Talk:Decimal time

A modest proposal

I was just stumbling over this talk page on recent changes and remembering all the fun we had with Mr. Metric Time, and I realized that this page is a total mess and utterly confusing to anyone who has not been there during the discussions. Now that Mr Voorman has left (for good, hopefully :P) and won't be clearing the page anymore, would it be appropriate to at least sort the old discussions chronologically? I know that editing other people's comments on talk pages is a big no-no, that's why I don't just go ahead and do it, but i think that sorting the discussions might really benefit this page. -- Ferkelparade π 00:21, 22 Sep 2004 (UTC)

I think refactoring would be fine, as long as you dont lose content or context: in fact, your right in saying we would get more context if you refactored. I would do it myself, only I still shuder whenever these pages appear on my watchlist, and so I dont think I can be sufficently neutral! Iain 08:37, 22 Sep 2004 (UTC)

A Google search reveals that Andre Fischer is famous as "a member from the Decimal Time forum." There seems to be nothing published by him anywhere else. Since the odds that there are two Andre Fischer in the decimal time community are slim, to put it mildly, it's likely that that is indeed the Fischer, and that everything posted about him here has been posted by said member of the "Decimal Time forum" himself. 213.112.5.132 11:30, 13 Dec 2004 (UTC)

I have not posted anything here, however someone I know has taken the liberty of doing so, without my permission. I contacted Wikipedia a year ago to have this copyright protected material removed. (as you can see below) My work is Not to be posted anywhere on this site. furtherfore, neither my name nor personal information is to be posted on this site. One sentence, in apparent violation of WP:NLT, has been removed here. The IP who posted it is welcome to replace this annotation with any clearer statement that is consistent with that policy. In that case, they should add "~~~ 02:10, 30 January 2006 & ~~~~~" in place of the "unsigned" notation at the end of this paragraph, to properly document both of their edits. Thank You! A.F. 30 January 2006. —The preceding unsigned comment was added by 81.225.195.17 (talk • contribs) 02:10, 30 January 2006 (UTC)

The IP user User:81.225.195.17, in the same 02:10, 30 January 2006 edit, has also created a forged post by modifying the post preceding it without removing the valid signature on it. The alterations were

1. reducing the first occurence of Andre Fischer to A. F.;
2. removing the second occurence of Andre Fischer; and
3. removing the words

   that that is indeed the Fischer

The unforged version has been restored.
--Jerzy•t 16:14, 7 February 2006 (UTC)

_ _ WP is exceedingly unusual among non-commercial Web sites in our scrupulous approach to violations of the exclusive rights of authors under applicable copyright law. On the other hand User:81.225.195.17's expectation of being permitted to remove references to a name, or of inducing others to make such removals, is not only unsupported by our copyright policies, but also in direct conflict with our policy of preserving past discussion and its context, to the full extent that is compatible with avoiding copyvios.

_ _ (Colleagues inclined to send flowers in recognition of my refraining from explicit characterization of the IP's request should instead contribute to the WM foundation in my name. Thank you.)
--Jerzy•t 16:14, 7 February 2006 (UTC)

Rewrite

A short note -- the mention of Microsoft Excel time equivalent was removed because, in this person's opinion, an encyclopedia should not be making reference to proprietary numerical systems that could change and render the page inaccurate.

Welcome to Wikipedia. This is a wiki, not printed paper volumes that are updated once a decade. Wikipedia changes every second of every day, and there are many pages devoted to proprietary systems. There is a whole article already on Microsoft Excel, for instance. (Not that Excel's serial dates have changed much since they copied them from Lotus 1-2-3 two decades ago, anyway.) Please see Wikipedia Policies and guidelines for information about what is appropriate.

Also, it's better to add notes to the bottom of the page, not to the middle, under an unrelated section heading. And the guidelines also recommend signing your notes with the meta tag ~~~~, which inserts your name and date/time, rather than posting anonymously; otherwise, it appears to part of the following comments, which were posted by someone else last year. While I'm at it, it's also recommended that you register a username. -- Nike 01:13, 12 August 2005 (UTC)

How about rewriting the article, itself? There's a number of issues with it, such as misstatements of fact, like "Decimal time remained in tentative use in France until the official introduction of the metric system (or Système International d'Unités [SI]) on April 7, 1795." (SI was not introduced until 1954, and is only the latest version of the metric system, differing significantly from the 1795 version.) The "Cent time" referred to has no source, and is simply one of many vanity decimal time systems. And I have no clue what either "serial time" or "integer time" are, except that they resemble, but not exactly, Unix time. (sic) These seem to be simply neologisms.

And "metric time" is simply the base unit of time interval (the second) as defined by the modern metric system (along with multiples and submultiples, like the millisecond) in spite of all the funky clocks individuals have made with that name. And since I see that there is also an article named Metric time, it probably also could use a rewrite, to distguish it from decimal time. (Most of that article seems to have little to do with the metric system, and should probably be moved to this article.)

I don't know which "decimal time advocates" are being referred to, but there does not seem to be an organized movement with stated goals. Decimal time is already used by astronomers, in the form of decimal fractions of the day (such as 2000 Jan. 1.5, where .5 represents noon) but this is only barely mentioned. More could also be said of French decimal time, and nothing has been said of ancient Egyptian and Chinese forms of decimal time. There are also other important applications of decimal time not mentioned, such as in computer programs like Microsoft Excel.

After all that, I guess I should volunteer, if nobody else wants to. -- Nike 06:12, 19 Dec 2004 (UTC)

I moved everything around, removed some irrelevant stuff and added material, including references. Since the article on metric time was similar to this one, they should either be distinct or merged, so I wrote this article to focus on decimal time as it is usually defined, that is, as time of day, and metric time refers specifically to units of measuring time interval defined using metric rules. I tried to make the two articles complementary, instead of contradictary. -- Nike 11:54, 23 Dec 2004 (UTC)

I have refactored the talk page, so that all comments are in chronological order. -- Nike 07:15, 25 Dec 2004 (UTC)

Copyright

It has come to my attention that my copyright protected material was posted here without my permission, it seems that someone had copied the material directly from the Decimal Time site. This material, which includes the Prodecimal System and Cent Time is not to be posted here. Fischer 17:10, 19 Apr 2005 (UTC) This simulated 4-tilde signature accurately reflects the editor's registered login, but the accurate UTC time of the edit that placed the time-stamp was 16:12, and they added minor changes to the 'graph at 16:19 and 16:28. - - - - At 02:11, 30 January 2006 (UTC), User:81.225.195.17 replaced (twice within this section including in this 'graph) an accurate piped lk to this contribution's editor's user page, with User:D.A., thereby referencing the potential user page of an account that has never been used to contribute. The accurate user lk has been restored.

Feel free to remove any material you know to be copyrighted and report it at Wikipedia:Copyrights. We try to remove copyrighted material here as soon as possible in order to adhere to the GNU Free Documentation License, so rest assured that your material will not be permitted to be used here if you can pick out what here is rightfully yours. — Ливай | ☺ 05:06, 20 Apr 2005 (UTC)

Thank you Ливай, I believe all proprietary material has been removed now.

