Editing Hour (section)

==History==

=== Antiquity ===

==== Ancient Egypt ====
In ancient Egypt the [[flooding of the Nile]] was, and still is, an important annual event, crucial for agriculture. It was accompanied by the rise of [[Sirius]] before the sunrise, and the appearance of 12 constellations across the night sky, to which the Egyptians assigned some significance. Influenced by this, the Egyptians divided the night into 12 equal intervals.<ref>{{Cite web |last=Andrewes |first=William J. H. |date=February 1, 2006 |title=A Chronicle Of Timekeeping |url=https://www.scientificamerican.com/article/a-chronicle-of-timekeeping-2006-02/ |access-date=2024-08-20 |website=Scientific American |language=en}}</ref> These were [[Unequal hours|seasonal hours]], shorter in the summer than in the winter. Subsequently, the day was divided into intervals as well, which eventually became more important than the nightly intervals. These subdivisions of a day spread to Greece, and later to Rome.

==== Ancient Greece ====
{{Further|Horae}}
The ancient Greeks kept time differently than is done today. Instead of dividing the time between one midnight and the next into 24 equal hours, they divided the time from sunrise to sunset into 12 "seasonal hours" (their actual duration depending on season), and the time from sunset to the next sunrise again in 12 "seasonal hours".<ref>{{cite book |first=James |last=Evans |year=1998 |title=The History and Practice of Ancient Astronomy |publisher=Oxford University Press |page=95 |isbn=978-0-19-509539-5 |url=https://books.google.com/books?id=nS51_7qbEWsC&pg=PA95 |via=Google Books}}</ref> Initially, only the day was divided into 12&nbsp;seasonal hours and the night into three or four night watches.<ref>
{{cite book
 | last1 = Liddell | first1 = Henry George | author-link1 = Henry Liddell
 | last2 = Scott   | first2 = Robert       | author-link2 = Robert Scott (philologist)
 | year = 1883
 | title = A Lexicon Abridged from Liddell & Scott's Greek-English Lexicon
 | edition = 20
 | publisher = Harper & Brothers
 | orig-year = 1883
 | page = 469
 | url = https://books.google.com/books?id=LeFFAQAAMAAJ&pg=PA469
 | access-date = 12 April 2021
 | quote = [...] from Homer downwards, the Greeks divided the night into three watches.
}}
</ref>

By the [[Hellenistic period]] the night was also divided into 12 hours.<ref>{{cite book |author=Polybius |title=Histories, Book 9 |chapter=15 Mode of Calculating Time |chapter-url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.01.0234%3Abook%3D9%3Achapter%3D15}}</ref> The day-and-night ({{lang|grc|νυχθήμερον}}) was probably first divided into 24 hours by [[Hipparchus of Nicaea]].<ref>{{cite book |last1=Liddell |first1=Henry George |last2=Scott |first2=Robert |last3=Jones |first3=Henry Stuart  |section=ὥρα |title=A Greek-English Lexicon |at=Α.ΙΙ.2 |section-url=https://lsj.gr/wiki/%E1%BD%A5%CF%81%CE%B1}}</ref> The Greek astronomer [[Andronicus of Cyrrhus]] oversaw the construction of a [[horologion]] called the [[Tower of the Winds]] in Athens during the first century BCE. This structure tracked a 24-hour day using both sundials and mechanical hour indicators.<ref name="nist">{{cite web |title=Early Clocks |date= 12 August 2009 |series=A Walk Through Time |publisher=[[National Institute of Standards and Technology]] |url=https://www.nist.gov/pml/time-and-frequency-division/popular-links/walk-through-time/walk-through-time-early-clocks |access-date= 13 October 2022}}</ref>

