" title="Clockwork">clockwork</a>; the term is used by extension for a similar mechanism not used in a timepiece. The <a href="/wiki/Electric_clock" title="Electric clock">electric clock</a> was patented in 1840, and electronic clocks were introduced in the 20th century, becoming widespread with the development of small battery-powered <a href="/wiki/Semiconductor_device" title="Semiconductor device">semiconductor devices</a>. </p><p>The timekeeping element in every modern clock is a <a href="/wiki/Harmonic_oscillator" title="Harmonic oscillator">harmonic oscillator</a>, a physical object (<a href="/wiki/Resonator" title="Resonator">resonator</a>) that vibrates or oscillates at a particular frequency.<sup id="cite_ref-Marrison_2-1" class="reference"><a href="#cite_note-Marrison-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> This object can be a <a href="/wiki/Pendulum" title="Pendulum">pendulum</a>, a <a href="/wiki/Balance_wheel" title="Balance wheel">balance wheel</a>, a <a href="/wiki/Tuning_fork" title="Tuning fork">tuning fork</a>, a <a href="/wiki/Crystal_oscillator" title="Crystal oscillator">quartz crystal</a>, or the vibration of <a href="/wiki/Electron" title="Electron">electrons</a> in <a href="/wiki/Atom" title="Atom">atoms</a> as they emit <a href="/wiki/Microwave" title="Microwave">microwaves</a>, the last of which is so precise that it serves as the definition of the <a href="/wiki/Second" title="Second">second</a>. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Casio_F-91W_82T38575.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d8/Casio_F-91W_82T38575.jpg/220px-Casio_F-91W_82T38575.jpg" decoding="async" width="220" height="146" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d8/Casio_F-91W_82T38575.jpg/330px-Casio_F-91W_82T38575.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d8/Casio_F-91W_82T38575.jpg/440px-Casio_F-91W_82T38575.jpg 2x" data-file-width="3000" data-file-height="1987" /></a><figcaption><a href="/wiki/Casio_F-91W" title="Casio F-91W">Casio F-91W</a> <a href="/wiki/Digital_clock" title="Digital clock">digital watch</a>, a historically popular watch introduced in 1989</figcaption></figure> <p>Clocks have different ways of displaying the time. Analog clocks indicate time with a traditional <a href="/wiki/Clock_face" title="Clock face">clock face</a> and moving hands. Digital clocks display a numeric representation of time. Two numbering systems are in use: <a href="/wiki/12-hour_time" class="mw-redirect" title="12-hour time">12-hour time</a> notation and <a href="/wiki/24-hour_clock" title="24-hour clock">24-hour</a> notation. Most digital clocks use electronic mechanisms and <a href="/wiki/LCD" class="mw-redirect" title="LCD">LCD</a>, <a href="/wiki/LED" class="mw-redirect" title="LED">LED</a>, or <a href="/wiki/Vacuum_fluorescent_display" title="Vacuum fluorescent display">VFD</a> displays. For the blind and for use over telephones, <a href="/wiki/Speaking_clock" title="Speaking clock">speaking clocks</a> state the time audibly in words. There are also clocks for the blind that have displays that can be read by touch. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Etymology">Etymology</h2></div> <p>The word <i>clock</i> derives from the medieval <a href="/wiki/Latin" title="Latin">Latin</a> word for 'bell'—<span title="Latin-language text"><i lang="la">clocca</i></span>—and has <a href="/wiki/Cognate" title="Cognate">cognates</a> in many European languages. Clocks spread to England from the <a href="/wiki/Low_Countries" title="Low Countries">Low Countries</a>,<sup id="cite_ref-Wedgwood_6-0" class="reference"><a href="#cite_note-Wedgwood-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> so the English word came from the Middle Low German and Middle Dutch <span title="Middle Dutch (ca. 1050-1350)-language text"><i lang="dum">Klocke</i></span>.<sup id="cite_ref-OED_7-0" class="reference"><a href="#cite_note-OED-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> The word is also derived from the <a href="/wiki/Middle_English" title="Middle English">Middle English</a> <span title="Middle English (1100-1500)-language text"><i lang="enm">clokke</i></span>, <a href="/wiki/Old_French" title="Old French">Old North French</a> <span title="Old French (842-ca. 1400)-language text"><i lang="fro">cloque</i></span>, or <a href="/wiki/Middle_Dutch" title="Middle Dutch">Middle Dutch</a> <span title="Middle Dutch (ca. 1050-1350)-language text"><i lang="dum">clocke</i></span>, all of which mean 'bell'. </p> <div class="mw-heading mw-heading2"><h2 id="History_of_time-measuring_devices">History of time-measuring devices</h2></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/History_of_timekeeping_devices" title="History of timekeeping devices">History of timekeeping devices</a></div> <div class="mw-heading mw-heading3"><h3 id="Sundials">Sundials</h3></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Sundial" title="Sundial">Sundial</a></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Garden_sundial_MN_2007.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/75/Garden_sundial_MN_2007.JPG/220px-Garden_sundial_MN_2007.JPG" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/75/Garden_sundial_MN_2007.JPG/330px-Garden_sundial_MN_2007.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/75/Garden_sundial_MN_2007.JPG/440px-Garden_sundial_MN_2007.JPG 2x" data-file-width="2576" data-file-height="1932" /></a><figcaption>Simple horizontal sundial</figcaption></figure> <p>The apparent position of the Sun in the sky changes over the course of each day, reflecting the rotation of the Earth. Shadows cast by stationary objects move correspondingly, so their positions can be used to indicate the time of day. A sundial shows the time by displaying the position of a shadow on a (usually) flat surface that has markings that correspond to the hours.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> Sundials can be horizontal, vertical, or in other orientations. Sundials were widely used in <a href="/wiki/Ancient_times" class="mw-redirect" title="Ancient times">ancient times</a>.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> With knowledge of latitude, a well-constructed sundial can measure local <a href="/wiki/Solar_time" title="Solar time">solar time</a> with reasonable accuracy, within a minute or two. Sundials continued to be used to monitor the performance of clocks until the 1830s, when the use of the telegraph and trains standardized time and time zones between cities.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Devices_that_measure_duration,_elapsed_time_and_intervals"><span id="Devices_that_measure_duration.2C_elapsed_time_and_intervals"></span>Devices that measure duration, elapsed time and intervals</h3></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Wooden_hourglass_3.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Wooden_hourglass_3.jpg/170px-Wooden_hourglass_3.jpg" decoding="async" width="170" height="344" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Wooden_hourglass_3.jpg/255px-Wooden_hourglass_3.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/70/Wooden_hourglass_3.jpg/340px-Wooden_hourglass_3.jpg 2x" data-file-width="967" data-file-height="1959" /></a><figcaption>The flow of sand in an <a href="/wiki/Hourglass" title="Hourglass">hourglass</a> can be used to keep track of elapsed time.</figcaption></figure> <p>Many devices can be used to mark the passage of time without respect to reference time (time of day, hours, minutes, etc.) and can be useful for measuring duration or intervals. Examples of such duration timers are <a href="/wiki/Candle_clock" title="Candle clock">candle clocks</a>, <a href="/wiki/Incense_clock" title="Incense clock">incense clocks</a>, and the <a href="/wiki/Hourglass" title="Hourglass">hourglass</a>. Both the candle clock and the incense clock work on the same principle, wherein the consumption of resources is more or less constant, allowing reasonably precise and repeatable estimates of time passages. In the hourglass, fine <a href="/wiki/Sand" title="Sand">sand</a> pouring through a tiny hole at a constant rate indicates an arbitrary, predetermined passage of time. The resource is not consumed, but re-used. </p> <div class="mw-heading mw-heading3"><h3 id="Water_clocks">Water clocks</h3></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Water_clock" title="Water clock">Water clock</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:MandalayWaterClock.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/34/MandalayWaterClock.jpg/170px-MandalayWaterClock.jpg" decoding="async" width="170" height="244" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/34/MandalayWaterClock.jpg/255px-MandalayWaterClock.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/34/MandalayWaterClock.jpg/340px-MandalayWaterClock.jpg 2x" data-file-width="2286" data-file-height="3286" /></a><figcaption>A water clock for <a href="/wiki/Goldbeating" class="mw-redirect" title="Goldbeating">goldbeating</a> <a href="/wiki/Goldleaf" class="mw-redirect" title="Goldleaf">goldleaf</a> in <a href="/wiki/Mandalay" title="Mandalay">Mandalay</a> (Myanmar)</figcaption></figure> <p>Water clocks, along with sundials, are possibly the oldest time-measuring instruments, with the only exception being the day-counting <a href="/wiki/Tally_stick" title="Tally stick">tally stick</a>.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Given their great antiquity, where and when they first existed is not known and is perhaps unknowable. The bowl-shaped outflow is the simplest form of a water clock and is known to have existed in <a href="/wiki/Babylon" title="Babylon">Babylon</a> and Egypt around the 16th century BC. Other regions of the world, including India and China, also have early evidence of water clocks, but the earliest dates are less certain. Some authors, however, write about water clocks appearing as early as 4000 BC in these regions of the world.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> </p><p>The <a href="/wiki/Ancient_Macedonia" class="mw-redirect" title="Ancient Macedonia">Macedonian</a> <a href="/wiki/Ancient_Greek_astronomy" title="Ancient Greek astronomy">astronomer</a> <a href="/wiki/Andronicus_of_Cyrrhus" title="Andronicus of Cyrrhus">Andronicus</a> of <a href="/wiki/Cyrrhus_(Macedonia)" title="Cyrrhus (Macedonia)">Cyrrhus</a> supervised the construction of the <a href="/wiki/Tower_of_the_Winds" title="Tower of the Winds">Tower of the Winds</a> in <a href="/wiki/Roman_Athens" class="mw-redirect" title="Roman Athens">Athens</a> in the 1st century BC, which housed a large clepsydra inside as well as multiple prominent sundials outside, allowing it to function as a kind of early <a href="/wiki/Clocktower" class="mw-redirect" title="Clocktower">clocktower</a>.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Ancient_Greece" title="Ancient Greece">Greek</a> and <a href="/wiki/Ancient_Rome" title="Ancient Rome">Roman</a> civilizations advanced water clock design with improved accuracy. These advances were passed on through <a href="/wiki/Byzantine_Empire" title="Byzantine Empire">Byzantine</a> and <a href="/wiki/Islamic" class="mw-redirect" title="Islamic">Islamic</a> times, eventually making their way back to Europe. Independently, the Chinese developed their own advanced water clocks (<span title="Chinese-language text"><span lang="zh">水鐘</span></span>) by 725 AD, passing their ideas on to Korea and Japan.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p><p>Some water clock designs were developed independently, and some knowledge was transferred through the spread of trade. <a href="/wiki/Pre-modern" class="mw-redirect" title="Pre-modern">Pre-modern</a> societies do not have the same precise timekeeping requirements that exist in modern industrial societies, where every hour of work or rest is monitored and work may start or finish at any time regardless of external conditions. Instead, water clocks in ancient societies were used mainly for <a href="/wiki/Astrology" title="Astrology">astrological</a> reasons. These early water clocks were calibrated with a sundial. While never reaching the level of accuracy of a modern timepiece, the water clock was the most accurate and commonly used timekeeping device for millennia until it was replaced by the more accurate <a href="/wiki/Pendulum_clock" title="Pendulum clock">pendulum clock</a> in 17th-century Europe. </p><p>Islamic civilization is credited with further advancing the accuracy of clocks through elaborate engineering. In 797 (or possibly 801), the <a href="/wiki/Abbasid" class="mw-redirect" title="Abbasid">Abbasid</a> <a href="/wiki/Caliph" class="mw-redirect" title="Caliph">caliph</a> of <a href="/wiki/Baghdad" title="Baghdad">Baghdad</a>, <a href="/wiki/Harun_al-Rashid" title="Harun al-Rashid">Harun al-Rashid</a>, presented <a href="/wiki/Charlemagne" title="Charlemagne">Charlemagne</a> with an <a href="/wiki/Asian_elephant" title="Asian elephant">Asian elephant</a> named <a href="/wiki/Abul-Abbas" title="Abul-Abbas">Abul-Abbas</a> together with a "particularly elaborate example" of a water<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> clock. <a href="/wiki/Pope_Sylvester_II" title="Pope Sylvester II">Pope Sylvester II</a> introduced clocks to northern and western Europe around 1000 AD.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Mechanical_water_clocks">Mechanical water clocks</h3></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/Automaton#Ancient" title="Automaton">Automaton § Ancient</a></div> <p>The first known <a href="/wiki/Gear" title="Gear">geared</a> clock was invented by the great mathematician, physicist, and engineer <a href="/wiki/Archimedes" title="Archimedes">Archimedes</a> during the 3rd century BC. Archimedes created his astronomical clock,<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup><sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="I can't find any record of this book, ISBN doesn't even seem to exist (April 2024)">citation needed</span></a></i>]</sup> which was also a cuckoo clock with birds singing and moving every hour. It is the first carillon clock as it plays music simultaneously with a person blinking his eyes, surprised by the singing birds. The Archimedes clock works with a system of four weights, counterweights, and strings regulated by a system of floats in a water container with siphons that regulate the automatic continuation of the clock. The principles of this type of clock are described by the mathematician and physicist Hero,<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> who says that some of them work with a chain that turns a gear in the mechanism.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> Another Greek clock probably constructed at the time of Alexander was in Gaza, as described by Procopius.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> The Gaza clock was probably a Meteoroskopeion, i.e., a building showing celestial phenomena and the time. It had a pointer for the time and some automations similar to the Archimedes clock. There were 12 doors opening one every hour, with Hercules performing his labors, the Lion at one o'clock, etc., and at night a lamp becomes visible every hour, with 12 windows opening to show the time. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:SuSongClock1.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/db/SuSongClock1.JPG/170px-SuSongClock1.JPG" decoding="async" width="170" height="278" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/db/SuSongClock1.JPG/255px-SuSongClock1.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/db/SuSongClock1.JPG/340px-SuSongClock1.JPG 2x" data-file-width="384" data-file-height="627" /></a><figcaption>A <a href="/wiki/Scale_model" title="Scale model">scale model</a> of <a href="/wiki/Su_Song" title="Su Song">Su Song</a>'s <a href="/wiki/Astronomical" class="mw-redirect" title="Astronomical">Astronomical</a> Clock Tower, built in 11th-century <a href="/wiki/Kaifeng" title="Kaifeng">Kaifeng</a>, China. It was driven by a large <a href="/wiki/Waterwheel" class="mw-redirect" title="Waterwheel">waterwheel</a>, <a href="/wiki/Chain_drive" title="Chain drive">chain drive</a>, and <a href="/wiki/Escapement" title="Escapement">escapement</a> mechanism.</figcaption></figure> <p>The <a href="/wiki/Tang_dynasty" title="Tang dynasty">Tang dynasty</a> Buddhist monk <a href="/wiki/Yi_Xing" title="Yi Xing">Yi Xing</a> along with government official <a href="/wiki/Liang_Lingzan" title="Liang Lingzan">Liang Lingzan</a> made the escapement in 723 (or 725) to the workings of a water-powered <a href="/wiki/Armillary_sphere" title="Armillary sphere">armillary sphere</a> and <a href="/wiki/Drive_wheel" title="Drive wheel">clock drive</a>, which was the world's first clockwork escapement.<sup id="cite_ref-needham_volume_4_part_2_165_21-0" class="reference"><a href="#cite_note-needham_volume_4_part_2_165-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Song_dynasty" title="Song dynasty">Song dynasty</a> <a href="/wiki/Polymath" title="Polymath">polymath</a> and genius <a href="/wiki/Su_Song" title="Su Song">Su Song</a> (1020–1101) incorporated it into his monumental innovation of the astronomical clock tower of <a href="/wiki/Kaifeng" title="Kaifeng">Kaifeng</a> in 1088.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citing_sources" title="Wikipedia:Citing sources"><span title="This citation requires a reference to the specific page or range of pages in which the material appears. (July 2011)">page needed</span></a></i>]</sup> His astronomical clock and rotating <a href="/wiki/Armillary_sphere" title="Armillary sphere">armillary sphere</a> still relied on the use of either flowing water during the spring, summer, and autumn seasons or <a href="/wiki/Mercury_(element)" title="Mercury (element)">liquid mercury</a> during the freezing temperatures of winter (i.e., <a href="/wiki/Hydraulics" title="Hydraulics">hydraulics</a>). In Su Song's waterwheel linkwork device, the action of the escapement's arrest and release was achieved by gravity exerted periodically as the continuous flow of liquid-filled containers of a limited size. In a single line of evolution, Su Song's clock therefore united the concepts of the clepsydra and the mechanical clock into one device run by mechanics and hydraulics. In his memorial, Su Song wrote about this concept: </p> <blockquote><p>According to your servant's opinion there have been many systems and designs for astronomical instruments during past dynasties all differing from one another in minor respects. But the principle of the use of water-power for the driving mechanism has always been the same. The heavens move without ceasing but so also does water flow (and fall). Thus if the water is made to pour with perfect evenness, then the comparison of the rotary movements (of the heavens and the machine) will show no discrepancy or contradiction; for the unresting follows the unceasing.</p></blockquote> <p>Song was also strongly influenced by the earlier armillary sphere created by <a href="/wiki/Zhang_Sixun" title="Zhang Sixun">Zhang Sixun</a> (976 AD), who also employed the escapement mechanism and used liquid <a href="/wiki/Mercury_(element)" title="Mercury (element)">mercury</a> instead of water in the waterwheel of his astronomical clock tower. The mechanical clockworks for Su Song's astronomical tower featured a great driving-wheel that was 11 feet in diameter, carrying 36 scoops, into each of which water was poured at a uniform rate from the "constant-level tank". The main driving shaft of iron, with its cylindrical necks supported on iron crescent-shaped bearings, ended in a pinion, which engaged a gear wheel at the lower end of the main vertical transmission shaft. This great astronomical hydromechanical clock tower was about ten metres high (about 30 feet), featured a clock <a href="/wiki/Escapement" title="Escapement">escapement</a>, and was indirectly powered by a rotating wheel either with falling water or <a href="/wiki/Mercury_(element)" title="Mercury (element)">liquid mercury</a>. A full-sized working replica of Su Song's clock exists in the <a href="/wiki/Republic_of_China" class="mw-redirect" title="Republic of China">Republic of China</a> (Taiwan)'s <a href="/wiki/National_Museum_of_Natural_Science" title="National Museum of Natural Science">National Museum of Natural Science</a>, <a href="/wiki/Taichung" title="Taichung">Taichung</a> city. This full-scale, fully functional replica, approximately 12 meters (39 feet) in height, was constructed from Su Song's original descriptions and mechanical drawings.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> The Chinese escapement spread west and was the source for Western escapement technology.<sup id="cite_ref-Derek_26-0" class="reference"><a href="#cite_note-Derek-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Al-jazari_elephant_clock.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/76/Al-jazari_elephant_clock.png/170px-Al-jazari_elephant_clock.png" decoding="async" width="170" height="266" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/76/Al-jazari_elephant_clock.png/255px-Al-jazari_elephant_clock.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/76/Al-jazari_elephant_clock.png/340px-Al-jazari_elephant_clock.png 2x" data-file-width="1013" data-file-height="1587" /></a><figcaption>An <a href="/wiki/Elephant_clock" title="Elephant clock">elephant clock</a> in a manuscript by <a href="/wiki/Al-Jazari" class="mw-redirect" title="Al-Jazari">Al-Jazari</a> (1206 AD) from <i>The Book of Knowledge of Ingenious Mechanical Devices</i><sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup></figcaption></figure> <p>In the 12th century, <a href="/wiki/Al-Jazari" class="mw-redirect" title="Al-Jazari">Al-Jazari</a>, an engineer from Mesopotamia (lived 1136–1206) who worked for the <a href="/wiki/Artuqid" class="mw-redirect" title="Artuqid">Artuqid</a> king of Diyar-Bakr, <a href="/wiki/Nasrudin" class="mw-redirect" title="Nasrudin">Nasir al-Din</a>, made numerous clocks of all shapes and sizes. The most reputed clocks included <a href="/wiki/Elephant_clock" title="Elephant clock">the elephant</a>, scribe, and <a href="/wiki/Castle_clock" class="mw-redirect" title="Castle clock">castle clocks</a>, some of which have been successfully reconstructed. As well as telling the time, these grand clocks were symbols of the status, grandeur, and wealth of the Urtuq State.<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> Knowledge of these mercury escapements may have spread through Europe with translations of Arabic and Spanish texts.<sup id="cite_ref-Hassan_29-0" class="reference"><a href="#cite_note-Hassan-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Ajram_30-0" class="reference"><a href="#cite_note-Ajram-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Fully_mechanical">Fully mechanical</h3></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/Clock" title="Special:EditPage/Clock">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">January 2024</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> <p>The word <span title="Greek-language text"><i lang="el-Latn">horologia</i></span> (from the Greek <span title="Greek-language text"><span lang="el">ὥρα</span></span>—'hour', and <span title="Greek-language text"><span lang="el">λέγειν</span></span>—'to tell') was used to describe early mechanical clocks,<sup id="cite_ref-wmsmith1875_31-0" class="reference"><a href="#cite_note-wmsmith1875-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> but the use of this word (still used in several <a href="/wiki/Romance_languages" title="Romance languages">Romance languages</a>)<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> for all timekeepers conceals the true nature of the mechanisms. For example, there is a record that in 1176, <a href="/wiki/Cath%C3%A9drale_Saint-%C3%89tienne_de_Sens" class="mw-redirect" title="Cathédrale Saint-Étienne de Sens">Sens Cathedral</a> in France installed an '<a href="/wiki/Horologe" class="mw-redirect" title="Horologe">horologe</a>',<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> but the mechanism used is unknown. According to <a href="/wiki/Jocelyn_de_Brakelond" title="Jocelyn de Brakelond">Jocelyn de Brakelond</a>, in 1198, during a fire at the abbey of St Edmundsbury (now <a href="/wiki/Bury_St_Edmunds" title="Bury St Edmunds">Bury St Edmunds</a>), the monks "ran to the clock" to fetch water, indicating that their water clock had a reservoir large enough to help extinguish the occasional fire.<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> The word <i>clock</i> (via <a href="/wiki/Medieval_Latin" title="Medieval Latin">Medieval Latin</a> <span title="Medieval Latin-language text"><i lang="la">clocca</i></span> from <a href="/wiki/Old_Irish" title="Old Irish">Old Irish</a> <span title="Old Irish (to 900)-language text"><i lang="sga">clocc</i></span>, both meaning 'bell'), which gradually supersedes "horologe", suggests that it was the sound of bells that also characterized the prototype mechanical clocks that appeared during the 13th century in Europe. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:L%C3%A4ck%C3%B6_slott_interior_27.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fc/L%C3%A4ck%C3%B6_slott_interior_27.jpg/260px-L%C3%A4ck%C3%B6_slott_interior_27.jpg" decoding="async" width="260" height="195" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fc/L%C3%A4ck%C3%B6_slott_interior_27.jpg/390px-L%C3%A4ck%C3%B6_slott_interior_27.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fc/L%C3%A4ck%C3%B6_slott_interior_27.jpg/520px-L%C3%A4ck%C3%B6_slott_interior_27.jpg 2x" data-file-width="4032" data-file-height="3024" /></a><figcaption>A 17th-century weight-driven clock in <a href="/wiki/L%C3%A4ck%C3%B6_Castle" title="Läckö Castle">Läckö Castle</a>, Sweden</figcaption></figure> <p>In Europe, between 1280 and 1320, there was an increase in the number of references to clocks and horologes in church records, and this probably indicates that a new type of clock mechanism had been devised. Existing clock mechanisms that used water power were being adapted to take their driving power from falling weights. This power was controlled by some form of oscillating mechanism, probably derived from existing bell-ringing or alarm devices. This controlled release of power – the escapement – marks the beginning of the true mechanical clock, which differed from the previously mentioned cogwheel clocks. The <a href="/wiki/Verge_escapement" title="Verge escapement">verge escapement</a> mechanism appeared during the surge of true mechanical clock development, which did not need any kind of fluid power, like water or mercury, to work. </p><p>These mechanical clocks were intended for two main purposes: for signalling and notification (e.g., the timing of services and public events) and for modeling the solar system. The former purpose is administrative; the latter arises naturally given the scholarly interests in astronomy, science, and astrology and how these subjects integrated with the religious philosophy of the time. The <a href="/wiki/Astrolabe" title="Astrolabe">astrolabe</a> was used both by astronomers and astrologers, and it was natural to apply a clockwork drive to the rotating plate to produce a working model of the solar system. </p><p>Simple clocks intended mainly for notification were installed in towers and did not always require faces or hands. They would have announced the <a href="/wiki/Canonical_hours" title="Canonical hours">canonical hours</a> or intervals between set times of prayer. Canonical hours varied in length as the times of sunrise and sunset shifted. The more sophisticated astronomical clocks would have had moving dials or hands and would have shown the time in various time systems, including <a href="/wiki/Hour#Counting_from_sunset" title="Hour">Italian hours</a>, canonical hours, and time as measured by astronomers at the time. Both styles of clocks started acquiring extravagant features, such as <a href="/wiki/Automata" class="mw-redirect" title="Automata">automata</a>. </p><p>In 1283, a large clock was installed at <a href="/wiki/Dunstable_Priory" title="Dunstable Priory">Dunstable Priory</a> in <a href="/wiki/Bedfordshire" title="Bedfordshire">Bedfordshire</a> in southern England; its location above the <a href="/wiki/Rood_screen" title="Rood screen">rood screen</a> suggests that it was not a water clock.<sup id="cite_ref-:0_36-0" class="reference"><a href="#cite_note-:0-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> In 1292, <a href="/wiki/Canterbury_Cathedral" title="Canterbury Cathedral">Canterbury Cathedral</a> installed a 'great horloge'. Over the next 30 years, there were mentions of clocks at a number of ecclesiastical institutions in England, Italy, and France. In 1322, a <a href="/wiki/Norwich_cathedral_astronomical_clock" class="mw-redirect" title="Norwich cathedral astronomical clock">new clock was installed in Norwich</a>, an expensive replacement for an earlier clock installed in 1273. This had a large (2 metre) astronomical dial with automata and bells. The costs of the installation included the full-time employment of two <a href="/wiki/Clockkeeper" title="Clockkeeper">clockkeepers</a> for two years.<sup id="cite_ref-:0_36-1" class="reference"><a href="#cite_note-:0-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Astronomical">Astronomical</h3></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Abbot_Richard_Wallingford.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Abbot_Richard_Wallingford.jpg/220px-Abbot_Richard_Wallingford.jpg" decoding="async" width="220" height="236" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Abbot_Richard_Wallingford.jpg/330px-Abbot_Richard_Wallingford.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Abbot_Richard_Wallingford.jpg/440px-Abbot_Richard_Wallingford.jpg 2x" data-file-width="696" data-file-height="748" /></a><figcaption><a href="/wiki/Richard_of_Wallingford" title="Richard of Wallingford">Richard of Wallingford</a> pointing to a clock, his gift to <a href="/wiki/St_Albans_Abbey" class="mw-redirect" title="St Albans Abbey">St Albans Abbey</a></figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Clock_machine_16th_century-Convent_of_Christ,Tomar,_Portugal.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/93/Clock_machine_16th_century-Convent_of_Christ%2CTomar%2C_Portugal.jpg/220px-Clock_machine_16th_century-Convent_of_Christ%2CTomar%2C_Portugal.jpg" decoding="async" width="220" height="149" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/93/Clock_machine_16th_century-Convent_of_Christ%2CTomar%2C_Portugal.jpg/330px-Clock_machine_16th_century-Convent_of_Christ%2CTomar%2C_Portugal.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/93/Clock_machine_16th_century-Convent_of_Christ%2CTomar%2C_Portugal.jpg/440px-Clock_machine_16th_century-Convent_of_Christ%2CTomar%2C_Portugal.jpg 2x" data-file-width="5237" data-file-height="3538" /></a><figcaption>16th-century clock machine <a href="/wiki/Convent_of_Christ" class="mw-redirect" title="Convent of Christ">Convent of Christ</a>, <a href="/wiki/Tomar" title="Tomar">Tomar</a>, Portugal</figcaption></figure> <p>An elaborate water clock, the 'Cosmic Engine', was invented by <a href="/wiki/Su_Song" title="Su Song">Su Song</a>, a Chinese <a href="/wiki/Polymath" title="Polymath">polymath</a>, designed and constructed in China in 1092. This great astronomical hydromechanical clock tower was about ten metres high (about 30 feet) and was indirectly powered by a rotating wheel with falling water and <a href="/wiki/Mercury_(element)" title="Mercury (element)">liquid mercury</a>, which turned an <a href="/wiki/Armillary_sphere" title="Armillary sphere">armillary sphere</a> capable of calculating complex astronomical problems. </p><p>In Europe, there were the clocks constructed by <a href="/wiki/Richard_of_Wallingford" title="Richard of Wallingford">Richard of Wallingford</a> in <a href="/wiki/St_Albans" title="St Albans">Albans</a> by 1336, and by Giovanni <a href="/wiki/Giovanni_Dondi_dell%27Orologio" class="mw-redirect" title="Giovanni Dondi dell'Orologio">de Dondi</a> in <a href="/wiki/Padua,_Italy" class="mw-redirect" title="Padua, Italy">Padua</a> from 1348 to 1364. They no longer exist, but detailed descriptions of their design and construction survive,<sup id="cite_ref-north_37-0" class="reference"><a href="#cite_note-north-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-king_38-0" class="reference"><a href="#cite_note-king-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> and modern reproductions have been made.<sup id="cite_ref-king_38-1" class="reference"><a href="#cite_note-king-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> They illustrate how quickly the theory of the mechanical clock had been translated into practical constructions, and also that one of the many impulses to their development had been the desire of astronomers to investigate celestial phenomena. </p><p>The Astrarium of Giovanni Dondi dell'Orologio was a complex astronomical clock built between 1348 and 1364 in <a href="/wiki/Padua" title="Padua">Padua</a>, Italy, by the doctor and clock-maker <a href="/wiki/Giovanni_Dondi_dell%27Orologio" class="mw-redirect" title="Giovanni Dondi dell'Orologio">Giovanni Dondi dell'Orologio</a>. The Astrarium had seven faces and 107 moving gears; it showed the positions of the sun, the moon and the five planets then known, as well as religious feast days. The astrarium stood about 1 metre high, and consisted of a seven-sided brass or iron framework resting on 7 decorative paw-shaped feet. The lower section provided a 24-hour dial and a large calendar drum, showing the fixed feasts of the church, the movable feasts, and the position in the zodiac of the moon's ascending node. The upper section contained 7 dials, each about 30 cm in diameter, showing the positional data for the <a href="/wiki/Primum_Mobile" title="Primum Mobile">Primum Mobile</a>, Venus, Mercury, the moon, Saturn, Jupiter, and Mars. Directly above the 24-hour dial is the dial of the <a href="/wiki/Primum_Mobile" title="Primum Mobile">Primum Mobile</a>, so called because it reproduces the diurnal motion of the stars and the annual motion of the sun against the background of stars. Each of the 'planetary' dials used complex clockwork to produce reasonably accurate models of the planets' motion. These agreed reasonably well both with Ptolemaic theory and with observations.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> </p><p>Wallingford's clock had a large astrolabe-type dial, showing the sun, the moon's age, phase, and node, a star map, and possibly the planets. In addition, it had a <a href="/wiki/Rota_Fortunae" title="Rota Fortunae">wheel of fortune</a> and an indicator of the state of the tide at <a href="/wiki/London_Bridge" title="London Bridge">London Bridge</a>. Bells rang every hour, the number of strokes indicating the time.<sup id="cite_ref-north_37-1" class="reference"><a href="#cite_note-north-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> Dondi's clock was a seven-sided construction, 1 metre high, with dials showing the time of day, including minutes, the motions of all the known planets, an automatic calendar of fixed and <a href="/wiki/Moveable_feast" title="Moveable feast">movable feasts</a>, and an eclipse prediction hand rotating once every 18 years.<sup id="cite_ref-king_38-2" class="reference"><a href="#cite_note-king-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> It is not known how accurate or reliable these clocks would have been. They were probably adjusted manually every day to compensate for errors caused by wear and imprecise manufacture. Water clocks are sometimes still used today, and can be examined in places such as ancient castles and museums. The <a href="/wiki/Salisbury_Cathedral_clock" title="Salisbury Cathedral clock">Salisbury Cathedral clock</a>, built in 1386, is considered to be the world's oldest surviving mechanical clock that strikes the hours.<sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Spring-driven">Spring-driven</h3></div> <ul class="gallery mw-gallery-packed-hover"> <li class="gallerycaption">Examples of spring-driven clocks</li> <li class="gallerybox" style="width: 192px"> <div class="thumb" style="width: 190px;"><span typeof="mw:File"><a href="/wiki/File:Matthew_Norman_carriage_clock_with_winding_key.jpg" class="mw-file-description" title="Matthew Norman carriage clock with winding key"><img alt="Matthew Norman carriage clock with winding key" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Matthew_Norman_carriage_clock_with_winding_key.jpg/285px-Matthew_Norman_carriage_clock_with_winding_key.jpg" decoding="async" width="190" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Matthew_Norman_carriage_clock_with_winding_key.jpg/428px-Matthew_Norman_carriage_clock_with_winding_key.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Matthew_Norman_carriage_clock_with_winding_key.jpg/570px-Matthew_Norman_carriage_clock_with_winding_key.jpg 2x" data-file-width="4256" data-file-height="3360" /></a></span></div> <div class="gallerytextwrapper" style="width: 170px"><div class="gallerytext">Matthew Norman carriage clock with winding key</div> </div> </li> <li class="gallerybox" style="width: 116.66666666667px"> <div class="thumb" style="width: 114.66666666667px;"><span typeof="mw:File"><a href="/wiki/File:1908_Gilbert_mantel_clock_decorated_with_Memento_Mori_decoupage.JPG" class="mw-file-description" title="Decorated William Gilbert mantel clock"><img alt="Decorated William Gilbert mantel clock" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3e/1908_Gilbert_mantel_clock_decorated_with_Memento_Mori_decoupage.JPG/172px-1908_Gilbert_mantel_clock_decorated_with_Memento_Mori_decoupage.JPG" decoding="async" width="115" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/3e/1908_Gilbert_mantel_clock_decorated_with_Memento_Mori_decoupage.JPG/259px-1908_Gilbert_mantel_clock_decorated_with_Memento_Mori_decoupage.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/3e/1908_Gilbert_mantel_clock_decorated_with_Memento_Mori_decoupage.JPG/345px-1908_Gilbert_mantel_clock_decorated_with_Memento_Mori_decoupage.JPG 2x" data-file-width="828" data-file-height="1080" /></a></span></div> <div class="gallerytextwrapper" style="width: 95px"><div class="gallerytext">Decorated William Gilbert mantel clock</div> </div> </li> </ul> <p>Clockmakers developed their art in various ways. Building smaller clocks was a technical challenge, as was improving accuracy and reliability. Clocks could be impressive showpieces to demonstrate skilled craftsmanship, or less expensive, mass-produced items for domestic use. The escapement in particular was an important factor affecting the clock's accuracy, so many different mechanisms were tried. </p><p>Spring-driven clocks appeared during the 15th century,<sup id="cite_ref-White2_42-0" class="reference"><a href="#cite_note-White2-42"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-43" class="reference"><a href="#cite_note-43"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Rossum_44-0" class="reference"><a href="#cite_note-Rossum-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> although they are often erroneously credited to <a href="/wiki/Nuremberg" title="Nuremberg">Nuremberg</a> watchmaker <a href="/wiki/Peter_Henlein" title="Peter Henlein">Peter Henlein</a> (or Henle, or Hele) around 1511.<sup id="cite_ref-45" class="reference"><a href="#cite_note-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-47" class="reference"><a href="#cite_note-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> The earliest existing spring driven clock is the chamber clock given to Phillip the Good, Duke of Burgundy, around 1430, now in the <a href="/wiki/Germanisches_Nationalmuseum" title="Germanisches Nationalmuseum">Germanisches Nationalmuseum</a>.<sup id="cite_ref-White_4-1" class="reference"><a href="#cite_note-White-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> Spring power presented clockmakers with a new problem: how to keep the clock <a href="/wiki/Movement_(clockwork)" title="Movement (clockwork)">movement</a> running at a constant rate as the spring ran down. This resulted in the invention of the <i><a href="/wiki/Stackfreed" title="Stackfreed">stackfreed</a></i> and the <a href="/wiki/Fusee_(horology)" title="Fusee (horology)">fusee</a> in the 15th century, and many other innovations, down to the invention of the modern <i>going <a href="/wiki/Barrel_(horology)" title="Barrel (horology)">barrel</a></i> in 1760. </p><p>Early clock dials did not indicate minutes and seconds. A clock with a dial indicating minutes was illustrated in a 1475 manuscript by Paulus Almanus,<sup id="cite_ref-haencyc_48-0" class="reference"><a href="#cite_note-haencyc-48"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup> and some 15th-century clocks in Germany indicated minutes and seconds.<sup id="cite_ref-49" class="reference"><a href="#cite_note-49"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup> An early record of a seconds hand on a clock dates back to about 1560 on a clock now in the Fremersdorf collection.<sup id="cite_ref-Landes_50-0" class="reference"><a href="#cite_note-Landes-50"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 417–418">: 417–418 </span></sup><sup id="cite_ref-51" class="reference"><a href="#cite_note-51"><span class="cite-bracket">[</span>51<span class="cite-bracket">]</span></a></sup> </p><p>During the 15th and 16th centuries, clockmaking flourished, particularly in the metalworking towns of <a href="/wiki/Nuremberg" title="Nuremberg">Nuremberg</a> and <a href="/wiki/Augsburg" title="Augsburg">Augsburg</a>, and in <a href="/wiki/Blois" title="Blois">Blois</a>, France. Some of the more basic table clocks have only one time-keeping hand, with the dial between the hour markers being divided into four equal parts making the clocks readable to the nearest 15 minutes. Other clocks were exhibitions of craftsmanship and skill, incorporating astronomical indicators and musical movements. The <a href="/wiki/Escapement#Cross-beat_escapement" title="Escapement">cross-beat escapement</a> was invented in 1584 by <a href="/wiki/Jost_B%C3%BCrgi" title="Jost Bürgi">Jost Bürgi</a>, who also developed the <a href="/wiki/Remontoire" title="Remontoire">remontoire</a>. Bürgi's clocks were a great improvement in accuracy as they were correct to within a minute a day.<sup id="cite_ref-52" class="reference"><a href="#cite_note-52"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-53" class="reference"><a href="#cite_note-53"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup> These clocks helped the 16th-century astronomer <a href="/wiki/Tycho_Brahe" title="Tycho Brahe">Tycho Brahe</a> to observe astronomical events with much greater precision than before.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (November 2014)">citation needed</span></a></i>]</sup><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Please_clarify" title="Wikipedia:Please clarify"><span title="Please clarify the preceding statement or statements with a good explanation from a reliable source. (November 2014)">how?</span></a></i>]</sup> </p> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Renaissance_Turret_Clock.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Renaissance_Turret_Clock.jpg/220px-Renaissance_Turret_Clock.jpg" decoding="async" width="220" height="284" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Renaissance_Turret_Clock.jpg/330px-Renaissance_Turret_Clock.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Renaissance_Turret_Clock.jpg/440px-Renaissance_Turret_Clock.jpg 2x" data-file-width="1938" data-file-height="2500" /></a><figcaption>Lantern clock, German, <abbr title="circa">c.</abbr><span style="white-space:nowrap;"> 1570</span></figcaption></figure> <div class="mw-heading mw-heading3"><h3 id="Pendulum">Pendulum</h3></div> <style data-mw-deduplicate="TemplateStyles:r1237032888/mw-parser-output/.tmulti">.mw-parser-output .tmulti .multiimageinner{display:flex;flex-direction:column}.mw-parser-output .tmulti .trow{display:flex;flex-direction:row;clear:left;flex-wrap:wrap;width:100%;box-sizing:border-box}.mw-parser-output .tmulti .tsingle{margin:1px;float:left}.mw-parser-output .tmulti .theader{clear:both;font-weight:bold;text-align:center;align-self:center;background-color:transparent;width:100%}.mw-parser-output .tmulti .thumbcaption{background-color:transparent}.mw-parser-output .tmulti .text-align-left{text-align:left}.mw-parser-output .tmulti .text-align-right{text-align:right}.mw-parser-output .tmulti .text-align-center{text-align:center}@media all and (max-width:720px){.mw-parser-output .tmulti .thumbinner{width:100%!important;box-sizing:border-box;max-width:none!important;align-items:center}.mw-parser-output .tmulti .trow{justify-content:center}.mw-parser-output .tmulti .tsingle{float:none!important;max-width:100%!important;box-sizing:border-box;text-align:center}.mw-parser-output .tmulti .tsingle .thumbcaption{text-align:left}.mw-parser-output .tmulti .trow>.thumbcaption{text-align:center}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .tmulti .multiimageinner img{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .tmulti .multiimageinner img{background-color:white}}</style><div class="thumb tmulti tleft"><div class="thumbinner multiimageinner" style="width:192px;max-width:192px"><div class="trow"><div class="tsingle" style="width:97px;max-width:97px"><div class="thumbimage" style="height:253px;overflow:hidden"><span typeof="mw:File"><a href="/wiki/File:Huygens_first_pendulum_clock_-_front_view.png" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/1/17/Huygens_first_pendulum_clock_-_front_view.png/95px-Huygens_first_pendulum_clock_-_front_view.png" decoding="async" width="95" height="252" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/17/Huygens_first_pendulum_clock_-_front_view.png/143px-Huygens_first_pendulum_clock_-_front_view.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/17/Huygens_first_pendulum_clock_-_front_view.png/190px-Huygens_first_pendulum_clock_-_front_view.png 2x" data-file-width="328" data-file-height="871" /></a></span></div></div><div class="tsingle" style="width:91px;max-width:91px"><div class="thumbimage" style="height:253px;overflow:hidden"><span typeof="mw:File"><a href="/wiki/File:Huygens_first_pendulum_clock.png" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/2/27/Huygens_first_pendulum_clock.png/89px-Huygens_first_pendulum_clock.png" decoding="async" width="89" height="254" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/27/Huygens_first_pendulum_clock.png/134px-Huygens_first_pendulum_clock.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/27/Huygens_first_pendulum_clock.png/178px-Huygens_first_pendulum_clock.png 2x" data-file-width="327" data-file-height="933" /></a></span></div></div></div><div class="trow" style="display:flex"><div class="thumbcaption">The first pendulum clock, designed by Christiaan Huygens in 1656</div></div></div></div> <p>The next development in accuracy occurred after 1656 with the invention of the <a href="/wiki/Pendulum_clock" title="Pendulum clock">pendulum clock</a>. <a href="/wiki/Galileo_Galilei" title="Galileo Galilei">Galileo</a> had the idea to use a swinging bob to regulate the motion of a time-telling device earlier in the 17th century. <a href="/wiki/Christiaan_Huygens" title="Christiaan Huygens">Christiaan Huygens</a>, however, is usually credited as the inventor. He determined the mathematical formula that related pendulum length to time (about 99.4 cm or 39.1 inches for the one second movement) and had the first pendulum-driven clock made. The first model clock was built in 1657 in <a href="/wiki/The_Hague" title="The Hague">the Hague</a>, but it was in England that the idea was taken up.<sup id="cite_ref-54" class="reference"><a href="#cite_note-54"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Longcase_clock" class="mw-redirect" title="Longcase clock">longcase clock</a> (also known as the <i>grandfather clock</i>) was created to house the pendulum and works by the English clockmaker William Clement in 1670 or 1671. It was also at this time that clock cases began to be made of wood and <a href="/wiki/Clock_face" title="Clock face">clock faces</a> to use <a href="/wiki/Vitreous_enamel" title="Vitreous enamel">enamel</a> as well as hand-painted ceramics. </p><p>In 1670, William Clement created the <a href="/wiki/Anchor_escapement" title="Anchor escapement">anchor escapement</a>,<sup id="cite_ref-55" class="reference"><a href="#cite_note-55"><span class="cite-bracket">[</span>55<span class="cite-bracket">]</span></a></sup> an improvement over Huygens' crown escapement. Clement also introduced the pendulum suspension spring in 1671. The concentric minute hand was added to the clock by <a href="/wiki/Daniel_Quare" title="Daniel Quare">Daniel Quare</a>, a London clockmaker and others, and the second hand was first introduced. </p> <div class="mw-heading mw-heading3"><h3 id="Hairspring">Hairspring</h3></div> <p>In 1675, Huygens and <a href="/wiki/Robert_Hooke" title="Robert Hooke">Robert Hooke</a> invented the <a href="/wiki/Spiral_balance" class="mw-redirect" title="Spiral balance">spiral balance spring</a>, or the hairspring, designed to control the oscillating speed of the <a href="/wiki/Balance_wheel" title="Balance wheel">balance wheel</a>. This crucial advance finally made accurate pocket watches possible. The great English clockmaker <a href="/wiki/Thomas_Tompion" title="Thomas Tompion">Thomas Tompion</a>, was one of the first to use this mechanism successfully in his <a href="/wiki/Pocket_watch" title="Pocket watch">pocket watches</a>, and he adopted the minute hand which, after a variety of designs were trialled, eventually stabilised into the modern-day configuration.