I am very grateful for your assurance. ~ best regards,

A.Fischer Fischer 10:41, 20 Apr 2005 (UTC This link accurately reflects the editor's registered login, but the accurate UTC time of the edit that placed the time-stamp was 16:12, and they added a minor change to the 'graph at 9:47. - - - - At 02:11, 30 January 2006 (UTC), User:81.225.195.17 replaced (twice within this section including in this 'graph) an accurate piped lk to this contribution's editor's user page, with User:D.A., thereby referencing the potential user page of an account that has never been used to contribute. The accurate user lk has been restored.

Livajo has been a bit imprecise, in a way that seldom matters. By "free to remove any material you know to be copyrighted" they mean to exclude, for instance, things that Fischer hold the copyright on, and that he edited onto WP himself -- for instance, everything on this page that bears his sig. In those cases, there is a copyright but no possibility of a copyvio, bcz in including it in a WP edit, Fischer placed it under GFDL; as such his copyright on it is still in effect (which is apparently crucial to the legal theory behind WP's use of GFDL), but that copyright has been gutted of the availability to assert almost all the exclusive rights that come with a copyright. Technically, Fischer has no more nor less right to remove it than anyone else, but where it is part of a discussion thread that others have responded to he has no practical right to do so. Anyone has the legal right to put it back, and will normally have the support of the rest of the community in doing so, since removing it destroys the context others were comment within, and thus changes the meaning of what they said in response. Fischer's desire to remove or alter something he said ends up being one guy against a multitude. Which is why i put it all back: i know it's worth the effort, even if he hasn't figured out that it's not worth his efforts to try to keep it out.
--Jerzy•t 01:30, 8 February 2006 (UTC)

FWIW, the user formerly known as Fischer claims that he did not post the material in question, in spite of the fact that the poster was on the same IP subnet. Rather, he says that someone he knows must have done it without his knowledge or permission. The original author did not use his name, and as I recall denied being Mr. Fischer. Given the information, I think we must assume that the copyright really was violated, although that does not justify all of the edits. --Nike 14:05, 8 February 2006 (UTC)

_ _ Sorry if i was unclear. My assumption so far is that (despite someone's early statement to the contrary) the claim about our article having infringed is accurate. In contrast to that, the IP claiming to be Fischer seeks removal of information added, outside the main namspace, in other WP edits signed in some cases by User:Fischer and in others by that IP, which were made under GFDL by their authors. These edits were clearly written with the purpose of posting them (under GDFL) on WP, so any claim that they were posted by someone other than their author would be so contrived as to lack credibility. The claims of a legal right to remove information from them, e.g. to reduce the name to cryptic initials, could thus have nothing to do with copyright (even if you could copyright you own name or prevent the paraphrasing of the ideas that you wrote). I was contesting that claim for removal, and not the copy-vio treatment of the removed main namespace material.
--Jerzy•t 01:51, 14 February 2006 (UTC)

Revolutionary Time

I see the problem. I had assumed that the existing text had quoted the correct decree for decimal time. In fact, as the first reference will show, the quoted paragraph is from the decree of 5 October 1793, which also established the Revolutionary Calendar - although without names, in the Quaker manner. Read your source, before claiming inaccuracy.

Indeed [1] the external link correctly says:

French decimal time was first declared by the decree of October 5, 1793, which was modified by the addition of the underlined words in the decree of November 24, 1793.

Reading the text, there or here would have shown that the modification consisted of naming the fractions of the day.

The claim that the Revolutionary calendar is based upon Egyptian usage is both unsourced and implausible. If any ancient parallel affected the decision, the Greek division of the lunar month (29 or 30 days) into three decades is preferable, if still unlikely and speculative. Septentrionalis 18:14, 15 May 2005 (UTC)

Source: report by Gilbert Romme on the Era of the Republic, September 10 1793, [2]

As for the decrees, the previous version was correct, and yours is wrong. You see, the external link you refer to is my own web page, so I am quite familiar with what it says, since I wrote it. The October decree did introduce the concept of decimal time, but the November decree included the entire text, including the units of the decimal hour, minute and second. According to your misquote, the October decree introduced decimal hours, but this was added by the November decree, as a careful reading of my web page, and the original decrees, make clear. --Nike 23:51, 4 August 2005 (UTC)

This is very strange; you misdescribe your own site. The section XI was cut and pasted from the decree of 5 Octobre 1793, as you scanned it. I can understand relying on one's memory of one's own website, but please look at it again. Would it help if I cited a printed edition?

Paragraph XI of the decree of 5 October is:

XI. Le jour, de minuit à minuit, est divisé en dix parties; chaque partie en dix autres, ainsi de suite jusqu'à la plus petite portion commensurable de la durée. Cet article ne sera de rigueur pour les actes publics qu'à compter du 1er du premier mois de la troisième année de la république.

Paragraph XI of the decree of 4 Frimaire is:

XI. Le jour, de minuit à minuit, est divisé en dix parties ou heures, chaque partie en dix autres, ainsi de suite jusqu’à la plus petite portion commensurable de la durée. La centième partie de l'heure est appelée minute décimale; la centième partie de la minute est appelée seconde décimale. Cet article ne sera de rigueur pour les actes publics, qu'à compter du 1er Vendémiaire, l'an trois de la République (I have not bothered to preserve italics.)Septentrionalis 01:03, 5 August 2005 (UTC)

Funny how you quote it correctly here, and yet incorrectly in the article. I did not rely on my memory, but read the actual web page. The section on my site is from the November decree, not the October one; I underlined the text which did not occur in the first decree (I could also have underlined the text which did occur) but you missed some of it. The October decree did not include the words ou heures. My web page makes this clear. The November (Frimaire) decree not only adds the second sentence, but changes the first. It is the Frimaire decree which established decimal time as it was (briefly) implemented, with decimal hours, minutes and seconds. The second decree was made ten months before the first even would have come into effect, and thus was the one which actually did.

BTW, SI also recognizes a standard day defined as being exactly 86400 SI seconds. Of course, there are other definitions of the standard second and day, but if you're going to insist on the SI second, then you should use the SI day. (I can provide references, if you doubt me.) The term "standard" here was meant to refer to the looser definition of a second as 1/86400 day, since the use of "standard time" predates SI. This could be the mean solar second, which is defined as 1/86400 mean solar day, or the ET second, which was defined as 1/86400 the mean solar day in 1900, etc. Perhaps another term could be used instead of "standard second" (Babylonian? sexigesimal?) but I think that this is preferable to "true second", "true hour", etc. This implies that decimal units are false. "True time" actually refers to apparent solar time as measured by local motion of the relative sun, which is not dependent on sexigesimal (standard) time units. --Nike 04:14, 5 August 2005 (UTC)

Agreed. Septentrionalis 16:22, 6 August 2005 (UTC)

Documentation of History Merge (2005 Sept)

Merging of a minor fraction of the content of Decimalization of time of day was accomplished earlier this month by copy and paste, with the history being overwritten with a rdr instead of merging it. I am performing the belated history merge, and recording here which edits were made under the name that has been turned into a rdr.