The [[canonical hours]] were inherited into [[early Christianity]]  from [[Second Temple Judaism]].
By AD 60, the ''[[Didache]]'' recommends disciples to pray the [[Lord's Prayer]] three times a day; this practice found its way into the canonical hours as well. By the second and third centuries, such [[Church Fathers]] as [[Clement of Alexandria]], [[Origen]], and [[Tertullian]] wrote of the practice of Morning and Evening Prayer, and of the prayers at the third, sixth and ninth hours.
In the early church, during the night before every feast, a [[vigil]] was kept. The word "Vigils", at first applied to the Night Office, comes from a Latin source, namely the ''Vigiliae'' or nocturnal watches or guards of the soldiers. The night from six o'clock in the evening to six o'clock in the morning was divided into four watches or vigils of three hours each, the first, the second, the third, and the fourth vigil.<ref>{{CE1913|last=Cabrol |first=Fernand |wstitle=Matins |volume=10}}</ref>

The ''[[Horae]]'' were originally personifications of seasonal aspects of nature, not of the time of day.
The list of 12 ''Horae'' representing the 12 hours of the day is recorded only in [[Late Antiquity]], by [[Nonnus]].<ref>{{cite book |author=[[Nonnus]] |title=Dionysiaca |at=41.263}}</ref> The first and twelfth of the ''Horae'' were added to the original set of ten:

# ''Auge'' (first light)
# ''Anatole'' (sunrise)
# ''Mousike'' (morning hour of music and study)
# ''Gymnastike'' (morning hour of exercise)
# ''Nymphe'' (morning hour of ablutions)
# ''Mesembria'' (noon)
# ''Sponde'' (libations poured after lunch)
# ''Elete'' (prayer)
# ''Akte'' (eating and pleasure)
# ''Hesperis'' (start of evening)
# ''Dysis'' (sunset)
# ''Arktos'' (night sky)

===Middle Ages===
{{main|Canonical hours}}
[[Image:Bishopstone sundial.jpg|right|thumb|200px|A 7th-century Saxon [[tide dial]] on the porch at [[Bishopstone, East Sussex|Bishopstone]] in [[Sussex]], with larger crosses marking the [[canonical hours]].{{sfnp|Wall|1912|p=67}}]]

Medieval astronomers such as [[al-Biruni]]<ref>{{ cite book | author=Al-Biruni | year=1879 | orig-year=1000 | title=The Chronology of Ancient Nations | url=https://books.google.com/books?id=pFIEAAAAIAAJ&pg=PA147 | pages=147–149 | translator-last=Sachau | translator-first=C. Edward | author-link=Al-Biruni}}</ref> and [[Sacrobosco]],<ref>{{ Citation | last = Nothaft | first = C. Philipp E. | date = 2018 | title = Scandalous Error: Calendar Reform and Calendrical Astronomy in Medieval Europe | publisher = Oxford University Press | place = Oxford | page = 126 | isbn = 9780198799559}}</ref>   divided the hour into 60 [[minute]]s, each of 60 [[second]]s; this derives from [[Babylonian astronomy]], where the corresponding terms{{clarify|date=April 2020}} denoted the time required for the Sun's apparent motion through the [[ecliptic]] to describe one minute or second of arc, respectively. In present terms, the Babylonian degree of time was thus four minutes long, the "minute" of time was thus four seconds long and the "second" 1/15 of a second.<ref>{{cite journal |last=Correll |first=Malcolm |journal=The Physics Teacher |volume=15 |pages=476–479 |issue=8 |date=November 1977 |title=Early Time Measurements|doi=10.1119/1.2339739 |bibcode=1977PhTea..15..476C }}</ref><ref>{{cite journal|journal=Journal for the History of Astronomy|author1=F. Richard Stephenson|author-link=F. Richard Stephenson|author2=Louay J. Fatoohi|date=May 1994|doi=10.1177/002182869402500203|title=The Babylonian Unit of Time|volume=25|issue=2|pages=99–110|bibcode=1994JHA....25...99S|s2cid=117951139}}</ref>