<sup id="cite_ref-56" class="reference"><a href="#cite_note-56"><span class="cite-bracket">[</span>56<span class="cite-bracket">]</span></a></sup> The rack and snail striking mechanism for <a href="/wiki/Striking_clock" title="Striking clock">striking clocks</a>, was introduced during the 17th century and had distinct advantages over the 'countwheel' (or 'locking plate') mechanism. During the 20th century there was a common misconception that <a href="/wiki/Edward_Barlow_(priest)" title="Edward Barlow (priest)">Edward Barlow</a> invented <i><a href="/wiki/Rack_and_snail" class="mw-redirect" title="Rack and snail">rack and snail</a></i> striking. In fact, his invention was connected with a repeating mechanism employing the rack and snail.<sup id="cite_ref-57" class="reference"><a href="#cite_note-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Repeater_(horology)" title="Repeater (horology)">repeating clock</a>, that chimes the number of hours (or even minutes) on demand was invented by either Quare or Barlow in 1676. <a href="/wiki/George_Graham_(clockmaker)" title="George Graham (clockmaker)">George Graham</a> invented the <a href="/wiki/Escapement#Deadbeat_escapement" title="Escapement">deadbeat escapement</a> for clocks in 1720. </p> <div class="mw-heading mw-heading3"><h3 id="Marine_chronometer">Marine chronometer</h3></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Marine_chronometer" title="Marine chronometer">Marine chronometer</a></div> <p>A major stimulus to improving the accuracy and reliability of clocks was the importance of precise time-keeping for navigation. The position of a ship at sea could be determined with reasonable accuracy if a navigator could refer to a clock that lost or gained less than about 10 seconds per day. This clock could not contain a pendulum, which would be virtually useless on a rocking ship. In 1714, the British government offered large <a href="/wiki/Longitude_prize" class="mw-redirect" title="Longitude prize">financial rewards</a> to the value of 20,000 pounds<sup id="cite_ref-Rigden2003_58-0" class="reference"><a href="#cite_note-Rigden2003-58"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> for anyone who could determine longitude accurately. <a href="/wiki/John_Harrison" title="John Harrison">John Harrison</a>, who dedicated his life to improving the accuracy of his clocks, later received considerable sums under the Longitude Act. </p><p>In 1735, Harrison built his first chronometer, which he steadily improved on over the next thirty years before submitting it for examination. The clock had many innovations, including the use of bearings to reduce friction, weighted balances to compensate for the ship's pitch and roll in the sea and the use of two different metals to reduce the problem of expansion from heat. The chronometer was tested in 1761 by Harrison's son and by the end of 10 weeks the clock was in error by less than 5 seconds.<sup id="cite_ref-gould_59-0" class="reference"><a href="#cite_note-gould-59"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Mass_production">Mass production</h3></div> <p>The British had dominated watch manufacture for much of the 17th and 18th centuries, but maintained a system of production that was geared towards high quality products for the elite.<sup id="cite_ref-60" class="reference"><a href="#cite_note-60"><span class="cite-bracket">[</span>60<span class="cite-bracket">]</span></a></sup> Although there was an attempt to modernise clock manufacture with mass-production techniques and the application of duplicating tools and machinery by the British Watch Company in 1843, it was in the United States that this system took off. In 1816, <a href="/wiki/Eli_Terry" title="Eli Terry">Eli Terry</a> and some other Connecticut clockmakers developed a way of mass-producing clocks by using <a href="/wiki/Interchangeable_parts" title="Interchangeable parts">interchangeable parts</a>.<sup id="cite_ref-61" class="reference"><a href="#cite_note-61"><span class="cite-bracket">[</span>61<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Aaron_Lufkin_Dennison" title="Aaron Lufkin Dennison">Aaron Lufkin Dennison</a> started a factory in 1851 in <a href="/wiki/Massachusetts" title="Massachusetts">Massachusetts</a> that also used interchangeable parts, and by 1861 was running a successful enterprise incorporated as the <a href="/wiki/Waltham_Watch_Company" title="Waltham Watch Company">Waltham Watch Company</a>.<sup id="cite_ref-Roe1916_62-0" class="reference"><a href="#cite_note-Roe1916-62"><span class="cite-bracket">[</span>62<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-63" class="reference"><a href="#cite_note-63"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup> </p> <div style="clear:both;" class=""></div> <div class="mw-heading mw-heading3"><h3 id="Early_electric">Early electric</h3></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Electric_clock" title="Electric clock">Electric clock</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Pendule_electrique_l_maitrier_05117.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/66/Pendule_electrique_l_maitrier_05117.jpg/170px-Pendule_electrique_l_maitrier_05117.jpg" decoding="async" width="170" height="307" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/66/Pendule_electrique_l_maitrier_05117.jpg/255px-Pendule_electrique_l_maitrier_05117.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/66/Pendule_electrique_l_maitrier_05117.jpg/340px-Pendule_electrique_l_maitrier_05117.jpg 2x" data-file-width="354" data-file-height="640" /></a><figcaption>Early French electromagnetic clock</figcaption></figure> <p>In 1815, the English scientist <a href="/wiki/Francis_Ronalds" title="Francis Ronalds">Francis Ronalds</a> published the <a href="/wiki/Electric_clock#History" title="Electric clock">first electric clock</a> powered by <a href="/wiki/Voltaic_pile#Dry_pile" title="Voltaic pile">dry pile</a> batteries.<sup id="cite_ref-64" class="reference"><a href="#cite_note-64"><span class="cite-bracket">[</span>64<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Alexander_Bain_(inventor)" title="Alexander Bain (inventor)">Alexander Bain</a>, a Scottish clockmaker, patented the <a href="/wiki/Electric_clock" title="Electric clock">electric clock</a> in 1840. The electric clock's mainspring is wound either with an electric motor or with an <a href="/wiki/Electromagnet" title="Electromagnet">electromagnet</a> and armature. In 1841, he first patented the <a href="/wiki/Electromagnetism" title="Electromagnetism">electromagnetic</a> pendulum. By the end of the nineteenth century, the advent of the dry cell battery made it feasible to use electric power in clocks. Spring or weight driven clocks that use electricity, either <a href="/wiki/Alternating_current" title="Alternating current">alternating current</a> (AC) or <a href="/wiki/Direct_current" title="Direct current">direct current</a> (DC), to rewind the spring or raise the weight of a mechanical clock would be classified as an <a href="/wiki/Electromechanical_clock" class="mw-redirect" title="Electromechanical clock">electromechanical clock</a>. This classification would also apply to clocks that employ an electrical impulse to propel the pendulum. In electromechanical clocks the electricity serves no time keeping function. These types of clocks were made as individual timepieces but more commonly used in synchronized time installations in schools, businesses, factories, railroads and government facilities as a <a href="/wiki/Master_clock" title="Master clock">master clock</a> and <a href="/wiki/Slave_clocks" class="mw-redirect" title="Slave clocks">slave clocks</a>. </p><p>Where an <a href="/wiki/Alternating_current" title="Alternating current">AC</a> electrical supply of stable frequency is available, timekeeping can be maintained very reliably by using a <a href="/wiki/Synchronous_motor" title="Synchronous motor">synchronous motor</a>, essentially counting the cycles. The supply current alternates with an accurate frequency of 50 <a href="/wiki/Hertz" title="Hertz">hertz</a> in many countries, and 60 hertz in others. While the frequency may vary slightly during the day as the load changes, generators are designed to maintain an accurate number of cycles over a day, so the clock may be a fraction of a second slow or fast at any time, but will be perfectly accurate over a long time. The <a href="/wiki/Rotor_(electric)" title="Rotor (electric)">rotor</a> of the motor rotates at a speed that is related to the alternation frequency. Appropriate gearing converts this rotation speed to the correct ones for the hands of the analog clock. Time in these cases is measured in several ways, such as by counting the cycles of the AC supply, vibration of a <a href="/wiki/Tuning_fork" title="Tuning fork">tuning fork</a>, the behaviour of <a href="/wiki/Quartz" title="Quartz">quartz</a> crystals, or the quantum vibrations of atoms. Electronic circuits divide these high-frequency oscillations to slower ones that drive the time display. </p> <div class="mw-heading mw-heading3"><h3 id="Quartz">Quartz</h3></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Inside_QuartzCrystal-Tuningfork.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Inside_QuartzCrystal-Tuningfork.jpg/220px-Inside_QuartzCrystal-Tuningfork.jpg" decoding="async" width="220" height="261" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Inside_QuartzCrystal-Tuningfork.jpg/330px-Inside_QuartzCrystal-Tuningfork.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Inside_QuartzCrystal-Tuningfork.jpg/440px-Inside_QuartzCrystal-Tuningfork.jpg 2x" data-file-width="640" data-file-height="759" /></a><figcaption>Picture of a quartz crystal resonator, used as the timekeeping component in quartz watches and clocks, with the case removed. It is formed in the shape of a tuning fork. Most such quartz clock crystals vibrate at a frequency of <span class="nowrap"><span data-sort-value="7004327680000000000♠"></span>32<span style="margin-left:.25em;">768</span> Hz</span>.</figcaption></figure> <p>The <a href="/wiki/Piezoelectric" class="mw-redirect" title="Piezoelectric">piezoelectric</a> properties of crystalline <a href="/wiki/Quartz" title="Quartz">quartz</a> were discovered by <a href="/wiki/Jacques_Curie" class="mw-redirect" title="Jacques Curie">Jacques</a> and <a href="/wiki/Pierre_Curie" title="Pierre Curie">Pierre Curie</a> in 1880.<sup id="cite_ref-nistrevolution_65-0" class="reference"><a href="#cite_note-nistrevolution-65"><span class="cite-bracket">[</span>65<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-66" class="reference"><a href="#cite_note-66"><span class="cite-bracket">[</span>66<span class="cite-bracket">]</span></a></sup> The first crystal oscillator was invented in 1917 by <a href="/wiki/Alexander_M._Nicholson" title="Alexander M. Nicholson">Alexander M. Nicholson</a>, after which the first quartz crystal oscillator was built by <a href="/wiki/Walter_Guyton_Cady" title="Walter Guyton Cady">Walter G. Cady</a> in 1921.<sup id="cite_ref-Marrison_2-2" class="reference"><a href="#cite_note-Marrison-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> In 1927 the first <a href="/wiki/Quartz_clock" title="Quartz clock">quartz clock</a> was built by Warren Marrison and J.W. Horton at <a href="/wiki/Bell_Telephone_Laboratories" class="mw-redirect" title="Bell Telephone Laboratories">Bell Telephone Laboratories</a> in Canada.<sup id="cite_ref-Marrison2_67-0" class="reference"><a href="#cite_note-Marrison2-67"><span class="cite-bracket">[</span>67<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Marrison_2-3" class="reference"><a href="#cite_note-Marrison-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The following decades saw the development of quartz clocks as precision time measurement devices in laboratory settings—the bulky and delicate counting electronics, built with <a href="/wiki/Vacuum_tube" title="Vacuum tube">vacuum tubes</a> at the time, limited their practical use elsewhere. The National Bureau of Standards (now <a href="/wiki/NIST" class="mw-redirect" title="NIST">NIST</a>) based the time standard of the United States on quartz clocks from late 1929 until the 1960s, when it changed to atomic clocks.<sup id="cite_ref-Sullivan_68-0" class="reference"><a href="#cite_note-Sullivan-68"><span class="cite-bracket">[</span>68<span class="cite-bracket">]</span></a></sup> In 1969, <a href="/wiki/Seiko" title="Seiko">Seiko</a> produced the world's first quartz <a href="/wiki/Watch" title="Watch">wristwatch</a>, the <a href="/wiki/Astron_(wristwatch)" title="Astron (wristwatch)">Astron</a>.<sup id="cite_ref-69" class="reference"><a href="#cite_note-69"><span class="cite-bracket">[</span>69<span class="cite-bracket">]</span></a></sup> Their inherent accuracy and low cost of production resulted in the subsequent proliferation of quartz clocks and watches.<sup id="cite_ref-nistrevolution_65-1" class="reference"><a href="#cite_note-nistrevolution-65"><span class="cite-bracket">[</span>65<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Atomic">Atomic</h3></div> <p>Currently, <a href="/wiki/Atomic_clock" title="Atomic clock">atomic clocks</a> are the most accurate clocks in existence. They are considerably more accurate than <a href="/wiki/Quartz_clock" title="Quartz clock">quartz clocks</a> as they can be accurate to within a few seconds over trillions of years.<sup id="cite_ref-70" class="reference"><a href="#cite_note-70"><span class="cite-bracket">[</span>70<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-auto_71-0" class="reference"><a href="#cite_note-auto-71"><span class="cite-bracket">[</span>71<span class="cite-bracket">]</span></a></sup> Atomic clocks were first theorized by <a href="/wiki/Lord_Kelvin" title="Lord Kelvin">Lord Kelvin</a> in 1879.<sup id="cite_ref-72" class="reference"><a href="#cite_note-72"><span class="cite-bracket">[</span>72<span class="cite-bracket">]</span></a></sup> In the 1930s the development of <a href="/wiki/Nuclear_magnetic_resonance" title="Nuclear magnetic resonance">magnetic resonance</a> created practical method for doing this.<sup id="cite_ref-Lombardi_73-0" class="reference"><a href="#cite_note-Lombardi-73"><span class="cite-bracket">[</span>73<span class="cite-bracket">]</span></a></sup> A prototype <a href="/wiki/Ammonia" title="Ammonia">ammonia</a> <a href="/wiki/Maser" title="Maser">maser</a> device was built in 1949 at the U.S. <a href="/wiki/National_Bureau_of_Standards" class="mw-redirect" title="National Bureau of Standards">National Bureau of Standards</a> (NBS, now <a href="/wiki/National_Institute_of_Standards_and_Technology" title="National Institute of Standards and Technology">NIST</a>). Although it was less accurate than existing <a href="/wiki/Quartz_clock" title="Quartz clock">quartz clocks</a>, it served to demonstrate the concept.<sup id="cite_ref-74" class="reference"><a href="#cite_note-74"><span class="cite-bracket">[</span>74<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-NISTshistorymeasuring_75-0" class="reference"><a href="#cite_note-NISTshistorymeasuring-75"><span class="cite-bracket">[</span>75<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-nistatomic_76-0" class="reference"><a href="#cite_note-nistatomic-76"><span class="cite-bracket">[</span>76<span class="cite-bracket">]</span></a></sup> The first accurate atomic clock, a <a href="/wiki/Caesium_standard" title="Caesium standard">caesium standard</a> based on a certain transition of the <a href="/wiki/Caesium-133" class="mw-redirect" title="Caesium-133">caesium-133</a> atom, was built by <a href="/wiki/Louis_Essen" title="Louis Essen">Louis Essen</a> in 1955 at the <a href="/wiki/National_Physical_Laboratory,_UK" class="mw-redirect" title="National Physical Laboratory, UK">National Physical Laboratory</a> in the UK.<sup id="cite_ref-77" class="reference"><a href="#cite_note-77"><span class="cite-bracket">[</span>77<span class="cite-bracket">]</span></a></sup> Calibration of the caesium standard atomic clock was carried out by the use of the astronomical time scale <i><a href="/wiki/Ephemeris_time" title="Ephemeris time">ephemeris time</a></i> (ET).<sup id="cite_ref-78" class="reference"><a href="#cite_note-78"><span class="cite-bracket">[</span>78<span class="cite-bracket">]</span></a></sup> As of 2013, the most stable atomic clocks are <a href="/wiki/Ytterbium" title="Ytterbium">ytterbium</a> clocks, which are stable to within less than two parts in 1 quintillion (<span class="nowrap"><span data-sort-value="6982200000000000000♠"></span>2<span style="margin-left:0.25em;margin-right:0.15em;">×</span>10<sup>−18</sup></span>).<sup id="cite_ref-auto_71-1" class="reference"><a href="#cite_note-auto-71"><span class="cite-bracket">[</span>71<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Operation">Operation</h2></div> <p>The invention of the mechanical clock in the 13th century initiated a change in timekeeping methods from continuous processes, such as the motion of the <a href="/wiki/Gnomon" title="Gnomon">gnomon</a>'s shadow on a sundial or the flow of liquid in a water clock, to periodic oscillatory processes, such as the swing of a pendulum or the vibration of a <a href="/wiki/Crystal_oscillator" title="Crystal oscillator">quartz crystal</a>,<sup id="cite_ref-Cipolla_3-1" class="reference"><a href="#cite_note-Cipolla-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Marrison1_79-0" class="reference"><a href="#cite_note-Marrison1-79"><span class="cite-bracket">[</span>79<span class="cite-bracket">]</span></a></sup> which had the potential for more accuracy. All modern clocks use oscillation. </p><p>Although the mechanisms they use vary, all oscillating clocks, mechanical, electric, and atomic, work similarly and can be divided into analogous parts.<sup id="cite_ref-Jespersen_80-0" class="reference"><a href="#cite_note-Jespersen-80"><span class="cite-bracket">[</span>80<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-81" class="reference"><a href="#cite_note-81"><span class="cite-bracket">[</span>81<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Milham_82-0" class="reference"><a href="#cite_note-Milham-82"><span class="cite-bracket">[</span>82<span class="cite-bracket">]</span></a></sup> They consist of an object that repeats the same motion over and over again, an <i><a href="/wiki/Oscillator" class="mw-redirect" title="Oscillator">oscillator</a></i>, with a precisely constant time interval between each repetition, or 'beat'. Attached to the oscillator is a <i>controller</i> device, which sustains the oscillator's motion by replacing the energy it loses to <a href="/wiki/Friction" title="Friction">friction</a>, and converts its oscillations into a series of pulses. The pulses are then counted by some type of <i>counter</i>, and the number of counts is converted into convenient units, usually seconds, minutes, hours, etc. Finally some kind of <i>indicator</i> displays the result in human readable form. </p> <div class="mw-heading mw-heading3"><h3 id="Power_source">Power source</h3></div> <style data-mw-deduplicate="TemplateStyles:r852221607">.mw-parser-output .flowlist ul{overflow-x:hidden;margin-left:0;padding-left:1.6em}.mw-parser-output .flowlist ol{overflow-x:hidden;margin-left:0;padding-left:3.2em}.mw-parser-output .flowlist dl{overflow-x:hidden}</style><div class="flowlist"> <ul><li>In mechanical clocks, the power source is typically either a weight suspended from a cord or chain wrapped around a <a href="/wiki/Pulley" title="Pulley">pulley</a>, <a href="/wiki/Sprocket" title="Sprocket">sprocket</a> or drum; or a spiral spring called a <a href="/wiki/Mainspring" title="Mainspring">mainspring</a>. Mechanical clocks must be <i>wound</i> periodically, usually by turning a knob or key or by pulling on the free end of the chain, to store energy in the weight or spring to keep the clock running.</li> <li>In <a href="/wiki/Electric_clock" title="Electric clock">electric clocks</a>, the power source is either a <a href="/wiki/Battery_(electricity)" class="mw-redirect" title="Battery (electricity)">battery</a> or the <a href="/wiki/Mains_power" class="mw-redirect" title="Mains power">AC power line</a>. In clocks that use AC power, a small backup battery is often included to keep the clock running if it is unplugged temporarily from the wall or during a power outage. Battery-powered analog wall clocks are available that operate over 15 years between battery changes.</li></ul> </div> <div style="clear:both;" class=""></div> <div class="mw-heading mw-heading3"><h3 id="Oscillator">Oscillator</h3></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Floating_Balance_Escapement.gif" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1d/Floating_Balance_Escapement.gif/220px-Floating_Balance_Escapement.gif" decoding="async" width="220" height="220" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/1/1d/Floating_Balance_Escapement.gif 1.5x" data-file-width="244" data-file-height="244" /></a><figcaption><a href="/wiki/Balance_wheel" title="Balance wheel">Balance wheel</a>, the oscillator in a mechanical <a href="/wiki/Mantel_clock" title="Mantel clock">mantel clock</a>. </figcaption></figure> <p>The timekeeping element in every modern clock is a <a href="/wiki/Harmonic_oscillator" title="Harmonic oscillator">harmonic oscillator</a>, a physical object (<a href="/wiki/Resonator" title="Resonator">resonator</a>) that vibrates or oscillates repetitively at a precisely constant frequency.<sup id="cite_ref-Marrison_2-4" class="reference"><a href="#cite_note-Marrison-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Mondschein_83-0" class="reference"><a href="#cite_note-Mondschein-83"><span class="cite-bracket">[</span>83<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Britannica_84-0" class="reference"><a href="#cite_note-Britannica-84"><span class="cite-bracket">[</span>84<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Bloomfield_85-0" class="reference"><a href="#cite_note-Bloomfield-85"><span class="cite-bracket">[</span>85<span class="cite-bracket">]</span></a></sup> </p> <ul><li>In mechanical clocks, this is either a pendulum or a <a href="/wiki/Balance_wheel" title="Balance wheel">balance wheel</a>.</li> <li>In some early electronic clocks and watches such as the <a href="/wiki/Accutron" class="mw-redirect" title="Accutron">Accutron</a>, they use a <a href="/wiki/Tuning_fork" title="Tuning fork">tuning fork</a>.</li> <li>In <a href="/wiki/Quartz_clock" title="Quartz clock">quartz clocks</a> and watches, it is a <a href="/wiki/Crystal_oscillator" title="Crystal oscillator">quartz crystal</a>.</li> <li>In <a href="/wiki/Atomic_clock" title="Atomic clock">atomic clocks</a>, it is the vibration of electrons in atoms as they emit microwaves.</li> <li>In early mechanical clocks before 1657, it was a crude balance wheel or <a href="/wiki/Verge_escapement" title="Verge escapement">foliot</a> which was not a harmonic oscillator because it lacked a <a href="/wiki/Balance_spring" title="Balance spring">balance spring</a>. As a result, they were very inaccurate, with errors of perhaps an hour a day.<sup id="cite_ref-86" class="reference"><a href="#cite_note-86"><span class="cite-bracket">[</span>86<span class="cite-bracket">]</span></a></sup></li></ul> <p>The advantage of a harmonic oscillator over other forms of oscillator is that it employs <a href="/wiki/Resonance" title="Resonance">resonance</a> to vibrate at a precise natural <a href="/wiki/Resonant_frequency" class="mw-redirect" title="Resonant frequency">resonant frequency</a> or "beat" dependent only on its physical characteristics, and resists vibrating at other rates. The possible precision achievable by a harmonic oscillator is measured by a parameter called its <a href="/wiki/Q_factor" title="Q factor">Q</a>,<sup id="cite_ref-87" class="reference"><a href="#cite_note-87"><span class="cite-bracket">[</span>87<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-88" class="reference"><a href="#cite_note-88"><span class="cite-bracket">[</span>88<span class="cite-bracket">]</span></a></sup> or quality factor, which increases (other things being equal) with its resonant frequency.<sup id="cite_ref-89" class="reference"><a href="#cite_note-89"><span class="cite-bracket">[</span>89<span class="cite-bracket">]</span></a></sup> This is why there has been a long-term trend toward higher frequency oscillators in clocks. Balance wheels and pendulums always include a means of adjusting the rate of the timepiece. Quartz timepieces sometimes include a rate screw that adjusts a <a href="/wiki/Capacitor" title="Capacitor">capacitor</a> for that purpose. Atomic clocks are <a href="/wiki/Standard_(technical)" class="mw-redirect" title="Standard (technical)">primary standards</a>, and their rate cannot be adjusted. </p> <div class="mw-heading mw-heading4"><h4 id="Synchronized_or_slave_clocks">Synchronized or slave clocks</h4></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Greenwich_clock_1-manipulated.