Since the history of Decimal time runs close to 200 entries, and the four entries of Decimalization of time of day's have only the merging edit of Decimal time interposing itself between any two of them, there is no benefit to copying here the whole pre-merge history of the older & non-rdr'd article.

Note Well: The undelete portion of the delete-move-undelete sequence apparently takes some time to be effective; until then the self redirect will be the most recent version available. A reversion to the 15 September 2005 revision may be necessary when it again becomes available.

OK, there it is; reverting momentarily.
--Jerzy•t 18:47, 17 September 2005 (UTC)--

Portion of Decimal time's History that includes the Period when Decimalization of time of day was an Article and when Histories were Merged

• 20:14, 15 September 2005 Jitse Niesen m (→Decimal time and speed - grammar)
• 09:50, 14 September 2005 Patrick (→Conversions - merge in Decimalization of time of day)
• 00:28, 12 August 2005 Nike m (rv changes by 12.18.96.89 to last version by 86.131.2.56)
• 22:59, 8 August 2005 12.18.96.89 (→Fractional days)
• 22:46, 8 August 2005 86.131.2.56 (→Conversions - link heart rate)
• 20:56, 8 August 2005 84.159.228.175 (equivilent->equivalent)

History of Decimalization of time of day Prior to History Merge

• 09:52, 14 September 2005 Patrick (#redirect Decimal time (merged))
• 23:27, 13 September 2005 MadMax m
• 23:25, 13 September 2005 MadMax m
• 20:26, 11 September 2005 Jerzy (stub; hopefully there's more worth saying, perhaps notable formal proposals)

Merged Portion of History for Corresponding Period

The four italicized entries were made under the title Decimalization of time of day

• 20:14, 15 September 2005 Jitse Niesen m (→Decimal time and speed - grammar)
• 09:52, 14 September 2005 Patrick (#redirect Decimal time (merged))
• 09:50, 14 September 2005 Patrick (→Conversions - merge in Decimalization of time of day)
• 23:27, 13 September 2005 MadMax m
• 23:25, 13 September 2005 MadMax m
• 00:28, 12 August 2005 Nike m (rv changes by 12.18.96.89 to last version by 86.131.2.56)
• 20:26, 11 September 2005 Jerzy (stub; hopefully there's more worth saying, perhaps notable formal proposals)
• 22:59, 8 August 2005 12.18.96.89 (→Fractional days)
• 22:46, 8 August 2005 86.131.2.56 (→Conversions - link heart rate)
• 20:56, 8 August 2005 84.159.228.175 (equivilent->equivalent)

---

Stop the decimal insanity

This obsession to convert everything to decimal is misguided. Decimal is an arbitrary and not very useful number base. The time system as it exists is much more useful than decimal, because it's easy to divide minutes or hours into into 2, 3, 4, 5, and 6 parts, or to divide days into 2, 3, 4 or 6 parts. With decimal you're limited to dividing your time periods evenly by 2, 5, and maybe 4.

We should change our number base, rather than our time system. See the Duodecimal, or "dozenal" system.

What does any of this have to do with the article? As it says on the Wikipedia:Talk page:

Wikipedians generally oppose the use of talk pages just for the purpose of partisan talk about the main subject. Wikipedia is not a soapbox, it's an encyclopedia. In other words, talk about the article, not about the subject.

There are other places online to attack the decimal system. If you want to post here, how about telling us specifically what you would change about the article? Also, you should sign your posts, so we know who is saying what and when; just type four tildes (~~~~) at the end of your message. --Nike 05:48, 7 February 2006 (UTC)

Well, the history page says it was 198.107.49.206 - of course maybe this is not the point. --gwc 04:48, 26 June 2006 (UTC)

It's a simple matter of Wikipedia etiquette. We shouldn't have to go to the history page to figure out who said what. Also, signatures let us know where one person's comments end and another's begins. Imagine if nobody bothered; you would have to check the history for every single comment, and would probably get confused about who actually said what. But I shouldn't need to explain that here: it's the policy across Wikipedia. --Nike 12:15, 26 June 2006 (UTC)

This talk page is for discussing this article itself, not for diatribes supporting or opposing decimal time. (There is a warning at the top of many Wikipedia talk pages that the talk page is for discussing how to develop and improve said article, not “for general discussion of the article's subject.”) Also, please no inflammatory language; it violates NPOV, is unprofessional, may turn people away from Wikipedia, and certainly does not serve the purposes of an encyclopedia. Per NPOV, this article, in turn, is not for arguing for or against decimal time, but for a general description of the subject. I myself, for instance, strongly support decimal time, for many reasons, in part because it is in line with the decimal nature of the rest of the metric system.--Solomonfromfinland (talk) 23:45, 7 March 2016 (UTC)

Ancient Egypt

Decimal time was said to have been introduced in Ancient Egypt

Was said by whom? Do you have any sources? MvR 16:26, 29 July 2006 (UTC)

I don't know where that came from. Maybe there is a conflation with the Republican system, since the French Revolutionary calendar was explicitly said to be based upon the Egyptian calendar.[3] However, the French noted that Egypt had a 24-hour day. I asked someone who has repeatedly made this claim for sources, and he had none. --Nike 07:01, 30 July 2006 (UTC)

Timezone of FRT

How was the zero point of French Revolutionary Time determined? Was it based on:

• GMT plus one standard hour
• GMT plus some round figure in decimal hours
• Paris Mean Time
• the mean solar time at the locality where it was used
• something else entirely?

Moreover, did they ever try to share their idea with the world? And if so, did they intend other parts of the world to adapt it into their own local time, or to follow their time in the style of Swatch Internet Time, or what? -- Smjg 15:23, 10 February 2007 (UTC)

To answer the first question, decimal time followed the same practice as duodecimal time, which was then true solar time, not mean solar time. GMT was not yet standard then even in England, and the French later used temps moyen de Paris until 1911, and never did use GMT by name even to this day, so they certainly would not have used Greenwich time in 1793. Thus, in Paris they would have used temps vrai de Paris, and elsewhere temps vrai that is, true or apparent time, for that location, as might be observed on a sun dial. At the time, people adjusted their clocks and watches daily according to the sun, since the devices were not that precise anyway. And in decimal time, there was no "zero" hour, but l'heure dix, hour 10. Documents of the period state that the first day of the Republican Calendar, of which decimal time was a part, was determined according to when the autumnal equinox was observed at the Paris Observatory in temps vrai.

Regarding the second question, the calendar was imposed throughout the Empire, in Europe and overseas, but decimal time was little used even in France. They certainly tried to get scientists in other countries involved with their whole new system of decimal measures, but this was hampered by the fact that they were often at war with these same countries. The rejection of decimal time outside France is often given as a primary reason why it was abandoned. However, had it been used elsewhere, it would have been according to local solar time, since there was then no radio or even telegraph to synchronize time between cities. The concept of standard time and of time zones had not yet been implemented, and would not be for the better part of the next century. --Nike 21:58, 10 February 2007 (UTC)

Asimov

In one of his essays, Isaac Asimov argued that a space-faring mankind would use the day as its base unit because of the circadian rythms of human body and the meaninglessness of Earth movements in outside of the Solar System. He proposed that the day would be divided decimally.

