# How did the world ever agree on the 24 hour clock? **URL:** \ **Category:** Factual Questions\ **Created:** [August 25, 2002, 9:52pm UTC](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526 "2002-08-25T21:52:50Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![Popup](https://avatars.discourse-cdn.com/v4/letter/p/94ad74/32.png) [@Popup](https://boards.straightdope.com/u/Popup)\ **Post date:** [August 27, 2002, 11:33am UTC](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526/21 "2002-08-27T11:33:35Z")
> [@](#): > > \*Originally posted by Derleth \* > \*\*AM = Ante Meridiem = Before noon. > \*\* And to make matters worse, the French sometimes write **am** for ‘apres-midi’ - afternoon! ---
**Author:** ![Sparc](https://avatars.discourse-cdn.com/v4/letter/s/65b543/32.png) [@Sparc](https://boards.straightdope.com/u/Sparc)\ **Post date:** [August 27, 2002, 12:08pm UTC](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526/22 "2002-08-27T12:08:11Z")
> [@](#): > > Originaly the day was divided in 12 parts, and the night in twelve. The (diurnal) hours were indeed longer during summer than during winter. That didn’t matter (much) for the Babylonians, as they’re pretty close to the equator, but further north it gets important. As I already noted two or three times in this thread: It was the **Egyptians** who divided the night and then subsequently the day into 12 hours **not** the Babylonians. Sparc ---
**Author:** ![Sparc](https://avatars.discourse-cdn.com/v4/letter/s/65b543/32.png) [@Sparc](https://boards.straightdope.com/u/Sparc)\ **Post date:** [August 27, 2002, 1:15pm UTC](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526/23 "2002-08-27T13:15:46Z")
> [@](#): > > The idea of starting to count from midnight, and having fixed-length hours probably arose independently, when the accuracy of mechanical clocks started to improve. (Anyone got a cite?) Again as noted a few times: Counting from midnight is a modern consequence of the 24-hour system and was made common by the military. Fixed-length diurnal hours came about during the Hellenistic era and were derived from the Babylonian division into sixty minutes and seconds (cites provided twice already). Varying diurnal hours continue to be in use in some places all the way up to the 7th century, when the canonical fixed hours are established as standard through the church - they stole them from the Romans though. At this time hours are still counted from sunrise. As to when noon and midnight became 12:00 for the first time, this happens sometime in the 14th century and probably had lots to do with the mechanical clock. This is not universal though, some clocks at that time still count from sunlight and use the seven canonical hours as base, which survives in parallel, and it is only around 1600 when pocket watches become more common that the 24 hour division counted twice from noon becomes universal (note that noon for a while acquired the meaning of both midday and midnight). The name [noon](http://www.bartleby.com/61/90/N0149000.html) was derived from the canonical hour nones, 3 P.M. in modern division. This in turn comes from the Latin hour nona, the ninth hour after sunrise. Sometime in the 12th century the main time for church prayer shifts form the hour nones to sext (ninth to sixth hour) the name of the ninth hour is still applied to that time of day though and presto, noon becomes six hours after sunrise or the middle of a an equatorial day. OED lists the earliest known use of noon to 1140. Sparc ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [August 27, 2002, 1:22pm UTC](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526/24 "2002-08-27T13:22:42Z")
Sparc, that’s just a little different than what you said before. > [@](#): > > \*Originally posted by Sparc \* > **The Baylonians started with the ‘Ra-given fact’ that the day has 24 hours and then applied 60 to that.** [I believe](http://mentock.home.mindspring.com/ifaq.htm#IFAQ009) that the Sumerians divided the day into 12 parts, the Egyptians borrowed that for their sundials, and then extended that to the night. Then, some clerk decided to standarize it. The hexidecimal stuff just got swept along, same as today. ---