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/61/Greenwich_clock_1-manipulated.jpg/220px-Greenwich_clock_1-manipulated.jpg" decoding="async" width="220" height="196" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/61/Greenwich_clock_1-manipulated.jpg/330px-Greenwich_clock_1-manipulated.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/61/Greenwich_clock_1-manipulated.jpg/440px-Greenwich_clock_1-manipulated.jpg 2x" data-file-width="2215" data-file-height="1972" /></a><figcaption>The <a href="/wiki/Shepherd_Gate_Clock" title="Shepherd Gate Clock">Shepherd Gate Clock</a> at the <a href="/wiki/Royal_Observatory,_Greenwich" title="Royal Observatory, Greenwich">Royal Observatory, Greenwich</a> receives its timing signal from within the <a href="/wiki/Royal_Observatory,_Greenwich" title="Royal Observatory, Greenwich">Royal Observatory, Greenwich</a>.</figcaption></figure> <p>Some clocks rely for their accuracy on an external oscillator; that is, they are automatically synchronized to a more accurate clock: </p> <ul><li><a href="/wiki/Slave_clock" title="Slave clock">Slave clocks</a>, used in large institutions and schools from the 1860s to the 1970s, kept time with a pendulum, but were wired to a <a href="/wiki/Master_clock" title="Master clock">master clock</a> in the building, and periodically received a signal to synchronize them with the master, often on the hour.<sup id="cite_ref-90" class="reference"><a href="#cite_note-90"><span class="cite-bracket">[</span>90<span class="cite-bracket">]</span></a></sup> Later versions without pendulums were triggered by a pulse from the master clock and certain sequences used to force rapid synchronization following a power failure.</li></ul> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Telechron_clock_2H07-Br_Administrator.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Telechron_clock_2H07-Br_Administrator.JPG/220px-Telechron_clock_2H07-Br_Administrator.JPG" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Telechron_clock_2H07-Br_Administrator.JPG/330px-Telechron_clock_2H07-Br_Administrator.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Telechron_clock_2H07-Br_Administrator.JPG/440px-Telechron_clock_2H07-Br_Administrator.JPG 2x" data-file-width="1600" data-file-height="1200" /></a><figcaption>Synchronous electric clock, around 1940. By 1940 the synchronous clock became the most common type of clock in the U.S.</figcaption></figure> <ul><li>Synchronous electric clocks do not have an internal oscillator, but count cycles of the 50 or 60 <a href="/wiki/Hertz" title="Hertz">Hz</a> oscillation of the AC power line, which is synchronized by the utility to a precision oscillator. The counting may be done electronically, usually in clocks with digital displays, or, in analog clocks, the AC may drive a <a href="/wiki/Synchronous_motor" title="Synchronous motor">synchronous motor</a> which rotates an exact fraction of a revolution for every cycle of the line voltage, and drives the gear train. Although changes in the grid line frequency due to load variations may cause the clock to temporarily gain or lose several seconds during the course of a day, the total number of cycles per 24 hours is maintained extremely accurately by the utility company, so that the clock keeps time accurately over long periods.</li> <li>Computer <a href="/wiki/Real-time_clock" title="Real-time clock">real-time clocks</a> keep time with a quartz crystal, but can be periodically (usually weekly) synchronized over the <a href="/wiki/Internet" title="Internet">Internet</a> to atomic clocks (<a href="/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time">UTC</a>), using the <a href="/wiki/Network_Time_Protocol" title="Network Time Protocol">Network Time Protocol</a> (NTP).</li> <li><a href="/wiki/Radio_clock" title="Radio clock">Radio clocks</a> keep time with a quartz crystal, but are periodically synchronized to <a href="/wiki/Radio_time_signal" class="mw-redirect" title="Radio time signal">time signals</a> transmitted from dedicated <a href="/wiki/Radio_clock#List_of_radio_time_signal_stations" title="Radio clock">standard time radio stations</a> or <a href="/wiki/Satellite_navigation" title="Satellite navigation">satellite navigation</a> signals, which are set by atomic clocks.</li></ul> <div class="mw-heading mw-heading3"><h3 id="Controller">Controller</h3></div> <p>This has the dual function of keeping the oscillator running by giving it 'pushes' to replace the energy lost to <a href="/wiki/Friction" title="Friction">friction</a>, and converting its vibrations into a series of pulses that serve to measure the time. </p> <ul><li>In mechanical clocks, this is the <a href="/wiki/Escapement" title="Escapement">escapement</a>, which gives precise pushes to the swinging pendulum or balance wheel, and releases one gear tooth of the <i>escape wheel</i> at each swing, allowing all the clock's wheels to move forward a fixed amount with each swing.</li> <li>In electronic clocks this is an <a href="/wiki/Electronic_oscillator" title="Electronic oscillator">electronic oscillator circuit</a> that gives the vibrating quartz crystal or tuning fork tiny 'pushes', and generates a series of electrical pulses, one for each vibration of the crystal, which is called the <a href="/wiki/Clock_signal" title="Clock signal">clock signal</a>.</li> <li>In atomic clocks the controller is an evacuated microwave <a href="/wiki/Cavity_resonator" class="mw-redirect" title="Cavity resonator">cavity</a> attached to a microwave <a href="/wiki/Electronic_oscillator" title="Electronic oscillator">oscillator</a> controlled by a <a href="/wiki/Microprocessor" title="Microprocessor">microprocessor</a>. A thin gas of <a href="/wiki/Caesium" title="Caesium">caesium</a> atoms is released into the cavity where they are exposed to microwaves. A laser measures how many atoms have absorbed the microwaves, and an electronic feedback control system called a <a href="/wiki/Phase-locked_loop" title="Phase-locked loop">phase-locked loop</a> tunes the microwave oscillator until it is at the frequency that causes the atoms to vibrate and absorb the microwaves. Then the microwave signal is divided by <a href="/wiki/Digital_counter" class="mw-redirect" title="Digital counter">digital counters</a> to become the <a href="/wiki/Clock_signal" title="Clock signal">clock signal</a>.<sup id="cite_ref-91" class="reference"><a href="#cite_note-91"><span class="cite-bracket">[</span>91<span class="cite-bracket">]</span></a></sup></li></ul> <p>In mechanical clocks, the low <a href="/wiki/Q_factor" title="Q factor">Q</a> of the balance wheel or pendulum oscillator made them very sensitive to the disturbing effect of the impulses of the escapement, so the escapement had a great effect on the accuracy of the clock, and many escapement designs were tried. The higher Q of resonators in electronic clocks makes them relatively insensitive to the disturbing effects of the drive power, so the driving oscillator circuit is a much less critical component.<sup id="cite_ref-Marrison_2-5" class="reference"><a href="#cite_note-Marrison-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Counter_chain">Counter chain</h3></div> <p>This counts the pulses and adds them up to get traditional time units of seconds, minutes, hours, etc. It usually has a provision for <i>setting</i> the clock by manually entering the correct time into the counter. </p> <ul><li>In mechanical clocks this is done mechanically by a <a href="/wiki/Gear_train" title="Gear train">gear train</a>, known as the <a href="/wiki/Wheel_train_(horology)" class="mw-redirect" title="Wheel train (horology)">wheel train</a>. The gear train also has a second function; to transmit mechanical power from the power source to run the oscillator. There is a friction coupling called the 'cannon pinion' between the gears driving the hands and the rest of the clock, allowing the hands to be turned to set the time.<sup id="cite_ref-92" class="reference"><a href="#cite_note-92"><span class="cite-bracket">[</span>92<span class="cite-bracket">]</span></a></sup></li> <li>In digital clocks a series of <a href="/wiki/Integrated_circuit" title="Integrated circuit">integrated circuit</a> <a href="/wiki/Counter_(digital)" title="Counter (digital)">counters</a> or dividers add the pulses up <a href="/wiki/Digital_data" title="Digital data">digitally</a>, using <a href="/wiki/Binary_numeral_system" class="mw-redirect" title="Binary numeral system">binary</a> logic. Often pushbuttons on the case allow the hour and minute counters to be incremented and decremented to set the time.</li></ul> <div class="mw-heading mw-heading3"><h3 id="Indicator">Indicator</h3></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><span><video id="mwe_player_0" poster="//upload.wikimedia.org/wikipedia/commons/thumb/a/a1/Cuckoo_strikes_the_8th_hour.ogv/220px--Cuckoo_strikes_the_8th_hour.ogv.jpg" controls="" preload="none" data-mw-tmh="" class="mw-file-element" width="220" height="165" data-durationhint="36" data-mwtitle="Cuckoo_strikes_the_8th_hour.ogv" data-mwprovider="wikimediacommons" resource="/wiki/File:Cuckoo_strikes_the_8th_hour.ogv"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/a/a1/Cuckoo_strikes_the_8th_hour.ogv/Cuckoo_strikes_the_8th_hour.ogv.240p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="240p.vp9.webm" data-width="320" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/a/a1/Cuckoo_strikes_the_8th_hour.ogv" type="video/ogg; codecs="theora, vorbis"" data-width="320" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/a/a1/Cuckoo_strikes_the_8th_hour.ogv/Cuckoo_strikes_the_8th_hour.ogv.360p.webm" type="video/webm; codecs="vp8, vorbis"" data-transcodekey="360p.webm" data-width="320" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/a/a1/Cuckoo_strikes_the_8th_hour.ogv/Cuckoo_strikes_the_8th_hour.ogv.144p.mjpeg.mov" type="video/quicktime" data-transcodekey="144p.mjpeg.mov" data-width="192" data-height="144" /></video></span><figcaption>A <a href="/wiki/Cuckoo_clock" title="Cuckoo clock">cuckoo clock</a> with mechanical automaton and sound producer striking on the eighth hour on the analog dial</figcaption></figure> <p>This displays the count of seconds, minutes, hours, etc. in a human readable form. </p> <ul><li>The earliest mechanical clocks in the 13th century did not have a visual indicator and signalled the time audibly by striking bells. Many clocks to this day are <a href="/wiki/Striking_clock" title="Striking clock">striking clocks</a> which strike the hour.</li> <li>Analog clocks display time with an analog <a href="/wiki/Clock_face" title="Clock face">clock face</a>, which consists of a dial with the numbers 1 through 12 or 24, the hours in the day, around the outside. The hours are indicated with an <a href="/wiki/Hour_hand" class="mw-redirect" title="Hour hand">hour hand</a>, which makes one or two revolutions in a day, while the minutes are indicated by a <a href="/wiki/Clock_face" title="Clock face">minute hand</a>, which makes one revolution per hour. In mechanical clocks a gear train drives the hands; in electronic clocks the circuit produces pulses every second which drive a <a href="/wiki/Stepper_motor" title="Stepper motor">stepper motor</a> and gear train, which move the hands.</li> <li><a href="/wiki/Digital_clock" title="Digital clock">Digital clocks</a> display the time in periodically changing digits on a digital display. A common misconception is that a digital clock is more accurate than an analog wall clock, but the indicator type is separate and apart from the accuracy of the timing source.</li> <li><a href="/wiki/Talking_clock" title="Talking clock">Talking clocks</a> and the <a href="/wiki/Speaking_clock" title="Speaking clock">speaking clock</a> services provided by telephone companies speak the time audibly, using either recorded or digitally <a href="/wiki/Voice_synthesis" class="mw-redirect" title="Voice synthesis">synthesized voices</a>.</li></ul> <div class="mw-heading mw-heading2"><h2 id="Types">Types</h2></div> <p>Clocks can be classified by the type of time display, as well as by the method of timekeeping. </p> <div class="mw-heading mw-heading3"><h3 id="Time_display_methods">Time display methods</h3></div> <div class="mw-heading mw-heading4"><h4 id="Analog">Analog</h4></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/Clock_face" title="Clock face">Clock face</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Rew17h09_1977.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Rew17h09_1977.jpg/220px-Rew17h09_1977.jpg" decoding="async" width="220" height="240" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Rew17h09_1977.jpg/330px-Rew17h09_1977.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Rew17h09_1977.jpg/440px-Rew17h09_1977.jpg 2x" data-file-width="1930" data-file-height="2107" /></a><figcaption>A modern quartz clock with a 24-hour face</figcaption></figure> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Picadillycircuslinearclock.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Picadillycircuslinearclock.jpg/220px-Picadillycircuslinearclock.jpg" decoding="async" width="220" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Picadillycircuslinearclock.jpg/330px-Picadillycircuslinearclock.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Picadillycircuslinearclock.jpg/440px-Picadillycircuslinearclock.jpg 2x" data-file-width="896" data-file-height="600" /></a><figcaption>A linear clock at London's <a href="/wiki/Piccadilly_Circus_tube_station" title="Piccadilly Circus tube station">Piccadilly Circus tube station</a>. The 24 hour band moves across the static map, keeping pace with the apparent movement of the sun above ground, and a pointer fixed on London points to the current time.</figcaption></figure> <p>Analog clocks usually use a <a href="/wiki/Clock_face" title="Clock face">clock face</a> which indicates time using rotating pointers called "hands" on a fixed numbered dial or dials. The standard clock face, known universally throughout the world, has a short "hour hand" which indicates the hour on a circular dial of 12 <a href="/wiki/Hour" title="Hour">hours</a>, making two revolutions per day, and a longer "minute hand" which indicates the minutes in the current hour on the same dial, which is also divided into 60 minutes. It may also have a "second hand" which indicates the seconds in the current minute. The only other widely used clock face today is the <a href="/wiki/24_hour_analog_dial" class="mw-redirect" title="24 hour analog dial">24 hour analog dial</a>, because of the use of <a href="/wiki/24_hour_time" class="mw-redirect" title="24 hour time">24 hour time</a> in military organizations and timetables. Before the modern clock face was standardized during the <a href="/wiki/Industrial_Revolution" title="Industrial Revolution">Industrial Revolution</a>, many other face designs were used throughout the years, including dials divided into 6, 8, 10, and 24 hours. During the <a href="/wiki/French_Revolution" title="French Revolution">French Revolution</a> the French government tried to introduce a <a href="/wiki/10-hour_clock" class="mw-redirect" title="10-hour clock">10-hour clock</a>, as part of their decimal-based <a href="/wiki/Metric_system" title="Metric system">metric system</a> of measurement, but it did not achieve widespread use. An Italian 6 hour clock was developed in the 18th century, presumably to save power (a clock or watch striking 24 times uses more power). </p><p>Another type of analog clock is the sundial, which tracks the sun continuously, registering the time by the shadow position of its <a href="/wiki/Gnomon" title="Gnomon">gnomon</a>. Because the sun does not adjust to daylight saving time, users must add an hour during that time. Corrections must also be made for the <a href="/wiki/Equation_of_time" title="Equation of time">equation of time</a>, and for the difference between the longitudes of the sundial and of the central meridian of the <a href="/wiki/Time_zone" title="Time zone">time zone</a> that is being used (i.e. 15 degrees east of the <a href="/wiki/Prime_meridian" title="Prime meridian">prime meridian</a> for each hour that the time zone is ahead of <a href="/wiki/GMT" class="mw-redirect" title="GMT">GMT</a>). Sundials use some or part of the 24 hour analog dial. There also exist clocks which use a digital display despite having an analog mechanism—these are commonly referred to as <a href="/wiki/Flip_clock" title="Flip clock">flip clocks</a>. Alternative systems have been proposed. For example, the "Twelv" clock indicates the current hour using one of twelve colors, and indicates the minute by showing a proportion of a circular disk, similar to a <a href="/wiki/Lunar_phase" title="Lunar phase">moon phase</a>.<sup id="cite_ref-93" class="reference"><a href="#cite_note-93"><span class="cite-bracket">[</span>93<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Digital">Digital</h4></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Digital_clock" title="Digital clock">Digital clock</a></div> <ul class="gallery mw-gallery-packed-hover"> <li class="gallerycaption">Examples of digital clocks</li> <li class="gallerybox" style="width: 224px"> <div class="thumb" style="width: 222px;"><span typeof="mw:File"><a href="/wiki/File:Kanazawa_Station_Water_Clock.jpg" class="mw-file-description" title="Digital clock displaying time by controlling valves on the fountain"><img alt="Digital clock displaying time by controlling valves on the fountain" src="//upload.wikimedia.org/wikipedia/commons/thumb/2/2f/Kanazawa_Station_Water_Clock.jpg/333px-Kanazawa_Station_Water_Clock.jpg" decoding="async" width="222" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/2f/Kanazawa_Station_Water_Clock.jpg/501px-Kanazawa_Station_Water_Clock.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/2f/Kanazawa_Station_Water_Clock.jpg/666px-Kanazawa_Station_Water_Clock.jpg 2x" data-file-width="1818" data-file-height="1228" /></a></span></div> <div class="gallerytextwrapper" style="width: 202px"><div class="gallerytext">Digital clock displaying time by controlling valves on the fountain</div> </div> </li> <li class="gallerybox" style="width: 226px"> <div class="thumb" style="width: 224px;"><span typeof="mw:File"><a href="/wiki/File:Digital-clock-radio-basic_hf.jpg" class="mw-file-description" title="Simplistic digital clock radio"><img alt="Simplistic digital clock radio" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/43/Digital-clock-radio-basic_hf.jpg/336px-Digital-clock-radio-basic_hf.jpg" decoding="async" width="224" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/43/Digital-clock-radio-basic_hf.jpg/505px-Digital-clock-radio-basic_hf.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/43/Digital-clock-radio-basic_hf.jpg/673px-Digital-clock-radio-basic_hf.jpg 2x" data-file-width="2002" data-file-height="1340" /></a></span></div> <div class="gallerytextwrapper" style="width: 204px"><div class="gallerytext">Simplistic digital clock radio</div> </div> </li> <li class="gallerybox" style="width: 174.66666666667px"> <div class="thumb" style="width: 172.66666666667px;"><span typeof="mw:File"><a href="/wiki/File:Analog_clock_with_digital_display.png" class="mw-file-description" title="Diagram of a mechanical digital display of a flip clock"><img alt="Diagram of a mechanical digital display of a flip clock" src="//upload.wikimedia.org/wikipedia/commons/thumb/5/5e/Analog_clock_with_digital_display.png/259px-Analog_clock_with_digital_display.png" decoding="async" width="173" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/5e/Analog_clock_with_digital_display.png/389px-Analog_clock_with_digital_display.png 1.5x, //upload.wikimedia.org/wikipedia/commons/5/5e/Analog_clock_with_digital_display.png 2x" data-file-width="500" data-file-height="435" /></a></span></div> <div class="gallerytextwrapper" style="width: 153px"><div class="gallerytext">Diagram of a mechanical digital display of a <a href="/wiki/Flip_clock" title="Flip clock">flip clock</a></div> </div> </li> <li class="gallerybox" style="width: 102px"> <div class="thumb" style="width: 100px;"><span typeof="mw:File"><a href="/wiki/File:SAMSUNG_Galaxy_S22_Ultra_BLACK.jpg" class="mw-file-description" title="A digital clock on a Samsung Galaxy smartphone"><img alt="A digital clock on a Samsung Galaxy smartphone" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a0/SAMSUNG_Galaxy_S22_Ultra_BLACK.jpg/150px-SAMSUNG_Galaxy_S22_Ultra_BLACK.jpg" decoding="async" width="100" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a0/SAMSUNG_Galaxy_S22_Ultra_BLACK.jpg/226px-SAMSUNG_Galaxy_S22_Ultra_BLACK.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a0/SAMSUNG_Galaxy_S22_Ultra_BLACK.jpg/301px-SAMSUNG_Galaxy_S22_Ultra_BLACK.jpg 2x" data-file-width="3481" data-file-height="5200" /></a></span></div> <div class="gallerytextwrapper" style="width: 80px"><div class="gallerytext">A digital clock on a <a href="/wiki/Samsung_Galaxy" title="Samsung Galaxy">Samsung Galaxy</a> smartphone</div> </div> </li> </ul> <p>Digital clocks display a numeric representation of time. Two numeric display formats are commonly used on <a href="/wiki/Digital_data" title="Digital data">digital</a> clocks: </p> <ul><li>the <a href="/wiki/24-hour_notation" class="mw-redirect" title="24-hour notation">24-hour notation</a> with hours ranging 00–23;</li> <li>the <a href="/wiki/12-hour_notation" class="mw-redirect" title="12-hour notation">12-hour notation</a> with AM/PM indicator, with hours indicated as 12AM, followed by 1AM–11AM, followed by 12PM, followed by 1PM–11PM (a notation mostly used in domestic environments).</li></ul> <p>Most digital clocks use electronic mechanisms and <a href="/wiki/LCD" class="mw-redirect" title="LCD">LCD</a>, <a href="/wiki/LED" class="mw-redirect" title="LED">LED</a>, or <a href="/wiki/Vacuum_fluorescent_display" title="Vacuum fluorescent display">VFD</a> displays; many other display technologies are used as well (<a href="/wiki/Cathode-ray_tube" title="Cathode-ray tube">cathode-ray tubes</a>, <a href="/wiki/Nixie_tube" title="Nixie tube">nixie tubes</a>, etc.). After a reset, battery change or power failure, these clocks without a backup battery or <a href="/wiki/Capacitor" title="Capacitor">capacitor</a> either start counting from 12:00, or stay at 12:00, often with blinking digits indicating that the time needs to be set. Some newer clocks will reset themselves based on radio or Internet <a href="/wiki/Time_server" title="Time server">time servers</a> that are tuned to national <a href="/wiki/Atomic_clock" title="Atomic clock">atomic clocks</a>. Since the introduction of digital clocks in the 1960s, there has been a notable decline in the use of analog clocks.<sup id="cite_ref-94" class="reference"><a href="#cite_note-94"><span class="cite-bracket">[</span>94<span class="cite-bracket">]</span></a></sup> </p><p>Some clocks, called '<a href="/wiki/Flip_clock" title="Flip clock">flip clocks</a>', have digital displays that work mechanically. The digits are painted on sheets of material which are mounted like the pages of a book. Once a minute, a page is turned over to reveal the next digit. These displays are usually easier to read in brightly lit conditions than LCDs or LEDs. Also, they do not go back to 12:00 after a power interruption. Flip clocks generally do not have electronic mechanisms. Usually, they are driven by <a href="/wiki/Alternating_current" title="Alternating current">AC</a>-<a href="/wiki/Synchronous_motor" title="Synchronous motor">synchronous motors</a>. </p> <div class="mw-heading mw-heading4"><h4 id="Hybrid_(analog-digital)"><span id="Hybrid_.28analog-digital.29"></span>Hybrid (analog-digital)</h4></div> <p>Clocks with analog quadrants, with a digital component, usually minutes and hours displayed analogously and seconds displayed in digital mode. </p> <div class="mw-heading mw-heading4"><h4 id="Auditory">Auditory</h4></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Talking_clock" title="Talking clock">Talking clock</a></div> <p>For convenience, distance, telephony or blindness, auditory clocks present the time as sounds. The sound is either spoken natural language, (e.g. "The time is twelve thirty-five"), or as auditory codes (e.g. number of sequential bell rings on the hour represents the number of the hour like the bell, <a href="/wiki/Big_Ben" title="Big Ben">Big Ben</a>). Most telecommunication companies also provide a <a href="/wiki/Speaking_clock" title="Speaking clock">speaking clock</a> service as well. </p> <div class="mw-heading mw-heading4"><h4 id="Word">Word</h4></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Word_clock_wallpaper_with_comic_speech_bubble_style.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/06/Word_clock_wallpaper_with_comic_speech_bubble_style.png/220px-Word_clock_wallpaper_with_comic_speech_bubble_style.png" decoding="async" width="220" height="138" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/06/Word_clock_wallpaper_with_comic_speech_bubble_style.png/330px-Word_clock_wallpaper_with_comic_speech_bubble_style.