I do not remember a reference, but these essays seem promising:

• About Time. Subject: the reform of time measurement. First Published In: Apr-60, The Magazine of Fantasy and Science Fiction
• Begin at the Beginning. Subject: counting the years. First Published In: Jan-65, The Magazine of Fantasy and Science Fiction. Collection(s): 1965 Of Time, Space, and Other Things, 1977 Asimov on Numbers.
• Moon Over Babylon. Subject: the week. First Published In: Apr-72, The Magazine of Fantasy and Science Fiction. Collection(s): 1973 The Tragedy of the Moon.
• The Week Excuse. Subject: calendar reform. First Published In: Jun-72, The Magazine of Fantasy and Science Fiction. Collection(s): 1973 The Tragedy of the Moon
• The Unforgiving Minute. Subject: /measurement of time. First Published In: Jan-89, The Magazine of Fantasy and Science Fiction. Collection(s): 1990 Out of the Everywhere.
• To the Stars!. Subject: the time requirements of space travel. First Published In: May-76, American Way (American Airlines). Collection(s): 1981 Change!.

--84.20.17.84 (talk) 10:53, 20 November 2007 (UTC)

From soc.culture.british's Peter J Lusby:

Many years ago the late Dr Asimov wrote a humourous, but intriguing article for American Airlines in-flight magazine, in which he pointed out that as mankind moves into space, it makes very little sense to drag with us a system of time measurement based on the orbital characteristics of an insignificant planet in an insignificant star system, in an insignificant corner of the galaxy, that in any case is subject to change without notice. He therefore proposed a decimal time system which made a lot of sense when I read it at the time, but the details of which have subsequently been overwritten in long-term storage.

--84.20.17.84 (talk) 11:05, 20 November 2007 (UTC)

Decimal Times in Fritz Lang's Metropolis

The reference to the apparent decimal time system used in the futuristic dystopia depicted in Metropolis is interesting if it is factual. However, evidence needs to be cited to back up the argument that the decimal clock portrayed in the film represents a lengthening of the standard work shift from 8 to 10 hours (if a work shift of 8 hours was indeed standard in 1927 Germany).

Also, the supporting statement: "Since a normal day cannot be divided into a whole number of such shifts, a 24-hour clock is displayed above the shift clock to give the actual time of day" is either incorrect or misleading. The 24-hour clock may be there for any reason Lang imagined it, perhaps to help workers acclimate to the decimal system. More importantly, the 20-decihour day can be evenly divided into 2 half-day shifts of 10 decihours each, making each shift (by our reckoning) 12 hours long. It's a draconian labor practice, but German weapons factories at the time the film was made did operate on a two-shift system, rather than the three-shift system we're accustomed to today. Rangergordon (talk) 10:38, 31 May 2008 (UTC)

Talk Reverts

There is currently a revert war on this talk page. The problem is that someone is repeatedly removing historical content. This is totally inappropriate. The claim is that the discussion somehow violates copyright. In fact, there are few details about the supposedly copyrighted material, and discussion about such material is not itself a violation of copyright, but rather fair use. Much of the deleted material was written by myself, and by others who did not consent to the deletion. You do not have the right to violate our free speech through your censorship. Such deletions are in violation of WP policy and will be reverted every time. I will also discuss this on my blog, which you cannot delete. --Nike (talk) 22:37, 28 March 2010 (UTC)

I removed any references to my copyrighted material that I could find, and inadvertently also removed text which I did not intend to remove, so I reverted the "rewrite" text. My apologies for the misunderstanding. There will be no further edits on my part, so long as no material of mine reappears. Best regards213.100.87.94 (talk) 23:28, 29 March 2010 (UTC)Fischer

I did not realize that you already reverted my revert while I was typing my previous comment. Once again you blanked out huge sections of this page. The copyrighted material was removed years ago. I am frankly puzzled as to why you keep deleting parts which don't even mention "prodecimal". Simply mentioning something is not a violation of copyright, and you do not have the right to edit or remove others' comments here, for reasons which have already been stated on this talk page. Given that this is a talk page, attached to an obscure article, few are likely to read what is posted here, but the irony is that by trying to redact it you are simply drawing attention to what you are trying to hide! --Nike (talk) 10:12, 30 March 2010 (UTC)

This is the text I have removed: "Here's the "prodecimal" section, which I couldn't find a reference to even on Google. Some of this has a source (included), but other parts seem very "inside baseball" and more like minutiae of interest only to Andre Fischer fans. Who's Andre Fischer anyway?! --Dablaze 07:43, Aug 14, 2004 (UTC)

How can you tell me that the copyrighted material was removed years ago when there is clearly a link to it under---"Archived text of Prodecimal system". Posting this text is unacceptable to me, and quite frankly also totally irrelevant to the discussion of Decimal time, so simply leave this text out of the discussion so that I no longer have to keep removing it, please. regards,213.100.87.94 (talk) 12:50, 30 March 2010 (UTC)A. Fischer

You might be OK to delete your own work that was posted w/o permission, but you do not have the right to remove the rest of what you did. In fact, part of what you deleted explained that to you. You should read it. If you want to remove the archived text of prodecimal system, you can make a case for that, as someone stated previously, but you should not delete the words of others. As someone wrote earlier, you can make a request as stated at Wikipedia:Copyrights to have your work removed. Also read what Jerzy posted on this page. --Nike (talk) 17:22, 30 March 2010 (UTC)

Chinese 'decimal' time

A decimal system implies a base of 10. Given that, how is this Chinese system of ke, shi and fen a decimal system? If the day is divided into 100 ke, and each ke is divided into 60 fen, then the bases are 100 and 60, not 10. I can't see that it's got anything to do with decimal at all.

I don't really know anything about this subject, so have no strong opinions on the matter. I just happened to read the article, and find it strange that an article on decimal time starts with a discussion of what appears to be a non-decimal system. Faagel (talk) 00:07, 28 April 2010 (UTC)

Only a pure decimal system would use a divisor/multiplier of 10, but no system is pure. Not even the SI system of units is pure—most of its units use a divisor/multiplier of 1000, not 10. United States currency is usually considered decimal, but it has non-decimal divisors/multipliers of 2 and 5. So 'decimal' becomes a matter of opinion. Even a single relationship of 10 or an integral power thereof (100, 1000, etc.) could be enough to be considered decimal in the opinion of some editors. — Joe Kress (talk) 03:13, 28 April 2010 (UTC)

I think you're mistaken. The SI units are 10-based, using a 10-based decimal system to represent units, both whole and fractional. For example, considering metres, 1.88 m = 18.8 dm = 188 cm = 1880 mm = 1880000 µm, etc. There are named prefixes for 10^1, 10^2 and 10^3, and 10^(-1), 10^(-2) and 10^(-3). Additional prefixes are only used for groups of three, but this is irrelevant to the base, which is 10. It's just a matter of convenience to avoid an excessive number of names.