**Author:** ![Meatros](https://avatars.discourse-cdn.com/v4/letter/m/b4bc9f/32.png) [@Meatros](https://boards.straightdope.com/u/Meatros)\ **Post date:** [August 27, 2002, 1:25pm UTC](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526/25 "2002-08-27T13:25:35Z")
Oh you people…How did the world ever agree on the 24 hour clock?? Simple. It didn’t-IT’S a conspiracy of COURSE!! > **[bet365 Bonus Code India 2021 \[BETMAX365\]: 15% up to Rs.4000 in Bet Credits](https://www.timecube.com/)** > > Use the bet365 bonus code India BETMAX365 and claim a sign up offer of 15% up to Rs. 4,000 in bet credits. 18+ and T&Cs Apply, New Customer Offer ---
**Author:** ![Sparc](https://avatars.discourse-cdn.com/v4/letter/s/65b543/32.png) [@Sparc](https://boards.straightdope.com/u/Sparc)\ **Post date:** [August 27, 2002, 1:37pm UTC](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526/26 "2002-08-27T13:37:15Z")
Small clarification regarding the counting of canonical hours; ‘counting from sunrise’ means counting from sunrise of an equatorial day so that sext always occurs at the time when the sun would be in zenith on the day of the equinox. This practice continued until the establishment of daylight saving time. DST was first proposed in an essay by Benjamin Franklin in 1784, but it was the Germans and Austrians that introduced the practice first in April 1916, most of Europe followed immediately, the Commonwealth outside the British Isles in 1917, while the US adopted DST in 1918. Sparc ---
**Author:** ![Sparc](https://avatars.discourse-cdn.com/v4/letter/s/65b543/32.png) [@Sparc](https://boards.straightdope.com/u/Sparc)\ **Post date:** [August 27, 2002, 1:55pm UTC](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526/27 "2002-08-27T13:55:09Z")
> [@](#): > > _Rm Mentock_ > > I believe that the Sumerians divided the day into 12 parts, the Egyptians borrowed that for their sundials, and then extended that to the night. Then, some clerk decided to standarize it. The hexidecimal stuff just got swept along, same as today. No! This is great though, we truly are proving how impossibly difficult this is. The Sumerians divided the whole day (night and day) into 12. The Egyptians on the other hand introduced a nocturnal division of 12 based on the Sumerian tradition. Later they transported this division of twelve into the diurnal hour. Sexagesimal divisions of the hours comes _after_ all that. Read the cite you provided; it says this, but that might slip by if you don’t read it carefully… it comes down to the incredible confusion afforded us by the application of the term day to both the sunlight hours and the whole revolution of the globe. Sparc ---
**Author:** ![ElwoodCuse](https://avatars.discourse-cdn.com/v4/letter/e/edb3f5/32.png) [@ElwoodCuse](https://boards.straightdope.com/u/ElwoodCuse)\ **Post date:** [August 28, 2002, 3:05am UTC](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526/28 "2002-08-28T03:05:07Z")
Part of Canada (Newfoundland?) is a half-hour ahead of Atlantic Time. That must be annoying. And re: China, damn, wouldn’t that make for some really screwed up night/day times? ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [August 28, 2002, 1:01pm UTC](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526/29 "2002-08-28T13:01:00Z")
> [@](#): > > \*Originally posted by Sparc \* > \*\*No! This is great though, we truly are proving how impossibly difficult this is. You’re right–I did accidently say “hexidecimal” when I meant “sexigesimal”. Late at night, too much sex, drugs, castanets, etc. > [@](#): > > Read the cite you provided; it says this, but that might slip by if you don’t read it carefully…\*\* LOL! I wrote that cite. Thanks for the affirmation, I think… ---
**Author:** ![toadspittle](https://avatars.discourse-cdn.com/v4/letter/t/c0e974/32.png) [@toadspittle](https://boards.straightdope.com/u/toadspittle)\ **Post date:** [August 28, 2002, 3:37pm UTC](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526/30 "2002-08-28T15:37:57Z")
Here’s a question we’re not addressing: when/how did the fertile-crescent-derived 24-hour system common to Europe get forced upon the rest of the world? How did the Chinese, the Japanese, the Indians, the Aztecs, the Australian aborigines, the Hawaiians, the Inuit(!), etc., divvy up their days before we muscled in? (If they did at all.) [Previous page](https://boards.straightdope.com/t/how-did-the-world-ever-agree-on-the-24-hour-clock/125526.md?page=1)