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/06/Word_clock_wallpaper_with_comic_speech_bubble_style.png/440px-Word_clock_wallpaper_with_comic_speech_bubble_style.png 2x" data-file-width="1280" data-file-height="800" /></a><figcaption>Software word clock</figcaption></figure> <p>Word clocks are clocks that display the time visually using sentences. E.g.: "It's about three o'clock." These clocks can be implemented in hardware or software. </p> <div class="mw-heading mw-heading4"><h4 id="Projection">Projection</h4></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Projection_clock" title="Projection clock">Projection clock</a></div> <p>Some clocks, usually digital ones, include an optical <a href="/wiki/Image_projector" class="mw-redirect" title="Image projector">projector</a> that shines a magnified image of the time display onto a screen or onto a surface such as an indoor ceiling or wall. The digits are large enough to be easily read, without using glasses, by persons with moderately imperfect vision, so the clocks are convenient for use in their bedrooms. Usually, the timekeeping circuitry has a battery as a backup source for an uninterrupted power supply to keep the clock on time, while the projection light only works when the unit is connected to an A.C. supply. Completely battery-powered portable versions resembling <a href="/wiki/Flashlight" title="Flashlight">flashlights</a> are also available. </p> <div class="mw-heading mw-heading4"><h4 id="Tactile">Tactile</h4></div> <p>Auditory and projection clocks can be used by people who are blind or have limited vision. There are also clocks for the blind that have displays that can be read by using the sense of touch. Some of these are similar to normal analog displays, but are constructed so the hands can be felt without damaging them. Another type is essentially digital, and uses devices that use a code such as <a href="/wiki/Braille" title="Braille">Braille</a> to show the digits so that they can be felt with the fingertips. </p> <div class="mw-heading mw-heading4"><h4 id="Multi-display">Multi-display</h4></div> <p>Some clocks have several displays driven by a single mechanism, and some others have several completely separate mechanisms in a single case. Clocks in public places often have several faces visible from different directions, so that the clock can be read from anywhere in the vicinity; all the faces show the same time. Other clocks show the current time in several time-zones. Watches that are intended to be carried by travellers often have two displays, one for the local time and the other for the time at home, which is useful for making pre-arranged phone calls. Some <a href="/wiki/Equation_clock" title="Equation clock">equation clocks</a> have two displays, one showing <a href="/wiki/Local_mean_time" title="Local mean time">mean time</a> and the other <a href="/wiki/Solar_time#Apparent_solar_time" title="Solar time">solar time</a>, as would be shown by a sundial. Some clocks have both analog and digital displays. Clocks with Braille displays usually also have conventional digits so they can be read by sighted people. </p> <div class="mw-heading mw-heading2"><h2 id="Purposes">Purposes</h2></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Robbins_NC_Clock.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Robbins_NC_Clock.jpg/170px-Robbins_NC_Clock.jpg" decoding="async" width="170" height="302" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Robbins_NC_Clock.jpg/255px-Robbins_NC_Clock.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Robbins_NC_Clock.jpg/340px-Robbins_NC_Clock.jpg 2x" data-file-width="2432" data-file-height="4320" /></a><figcaption>Many cities and towns traditionally have public clocks in a prominent location, such as a town square or city center. This one is on display at the center of the town of <a href="/wiki/Robbins,_North_Carolina" title="Robbins, North Carolina">Robbins, North Carolina</a> </figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Collections_of_Wang_Yung-Chang_Clock%26.Watch-02.2023-09-05.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Collections_of_Wang_Yung-Chang_Clock%26.Watch-02.2023-09-05.jpg/170px-Collections_of_Wang_Yung-Chang_Clock%26.Watch-02.2023-09-05.jpg" decoding="async" width="170" height="104" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Collections_of_Wang_Yung-Chang_Clock%26.Watch-02.2023-09-05.jpg/255px-Collections_of_Wang_Yung-Chang_Clock%26.Watch-02.2023-09-05.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Collections_of_Wang_Yung-Chang_Clock%26.Watch-02.2023-09-05.jpg/340px-Collections_of_Wang_Yung-Chang_Clock%26.Watch-02.2023-09-05.jpg 2x" data-file-width="1482" data-file-height="906" /></a><figcaption>A clock on sale in the store from <a href="/wiki/Taipei" title="Taipei">Taipei</a>, <a href="/wiki/Taiwan" title="Taiwan">Taiwan</a>.</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Rellotge_al_museu_de_Belles_Arts_de_Val%C3%A8ncia.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/14/Rellotge_al_museu_de_Belles_Arts_de_Val%C3%A8ncia.JPG/170px-Rellotge_al_museu_de_Belles_Arts_de_Val%C3%A8ncia.JPG" decoding="async" width="170" height="130" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/14/Rellotge_al_museu_de_Belles_Arts_de_Val%C3%A8ncia.JPG/255px-Rellotge_al_museu_de_Belles_Arts_de_Val%C3%A8ncia.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/14/Rellotge_al_museu_de_Belles_Arts_de_Val%C3%A8ncia.JPG/340px-Rellotge_al_museu_de_Belles_Arts_de_Val%C3%A8ncia.JPG 2x" data-file-width="3630" data-file-height="2767" /></a><figcaption>A <a href="/wiki/Napoleon_III_style" class="mw-redirect" title="Napoleon III style">Napoleon III</a> mantel clock, from the third quarter of the 19th century, in the <a href="/wiki/Museu_de_Belles_Arts_de_Val%C3%A8ncia" title="Museu de Belles Arts de València">Museu de Belles Arts de València</a> from Spain</figcaption></figure> <p>Clocks are in homes, offices and many other places; smaller ones (watches) are carried on the wrist or in a pocket; larger ones are in public places, e.g. a railway station or church. A small clock is often shown in a corner of computer displays, mobile phones and many <a href="/wiki/MP3_player" class="mw-redirect" title="MP3 player">MP3 players</a>. </p><p>The primary purpose of a clock is to <i>display</i> the time. Clocks may also have the facility to make a loud alert signal at a specified time, typically to waken a sleeper at a preset time; they are referred to as <i><a href="/wiki/Alarm_clock" title="Alarm clock">alarm clocks</a></i>. The alarm may start at a low volume and become louder, or have the facility to be switched off for a few minutes then resume. Alarm clocks with visible indicators are sometimes used to indicate to children too young to read the time that the time for sleep has finished; they are sometimes called <i>training clocks</i>. </p><p>A clock mechanism may be used to <i>control</i> a device according to time, e.g. a central heating system, a <a href="/wiki/VCR" class="mw-redirect" title="VCR">VCR</a>, or a <a href="/wiki/Time_bomb" title="Time bomb">time bomb</a> (see: <a href="/wiki/Digital_counter" class="mw-redirect" title="Digital counter">digital counter</a>). Such mechanisms are usually called <a href="/wiki/Timer" title="Timer">timers</a>. Clock mechanisms are also used to drive devices such as <a href="/wiki/Solar_tracker#Chronological_tracker" title="Solar tracker">solar trackers</a> and <a href="/wiki/Telescope_mount#Equatorial_mounts" title="Telescope mount">astronomical telescopes</a>, which have to turn at accurately controlled speeds to counteract the rotation of the Earth. </p><p>Most <a href="/wiki/Digital_computer" class="mw-redirect" title="Digital computer">digital computers</a> depend on an internal signal at constant frequency to synchronize processing; this is referred to as a <a href="/wiki/Clock_signal" title="Clock signal">clock signal</a>. (A few research projects are developing CPUs based on <a href="/wiki/Asynchronous_circuit" title="Asynchronous circuit">asynchronous circuits</a>.) Some equipment, including computers, also maintains time and date for use as required; this is referred to as time-of-day clock, and is distinct from the system clock signal, although possibly based on counting its cycles. </p> <div class="mw-heading mw-heading3"><h3 id="Time_standards">Time standards</h3></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main articles: <a href="/wiki/Time_standard" title="Time standard">Time standard</a> and <a href="/wiki/Atomic_clock" title="Atomic clock">Atomic clock</a></div> <p>For some scientific work timing of the utmost accuracy is essential. It is also necessary to have a standard of the maximum accuracy against which working clocks can be calibrated. An ideal clock would give the time to unlimited accuracy, but this is not realisable. Many physical processes, in particular including some <a href="/wiki/Electronic_transition" class="mw-redirect" title="Electronic transition">transitions</a> between atomic <a href="/wiki/Energy_level" title="Energy level">energy levels</a>, occur at exceedingly stable frequency; counting cycles of such a process can give a very accurate and consistent time—clocks which work this way are usually called atomic clocks. Such clocks are typically large, very expensive, require a controlled environment, and are far more accurate than required for most purposes; they are typically used in a <a href="/wiki/Metrology#Laboratories" title="Metrology">standards laboratory</a>. </p> <div class="mw-heading mw-heading3"><h3 id="Navigation">Navigation</h3></div> <p>Until advances in the late twentieth century, navigation depended on the ability to measure <a href="/wiki/Latitude" title="Latitude">latitude</a> and <a href="/wiki/Longitude" title="Longitude">longitude</a>. Latitude can be determined through <a href="/wiki/Celestial_navigation" title="Celestial navigation">celestial navigation</a>; the measurement of longitude requires accurate knowledge of time. This need was a major motivation for the development of accurate mechanical clocks. <a href="/wiki/John_Harrison" title="John Harrison">John Harrison</a> created the first highly accurate <a href="/wiki/Marine_chronometer" title="Marine chronometer">marine chronometer</a> in the mid-18th century. The <a href="/wiki/Noon_gun" class="mw-redirect" title="Noon gun">Noon gun</a> in <a href="/wiki/Cape_Town" title="Cape Town">Cape Town</a> still fires an accurate signal to allow ships to check their chronometers. Many buildings near major ports used to have (some still do) a large <a href="/wiki/Time_ball" title="Time ball">ball</a> mounted on a tower or mast arranged to drop at a pre-determined time, for the same purpose. While <a href="/wiki/Satellite_navigation" title="Satellite navigation">satellite navigation</a> systems such as GPS require unprecedentedly accurate knowledge of time, this is supplied by equipment on the satellites; vehicles no longer need timekeeping equipment. </p> <div class="mw-heading mw-heading3"><h3 id="Sports_and_games">Sports and games</h3></div> <p>Clocks can be used to measure varying periods of time in games and sports. <a href="/wiki/Stopwatch" title="Stopwatch">Stopwatches</a> can be used to time the performance of <a href="/wiki/Track_athlete" class="mw-redirect" title="Track athlete">track athletes</a>. <a href="/wiki/Chess_clock" title="Chess clock">Chess clocks</a> are used to limit the board game players' time to make a move. In various sports, <i><style data-mw-deduplicate="TemplateStyles:r1238216509">.mw-parser-output .vanchor>:target~.vanchor-text{background-color:#b1d2ff}@media screen{html.skin-theme-clientpref-night .mw-parser-output .vanchor>:target~.vanchor-text{background-color:#0f4dc9}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .vanchor>:target~.vanchor-text{background-color:#0f4dc9}}</style><span class="vanchor"><span id="Game_clock"></span><span class="vanchor-text">game clocks</span></span></i> measure the duration the game or subdivisions of the game,<sup id="cite_ref-95" class="reference"><a href="#cite_note-95"><span class="cite-bracket">[</span>95<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-96" class="reference"><a href="#cite_note-96"><span class="cite-bracket">[</span>96<span class="cite-bracket">]</span></a></sup> while other clocks may be used for tracking different durations; these include <a href="/wiki/Play_clock" title="Play clock">play clocks</a>, <a href="/wiki/Shot_clock" title="Shot clock">shot clocks</a>, and <a href="/wiki/Pitch_clock" title="Pitch clock">pitch clocks</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Culture">Culture</h2></div> <div class="mw-heading mw-heading3"><h3 id="Folklore_and_superstition">Folklore and superstition</h3></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Skull_Watch_160824001.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/62/Skull_Watch_160824001.jpg/220px-Skull_Watch_160824001.jpg" decoding="async" width="220" height="238" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/62/Skull_Watch_160824001.jpg/330px-Skull_Watch_160824001.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/62/Skull_Watch_160824001.jpg/440px-Skull_Watch_160824001.jpg 2x" data-file-width="2091" data-file-height="2258" /></a><figcaption>A seventeenth century watch in the shape of a skull</figcaption></figure> <p>In the <a href="/wiki/United_Kingdom" title="United Kingdom">United Kingdom</a>, clocks are associated with various beliefs, many involving death or bad luck. In legends, clocks have reportedly stopped of their own accord upon a nearby person's death, especially those of monarchs. The clock in the <a href="/wiki/House_of_Lords" title="House of Lords">House of Lords</a> supposedly stopped at "nearly" the hour of <a href="/wiki/George_III" title="George III">George III</a>'s death in 1820, the one at <a href="/wiki/Balmoral_Castle" title="Balmoral Castle">Balmoral Castle</a> stopped during the hour of <a href="/wiki/Queen_Victoria" title="Queen Victoria">Queen Victoria</a>'s death, and similar legends are related about clocks associated with <a href="/wiki/William_IV" title="William IV">William IV</a> and <a href="/wiki/Elizabeth_I" title="Elizabeth I">Elizabeth I</a>.<sup id="cite_ref-97" class="reference"><a href="#cite_note-97"><span class="cite-bracket">[</span>97<span class="cite-bracket">]</span></a></sup> Many superstitions exist about clocks. One stopping before a person has died may foretell coming death.<sup id="cite_ref-98" class="reference"><a href="#cite_note-98"><span class="cite-bracket">[</span>98<span class="cite-bracket">]</span></a></sup> Similarly, if a clock strikes during a church hymn or a marriage ceremony, death or calamity is prefigured for the parishioners or a spouse, respectively.<sup id="cite_ref-99" class="reference"><a href="#cite_note-99"><span class="cite-bracket">[</span>99<span class="cite-bracket">]</span></a></sup> Death or ill events are foreshadowed if a clock strikes the wrong time. It may also be unlucky to have a clock face a fire or to speak while a clock is striking.<sup id="cite_ref-100" class="reference"><a href="#cite_note-100"><span class="cite-bracket">[</span>100<span class="cite-bracket">]</span></a></sup> </p><p>In Chinese culture, <a href="/wiki/Homophonic_puns_in_Mandarin_Chinese#Gifts" class="mw-redirect" title="Homophonic puns in Mandarin Chinese">giving a clock</a> (<a href="/wiki/Traditional_Chinese_characters" title="Traditional Chinese characters">traditional Chinese</a>: <span lang="zh-Hant">送鐘</span>; <a href="/wiki/Simplified_Chinese_characters" title="Simplified Chinese characters">simplified Chinese</a>: <span lang="zh-Hans">送钟</span>; <a href="/wiki/Pinyin" title="Pinyin">pinyin</a>: <i><span lang="zh-Latn">sòng zhōng</span></i>) is often taboo, especially to the elderly, as it <a href="/wiki/Faux_pas_derived_from_Chinese_pronunciation#Clock" title="Faux pas derived from Chinese pronunciation">is a homophone</a> of the act of attending another's funeral (<a href="/wiki/Traditional_Chinese_characters" title="Traditional Chinese characters">traditional Chinese</a>: <span lang="zh-Hant"><a href="https://en.wiktionary.org/wiki/%E9%80%81%E7%B5%82" class="extiw" title="wikt:送終">送終</a></span>; <a href="/wiki/Simplified_Chinese_characters" title="Simplified Chinese characters">simplified Chinese</a>: <span lang="zh-Hans"><a href="https://en.wiktionary.org/wiki/%E9%80%81%E7%BB%88" class="extiw" title="wikt:送终">送终</a></span>; <a href="/wiki/Pinyin" title="Pinyin">pinyin</a>: <i><span lang="zh-Latn">sòngzhōng</span></i>).<sup id="cite_ref-101" class="reference"><a href="#cite_note-101"><span class="cite-bracket">[</span>101<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-102" class="reference"><a href="#cite_note-102"><span class="cite-bracket">[</span>102<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-103" class="reference"><a href="#cite_note-103"><span class="cite-bracket">[</span>103<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Specific_types">Specific types</h2></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/List_of_clocks" title="List of clocks">List of clocks</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Clock_sculpture_-_Drexel_University_-_IMG_7332.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/31/Clock_sculpture_-_Drexel_University_-_IMG_7332.JPG/170px-Clock_sculpture_-_Drexel_University_-_IMG_7332.JPG" decoding="async" width="170" height="227" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/31/Clock_sculpture_-_Drexel_University_-_IMG_7332.JPG/255px-Clock_sculpture_-_Drexel_University_-_IMG_7332.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/31/Clock_sculpture_-_Drexel_University_-_IMG_7332.JPG/340px-Clock_sculpture_-_Drexel_University_-_IMG_7332.JPG 2x" data-file-width="2448" data-file-height="3264" /></a><figcaption>A monumental conical pendulum clock by <a href="/wiki/Eug%C3%A8ne_Farcot" title="Eugène Farcot">Eugène Farcot</a>, 1867. Drexel University, Philadelphia, US</figcaption></figure> <table> <tbody><tr> <td>By mechanism </td> <td>By function </td> <td>By style </td></tr> <tr> <td style="width:30%;vertical-align:top"> <ul><li><a href="/wiki/Astronomical_clock" title="Astronomical clock">Astronomical clock</a></li> <li><a href="/wiki/Atomic_clock" title="Atomic clock">Atomic clock</a></li> <li><a href="/wiki/Candle_clock" title="Candle clock">Candle clock</a></li> <li><a href="/wiki/Congreve_clock" title="Congreve clock">Congreve clock</a></li> <li><a href="/wiki/Conical_pendulum" title="Conical pendulum">Conical pendulum</a> clock</li> <li><a href="/wiki/Digital_clock" title="Digital clock">Digital clock</a></li> <li><a href="/wiki/Electric_clock" title="Electric clock">Electric clock</a></li> <li><a href="/wiki/Analog_clock_with_digital_display" class="mw-redirect" title="Analog clock with digital display">Flip clock</a></li> <li><a href="/wiki/Flying_pendulum_clock" title="Flying pendulum clock">Flying pendulum clock</a></li> <li><a href="/wiki/Hourglass" title="Hourglass">Hourglass</a></li> <li><a href="/wiki/Incense_clock" title="Incense clock">Incense clock</a></li> <li><a href="/wiki/Lamport_timestamp" title="Lamport timestamp">Lamport clock</a></li> <li><a href="/wiki/Mechanical_watch" title="Mechanical watch">Mechanical watch</a></li> <li><a href="/wiki/Observatory_chronometer" title="Observatory chronometer">Observatory chronometer</a></li> <li><a href="/wiki/Oil-lamp_clock" title="Oil-lamp clock">Oil-lamp clock</a></li> <li><a href="/wiki/Pendulum_clock" title="Pendulum clock">Pendulum clock</a></li> <li><a href="/wiki/Projection_clock" title="Projection clock">Projection clock</a></li> <li><a href="/wiki/Pulsar_clock" title="Pulsar clock">Pulsar clock</a></li> <li><a href="/wiki/Quantum_clock" class="mw-redirect" title="Quantum clock">Quantum clock</a></li> <li><a href="/wiki/Quartz_clock" title="Quartz clock">Quartz clock</a></li> <li><a href="/wiki/Radio_clock" title="Radio clock">Radio clock</a></li> <li><a href="/wiki/Rolling_ball_clock" title="Rolling ball clock">Rolling ball clock</a></li> <li><a href="/wiki/Spring_Drive" title="Spring Drive">Spring drive watch</a></li> <li><a href="/wiki/Steam_clock" title="Steam clock">Steam clock</a></li> <li><a href="/wiki/Sundial" title="Sundial">Sundial</a></li> <li><a href="/wiki/Torsion_pendulum_clock" title="Torsion pendulum clock">Torsion pendulum clock</a> <ul><li><a href="/wiki/Atmos_clock" title="Atmos clock">Atmos clock</a></li></ul></li> <li><a href="/wiki/Water_clock" title="Water clock">Water clock</a></li></ul> </td> <td style="width:30%;vertical-align:top"> <ul><li><a href="/wiki/10-hour_clock" class="mw-redirect" title="10-hour clock">10-hour clock</a></li> <li><a href="/wiki/Alarm_clock" title="Alarm clock">Alarm clock</a></li> <li><a href="/wiki/Binary_clock" title="Binary clock">Binary clock</a></li> <li><a href="/wiki/Braille_watch" title="Braille watch">Braille watch</a></li> <li><a href="/wiki/Chronometer_watch" title="Chronometer watch">Chronometer watch</a></li> <li><a href="/wiki/Cuckoo_clock" title="Cuckoo clock">Cuckoo clock</a></li> <li><a href="/wiki/Duodecimal" title="Duodecimal">Duodecimal</a> clock</li> <li><a href="/wiki/Equation_clock" title="Equation clock">Equation clock</a></li> <li><a href="/wiki/Game_clock" class="mw-redirect" title="Game clock">Game clock</a></li> <li><a href="/wiki/Japanese_clock" title="Japanese clock">Japanese clock</a></li> <li><a href="/wiki/Master_clock" title="Master clock">Master clock</a></li> <li><a href="/wiki/Musical_clock" title="Musical clock">Musical clock</a></li> <li><a href="/wiki/Railroad_chronometer" title="Railroad chronometer">Railroad chronometer</a></li> <li><a href="/wiki/Slave_clock" title="Slave clock">Slave clock</a></li> <li><a href="/wiki/Speaking_clock" title="Speaking clock">Speaking clock</a></li> <li><a href="/wiki/Stopwatch" title="Stopwatch">Stopwatch</a></li> <li><a href="/wiki/Striking_clock" title="Striking clock">Striking clock</a></li> <li><a href="/wiki/Talking_clock" title="Talking clock">Talking clock</a></li> <li><a href="/wiki/Tide_clock" title="Tide clock">Tide clock</a></li> <li><a href="/wiki/Time_ball" title="Time ball">Time ball</a></li> <li><a href="/wiki/Time_clock" title="Time clock">Time clock</a></li> <li><a href="/wiki/World_clock" title="World clock">World clock</a></li></ul> </td> <td style="width:30%;vertical-align:top"> <ul><li><a href="/wiki/American_clock" title="American clock">American clock</a></li> <li><a href="/wiki/Automaton_clock" title="Automaton clock">Automaton clock</a></li> <li><a href="/wiki/Balloon_clock" title="Balloon clock">Balloon clock</a></li> <li><a href="/wiki/Banjo_clock" title="Banjo clock">Banjo clock</a></li> <li><a href="/wiki/Bracket_clock" title="Bracket clock">Bracket clock</a></li> <li><a href="/wiki/Carriage_clock" title="Carriage clock">Carriage clock</a></li> <li><a href="/wiki/Cartel_clock" title="Cartel clock">Cartel clock</a></li> <li><a href="/wiki/Kit-Cat_Klock" title="Kit-Cat Klock">Cat clock</a></li> <li><a href="/wiki/Chariot_clock" title="Chariot clock">Chariot clock</a></li> <li><a href="/wiki/Clock_tower" title="Clock tower">Clock tower</a></li> <li><a href="/wiki/Cuckoo_clock" title="Cuckoo clock">Cuckoo clock</a></li> <li><a href="/wiki/Doll%27s_head_clock" title="Doll's head clock">Doll's head clock</a></li> <li><a href="/wiki/Floral_clock" title="Floral clock">Floral clock</a></li> <li><a href="/wiki/French_Empire_mantel_clock" title="French Empire mantel clock">French Empire mantel clock</a></li> <li><a href="/wiki/Grandfather_clock" title="Grandfather clock">Grandfather clock</a></li> <li><a href="/wiki/Mora_clock" title="Mora clock">Mora clock</a></li> <li><a href="/wiki/Lantern_clock" title="Lantern clock">Lantern clock</a></li> <li><a href="/wiki/Corpus_Clock" title="Corpus Clock">Corpus Clock</a></li> <li><a href="/wiki/Lighthouse_clock" title="Lighthouse clock">Lighthouse clock</a></li> <li><a href="/wiki/Mantel_clock" title="Mantel clock">Mantel clock</a></li> <li><a href="/wiki/Skeleton_clock" title="Skeleton clock">Skeleton clock</a></li> <li><a href="/wiki/Turret_clock" title="Turret clock">Turret clock</a></li> <li><a href="/wiki/Watch" title="Watch">Watch</a></li></ul> </td></tr></tbody></table> <div style="clear:both;" class=""></div> <div class="mw-heading mw-heading2"><h2 id="Awards">Awards</h2></div> <ul><li><a href="/w/index.php?title=Grand_Prix_d%27Horlogerie_de_Gen%C3%A8ve&action=edit&redlink=1" class="new" title="Grand Prix d'Horlogerie de Genève (page does not exist)">Grand Prix d'Horlogerie de Genève</a><sup class="noprint" style="font-style: normal;"> [<a href="https://de.wikipedia.org/wiki/Grand_Prix_d%27Horlogerie_de_Gen%C3%A8ve" class="extiw" title="de:Grand Prix d'Horlogerie de Genève">de</a>]</sup> (GPHG)</li> <li><a href="/w/index.php?title=Goldene_Unruh&action=edit&redlink=1" class="new" title="Goldene Unruh (page does not exist)">Goldene Unruh</a><sup class="noprint" style="font-style: normal;"> [<a href="https://de.wikipedia.org/wiki/Goldene_Unruh" class="extiw" title="de:Goldene Unruh">de</a>]</sup></li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2></div> <style data-mw-deduplicate="TemplateStyles:r1184024115">.