In medieval Europe, the Roman hours continued to be marked on [[sundial]]s but the more important units of time were the [[canonical hours]] of the [[Greek Orthodox Church|Orthodox]] and [[Catholic Church]]. During daylight, these followed the pattern set by the three-hour bells of the [[forum (market)|Roman markets]], which were succeeded by the [[church bell|bells]] of local churches. They rang [[prime (liturgy)|prime]] at about 6{{nbsp}}am, [[terce]] at about 9{{nbsp}}am, [[sext]] at noon, [[nones (liturgy)|nones]] at about 3{{nbsp}}pm, and [[vespers]] at either 6{{nbsp}}pm or [[sunset]]. [[Matins]] and [[lauds]] precede these irregularly in the morning hours; [[compline]] follows them irregularly before sleep; and the [[midnight office]] follows that. [[Vatican II]] ordered their reformation for the Catholic Church in 1963,<ref>{{citation |author=Paul&nbsp;VI |author-link=Pope Paul VI |date=4 December 1963 |title=Constitution on<!--sic--> the Sacred Liturgy |url=https://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19631204_sacrosanctum-concilium_en.html |location=Vatican City |at=§89(d) }}</ref> though they continue to be observed in the Orthodox churches.

When mechanical [[clock]]s began to be used to show hours of daylight or nighttime, their period needed to be changed every morning and evening (for example, by changing the length of their [[pendula]]). The use of 24 hours for the entire day meant hours varied much less and the clocks needed to be adjusted only a few times a month.

===Modernity===
{{main|Decimal time|Metric system}}
The minor irregularities of the apparent solar day were smoothed by measuring time using the [[mean solar day]], using the Sun's movement along the [[celestial equator]] rather than along the [[ecliptic]]. The irregularities of this time system were so minor that most clocks reckoning such hours did not need adjustment. However, scientific measurements eventually became precise enough to note the effect of [[tidal deceleration]] of the [[Earth]] by the [[Moon]], which gradually lengthens the Earth's days.

During the [[French Revolution]], a [[French Revolutionary units|general decimalisation of measures]] was enacted, including [[decimal time]] between 1794 and 1800. Under its provisions, the French hour ({{langx|fr|{{linktext|heure}}}}) was {{frac|10}} of the day and divided formally into 100 decimal minutes (''{{lang|fr|minute décimale}}'') and informally into 10 tenths (''{{lang|fr|{{linktext|décime}}}}''). Mandatory use for all public records  began in 1794, but was suspended six months later by the same 1795 legislation that first established the metric system. In spite of this, a few localities continued to use decimal time for six years for civil status records, until 1800, after Napoleon's Coup of 18 Brumaire.

The [[metric system]] bases its measurements of time upon the [[second]], defined since 1952 in terms of the Earth's rotation in AD{{nbsp}}1900. Its hours are a secondary unit computed as precisely 3,600 seconds.<ref name=sportsillustrated>{{citation |url=http://www.bipm.org/en/publications/si-brochure/ |title=The International System of Units (SI), ''8th ed.'' |contribution-url=http://www.bipm.org/en/publications/si-brochure/table6.html |contribution=Non-SI Units Accepted for Use with the SI, and Units Based on Fundamental Constants (contd.) |publisher=International Bureau of Weights and Measures |date=2014 |location=Paris }}</ref> However, an hour of [[Coordinated Universal Time]] (UTC), used as the basis of most civil time, has lasted 3,601 seconds 27 times since 1972 in order to keep it within 0.9 seconds of [[UT1|universal time]], which is based on measurements of the [[mean solar day]] at [[0° longitude]]. The addition of these seconds accommodates the very gradual slowing of the [[Earth's rotation|rotation]] of the [[Earth]].

In modern life, the ubiquity of clocks and other timekeeping devices means that segmentation of days according to their hours is commonplace. Most forms of [[employment]], whether [[wage labor|wage]] or [[salaried]] labour, involve compensation based upon measured or expected hours worked. The fight for an [[eight-hour day]] was a part of [[labour movement]]s around the world. Informal [[rush hour]]s and [[happy hour]]s cover the times of day when commuting slows down due to congestion or alcoholic drinks being available at discounted prices. The [[hour record]] for the greatest distance travelled by a cyclist within the span of an hour is one of [[cycle sport|cycling]]'s greatest honours.