In relation to currency, currencies like the euro, US dollar or UK pound (after 1971) are 'decimal' because values are written in decimal form, e.g. €1.23 (or €1,23 in most languages other than English), which is one euro 23 cents or equivalently 1.23 euro (where 1.23 is read as 'one point twenty-three', i.e. a simple decimal number).

With non-decimal currencies, such as the pre-1971 UK pound, decimal representation was not used. Instead, whole or fractional (half, quarter) currency units were always used. For example, £5-2-4 was five pounds, two shillings and four pence. £5-2-0, which was five pounds two shillings, would never be written in decimal form as £5.1 (or £5.10), even though this is the equivalent decimal representation.

The pre-decimal UK pound is actually a good example of why the logic of calling ke 'decimal time' is flawed. The old pound was divided into many units, such as shillings, pence, florins, crowns and so on. It happens that a florin was in fact equal to 1/10 of a pound (£0,10). Using the faulty logic in this article, the pre-decimal UK currency would therefore qualify as a decimal currency, even though the values were never written in decimal form. Such an argument is plainly absurd.

Only if the Chinese used a decimal number system to represent days in terms of ke and fractions of ke (e.g. 0.1 days for 1 ke, 0.01 days for 1/10 ke, etc.) can this be called in any sense a decimal time system. If they didn't use a decimal representation, then it was not a decimal time system merely because the number of ke in a day happened to be 100, any more than the old UK pound was a decimal currency merely because the number of florins in a pound happened to be 10. -- Faagel (talk) 12:55, 29 April 2010 (UTC)

So are you suggesting that this section be removed? Or simply reworded? If the latter, how would you prefer it be stated?

Being decimal does not require that multiples and divisions be a factor of ten, but integer powers of ten. For instance, the French divided the decimal hour into 100 minutes, and the decimal minute into 100 seconds, and they did not use decimal notation, e.g. 9.5 decimal hours, but would instead say 9 hours 50 minutes decimal. Likewise, the right angle was divided into 100 grades.

I would defend the ke as a decimal time unit, because it divides the day by a power of ten. Obviously, none of the other units mentioned are decimal. But I think that the ke is significant to this article, as it is equivalent to what Lagrange called centi-jour or centiday, and Rey-Pailhade called cé, and the Chinese were likely the first to use the decimal system. It could be worded differently, however. --Nike (talk) 23:39, 29 April 2010 (UTC)

As written, I think it should be removed. I simply can't see that the system described has any relevance at all to decimal time. It appears to be purely a coincidence that the Chinese picked 100 as the number of ke in a day. They might just as easily have chosen 60, 144, 360, etc. Moreover, the other units in the system, shi and fen, used bases of 12 and 60, respectively. The citation also appears to be in error (either the wrong author or the wrong year).

French Revolutionary Time is a decimal time system because all the units are based on 10. This means that, for example, 9.5 (nine point five) hours is implicitly the same thing as 9:50 (nine hours fifty minutes). Using standard SI terminology, 0.1 hours could be called a 'decihour', a minute could be called a 'centihour' and so on, but the names are really beside the point. In contrast to this, under the Chinese system described in the article, 9 ke and 50 fen would be approximately 9.833 ke. That simply isn't a decimal system. It's merely a coincidence, like the coincidence of 10 florins in a pre-decimal UK pound.

In contrast to the description in this article, Jean-Claude Martzloff (in Mathematics across cultures: the history of non-western mathematics, 2000, edited by Helaine Selin, p. 393) describes an actual Chinese decimal time system developed in the 13th century by Guo Shoujing, as part of the Shoushi li computus. According to Martzloff, this system divided a day into 100 ke, a ke into 100 fen and a fen into 100 miao. Moreover, this was used with a base-10 (not base-100) positional decimal system, which by that time was in use in China.

If Martzloff is correct (and I've no reason to believe he isn't), then the Chinese did developed the first known decimal time system, and it is certainly worth discussing in the article. However, it was not the system described in the current article, and was not developed two or three millennia ago. It was developed about 730 years ago, under the Mongol Yuan dynasty and perhaps with some influence from Arab scientists working for the Mongol Khans (see Li, Qi and Shu: An Introduction to Science and Civilization in China, 1985/2000, by Ho Peng Yoke, p. 167). Faagel (talk) 14:29, 30 April 2010 (UTC)

The article originally just referred to to ke, for which I have seen a number of references. I am not familiar with the other units, but it seems implied that ke originated as a decimal division of the day, that shi originated independently (likely from the 24-hour system of the Middle East) and fen was introduced later to rationalize the two incompatible systems. Perhaps shi and fen are not appropriate to the article (I have noticed that WP articles tend to accumulate irrelevant crud over time) but that does not mean that ke isn't. I would like to see the source for "two or three millennia" for ke, but I have read that the decimal system, itself, was in use in China in the 6th century BCE. The Chinese had an ancient history of using the decimal system, so it seems doubtful that they chose 100 by coincidence, but even if they did, it would still be a decimal division of the day, regardless of that fact that nondecimal time units also existed. --Nike (talk) 05:53, 1 May 2010 (UTC)

According to Martzloff, prior to 1281 (when the decimal Shoushi li calendar was adopted by the Mongols, a year after its completion in 1280), the Chinese used pseudo-sexagesimal systems. One guess as to the source of the confusion in the article may be that unit names were re-used. It would require research to confirm, but if the names of the decimal units in the Shoushi li calendar were identical with earlier, non-decimal unit names, then this would explain both the confusion over the age of the Chinese decimal time system and over the decimal nature of the units (e.g. the claim of 60 fen in a ke, rather than 100). Faagel (talk) 11:29, 1 May 2010 (UTC)

Joseph Needham, et al., Heavenly clockwork: the great astronomical clocks of medieval China 199–202 states that the midnight-to-midnight day was divided into both 12 double hours, shih (Wade-Giles, Pinyin: shi), and 100 k'o (Wade-Giles, Pinyin: ke) since at least the 1st millennium BC. Each ke was subdivided into either 60 or 100 fen in the several (50–100) calendars since then. Needham thinks it likely that 12 double hours was transmitted from Babylon, but that 100 ke was a native Chinese invention. 100 ke and the associated base-10 positional counting rods were invented long before the Indian decimal system. Needham mentions that 100 ke was changed to 120 ke for a few years beginning in 5 BC, but the emporer's illness did not improve, so the advocates of 120 ke were executed and 100 ke reinstated. In 507, 96 ke was tried, then in 544 108 ke was tried before 100 ke was reinstated by 565. — Joe Kress (talk) 03:58, 3 May 2010 (UTC)

So this section clearly should be clarified. Not only was the ke or k'o a decimal division of the day, at least part of the time, but it was also divided decimally, at least part of the time. The fact that the history of time in China going back thousands of years is somewhat complicated should probably not be surprising. It was also complicated in the West. --Nike (talk) 09:41, 3 May 2010 (UTC)

I'll modify the article after some additional research. The Martzloff citation is one of the better discussions I've seen about the Chinese calendar. The book mentioned in his author profile, "he is now [2000] writing a book on traditional Chinese calendrical computations and mathematical astronomy", was published in 2009 as Le calendrier chinois by Jean-Claude Martzloff, ISBN 9782745319111.