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output .div-col ul{margin-top:0}.mw-parser-output .div-col li,.mw-parser-output .div-col dd{page-break-inside:avoid;break-inside:avoid-column}</style><div class="div-col" style="column-width: 22em;"> <ul><li><a href="/wiki/24-hour_analog_dial" title="24-hour analog dial">24-hour analog dial</a></li> <li><a href="/wiki/Allan_variance" title="Allan variance">Allan variance</a></li> <li><a href="/wiki/Allen-Bradley_Clock_Tower_at_Rockwell_Automation_Headquarters_Building" class="mw-redirect" title="Allen-Bradley Clock Tower at Rockwell Automation Headquarters Building">Allen-Bradley Clock Tower at Rockwell Automation Headquarters Building</a> (Wisconsin)</li> <li><a href="/wiki/American_Watchmakers-Clockmakers_Institute" title="American Watchmakers-Clockmakers Institute">American Watchmakers-Clockmakers Institute</a></li> <li><a href="/wiki/BaselWorld" class="mw-redirect" title="BaselWorld">BaselWorld</a></li> <li><a href="/wiki/Circadian_rhythm" title="Circadian rhythm">Biological clock</a></li> <li><a href="/wiki/Clockarium" title="Clockarium">Clockarium</a></li> <li><a href="/wiki/The_clock_as_herald_of_the_Industrial_Revolution" class="mw-redirect" title="The clock as herald of the Industrial Revolution">The clock as herald of the Industrial Revolution</a> (Lewis Mumford)</li> <li><a href="/wiki/Clock_drift" title="Clock drift">Clock drift</a></li> <li><a href="/wiki/Clock_ident" title="Clock ident">Clock ident</a></li> <li><a href="/wiki/Clock_network" title="Clock network">Clock network</a></li> <li><a href="/wiki/Clock_of_the_Long_Now" title="Clock of the Long Now">Clock of the Long Now</a></li> <li><a href="/wiki/Colgate_Clock_(Indiana)" title="Colgate Clock (Indiana)">Colgate Clock (Indiana)</a></li> <li><a href="/wiki/Colgate_Clock_(New_Jersey)" class="mw-redirect" title="Colgate Clock (New Jersey)">Colgate Clock (New Jersey)</a>, largest clock in US</li> <li><a href="/wiki/Cosmo_Clock_21" title="Cosmo Clock 21">Cosmo Clock 21</a>, world's largest clock</li> <li><a href="/wiki/Cox%27s_timepiece" title="Cox's timepiece">Cox's timepiece</a></li> <li><a href="/wiki/Cuckooland_Museum" title="Cuckooland Museum">Cuckooland Museum</a></li> <li><a href="/wiki/Date_and_time_representation_by_country" title="Date and time representation by country">Date and time representation by country</a></li> <li><a href="/wiki/Debt_clock" title="Debt clock">Debt clock</a></li> <li><a href="/wiki/Le_D%C3%A9fenseur_du_Temps" title="Le Défenseur du Temps">Le Défenseur du Temps</a> (automata)</li> <li><a href="/wiki/Department_of_Defense_master_clock" title="Department of Defense master clock">Department of Defense master clock</a> (U.S.)</li> <li><a href="/wiki/Doomsday_Clock" title="Doomsday Clock">Doomsday Clock</a></li> <li><a href="/wiki/Earth_clock" title="Earth clock">Earth clock</a></li> <li><a href="/wiki/Federation_of_the_Swiss_Watch_Industry_FH" class="mw-redirect" title="Federation of the Swiss Watch Industry FH">Federation of the Swiss Watch Industry FH</a></li> <li><a href="/wiki/Guard_tour_patrol_system" title="Guard tour patrol system">Guard tour patrol system</a> (watchclocks)</li> <li><a href="/wiki/Iron_Ring_Clock" class="mw-redirect" title="Iron Ring Clock">Iron Ring Clock</a></li> <li><a href="/wiki/Jens_Olsen%27s_World_Clock" title="Jens Olsen's World Clock">Jens Olsen's World Clock</a></li> <li><a href="/wiki/Jewel_bearing" title="Jewel bearing">Jewel bearing</a></li> <li><a href="/wiki/List_of_biggest_clock_faces" class="mw-redirect" title="List of biggest clock faces">List of biggest clock faces</a></li> <li><a href="/wiki/List_of_international_common_standards" title="List of international common standards">List of international common standards</a></li> <li><a href="/wiki/List_of_largest_cuckoo_clocks" title="List of largest cuckoo clocks">List of largest cuckoo clocks</a></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></li> <li><a href="/wiki/Replica_watch" class="mw-redirect" title="Replica watch">Replica watch</a></li> <li><a href="/wiki/Rubik%27s_Clock" title="Rubik's Clock">Rubik's Clock</a></li> <li><a href="/wiki/Star_clock" class="mw-redirect" title="Star clock">Star clock</a></li> <li><a href="/wiki/Singing_bird_box" title="Singing bird box">Singing bird box</a></li> <li><a href="/wiki/System_time" title="System time">System time</a></li> <li><a href="/wiki/Timeline_of_time_measurement_technology" class="mw-redirect" title="Timeline of time measurement technology">Timeline of time measurement technology</a></li> <li><a href="/wiki/Watchmaker" title="Watchmaker">Watchmaker</a></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="Notes_and_references">Notes and references</h2></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"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-Dohrn-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-Dohrn_1-0">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFDohrn-van_Rossum1996" class="citation book cs1">Dohrn-van Rossum, Gerhard (1996). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=xYhlNoUu-toC&q=verge+escapement+technology"><i>History of the Hour: Clocks and Modern Temporal Orders</i></a>. Univ. of Chicago Press. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-226-15511-1" title="Special:BookSources/978-0-226-15511-1"><bdi>978-0-226-15511-1</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703112705/https://books.google.com/books?id=xYhlNoUu-toC&q=verge+escapement+technology">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">October 30,</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=History+of+the+Hour%3A+Clocks+and+Modern+Temporal+Orders&rft.pub=Univ.+of+Chicago+Press&rft.date=1996&rft.isbn=978-0-226-15511-1&rft.aulast=Dohrn-van+Rossum&rft.aufirst=Gerhard&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DxYhlNoUu-toC%26q%3Dverge%2Bescapement%2Btechnology&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span>, pp. 103–104.</span> </li> <li id="cite_note-Marrison-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-Marrison_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Marrison_2-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Marrison_2-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Marrison_2-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Marrison_2-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-Marrison_2-5"><sup><i><b>f</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMarrison1948" class="citation journal cs1">Marrison, Warren (1948). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20141110143908/http://timepieceperfection.com/THE-BELL-SYSTEM.pdf">"The Evolution of the Quartz Crystal Clock"</a> <span class="cs1-format">(PDF)</span>. <i>Bell System Technical Journal</i>. <b>27</b> (3): 510–588. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1002%2Fj.1538-7305.1948.tb01343.x">10.1002/j.1538-7305.1948.tb01343.x</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/0005-8580">0005-8580</a>. Archived from <a rel="nofollow" class="external text" href="http://timepieceperfection.com/THE-BELL-SYSTEM.pdf">the original</a> <span class="cs1-format">(PDF)</span> on November 10, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">November 10,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Bell+System+Technical+Journal&rft.atitle=The+Evolution+of+the+Quartz+Crystal+Clock&rft.volume=27&rft.issue=3&rft.pages=510-588&rft.date=1948&rft_id=info%3Adoi%2F10.1002%2Fj.1538-7305.1948.tb01343.x&rft.issn=0005-8580&rft.aulast=Marrison&rft.aufirst=Warren&rft_id=http%3A%2F%2Ftimepieceperfection.com%2FTHE-BELL-SYSTEM.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-Cipolla-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-Cipolla_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Cipolla_3-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCipolla2004" class="citation book cs1">Cipolla, Carlo M. (2004). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=YSf9MVxa2JEC&q=verge+escapement+technology&pg=PA31"><i>Clocks and Culture, 1300 to 1700</i></a>. W.W. Norton & Co. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-393-32443-3" title="Special:BookSources/978-0-393-32443-3"><bdi>978-0-393-32443-3</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703112708/https://books.google.com/books?id=YSf9MVxa2JEC&q=verge+escapement+technology&pg=PA31">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">October 30,</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Clocks+and+Culture%2C+1300+to+1700&rft.pub=W.W.+Norton+%26+Co.&rft.date=2004&rft.isbn=978-0-393-32443-3&rft.aulast=Cipolla&rft.aufirst=Carlo+M.&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DYSf9MVxa2JEC%26q%3Dverge%2Bescapement%2Btechnology%26pg%3DPA31&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span>, p. 31.</span> </li> <li id="cite_note-White-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-White_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-White_4-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWhite1962" class="citation book cs1">White, Lynn Jr. (1962). <i>Medieval Technology and Social Change</i>. UK: Oxford Univ. Press. p. 119.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Medieval+Technology+and+Social+Change&rft.place=UK&rft.pages=119&rft.pub=Oxford+Univ.+Press&rft.date=1962&rft.aulast=White&rft.aufirst=Lynn+Jr.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://dictionary.cambridge.org/dictionary/english/clock">"Cambridge Advanced Learner's Dictionary"</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230307021636/https://dictionary.cambridge.org/dictionary/english/clock">Archived</a> from the original on March 7, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">January 29,</span> 2018</span>. <q>a device for measuring and showing time, which is usually found in or on a building and is not worn by a person</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Cambridge+Advanced+Learner%27s+Dictionary&rft_id=https%3A%2F%2Fdictionary.cambridge.org%2Fdictionary%2Fenglish%2Fclock&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-Wedgwood-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-Wedgwood_6-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWedgwood1859" class="citation book cs1">Wedgwood, Hensleigh (1859). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=AGdJAAAAcAAJ&q=clock&pg=PA354"><i>A Dictionary of English Etymology: A –  D, Vol. 1</i></a>. London: Trübner and Co. p. 354. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703112706/https://books.google.com/books?id=AGdJAAAAcAAJ&q=clock&pg=PA354">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">October 30,</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+Dictionary+of+English+Etymology%3A+A+%26ndash%3B%26%2332%3B+D%2C+Vol.+1&rft.place=London&rft.pages=354&rft.pub=Tr%C3%BCbner+and+Co.&rft.date=1859&rft.aulast=Wedgwood&rft.aufirst=Hensleigh&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DAGdJAAAAcAAJ%26q%3Dclock%26pg%3DPA354&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-OED-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-OED_7-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFStevensonWaite2011" class="citation book cs1">Stevenson, Angus; Waite, Maurice (2011). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=sYScAQAAQBAJ&q=clock+clogga&pg=PA270"><i>Concise Oxford English Dictionary: Luxury Edition</i></a>. Oxford University. pp. 269–270. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-19-960111-0" title="Special:BookSources/978-0-19-960111-0"><bdi>978-0-19-960111-0</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703112706/https://books.google.com/books?id=sYScAQAAQBAJ&q=clock+clogga&pg=PA270">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">October 30,</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Concise+Oxford+English+Dictionary%3A+Luxury+Edition&rft.pages=269-270&rft.pub=Oxford+University&rft.date=2011&rft.isbn=978-0-19-960111-0&rft.aulast=Stevenson&rft.aufirst=Angus&rft.au=Waite%2C+Maurice&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DsYScAQAAQBAJ%26q%3Dclock%2Bclogga%26pg%3DPA270&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://sundialsoc.org.uk/discussions/how-do-sundials-work/">"How Sundials Work"</a>. The British Sundial Society. November 7, 2013. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20141110144533/http://sundialsoc.org.uk/discussions/how-do-sundials-work/">Archived</a> from the original on November 10, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">November 10,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=How+Sundials+Work&rft.pub=The+British+Sundial+Society&rft.date=2013-11-07&rft_id=http%3A%2F%2Fsundialsoc.org.uk%2Fdiscussions%2Fhow-do-sundials-work%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://sundials.org/index.php/all-things-sundial/ancient-sundials">"Ancient Sundials"</a>. North American Sundial Society. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20141110142221/http://sundials.org/index.php/all-things-sundial/ancient-sundials">Archived</a> from the original on November 10, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">November 10,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Ancient+Sundials&rft.pub=North+American+Sundial+Society&rft_id=http%3A%2F%2Fsundials.org%2Findex.php%2Fall-things-sundial%2Fancient-sundials&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLankford1997" class="citation book cs1">Lankford, John (1997). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=Xev7zOrwLHgC&pg=PA502"><i>History of Astronomy: An Encyclopedia</i></a>. Taylor & Francis. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-8153-0322-0" title="Special:BookSources/978-0-8153-0322-0"><bdi>978-0-8153-0322-0</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=History+of+Astronomy%3A+An+Encyclopedia&rft.pub=Taylor+%26+Francis&rft.date=1997&rft.isbn=978-0-8153-0322-0&rft.aulast=Lankford&rft.aufirst=John&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DXev7zOrwLHgC%26pg%3DPA502&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><a href="#CITEREFTurner1984">Turner 1984</a>, p. 1</span> </li> <li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><a href="#CITEREFCowan1958">Cowan 1958</a>, p. 58</span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.sailingissues.com/yachting-guide/tower-of-winds-1.html">"Tower of the Winds – Athens"</a>. <i>sailingissues.com</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20081209015740/http://sailingissues.com/yachting-guide/tower-of-winds-1.html">Archived</a> from the original on December 9, 2008<span class="reference-accessdate">. Retrieved <span class="nowrap">November 4,</span> 2008</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=sailingissues.com&rft.atitle=Tower+of+the+Winds+%E2%80%93+Athens&rft_id=http%3A%2F%2Fwww.sailingissues.com%2Fyachting-guide%2Ftower-of-winds-1.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</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.metmuseum.org/art/collection/search/696219">"Water Clock | China | Western Han dynasty (206 BCE–9 CE)"</a>. <i>The Metropolitan Museum of Art</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230405125014/https://www.metmuseum.org/art/collection/search/696219">Archived</a> from the original on April 5, 2023.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+Metropolitan+Museum+of+Art&rft.atitle=Water+Clock+%7C+China+%7C+Western+Han+dynasty+%28206+BCE%E2%80%939+CE%29&rft_id=https%3A%2F%2Fwww.metmuseum.org%2Fart%2Fcollection%2Fsearch%2F696219&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJames1995" class="citation book cs1">James, Peter (1995). <a rel="nofollow" class="external text" href="https://archive.org/details/ancientinvention00jame/page/126"><i>Ancient Inventions</i></a>. New York: Ballantine Books. p. <a rel="nofollow" class="external text" href="https://archive.org/details/ancientinvention00jame/page/126">126</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-345-40102-1" title="Special:BookSources/978-0-345-40102-1"><bdi>978-0-345-40102-1</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Ancient+Inventions&rft.place=New+York&rft.pages=126&rft.pub=Ballantine+Books&rft.date=1995&rft.isbn=978-0-345-40102-1&rft.aulast=James&rft.aufirst=Peter&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fancientinvention00jame%2Fpage%2F126&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWilliam_Godwin1876" class="citation book cs1">William Godwin (1876). <a rel="nofollow" class="external text" href="https://archive.org/details/livesnecromance04godwgoog"><i>Lives of the Necromancers</i></a>. London, F.J. Mason. p. 232.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Lives+of+the+Necromancers&rft.pages=232&rft.pub=London%2C+F.J.+Mason&rft.date=1876&rft.au=William+Godwin&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Flivesnecromance04godwgoog&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMoussas2018" class="citation book cs1">Moussas, Xenophon (2018). <i>The Antikythera Mechanism, the first mechanical cosmos (in Greek)</i>. Athens: Canto Mediterraneo. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-618-83695-0-4" title="Special:BookSources/978-618-83695-0-4"><bdi>978-618-83695-0-4</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Antikythera+Mechanism%2C+the+first+mechanical+cosmos+%28in+Greek%29&rft.place=Athens&rft.pub=Canto+Mediterraneo&rft.date=2018&rft.isbn=978-618-83695-0-4&rft.aulast=Moussas&rft.aufirst=Xenophon&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDasypodius1580" class="citation book cs1">Dasypodius, K. (1580). <i>Heron mechanicus</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Heron+mechanicus.&rft.date=1580&rft.aulast=Dasypodius&rft.aufirst=K.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHero" class="citation book cs1">Hero, of Alexandria. <i>see Hero's books: Pneumatica (Πνευματικά), Automata, Mechanica, Metrica, Dioptra</i>. Alexandria.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=see+Hero%27s+books%3A+Pneumatica+%28%CE%A0%CE%BD%CE%B5%CF%85%CE%BC%CE%B1%CF%84%CE%B9%CE%BA%CE%AC%29%2C+Automata%2C+Mechanica%2C+Metrica%2C+Dioptra&rft.place=Alexandria&rft.aulast=Hero&rft.aufirst=of+Alexandria&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-20">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFProcopius_of_Caesareac._500s" class="citation book cs1">Procopius of Caesarea, Προκόπιος ὁ Καισαρεύς (c. 500s). <i>Περὶ Κτισμάτων, Perì Ktismáton; Latin: De Aedificiis, On Buildings</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=%CE%A0%CE%B5%CF%81%E1%BD%B6+%CE%9A%CF%84%CE%B9%CF%83%CE%BC%CE%AC%CF%84%CF%89%CE%BD%2C+Per%C3%AC+Ktism%C3%A1ton%3B+Latin%3A+De+Aedificiis%2C+On+Buildings&rft.aulast=Procopius+of+Caesarea&rft.aufirst=%CE%A0%CF%81%CE%BF%CE%BA%CF%8C%CF%80%CE%B9%CE%BF%CF%82+%E1%BD%81+%CE%9A%CE%B1%CE%B9%CF%83%CE%B1%CF%81%CE%B5%CF%8D%CF%82&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-needham_volume_4_part_2_165-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-needham_volume_4_part_2_165_21-0">^</a></b></span> <span class="reference-text">Needham, Joseph (1986). <i>Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 2, Mechanical Engineering</i>. Taipei: Caves Books Ltd, p. 165.</span> </li> <li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text">Needham, Joseph (1986). <i>Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 2, Mechanical Engineering</i>. Taipei: Caves Books Ltd, p. 319.</span> </li> <li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text"><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.uh.edu/engines/epi120.htm">"No. 120: Su-Sung's Clock"</a>. <i>www.uh.edu</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210226194506/https://uh.edu/engines/epi120.htm">Archived</a> from the original on February 26, 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">February 18,</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=www.uh.edu&rft.atitle=No.+120%3A+Su-Sung%27s+Clock&rft_id=https%3A%2F%2Fwww.uh.edu%2Fengines%2Fepi120.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text">History of Song 宋史, Vol. 340</span> </li> <li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://revolutionwatch.com/past-masters-the-astronomical-water-clock-of-su-song/">"Past Masters: The Astronomical Water Clock Of Su Song"</a>. <i>revolutionwatch.com</i>. August 8, 2014. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20220407055722/https://revolutionwatch.com/past-masters-the-astronomical-water-clock-of-su-song/">Archived</a> from the original on April 7, 2022<span class="reference-accessdate">. Retrieved <span class="nowrap">June 4,</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=revolutionwatch.com&rft.atitle=Past+Masters%3A+The+Astronomical+Water+Clock+Of+Su+Song&rft.date=2014-08-08&rft_id=https%3A%2F%2Frevolutionwatch.com%2Fpast-masters-the-astronomical-water-clock-of-su-song%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-Derek-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-Derek_26-0">^</a></b></span> <span class="reference-text"><a href="/wiki/Derek_J._de_Solla_Price" title="Derek J. de Solla Price">Derek J. de Solla Price</a>, <a rel="nofollow" class="external text" href="http://www.gutenberg.org/files/30001/30001-h/30001-h.htm">On the Origin of Clockwork, Perpetual Motion Devices, and the Compass</a>, p.86</span> </li> <li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text"><a href="/wiki/Ibn_al-Razzaz_Al-Jazari" class="mw-redirect" title="Ibn al-Razzaz Al-Jazari">Ibn al-Razzaz Al-Jazari</a> (ed. 1974), <i>The Book of Knowledge of Ingenious Mechanical Devices</i>. Translated and annotated by <a href="/wiki/Donald_Routledge_Hill" class="mw-redirect" title="Donald Routledge Hill">Donald Routledge Hill</a>, Dordrecht/<a href="/wiki/D._Reidel" title="D. Reidel">D. Reidel</a>.</span> </li> <li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://makezine.com/projects/remaking-history-ismail-al-jazari-and-the-elephant-water-clock/">"Remaking History: Ismail al-Jazari and the Elephant Water Clock - Make"</a>. <i>Make: DIY Projects and Ideas for Makers</i>. May 7, 2021. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230111190253/https://makezine.com/projects/remaking-history-ismail-al-jazari-and-the-elephant-water-clock/">Archived</a> from the original on January 11, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">January 11,</span> 2023</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Make%3A+DIY+Projects+and+Ideas+for+Makers&rft.atitle=Remaking+History%3A+Ismail+al-Jazari+and+the+Elephant+Water+Clock+-+Make&rft.date=2021-05-07&rft_id=https%3A%2F%2Fmakezine.com%2Fprojects%2Fremaking-history-ismail-al-jazari-and-the-elephant-water-clock%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-Hassan-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-Hassan_29-0">^</a></b></span> <span class="reference-text"><a href="/wiki/Ahmad_Y_Hassan" class="mw-redirect" title="Ahmad Y Hassan">Hassan, Ahmad Y</a>, <a rel="nofollow" class="external text" href="http://www.history-science-technology.com/Articles/articles%2071.html">Transfer Of Islamic Technology To The West, Part II: Transmission Of Islamic Engineering</a>, <i>History of Science and Technology in Islam</i></span> </li> <li id="cite_note-Ajram-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-Ajram_30-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAjram1992" class="citation book cs1">Ajram, K. (1992). "Appendix B". <i>Miracle of Islamic Science</i>. Knowledge House Publishers. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-911119-43-4" title="Special:BookSources/0-911119-43-4"><bdi>0-911119-43-4</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Appendix+B&rft.btitle=Miracle+of+Islamic+Science&rft.pub=Knowledge+House+Publishers&rft.date=1992&rft.isbn=0-911119-43-4&rft.aulast=Ajram&rft.aufirst=K.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-wmsmith1875-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-wmsmith1875_31-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLeonhard_SchmitzSmith1875" class="citation book cs1">Leonhard Schmitz; Smith, William (1875). <a rel="nofollow" class="external text" href="https://penelope.uchicago.edu/Thayer/E/Roman/Texts/secondary/SMIGRA*/Horologium.html"><i>A Dictionary of Greek and Roman Antiquities</i></a>. London: John Murray. pp. 615‑617. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703112706/https://penelope.uchicago.edu/Thayer/E/Roman/Texts/secondary/SMIGRA%2A/Horologium.html">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">February 19,</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+Dictionary+of+Greek+and+Roman+Antiquities&rft.place=London&rft.pages=615%E2%80%91617&rft.pub=John+Murray&rft.date=1875&rft.au=Leonhard+Schmitz&rft.au=Smith%2C+William&rft_id=https%3A%2F%2Fpenelope.uchicago.edu%2FThayer%2FE%2FRoman%2FTexts%2Fsecondary%2FSMIGRA%2A%2FHorologium.