I was too conservative when I mentioned counting rods as an early example of Chinese decimals. Martzloff in A history of Chinese mathematics states "Chinese mathematics is universally dominated by systems of metrology and numeration fundamentally decimal and often positional" (p.190). Shang dynasty oracle bones (c. 1500 BC), which contain the earliest surviving archaeological evidence of Chinese writing, include a fully developed decimal positional notation that used the same symbols for 1–9 in all positions but named all positions, units, tens, hundreds, thousands, etc. For example, 659 was written "six hundred and five ten[s} and nine", where symbols for "six" and "five" were joined to symbols for "hundred" and "ten" (most Chinese ideographs are joint). This same system, slightly modified, is still used in China alongside our modern system.

Martzloff's 1997 book A history of Chinese mathematics is a translation of his 1987 book Histoire des mathématiques chinoises, implying it may take ten years before his Le calendrier chinois is translated into English. — Joe Kress (talk) 07:07, 10 May 2010 (UTC)

Link Removal

Why was the link to the Decimal Time Applet removed and replaced on 30 June 2011? The existing link was relevant and produced the correct decimal time (for me at least). I can understand adding a new link but why remove a relevent link? --Stevep99 (talk) 12:26, 9 July 2011 (UTC)

File:Horloge-republicaine0.jpg Nominated for speedy Deletion

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Decimal Year

In the section "Decimal Year" with definition and conversion table; I believe "More exactly, a year is 365.25 days long, so a tenth of the year is 36.525 days (36 days, 12 hours, 36 minutes)" should use the more accurate 365.24 days per year. This is no more confusing while marginally more precise and informative. If so, the tabular values should also be adjusted.

More exactly, a year is 365.24 days long, so a tenth of the year is 36.524 days (36 days, 12 hours, 35 minutes)

(or 34.56 minutes). If necessary references can easily link to other Wikipedia topics. I leave this for consensus by others more expert than I. HalFonts (talk) 02:38, 19 February 2012 (UTC)

Since 1984, the astronomical year used for calculations has been the Julian year containing exactly 365.25 days, not the tropical or Besselian year used before 1984, about 365.2422 days, which I assume you approximated as 365.24 days. — Joe Kress (talk) 07:22, 19 February 2012 (UTC)

365.24 days is commonly used as the 2-digit approximation in numerous other Wikipedia time, articles -- all of which need to be cleaned up and coordinated. (In process?)

As an aside I thought, Why invent something new? With GPS and Global Time Standards, all using decimal (or binary) computational equipment -- What has become the defacto decimal time standard? Horror-of-horrors, GPS uses "Weeks and Seconds" in it's global time transmissions. And SI/Metric standardized on The Second (with no rational relation to Earth Day or Year). So, I give up any hope for (decimal/binary) calendar rationality. Just give it back to the churches, and be done with it HalFonts (talk) 18:44, 19 February 2012 (UTC)

The use determines the approximation. If the mean tropical year is under discussion, then an approximation of 365.24 days might be appropriate. But the decimal year is under discussion here, and astronomical epochs within a year have used the Julian year since 1984. Before 1984, the Besselian year, a kind of mean tropical year, was used. Epochs wihin both years were specified as decimal fractions of a year. These epochs are used whenever some variable changes over the course of a year, requiring the position within a year to be specified, where 2000.0 means the beginning of that year whereas 2000.5 means the middle of that year. The change was necessary because the mean tropical year changes from year-to-year and even within a particular year, making calulations using it inherently imprecise. The Julian year was chosen because it is a simple approximation of a calendar year, even simpler than an average Gregorian year of 365.2425 days (changing to an Egyptian year of exactly 365 days would have been too extreme). Furthermore, the day within the Julian year contains exactly 86400 SI seconds, avoiding the variable length of the day over various time scales from days to millennia, again a change needed for precision. The days within the former Besselian year were variable mean solar days instead of uniform SI days now used. — Joe Kress (talk) 00:08, 20 February 2012 (UTC)

Merge with Metric Time article?

Might be appropriate to make them into a single article: Metric time. Interlaker (talk) 14:52, 19 March 2013 (UTC)

The Metric time article is primarily about time units in the metric system. I know that decimal time is sometimes erroneously called metric time, but it is not a part of the metric system, and fear that merging them would encourage confusion. --Nike (talk) 05:57, 22 March 2013 (UTC)

Fractional time translation

I noticed that there is a French quote without any translation here:

   ... et la distance périhélie, égale à 1,053095 ; ce qui a donné pour l'instant du passage au périhélie, sept.29j,10239, temps moyen compté de minuit à Paris.
   Les valeurs précédentes de a, b, h, l, relatives à trois observations, ont donné la distance périhélie égale à 1,053650; et pour l'instant du passage, sept.29j,04587; ce qui diffère peu des résultats fondés sur cinq observations.
   — Pierre-Simon Laplace ,  Traité de Mécanique Céleste

I'm proposing the following translation:

   ... and the herihelion distance, equal to 1.053095; which has given the time of passage at the perihelion as sept.29d.10239, mean time counted from midnight in Paris.
   The preceding values of a, b, h, l, relative to three observations, have given a perihelion distance equal to 1.053650; and for the the time of passage, sept.29d.04587; which differs little from the results founded on five observations.

I'm not putting it right in the article because I'm not sure how the "sept.29j,10239" should be formatted. The "j" would have to become "d", it seems (jour = day), but would the comma become a period? Does the comma signify the decimal point here?

Also, I'm not sure of the formatting for an in-text translation.

Terrencereilly (talk) 11:48, 23 May 2013 (UTC)

The translation seems fine. I'm not sure of the proper format, either, but if there is one, somebody is likely to fix it for you. The context does not matter much. The important parts are the dates showing the decimal fraction, e.g. sept.29^j,10239, temps moyen compté de minuit à Paris, i.e. 1h 2m 39s decimal Paris Mean Time.

Comma is the decimal sign in most European languages, so it should indeed be changed to a period in English. In the 19th century, the center dot was used as the English decimal sign, as is seen in the Herschel quote, but today only the bottom dot, or period, is used. You can see that it was also then the practice to place the unit symbol in superscript before the decimal sign, in both languages, whereas today SI states that is is placed after the last decimal digit and a space, e.g. Sept. 29.10239 d. Also, in English translation the month should always be capitalized, i.e. Sept. rather than sept.

The Laplace quote is the earliest example I am aware of, and he has been credited with introducing decimal time to science, but many others can be found in astronomical circulars over the past century. You can see that the unit, i.e. d or j, is no longer included at all, e.g. Elements and Ephemeris for 216P/LINEAR: Epoch 2013 Apr. 18.0 TT = JDT 2456400.5 / T 2016 May 31.3854 TT. --Nike (talk) 06:12, 5 June 2013 (UTC)

External Links

Someone added an external link which appears totally unsuitable, for several reasons. I looked at the other links, and all of them also have issues. One of them had a 404 error, so I removed it. (Another had an expired certificate that my computer blocked.) I see the value of demonstrating decimal time, but don't know of any links that aren't original research or have other issues. Perhaps we could just show the decimal time with a template and not use any external links. --Nike (talk) 08:45, 2 April 2015 (UTC)

Link to decimal time clock

Sirs,

The said clock Decimal Clock (Decimal date and time Java JRE by Grant Hardy.) meets and is added based on your own criteria in response to a user in Nike's talk page, as

quote begins

Because the application in question does not relate to the article. Read the article. Metric units of time are the second, kilosecond, millisecond, etc. The metric system specifies time interval, not time of day. Your clock actually displays decimal time of day, not metric time.

Also, just because someone else does something does not make it right. Read the manual of style. Links are supposed to have information about the subject of the article, not advertise applications which are not even related to the article.

quote ends

Please do not undo my edits 86.31.47.92 (talk) 09:44, 2 April 2015 (UTC)

First of all, the page you linked is not specifically about decimal time. Rather, the title is "Messiah Decimal Calendar to make Modern Time keeping More Precise", and it's all original research, which is not allowed on Wikipedia. Secondly, you are referring to some Java apps which must be downloaded and run on a user's own computer; the first one has a bunch of unexplained things which may or may not be related to decimal time, and does not seem to be correlated with any version of decimal time I'm aware of. The "analogue clock" won't even run on my computer. I'm guessing it's "Messiah's Time", which is original research and/or not notable. Again, please read the Wikipedia link policies, which you link to above. --Nike (talk) 17:50, 2 April 2015 (UTC) Duodi 12 Germinal an CCXXIII à 7 heures 49 minutes décimales t.m.P., MJD 57114.743

Sirs, The mentioned link is a sub-page address and connects (at the bottom of the page) only to the picture of Java software implementation of a decimal clock that divides solar day to 20 hours. That is, at coordinates of equator daylight is counted 10 (i.e., deci) hours (instead of 12 in traditional clock and 5 in French Revolution clock) and night also 10 (i.e., deci) hours (instead of 12 in traditional clock and 5 in French Revolution clock). The clock is similar to mechanical one at the picture at the top of the article but it is twice precise in its established standard (not the measurement precision) than the pictured clock. Each hour is one hectominutes and each minute one hectosecond. The removed link is not a link to the original study or studies in that website. To run the program, for those who are interested, please install Java JRE which is already installed on almost any computer. If your computer is Linux you need to elevate permission of the file to an executable, before double clicking on it. 86.31.47.92 (talk) 10:13, 15 April 2015 (UTC)

It requires Java...in other words, it runs afoul of WP:ELNO #8. Yet another reason the link should not be included. —C.Fred (talk) 02:52, 16 April 2015 (UTC)

Ah Sir, Your computer needs many things to be enabled to run anything such as Wikipedia, such as OS, Java, html. Java is one pillar of computing. The rule you mentioned says,

Direct links to documents that require external applications or plugins (such as Flash or Java) to view the content, unless the article is about such file formats. See rich media for more details.

(My emphasizes.) My mentioned link does not fall in this category it links to an html/text page. There, there is a decimal-time clock similar to one that its picture being put atop of this article as the mechanical French Revolution clock, but it is not mechanical; it is digital. For example, you have mechanical Slide Rule that if you are interested in history you buy it as a collectible item, and now you have digital slide rules on the internet that people who are interested but have not money can put on their computer and use it and get the feeling.86.31.47.92 (talk) 06:57, 16 April 2015 (UTC)

Yes, it links to an HTML page, which is in itself a problem, because the content contains original research, and is not primarily related to the article. You give the link title as "Decimal Clock", which is deceptive because the actual title is "Messiah Decimal Calendar to make Modern Time keeping More Precise". And I see that the clock app has been fixed and an image inserted since I last looked, which suggests that it may have happened in response to discussion here. Since you are anonymous, there is no way to determine that you are not affiliated with the web site in question, and therefore self-promoting. "Adding external links to an article or user page for the purpose of promoting a website or a product is not allowed, and is considered to be spam." Linking to your own content could be a conflict of interest. There are many sites which have decimal clocks and don't require files be downloaded. In fact, for the past 15 years I, myself, have had an entire web site dedicated to decimal time, with a number of decimal clock Java applets and JavaScript widgets, but I have avoided linking to it in the article because that would be self-promotion, so I cannot be an unbiased judge. (If someone else thinks it should be included, that's different.) --Nike (talk) 23:02, 17 April 2015 (UTC), Septidi 27 Germinal an CCXXIII à 9 heures 56 minutes décimales t.m.P., MJD 57129.950, @992.beats

Sir, You are not owner of Wikipedia and god forbids a sock-puppet. You also have not any gain or personal conflicting interest in promoting the obsolete French Revolution symbols. It is only that you enjoy perhaps using decimal-metric ideas; it is only you find that thing interesting. I noticed the clock picture is different from and more readable than the version I am using on my desktop. That page is always under revision and correction as it announces certain solar times changing on a seasonal basis. It is written in a corner of their page. I am not as deceptive as Wikipedia foundation overall. The link refers to just the sub-page part of the web-page, the part related to clock and calendar. The calendar at that place has divided each interval between two consecutive equinox into ten months which is also decimal and interesting. I enjoy using things in metric system and divisions of ten. I also am a frequent to many slide rule websites. None of them has any personal promotion for me. I enjoy watching and using a slide rule. By the way I can remain more anonymous than now if I choose some log-in user name and prop up an immediate yahoo or google mail. You are also anonymous. 86.31.47.92 (talk) 11:45, 18 April 2015 (UTC)

Use within speed skating

I'm not sure whether it's relevant for this article, but when I read it I came to think of how speed skating results are handled. When a 500 m competition, for example in the Olympics, is run, each skater run the distance twice and the times are added. Say that a skater runs once in 35 s and once in 36 s. The result is then written as 71 s, not as 1 min 11 s or something alike.

Also the samalog rules used in speed skating competitions and statistics might qualify as a kind of decimal time. Fomalhaut76 (talk) 07:54, 23 September 2015 (UTC)

A fun little note

My first ever edit on wikipedia, ten years ago, was to add a conversions section, which survives to this day but happily much improved. The incremental improvements and expansions on wikipedia through its history have been amazing. Let noone say that that wikipedia is not a fantastic place. :-) --Nanite (talk) 23:05, 25 November 2015 (UTC)

Decimal Time Zones

I'm trying to figure out which time zone I would be in when decimal time is finally seen as sane and "why didn't we do this sooner?". Taking current longitude (118*W; Pacific Time Zone) and dividing by 36, gives me 3.2778. Question is, do I round up (to 4 in this case; knock the bits off to the right of the decimal point), am I in the third time zone (keep the bits to the right of the decimal point), or should I figure it out via International Date Line (where 10:00:00/00:00:00 would be)? 108.13.17.82 (talk) 23:00, 2 June 2016 (UTC)

There is no such thing as decimal time zones. You are free to devise any system you like, as original research, for your personal use, but it would have no notable use, and thus be outside the scope of Wikipedia. If you wish to discuss the issue further, you should look for an appropriate forum, or ask me on my personal talk page. --Nike (talk) 04:13, 3 June 2016 (UTC) (MJD 57542.17463)

Myriasecond?