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-32">^</a></b></span> <span class="reference-text">Modern French <span title="French-language text"><i lang="fr">horloge</i></span> is very close; Spanish <span title="Spanish-language text"><i lang="es">reloj</i></span> and Portuguese <span title="Portuguese-language text"><i lang="pt">relógio</i></span> drop the first part of the word.</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"><i>Bulletin de la société archéologique de Sens</i>, year 1867, vol. IX, p. 390, available at www.archive.org.</span> </li> <li id="cite_note-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-34">^</a></b></span> <span class="reference-text">See also <a href="https://fr.wikipedia.org/wiki/Discussion:Horloge" class="extiw" title="fr:Discussion:Horloge">fr:Discussion:Horloge</a><sup class="noprint Inline-Template noprint Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Verifiability#Wikipedia_and_sources_that_mirror_or_use_it" title="Wikipedia:Verifiability"><span title="This claim cites another Wikipedia article. Articles need references to reliable third-party sources. (April 2024)">circular reference</span></a></i>]</sup></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"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1"><i>The Chronicle of Jocelin of Brakelond, Monk of St. Edmundsbury: A Picture of Monastic and Social Life on the XIIth Century</i>. London: Chatto and Windus. Translated and edited by L.C. Jane. 1910.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Chronicle+of+Jocelin+of+Brakelond%2C+Monk+of+St.+Edmundsbury%3A+A+Picture+of+Monastic+and+Social+Life+on+the+XIIth+Century&rft.place=London&rft.pub=Chatto+and+Windus.+Translated+and+edited+by+L.C.+Jane&rft.date=1910&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-:0-36"><span class="mw-cite-backlink">^ <a href="#cite_ref-:0_36-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:0_36-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.crystalinks.com/clocks.html">"Clocks –  Crystalinks"</a>. <i>www.crystalinks.com</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190606155715/https://www.crystalinks.com/clocks.html">Archived</a> from the original on June 6, 2019<span class="reference-accessdate">. Retrieved <span class="nowrap">June 6,</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.crystalinks.com&rft.atitle=Clocks+%26ndash%3B%26%2332%3B+Crystalinks&rft_id=https%3A%2F%2Fwww.crystalinks.com%2Fclocks.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-north-37"><span class="mw-cite-backlink">^ <a href="#cite_ref-north_37-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-north_37-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">North, John. God's Clockmaker: Richard of Wallingford and the Invention of Time. London: Hambledon and London (2005).</span> </li> <li id="cite_note-king-38"><span class="mw-cite-backlink">^ <a href="#cite_ref-king_38-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-king_38-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-king_38-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">King, Henry "Geared to the Stars: the evolution of planetariums, orreries, and astronomical clocks", University of Toronto Press, 1978</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"><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.cabinet.ox.ac.uk/giovanni-dondis-astrarium-1364-0">"Giovanni Dondi's Astrarium, 1364 | cabinet"</a>. <i>www.cabinet.ox.ac.uk</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20211120141134/https://www.cabinet.ox.ac.uk/giovanni-dondis-astrarium-1364-0">Archived</a> from the original on November 20, 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">June 5,</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.cabinet.ox.ac.uk&rft.atitle=Giovanni+Dondi%27s+Astrarium%2C+1364+%7C+cabinet&rft_id=https%3A%2F%2Fwww.cabinet.ox.ac.uk%2Fgiovanni-dondis-astrarium-1364-0&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-40">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAbrams2018" class="citation news cs1">Abrams, Melanie (February 16, 2018). <a rel="nofollow" class="external text" href="https://www.nytimes.com/2018/02/16/style/watches-clocks-mbandf-breuget.html">"<span class="cs1-kern-left"></span>'The Beauty of Time'<span class="cs1-kern-right"></span>"</a>. <i>The New York Times</i>. <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/0362-4331">0362-4331</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20220604212633/https://www.nytimes.com/2018/02/16/style/watches-clocks-mbandf-breuget.html">Archived</a> from the original on June 4, 2022<span class="reference-accessdate">. Retrieved <span class="nowrap">June 5,</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+New+York+Times&rft.atitle=%27The+Beauty+of+Time%27&rft.date=2018-02-16&rft.issn=0362-4331&rft.aulast=Abrams&rft.aufirst=Melanie&rft_id=https%3A%2F%2Fwww.nytimes.com%2F2018%2F02%2F16%2Fstyle%2Fwatches-clocks-mbandf-breuget.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-41">^</a></b></span> <span class="reference-text">Singer, Charles, et al. <i>Oxford History of Technology: volume II, from the Renaissance to the Industrial Revolution</i> (OUP 1957) pp. 650–651</span> </li> <li id="cite_note-White2-42"><span class="mw-cite-backlink"><b><a href="#cite_ref-White2_42-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWhite1966" class="citation book cs1">White, Lynn Jr. (1966). <a rel="nofollow" class="external text" href="https://archive.org/details/medievaltechnolo00whit/page/126"><i>Medieval Technology and Social Change</i></a>. New York: Oxford Univ. Press. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/medievaltechnolo00whit/page/126">126–127</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-19-500266-9" title="Special:BookSources/978-0-19-500266-9"><bdi>978-0-19-500266-9</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Medieval+Technology+and+Social+Change&rft.place=New+York&rft.pages=126-127&rft.pub=Oxford+Univ.+Press&rft.date=1966&rft.isbn=978-0-19-500266-9&rft.aulast=White&rft.aufirst=Lynn+Jr.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fmedievaltechnolo00whit%2Fpage%2F126&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-43"><span class="mw-cite-backlink"><b><a href="#cite_ref-43">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFUsher1988" class="citation book cs1">Usher, Abbot Payson (1988). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=xuDDqqa8FlwC&pg=PA305"><i>A History of Mechanical Inventions</i></a>. Courier Dover. p. 305. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-486-25593-4" title="Special:BookSources/978-0-486-25593-4"><bdi>978-0-486-25593-4</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703112708/https://books.google.com/books?id=xuDDqqa8FlwC&pg=PA305">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">June 5,</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+History+of+Mechanical+Inventions&rft.pages=305&rft.pub=Courier+Dover&rft.date=1988&rft.isbn=978-0-486-25593-4&rft.aulast=Usher&rft.aufirst=Abbot+Payson&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DxuDDqqa8FlwC%26pg%3DPA305&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-Rossum-44"><span class="mw-cite-backlink"><b><a href="#cite_ref-Rossum_44-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDohrn-van_Rossum1997" class="citation book cs1">Dohrn-van Rossum, Gerhar (1997). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=53K32RiEigMC&pg=PA121"><i>History of the Hour: Clocks and Modern Temporal Orders</i></a>. Univ. of Chicago Press. p. 121. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-226-15510-4" title="Special:BookSources/978-0-226-15510-4"><bdi>978-0-226-15510-4</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703113720/https://books.google.com/books?id=53K32RiEigMC&pg=PA121">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">June 5,</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=History+of+the+Hour%3A+Clocks+and+Modern+Temporal+Orders&rft.pages=121&rft.pub=Univ.+of+Chicago+Press&rft.date=1997&rft.isbn=978-0-226-15510-4&rft.aulast=Dohrn-van+Rossum&rft.aufirst=Gerhar&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3D53K32RiEigMC%26pg%3DPA121&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-45"><span class="mw-cite-backlink"><b><a href="#cite_ref-45">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMilham1945" class="citation book cs1">Milham, Willis I. (1945). <i>Time and Timekeepers</i>. New York: MacMillan. p. 121. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-7808-0008-3" title="Special:BookSources/978-0-7808-0008-3"><bdi>978-0-7808-0008-3</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Time+and+Timekeepers&rft.place=New+York&rft.pages=121&rft.pub=MacMillan&rft.date=1945&rft.isbn=978-0-7808-0008-3&rft.aulast=Milham&rft.aufirst=Willis+I.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-46"><span class="mw-cite-backlink"><b><a href="#cite_ref-46">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation encyclopaedia cs1"><a rel="nofollow" class="external text" href="https://books.google.com/books?id=Eb0qAAAAMAAJ&q=peter+Henlein">"Clock"</a>. <i>The New Encyclopædia Britannica</i>. Vol. 4. Univ. of Chicago. 1974. p. 747. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-85229-290-7" title="Special:BookSources/978-0-85229-290-7"><bdi>978-0-85229-290-7</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Clock&rft.btitle=The+New+Encyclop%C3%A6dia+Britannica&rft.pages=747&rft.pub=Univ.+of+Chicago&rft.date=1974&rft.isbn=978-0-85229-290-7&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DEb0qAAAAMAAJ%26q%3Dpeter%2BHenlein&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-47"><span class="mw-cite-backlink"><b><a href="#cite_ref-47">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAnzovinPodell,_Janet2000" class="citation book cs1">Anzovin, Steve; Podell, Janet (2000). <a rel="nofollow" class="external text" href="https://archive.org/details/famousfirstfacts00anzo/page/440"><i>Famous First Facts: A record of first happenings, discoveries, and inventions in world history</i></a>. H.W. Wilson. p. <a rel="nofollow" class="external text" href="https://archive.org/details/famousfirstfacts00anzo/page/440">440</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-8242-0958-2" title="Special:BookSources/978-0-8242-0958-2"><bdi>978-0-8242-0958-2</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Famous+First+Facts%3A+A+record+of+first+happenings%2C+discoveries%2C+and+inventions+in+world+history&rft.pages=440&rft.pub=H.W.+Wilson&rft.date=2000&rft.isbn=978-0-8242-0958-2&rft.aulast=Anzovin&rft.aufirst=Steve&rft.au=Podell%2C+Janet&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Ffamousfirstfacts00anzo%2Fpage%2F440&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-haencyc-48"><span class="mw-cite-backlink"><b><a href="#cite_ref-haencyc_48-0">^</a></b></span> <span class="reference-text">p. 529, "Time and timekeeping instruments", <i>History of astronomy: an encyclopedia</i>, John Lankford, Taylor & Francis, 1997, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-8153-0322-X" title="Special:BookSources/0-8153-0322-X">0-8153-0322-X</a>.</span> </li> <li id="cite_note-49"><span class="mw-cite-backlink"><b><a href="#cite_ref-49">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFUsher1988" class="citation book cs1">Usher, Abbott Payson (1988). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=xuDDqqa8FlwC&q=A+history+of+mechanical+inventions,+Abbott+Payson+Usher"><i>A history of mechanical inventions</i></a>. Courier Dover Publications. p. 209. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-486-25593-4" title="Special:BookSources/978-0-486-25593-4"><bdi>978-0-486-25593-4</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703113711/https://books.google.com/books?id=xuDDqqa8FlwC&q=A+history+of+mechanical+inventions,+Abbott+Payson+Usher">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">October 30,</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+history+of+mechanical+inventions&rft.pages=209&rft.pub=Courier+Dover+Publications&rft.date=1988&rft.isbn=978-0-486-25593-4&rft.aulast=Usher&rft.aufirst=Abbott+Payson&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DxuDDqqa8FlwC%26q%3DA%2Bhistory%2Bof%2Bmechanical%2Binventions%2C%2BAbbott%2BPayson%2BUsher&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-Landes-50"><span class="mw-cite-backlink"><b><a href="#cite_ref-Landes_50-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLandes1983" class="citation book cs1">Landes, David S. (1983). <a href="/wiki/Revolution_in_Time" title="Revolution in Time"><i>Revolution in Time</i></a>. Cambridge, Massachusetts: Harvard University Press. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-674-76802-4" title="Special:BookSources/978-0-674-76802-4"><bdi>978-0-674-76802-4</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Revolution+in+Time&rft.place=Cambridge%2C+Massachusetts&rft.pub=Harvard+University+Press&rft.date=1983&rft.isbn=978-0-674-76802-4&rft.aulast=Landes&rft.aufirst=David+S.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-51"><span class="mw-cite-backlink"><b><a href="#cite_ref-51">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWillsberger1975" class="citation book cs1">Willsberger, Johann (1975). <a rel="nofollow" class="external text" href="https://archive.org/details/clockswatchessix0000will"><i>Clocks & watches</i></a>. New York: Dial Press. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-8037-4475-2" title="Special:BookSources/978-0-8037-4475-2"><bdi>978-0-8037-4475-2</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Clocks+%26+watches&rft.place=New+York&rft.pub=Dial+Press&rft.date=1975&rft.isbn=978-0-8037-4475-2&rft.aulast=Willsberger&rft.aufirst=Johann&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fclockswatchessix0000will&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span> full page color photo: 4th caption page, 3rd photo thereafter (neither pages nor photos are numbered).</span> </li> <li id="cite_note-52"><span class="mw-cite-backlink"><b><a href="#cite_ref-52">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLance_DayIan_McNeil1996" class="citation book cs1">Lance Day; Ian McNeil, eds. (1996). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=nqAOAAAAQAAJ&pg=PA116"><i>Biographical dictionary of the history of technology</i></a>. <a href="/wiki/Routledge" title="Routledge">Routledge</a> (Routledge Reference). p. 116. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-415-06042-4" title="Special:BookSources/978-0-415-06042-4"><bdi>978-0-415-06042-4</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703113711/https://books.google.com/books?id=nqAOAAAAQAAJ&pg=PA116">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. 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Guilford Press. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-57230-589-2" title="Special:BookSources/978-1-57230-589-2"><bdi>978-1-57230-589-2</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703113711/https://books.google.com/books?id=cVUSauNST8EC&q=British+Watch+Company+mass+production">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. 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Archived from <a rel="nofollow" class="external text" href="http://tf.nist.gov/timefreq/general/pdf/1485.pdf">the original</a> <span class="cs1-format">(PDF)</span> on September 27, 2011.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Time+and+frequency+measurement+at+NIST%3A+The+first+100+years&rft.pages=5&rft.pub=Time+and+Frequency+Division%2C+National+Institute+of+Standards+and+Technology&rft.date=2001&rft.aulast=Sullivan&rft.aufirst=D.B.&rft_id=http%3A%2F%2Ftf.nist.gov%2Ftimefreq%2Fgeneral%2Fpdf%2F1485.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-69"><span class="mw-cite-backlink"><b><a href="#cite_ref-69">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://ethw.org/Milestones:Electronic_Quartz_Wristwatch,_1969">"Electronic Quartz Wristwatch, 1969"</a>. 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New York: Courier Dover. p. 39. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-486-40913-9" title="Special:BookSources/978-0-486-40913-9"><bdi>978-0-486-40913-9</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703114213/https://books.google.com/books?id=Z7chuo4ebUAC&q=clock+resonance+pendulum&pg=PA42">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. 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New York: MacMillan. p. 74. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-7808-0008-3" title="Special:BookSources/978-0-7808-0008-3"><bdi>978-0-7808-0008-3</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Time+and+Timekeepers&rft.place=New+York&rft.pages=74&rft.pub=MacMillan&rft.date=1945&rft.isbn=978-0-7808-0008-3&rft.aulast=Milham&rft.aufirst=Willis+I.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-Mondschein-83"><span class="mw-cite-backlink"><b><a href="#cite_ref-Mondschein_83-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMondschein2020" class="citation book cs1">Mondschein, Kenneth (2020). <i>On Time: A History of Western Timekeeping</i>. Johns Hopkins University Press. p. 88. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-4214-3827-6" title="Special:BookSources/978-1-4214-3827-6"><bdi>978-1-4214-3827-6</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=On+Time%3A+A+History+of+Western+Timekeeping&rft.pages=88&rft.pub=Johns+Hopkins+University+Press&rft.date=2020&rft.isbn=978-1-4214-3827-6&rft.aulast=Mondschein&rft.aufirst=Kenneth&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-Britannica-84"><span class="mw-cite-backlink"><b><a href="#cite_ref-Britannica_84-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation encyclopaedia cs1"><a rel="nofollow" class="external text" href="https://www.britannica.com/science/mechanics/Simple-harmonic-oscillations">"Mechanics: Simple harmonic oscillations"</a>. <i>Encyclopedia Britannica online</i>. 2020<span class="reference-accessdate">. Retrieved <span class="nowrap">January 4,</span> 2023</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Mechanics%3A+Simple+harmonic+oscillations&rft.btitle=Encyclopedia+Britannica+online&rft.date=2020&rft_id=https%3A%2F%2Fwww.britannica.com%2Fscience%2Fmechanics%2FSimple-harmonic-oscillations&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-Bloomfield-85"><span class="mw-cite-backlink"><b><a href="#cite_ref-Bloomfield_85-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBloomfield2007" class="citation book cs1">Bloomfield, Louis (2007). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=_ZNxDwAAQBAJ"><i>How Everything Works: Making Physics Out of the Ordinary</i></a>. Wiley. p. 296. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-470-17066-3" title="Special:BookSources/978-0-470-17066-3"><bdi>978-0-470-17066-3</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230404215125/https://books.google.com/books?id=_ZNxDwAAQBAJ">Archived</a> from the original on April 4, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">March 19,</span> 2023</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=How+Everything+Works%3A+Making+Physics+Out+of+the+Ordinary&rft.pages=296&rft.pub=Wiley&rft.date=2007&rft.isbn=978-0-470-17066-3&rft.aulast=Bloomfield&rft.aufirst=Louis&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3D_ZNxDwAAQBAJ&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-86"><span class="mw-cite-backlink"><b><a href="#cite_ref-86">^</a></b></span> <span class="reference-text">Milham, 1945, p. 85</span> </li> <li id="cite_note-87"><span class="mw-cite-backlink"><b><a href="#cite_ref-87">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20080504160852/http://tf.nist.gov/general/enc-q.htm">"Quality factor, Q"</a>. <i>Glossary</i>. Time and Frequency Division, NIST (National Institute of Standards and Technology). 2008. Archived from <a rel="nofollow" class="external text" href="http://tf.nist.gov/general/enc-q.htm">the original</a> on May 4, 2008<span class="reference-accessdate">. Retrieved <span class="nowrap">June 4,</span> 2008</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Glossary&rft.atitle=Quality+factor%2C+Q&rft.date=2008&rft_id=http%3A%2F%2Ftf.nist.gov%2Fgeneral%2Fenc-q.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-88"><span class="mw-cite-backlink"><b><a href="#cite_ref-88">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJespersenFitz-Randolph1999" class="citation book cs1">Jespersen, James; Fitz-Randolph, Jane (January 1999). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=Z7chuo4ebUAC&pg=PA44"><i>Jespersen 1999, pp. 47–50</i></a>. Courier Corporation. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-486-40913-9" title="Special:BookSources/978-0-486-40913-9"><bdi>978-0-486-40913-9</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703114215/https://books.google.com/books?id=Z7chuo4ebUAC&pg=PA44">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">November 6,</span> 2015</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Jespersen+1999%2C+pp.+47%E2%80%9350&rft.pub=Courier+Corporation&rft.date=1999-01&rft.isbn=978-0-486-40913-9&rft.aulast=Jespersen&rft.aufirst=James&rft.au=Fitz-Randolph%2C+Jane&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DZ7chuo4ebUAC%26pg%3DPA44&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-89"><span class="mw-cite-backlink"><b><a href="#cite_ref-89">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRiehle2004" class="citation book cs1">Riehle, Fritz (2004). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=WZ34pQV-DXMC&q=Q+linewidth+%22split+the+line%22&pg=PA9"><i>Frequency Standards: Basics and Applications</i></a>. Germany: Wiley VCH Verlag & Co. p. 9. <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/2004fsba.book.....R">2004fsba.book.....R</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-3-527-40230-4" title="Special:BookSources/978-3-527-40230-4"><bdi>978-3-527-40230-4</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Frequency+Standards%3A+Basics+and+Applications&rft.place=Germany&rft.pages=9&rft.pub=Wiley+VCH+Verlag+%26+Co.&rft.date=2004&rft_id=info%3Abibcode%2F2004fsba.book.....R&rft.isbn=978-3-527-40230-4&rft.aulast=Riehle&rft.aufirst=Fritz&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DWZ34pQV-DXMC%26q%3DQ%2Blinewidth%2B%2522split%2Bthe%2Bline%2522%26pg%3DPA9&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span><sup class="noprint Inline-Template"><span style="white-space: nowrap;">[<i><a href="/wiki/Wikipedia:Link_rot" title="Wikipedia:Link rot"><span title=" Dead link tagged February 2024">permanent dead link</span></a></i><span style="visibility:hidden; color:transparent; padding-left:2px">‍</span>]</span></sup></span> </li> <li id="cite_note-90"><span class="mw-cite-backlink"><b><a href="#cite_ref-90">^</a></b></span> <span class="reference-text">Milham, 1945, pp. 325–328</span> </li> <li id="cite_note-91"><span class="mw-cite-backlink"><b><a href="#cite_ref-91">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJespersenFitz-Randolph1999" class="citation book cs1">Jespersen, James; Fitz-Randolph, Jane (January 1999). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=Z7chuo4ebUAC&pg=PA61"><i>Jespersen 1999, pp. 52–62</i></a>. Courier Corporation. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-486-40913-9" title="Special:BookSources/978-0-486-40913-9"><bdi>978-0-486-40913-9</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703114216/https://books.google.com/books?id=Z7chuo4ebUAC&pg=PA61">Archived</a> from the original on July 3, 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">November 6,</span> 2015</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Jespersen+1999%2C+pp.+52%E2%80%9362&rft.pub=Courier+Corporation&rft.date=1999-01&rft.isbn=978-0-486-40913-9&rft.aulast=Jespersen&rft.aufirst=James&rft.au=Fitz-Randolph%2C+Jane&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DZ7chuo4ebUAC%26pg%3DPA61&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-92"><span class="mw-cite-backlink"><b><a href="#cite_ref-92">^</a></b></span> <span class="reference-text">Milham, 1945, p. 113</span> </li> <li id="cite_note-93"><span class="mw-cite-backlink"><b><a href="#cite_ref-93">^</a></b></span> <span class="reference-text"><span><a rel="nofollow" class="external text" href="https://patents.google.com/patent/US7079452">U.S. patent 7,079,452</a></span>, <span><a rel="nofollow" class="external text" href="https://patents.google.com/patent/US7221624">U.S. patent 7,221,624</a></span></span> </li> <li id="cite_note-94"><span class="mw-cite-backlink"><b><a href="#cite_ref-94">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSadraey2020" class="citation book cs1">Sadraey, Mohammad H. (2020). <i>Design of Unmanned Aerial Systems</i>. John Wiley & Sons. p. 332. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-119-50870-0" title="Special:BookSources/978-1-119-50870-0"><bdi>978-1-119-50870-0</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Design+of+Unmanned+Aerial+Systems&rft.pages=332&rft.pub=John+Wiley+%26+Sons&rft.date=2020&rft.isbn=978-1-119-50870-0&rft.aulast=Sadraey&rft.aufirst=Mohammad+H.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-95"><span class="mw-cite-backlink"><b><a href="#cite_ref-95">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRizzo2023" class="citation web cs1">Rizzo, John (September 10, 2023). <a rel="nofollow" class="external text" href="https://www.metroleague.org/nfl-clock-stop-rules_af/">"NFL Clock Stop Rules: A Comprehensive Guide"</a>. <i>Metro League</i><span class="reference-accessdate">. Retrieved <span class="nowrap">September 11,</span> 2023</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Metro+League&rft.atitle=NFL+Clock+Stop+Rules%3A+A+Comprehensive+Guide&rft.date=2023-09-10&rft.aulast=Rizzo&rft.aufirst=John&rft_id=https%3A%2F%2Fwww.metroleague.org%2Fnfl-clock-stop-rules_af%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-96"><span class="mw-cite-backlink"><b><a href="#cite_ref-96">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.ikonet.com/en/visualdictionary/sports-and-games/sports-facilities/scoreboard.php">"sports and games > sports facilities > scoreboard image - Visual Dictionary"</a>. <i>www.ikonet.com</i><span class="reference-accessdate">. Retrieved <span class="nowrap">September 11,</span> 2023</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.ikonet.com&rft.atitle=sports+and+games+%3E+sports+facilities+%3E+scoreboard+image+-+Visual+Dictionary&rft_id=http%3A%2F%2Fwww.ikonet.com%2Fen%2Fvisualdictionary%2Fsports-and-games%2Fsports-facilities%2Fscoreboard.php&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-97"><span class="mw-cite-backlink"><b><a href="#cite_ref-97">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFOpieTatem1989" class="citation book cs1">Opie, Iona; Tatem, Moira (1989). <i>A Dictionary of Superstitions</i>. <a href="/wiki/Oxford_University_Press" title="Oxford University Press">Oxford University Press</a> (published 1990). pp. 84–5. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780760714829" title="Special:BookSources/9780760714829"><bdi>9780760714829</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+Dictionary+of+Superstitions&rft.pages=84-5&rft.pub=Oxford+University+Press&rft.date=1989&rft.isbn=9780760714829&rft.aulast=Opie&rft.aufirst=Iona&rft.au=Tatem%2C+Moira&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-98"><span class="mw-cite-backlink"><b><a href="#cite_ref-98">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFOpieTatem1989" class="citation book cs1">Opie, Iona; Tatem, Moira (1989). <i>A Dictionary of Superstitions</i>. <a href="/wiki/Oxford_University_Press" title="Oxford University Press">Oxford University Press</a> (published 1990). p. 85. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780760714829" title="Special:BookSources/9780760714829"><bdi>9780760714829</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+Dictionary+of+Superstitions&rft.pages=85&rft.pub=Oxford+University+Press&rft.date=1989&rft.isbn=9780760714829&rft.aulast=Opie&rft.aufirst=Iona&rft.au=Tatem%2C+Moira&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-99"><span class="mw-cite-backlink"><b><a href="#cite_ref-99">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFOpieTatem1989" class="citation book cs1">Opie, Iona; Tatem, Moira (1989). <i>A Dictionary of Superstitions</i>. <a href="/wiki/Oxford_University_Press" title="Oxford University Press">Oxford University Press</a> (published 1990). pp. 85–6. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780760714829" title="Special:BookSources/9780760714829"><bdi>9780760714829</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+Dictionary+of+Superstitions&rft.pages=85-6&rft.pub=Oxford+University+Press&rft.date=1989&rft.isbn=9780760714829&rft.aulast=Opie&rft.aufirst=Iona&rft.au=Tatem%2C+Moira&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-100"><span class="mw-cite-backlink"><b><a href="#cite_ref-100">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFOpieTatem1989" class="citation book cs1">Opie, Iona; Tatem, Moira (1989). <i>A Dictionary of Superstitions</i>. <a href="/wiki/Oxford_University_Press" title="Oxford University Press">Oxford University Press</a> (published 1990). pp. 84–6. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780760714829" title="Special:BookSources/9780760714829"><bdi>9780760714829</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+Dictionary+of+Superstitions&rft.pages=84-6&rft.pub=Oxford+University+Press&rft.date=1989&rft.isbn=9780760714829&rft.aulast=Opie&rft.aufirst=Iona&rft.au=Tatem%2C+Moira&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-101"><span class="mw-cite-backlink"><b><a href="#cite_ref-101">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBrown2006" class="citation book cs1">Brown, Ju (2006). <i>China, Japan, Korea Culture and Customs</i>. p. 57.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=China%2C+Japan%2C+Korea+Culture+and+Customs&rft.pages=57&rft.date=2006&rft.aulast=Brown&rft.aufirst=Ju&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-102"><span class="mw-cite-backlink"><b><a href="#cite_ref-102">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSeligman1999" class="citation book cs1">Seligman, Scott D. (1999). <i>Chinese business etiquette:: a guide to protocol, manners, and culture in the People's Republic of China</i>. Hachette Digital, Inc.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Chinese+business+etiquette%3A%3A+a+guide+to+protocol%2C+manners%2C+and+culture+in+the+People%27s+Republic+of+China&rft.pub=Hachette+Digital%2C+Inc.&rft.date=1999&rft.aulast=Seligman&rft.aufirst=Scott+D.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></span> </li> <li id="cite_note-103"><span class="mw-cite-backlink"><b><a href="#cite_ref-103">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external free" href="http://www.sohu.com/a/160882715_578225">http://www.sohu.com/a/160882715_578225</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20180105233649/http://www.sohu.com/a/160882715_578225">Archived</a> January 5, 2018, at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a> 别人过节喜庆的时候, 不送钟表.送终和送钟谐音.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="Bibliography">Bibliography</h2></div> <ul><li>Baillie, G.H., O. Clutton, & C.A. Ilbert. <i>Britten's Old Clocks and Watches and Their Makers</i> (7th ed.). Bonanza Books (1956).</li> <li>Bolter, David J. <i>Turing's Man: Western Culture in the Computer Age</i>. The University of North Carolina Press, Chapel Hill, NC (1984). <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-8078-4108-0" title="Special:BookSources/0-8078-4108-0">0-8078-4108-0</a> pbk. Summary of the role of "the clock" in its setting the direction of philosophic movement for the "Western World". Cf. picture on p. 25 showing the <i>verge</i> and <i>foliot</i>. Bolton derived the picture from Macey, p. 20.</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBruton1982" class="citation book cs1">Bruton, Eric (1982). <i><span></span></i>The History of Clocks and Watches<i><span></span></i>. New York: Crescent Books Distributed by Crown. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-517-37744-4" title="Special:BookSources/978-0-517-37744-4"><bdi>978-0-517-37744-4</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+History+of+Clocks+and+Watches&rft.place=New+York&rft.pub=Crescent+Books+Distributed+by+Crown&rft.date=1982&rft.isbn=978-0-517-37744-4&rft.aulast=Bruton&rft.aufirst=Eric&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCowan1958" class="citation book cs1">Cowan, Harrison J. (1958). <i>Time and Its Measurement: From the stone age to the nuclear age</i>. Ohio: The World Publishing Company. <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/1958tmfs.book.....C">1958tmfs.book.....C</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Time+and+Its+Measurement%3A+From+the+stone+age+to+the+nuclear+age&rft.place=Ohio&rft.pub=The+World+Publishing+Company&rft.date=1958&rft_id=info%3Abibcode%2F1958tmfs.book.....C&rft.aulast=Cowan&rft.aufirst=Harrison+J.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDohrn-van_Rossum1996" class="citation book cs1">Dohrn-van Rossum, Gerhard (1996). <i>History of the Hour: Clocks and Modern Temporal Orders</i>. Trans. Thomas Dunlap. Chicago: The University of Chicago Press. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-226-15510-4" title="Special:BookSources/978-0-226-15510-4"><bdi>978-0-226-15510-4</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=History+of+the+Hour%3A+Clocks+and+Modern+Temporal+Orders&rft.place=Chicago&rft.pub=The+University+of+Chicago+Press&rft.date=1996&rft.isbn=978-0-226-15510-4&rft.aulast=Dohrn-van+Rossum&rft.aufirst=Gerhard&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></li> <li>Edey, Winthrop. <i>French Clocks</i>. New York: Walker & Co. (1967).</li> <li>Kak, Subhash, Babylonian and Indian Astronomy: Early Connections. 2003.</li> <li>Kumar, Narendra "Science in Ancient India" (2004). <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/81-261-2056-8" title="Special:BookSources/81-261-2056-8">81-261-2056-8</a>.</li> <li>Landes, David S. <i>Revolution in Time: Clocks and the Making of the Modern World</i>. Cambridge: Harvard University Press (1983).</li> <li>Landes, David S. <i>Clocks & the Wealth of Nations</i>, <a href="/wiki/Daedalus_(journal)" title="Daedalus (journal)">Daedalus Journal</a>, Spring 2003.</li> <li>Lloyd, Alan H. "Mechanical Timekeepers", <i>A History of Technology,</i> Vol. III. Edited by Charles Joseph Singer et al. Oxford: Clarendon Press (1957), pp. 648–675.</li> <li>Macey, Samuel L., <i>Clocks and the Cosmos: Time in Western Life and Thought</i>, Archon Books, Hamden, Conn. (1980).</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFNeedham2000" class="citation book cs1"><a href="/wiki/Joseph_Needham" title="Joseph Needham">Needham, Joseph</a> (2000) [1965]. <i>Science & Civilisation in China, Vol. 4, Part 2: Mechanical Engineering</i>. Cambridge: Cambridge University Press. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-521-05803-2" title="Special:BookSources/978-0-521-05803-2"><bdi>978-0-521-05803-2</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Science+%26+Civilisation+in+China%2C+Vol.+4%2C+Part+2%3A+Mechanical+Engineering&rft.place=Cambridge&rft.pub=Cambridge+University+Press&rft.date=2000&rft.isbn=978-0-521-05803-2&rft.aulast=Needham&rft.aufirst=Joseph&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></li> <li>North, John. <i>God's Clockmaker: Richard of Wallingford and the Invention of Time</i>. London: Hambledon and London (2005).</li> <li>Opie, Iona, & Moira Tatem. "A Dictionary of Superstitions". Oxford: Oxford University Press (1990).</li> <li>Palmer, Brooks. <i>The Book of American Clocks</i>, The Macmillan Co. (1979).</li> <li>Robinson, Tom. <i>The Longcase Clock</i>. Suffolk, England: Antique Collector's Club (1981).</li> <li>Smith, Alan. <i>The International Dictionary of Clocks</i>. London: Chancellor Press (1996).</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFStephens2002" class="citation book cs1">Stephens, Carlene E. (2002). <i>On Time: How America Has Learned to Live by the Clock</i> (First ed.). Boston: Little, Brown and Company. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-8212-2779-3" title="Special:BookSources/0-8212-2779-3"><bdi>0-8212-2779-3</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=On+Time%3A+How+America+Has+Learned+to+Live+by+the+Clock&rft.place=Boston&rft.edition=First&rft.pub=Little%2C+Brown+and+Company&rft.date=2002&rft.isbn=0-8212-2779-3&rft.aulast=Stephens&rft.aufirst=Carlene+E.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></li> <li>Tardy. <i>French Clocks the World Over</i>. Part I and II. Translated with the assistance of Alexander Ballantyne. Paris: Tardy (1981).</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFTurner1984" class="citation book cs1 cs1-prop-long-vol">Turner, Anthony J. (1984). <i>The Time Museum</i>. Vol. I: <i>Time Measuring Instruments</i>. Rockford, IL: The Museum. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-912947-01-2" title="Special:BookSources/0-912947-01-2"><bdi>0-912947-01-2</bdi></a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/159866762">159866762</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Time+Museum&rft.place=Rockford%2C+IL&rft.pub=The+Museum&rft.date=1984&rft_id=info%3Aoclcnum%2F159866762&rft.isbn=0-912947-01-2&rft.aulast=Turner&rft.aufirst=Anthony+J.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></li> <li><a href="/wiki/Joella_Yoder" title="Joella Yoder">Yoder, Joella Gerstmeyer</a>. <i>Unrolling Time: Christiaan Huygens and the Mathematization of Nature</i>. New York: Cambridge University Press (1988).</li> <li>Zea, Philip, & Robert Cheney. <i>Clock Making in New England: 1725–1825</i>. Old Sturbridge Village (1992).</li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div> <style data-mw-deduplicate="TemplateStyles:r1235611614">.mw-parser-output .spoken-wikipedia{border:1px solid #a2a9b1;background-color:var(--background-color-interactive-subtle,#f8f9fa);margin:0.5em 0;padding:0.2em;line-height:1.5em;font-size:90%}.mw-parser-output .spoken-wikipedia-header{text-align:center}.mw-parser-output .spoken-wikipedia-listen-to{font-weight:bold}.mw-parser-output .spoken-wikipedia-files{text-align:center;margin-top:10px;margin-bottom:0.4em}.mw-parser-output .spoken-wikipedia-icon{float:left;margin-left:5px;margin-top:10px}.mw-parser-output .spoken-wikipedia-disclaimer{margin-left:60px;margin-top:10px;font-size:95%;line-height:1.4em}.mw-parser-output .spoken-wikipedia-footer{margin-top:10px;text-align:center}@media(min-width:720px){.mw-parser-output .spoken-wikipedia{width:20em;float:right;clear:right;margin-left:1em}}</style><div class="spoken-wikipedia noprint haudio"><div class="spoken-wikipedia-header"><span class="spoken-wikipedia-listen-to">Listen to this article</span> (<span class="duration"><span class="min">45</span> minutes</span>)</div><div class="spoken-wikipedia-files"><figure class="mw-halign-center" typeof="mw:File"><span><audio id="mwe_player_1" controls="" preload="none" data-mw-tmh="" class="mw-file-element" width="200" style="width:200px;" data-durationhint="2720" data-mwtitle="Clock.ogg" data-mwprovider="wikimediacommons"><source src="//upload.wikimedia.org/wikipedia/commons/6/68/Clock.ogg" type="audio/ogg; 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Vol. VI (9th ed.). 1878. pp. 13–35.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Clocks&rft.btitle=Encyclop%C3%A6dia+Britannica&rft.pages=13-35&rft.edition=9th&rft.date=1878&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation encyclopaedia cs1"><span class="cs1-ws-icon" title="s:1911 Encyclopædia Britannica/Clock"><a class="external text" href="https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica/Clock">"Clock" </a></span>. <i><a href="/wiki/Encyclop%C3%A6dia_Britannica_Eleventh_Edition" title="Encyclopædia Britannica Eleventh Edition">Encyclopædia Britannica</a></i>. Vol. 6 (11th ed.). 1911. pp. 536–553.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Clock&rft.btitle=Encyclop%C3%A6dia+Britannica&rft.pages=536-553&rft.edition=11th&rft.date=1911&rfr_id=info%3Asid%2Fen.wikipedia.org%3AClock" class="Z3988"></span></li> <li><a rel="nofollow" class="external text" href="https://www.gutenberg.org/ebooks/73581">Blackboard clock</a></li></ul> <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 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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"><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 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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 href="/wiki/Chronometry" title="Chronometry">Chronometry</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time">UTC</a></li> <li><a href="/wiki/Universal_Time" title="Universal Time">UT</a></li> <li><a href="/wiki/International_Atomic_Time" title="International Atomic Time">TAI</a></li> <li><a href="/wiki/Unit_of_time" title="Unit of time">Unit of time</a></li> <li><a href="/wiki/Orders_of_magnitude_(time)" title="Orders of magnitude (time)">Orders of magnitude (time)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/System_of_measurement" class="mw-redirect" title="System of measurement">Measurement<br />systems</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Italian_six-hour_clock" title="Italian six-hour clock">Italian six-hour clock</a></li> <li><a href="/wiki/Thai_six-hour_clock" title="Thai six-hour clock">Thai six-hour clock</a></li> <li><a href="/wiki/12-hour_clock" title="12-hour clock">12-hour clock</a></li> <li><a href="/wiki/24-hour_clock" title="24-hour clock">24-hour clock</a></li> <li><a href="/wiki/Relative_hour" title="Relative hour">Relative hour</a></li> <li><a href="/wiki/Daylight_saving_time" title="Daylight saving time">Daylight saving time</a></li> <li><a href="/wiki/Traditional_Chinese_timekeeping" title="Traditional Chinese timekeeping">Chinese</a></li> <li><a href="/wiki/Decimal_time" title="Decimal time">Decimal</a></li> <li><a href="/wiki/Hexadecimal_time" title="Hexadecimal time">Hexadecimal</a></li> <li><a href="/wiki/Hindu_units_of_time" title="Hindu units of time">Hindu</a></li> <li><a href="/wiki/Metric_time" title="Metric time">Metric</a></li> <li><a href="/wiki/Roman_timekeeping" title="Roman timekeeping">Roman</a></li> <li><a href="/wiki/Sidereal_time" title="Sidereal time">Sidereal</a></li> <li><a href="/wiki/Solar_time" title="Solar time">Solar</a></li> <li><a href="/wiki/Time_zone" title="Time zone">Time zone</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/Calendar" title="Calendar">Calendars</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Calendar#Systems" title="Calendar">Main types</a> <ul><li><a href="/wiki/Solar_calendar" title="Solar calendar">Solar</a></li> <li><a href="/wiki/Lunar_calendar" title="Lunar calendar">Lunar</a></li> <li><a href="/wiki/Lunisolar_calendar" title="Lunisolar calendar">Lunisolar</a></li></ul></li> <li><a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian</a></li> <li><a href="/wiki/Julian_calendar" title="Julian calendar">Julian</a></li> <li><a href="/wiki/Hebrew_calendar" title="Hebrew calendar">Hebrew</a></li> <li><a href="/wiki/Islamic_calendar" title="Islamic calendar">Islamic</a></li> <li><a href="/wiki/Solar_Hijri_calendar" title="Solar Hijri calendar">Solar Hijri</a></li> <li><a href="/wiki/Chinese_calendar" title="Chinese calendar">Chinese</a></li> <li><a href="/wiki/Hindu_calendar" title="Hindu calendar">Hindu Panchang</a></li> <li><a href="/wiki/Maya_calendar" title="Maya calendar">Maya</a></li> <li><i><a href="/wiki/List_of_calendars" title="List of calendars">List</a></i></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a class="mw-selflink selflink">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 class="mw-selflink-fragment" href="#Types">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 href="/wiki/Chronometry" title="Chronometry">Chronometry</a></li> <li><a href="/wiki/Orders_of_magnitude_(time)" title="Orders of magnitude (time)">Orders of magnitude</a></li> <li><a href="/wiki/Time_metrology" class="mw-redirect" title="Time metrology">Metrology</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">International standards</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time">Coordinated Universal Time</a> <ul><li><a href="/wiki/UTC_offset" title="UTC offset">offset</a></li></ul></li> <li><a href="/wiki/Universal_Time" title="Universal Time">UT</a></li> <li><a href="/wiki/%CE%94T_(timekeeping)" title="ΔT (timekeeping)">ΔT</a></li> <li><a href="/wiki/DUT1" title="DUT1">DUT1</a></li> <li><a href="/wiki/International_Earth_Rotation_and_Reference_Systems_Service" title="International Earth Rotation and Reference Systems Service">International Earth Rotation and Reference Systems Service</a></li> <li><a href="/wiki/ISO_31-1" title="ISO 31-1">ISO 31-1</a></li> <li><a href="/wiki/ISO_8601" title="ISO 8601">ISO 8601</a></li> <li><a href="/wiki/International_Atomic_Time" title="International Atomic Time">International Atomic Time</a></li> <li><a href="/wiki/12-hour_clock" title="12-hour clock">12-hour clock</a></li> <li><a href="/wiki/24-hour_clock" title="24-hour clock">24-hour clock</a></li> <li><a href="/wiki/Barycentric_Coordinate_Time" title="Barycentric Coordinate Time">Barycentric Coordinate Time</a></li> <li><a href="/wiki/Barycentric_Dynamical_Time" title="Barycentric Dynamical Time">Barycentric Dynamical Time</a></li> <li><a href="/wiki/Civil_time" title="Civil time">Civil time</a></li> <li><a href="/wiki/Daylight_saving_time" title="Daylight saving time">Daylight saving time</a></li> <li><a href="/wiki/Geocentric_Coordinate_Time" title="Geocentric Coordinate Time">Geocentric Coordinate Time</a></li> <li><a href="/wiki/International_Date_Line" title="International Date Line">International Date Line</a></li> <li><a href="/wiki/IERS_Reference_Meridian" title="IERS Reference Meridian">IERS Reference Meridian</a></li> <li><a href="/wiki/Leap_second" title="Leap second">Leap second</a></li> <li><a href="/wiki/Solar_time" title="Solar time">Solar time</a></li> <li><a href="/wiki/Terrestrial_Time" title="Terrestrial Time">Terrestrial Time</a></li> <li><a href="/wiki/Time_zone" title="Time zone">Time zone</a></li> <li><a href="/wiki/180th_meridian" title="180th meridian">180th meridian</a></li></ul> </div></td><td class="noviewer navbox-image" rowspan="9" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"><a href="/wiki/Hourglass" title="Hourglass"><img alt="template illustration" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Marine_sandglass_MMM.jpg/75px-Marine_sandglass_MMM.jpg" decoding="async" width="75" height="175" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Marine_sandglass_MMM.jpg/113px-Marine_sandglass_MMM.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/70/Marine_sandglass_MMM.jpg/150px-Marine_sandglass_MMM.jpg 2x" data-file-width="1637" data-file-height="3819" /></a></span><br /><span typeof="mw:File"><a href="/wiki/Time_zone" title="Time zone"><img alt="template illustration" src="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png/75px-Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png" decoding="async" width="75" height="152" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png/113px-Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/63/Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png/150px-Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png 2x" data-file-width="496" data-file-height="1007" /></a></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Obsolete standards</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ephemeris_time" title="Ephemeris time">Ephemeris time</a></li> <li><a href="/wiki/Greenwich_Mean_Time" title="Greenwich Mean Time">Greenwich Mean Time</a></li> <li><a href="/wiki/Prime_meridian" title="Prime meridian">Prime meridian</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Time_in_physics" title="Time in physics">Time in physics</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Absolute_space_and_time" title="Absolute space and time">Absolute space and time</a></li> <li><a href="/wiki/Spacetime" title="Spacetime">Spacetime</a></li> <li><a href="/wiki/Chronon" title="Chronon">Chronon</a></li> <li><a href="/wiki/Continuous_signal" class="mw-redirect" title="Continuous signal">Continuous signal</a></li> <li><a href="/wiki/Coordinate_time" title="Coordinate time">Coordinate time</a></li> <li><a href="/wiki/Cosmological_decade" title="Cosmological decade">Cosmological decade</a></li> <li><a href="/wiki/Discrete_time_and_continuous_time" title="Discrete time and continuous time">Discrete time and continuous time</a></li> <li><a href="/wiki/Proper_time" title="Proper time">Proper time</a></li> <li><a href="/wiki/Theory_of_relativity" title="Theory of relativity">Theory of relativity</a></li> <li><a href="/wiki/Time_dilation" title="Time dilation">Time dilation</a></li> <li><a href="/wiki/Gravitational_time_dilation" title="Gravitational time dilation">Gravitational time dilation</a></li> <li><a href="/wiki/Time_domain" title="Time domain">Time domain</a></li> <li><a href="/wiki/Time-translation_symmetry" title="Time-translation symmetry">Time-translation symmetry</a></li> <li><a href="/wiki/T-symmetry" title="T-symmetry">T-symmetry</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Horology" class="mw-redirect" title="Horology">Horology</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a class="mw-selflink selflink">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 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