I've used the decimal system for over 30 years in my professional work and never seen this term, probably because it was obsolete before I was born. More useful and used are decasecond and heptosecond, but we don’t introduce these. By the time we get to kilosecond (a little over 1/4 hour), we shift to units of minutes, hours, days, or whatever is appropriate. I think this bit of historical trivia should be deleted or replaced. Someone has engaged in an exposition of their erudition IMHO.Sbalfour (talk) 19:01, 20 October 2020 (UTC)

So far as I know, this is original research, and nobody has actually used or proposed myriasecond. --Nike (talk) 04:36, 13 November 2020 (UTC) (Tridi 23 Brumaire an CCXXIX à 1 heure 98 minutes décimales t.m.P.)

Historic representation

In modern representation of time of day, colons (:) are used to separate sexigesimal divisions, especially in English-speaking countries. In historical documents, units were typically followed by their names, or abbreviations thereof, i.e. hours, minutes, and seconds (hms). This is still practiced in francophone countries. In addition, sometimes the superscripts that are still used for sexigesimal divisions of angular degrees was used for time of day, e.g. 12h 0' 0". These same methods were also used to represent decimal time of day during the Revolution. An example with abbreviations may be seen in the article: 9 h. 92 m.

Connoissance des temps

An example of the alternate representation: à 3^h 86’, which is also represented as 0,386 or 0^j386, that is, 3 decimal hours 86 decimal minutes, or 0.386 day.

Does anyone know when and how colons were introduced?

--Nike (talk) 04:28, 13 November 2020 (UTC) (Tridi 23 Brumaire an CCXXIX à 1^h 92’ t.m.P.)

Decimal time association & Decimal time clock and calendar

There is a website from the decimal time association with a decimal time clock and calendar: decimal-time.org. — Preceding unsigned comment added by 77.191.128.242 (talk) 17:26, 7 May 2022 (UTC)

Aviation example seems poor

I think the example of aviation using decimal hours is a poor one, as this is not a common thing across the rest of aviation in my experience. The example given is specifically the recording of flight time in the Pilot's Logbook which is an official legal document which can be used to verify things like currency requirements (minimum recent flight experience needed to perform certain operations, etc.) so the fact that this is recorded in decimal hours and fractions thereof is convenient as it makes it quick to manually total up. But the PRIMARY reason this is done is that typically it's a record of the engine total operating time meter in the plane (often referred to as the Hobbs Meter https://en.wikipedia.org/wiki/Hobbs_meter) which records a continuous non-resettable count of hours and (generally) tenths of hours. But such meters and their recording for maintenance or other purposes is not specific to aviation but is very common across many electro-mechanical systems (engines of all sorts, mainframe computers and some peripherals, etc.) so I feel the current entry will make people think this is some general feature of aviation and I don't think that's the case. 2601:245:4100:B781:C53D:3AB:992B:444F (talk) 00:23, 14 May 2022 (UTC)

Epoch Day

What is this? The only source is a personal GitHub page, so it appears to be personal research, as well as not notable, and therefore needs to be deleted, unless shown to be otherwise. ------ L'an CCXXXI De la Republique francaise une et indivisible Le Six frimaire à Deux heures Neuf Décimes temps moyen du Paris Nike (talk) 06:51, 27 November 2022 (UTC)

Confusing table

The table at the top of start of the topic is a little confusing. I guess that the discrepancy between the three representations is due to the different zones, but this is far from obvious. An explanatory caption would help. Roly (talk) 14:30, 25 March 2023 (UTC)

I agree. But I also see the problem in that Swatch Internet Time is fixed to Central European Time (UTC+1), so if they should be comparable, we would have to stick to showing all four time representations in that table in CET (UTC+1). I guess the current table also illustrates that there is still plenty of room for confusion even with decimal time – and especially that the 24 hour division of time zones makes time zone differences much more confusing when using decimal time. --Jhertel (talk) 15:09, 25 March 2023 (UTC)

Feel free to write a caption. The French based their system on the Paris Observatory which defined their Meridian. Swatch based theirs on the time in Switzerland. Fractional days are typically used with astronomy in Universal Time, based upon Greenwich.

𝓛'𝓪𝓷 𝓭𝓮𝓾𝔁 𝓬𝓮𝓷𝓽 𝓽𝓻𝓮𝓷𝓽𝓮 𝓾𝓷 𝓭𝓮 𝓵𝓪 𝓡𝓮́𝓹𝓾𝓫𝓵𝓲𝓺𝓾𝓮 𝓯𝓻𝓪𝓷𝓬̧𝓪𝓲𝓼𝓮 𝓾𝓷𝓮 𝓮𝓽 𝓲𝓷𝓭𝓲𝓿𝓲𝓼𝓲𝓫𝓵𝓮 𝓵𝓮 𝓹𝓻𝓮𝓶𝓲𝓮𝓻 𝓺𝓾𝓪𝓻𝓽𝓲𝓭𝓲 𝓵𝓮 𝓳𝓸𝓾𝓻 𝓺𝓾𝓪𝓽𝓻𝓮 𝓭𝓾 𝓶𝓸𝓲𝓼 𝓭𝓮 𝓥𝓮𝓷𝓽𝓸̂𝓼𝓮, 𝓵𝓮 𝓳𝓸𝓾𝓻 𝓭𝓮 𝓵𝓪 𝓽𝓾𝓵𝓲𝓹𝓮 𝓪̀ 𝓼𝓮𝓹𝓽 𝓱𝓮𝓾𝓻𝓮𝓼 𝓺𝓾𝓪𝓻𝓪𝓷𝓽𝓮 𝓶𝓲𝓷𝓾𝓽𝓮𝓼 𝓷𝓮𝓾𝓯 𝓼𝓮𝓬𝓸𝓷𝓭𝓮𝓼 𝓭𝓮́𝓬𝓲𝓶𝓪𝓵𝓮𝓼 𝓽.𝓶.𝓟. Nike (talk) 17:35, 25 March 2023 (UTC)

I've added a short note to the table. I hope I haven't just made the confusion worse. Roly (talk) 18:10, 25 March 2023 (UTC)

Possible mistake in table "Conversion between decimal years and date (in a common year)"

Some of the dates seem to be incorrect (off-by-ones?): Table: Mar 15, Apr 20, May 27, Aug 8, Sep 13, Oct 20, Nov 25. Suggested correction: Mar 14, Apr 19, May 26, Aug 7, Sep 12, Oct 19, Nov 24. Other dates and times seem to be correct. Grateful if somebody could verify this? Domschl (talk) 12:15, 10 June 2023 (UTC)

The table is correct. Remember, the first day of the year is 0, so 73 is March 15. — J2023.443565 Nike (talk) 06:18, 12 June 2023 (UTC)