Talk:12-hour clock/Archive 1

message: There is an article a.m., but no article p.m. - I was just wondering whether it was necessary to have an a.m. article, when it seems that this one will suffice.  If it is deemed necessary, perhaps there should be a p.m. article as well (though I think the first solution might suffice).
Additionally, although I have not yet found a mention in the Wikipedia:Manual_of_Style, I think it might be a worthy effort to begin discussion here concerning whether to use A.M., AM, a.m., or am (Which is what seems to be in use here and is preferred by myself).  Should anyone feel that they can add to this please do. User:Moogle 15 Dec 04
There already was a "Post Meridiem" article as well as a "Ante Meridiem" article in addition to the A.M. article. I made the shorter Ante Meridiem a redirect to the A.M. article and made Post Meridiem redirect to a new P.M. article for consistency. I'm not so sure we need either, but I don't have strong feelings about it. As far as A.M., AM, a.m., and am I prefer am with A.M. as a second choice. I think a.m. is just wrong, and AM isn't as typographically pretty as am. Zenyu 18:37, Dec 15, 2004 (UTC)
I thought that the A.M. article was silly the first time I saw it, so I'll merge it and P.M. here. Typographically, I dislike "am" because it's a word, and I also dislike periods (although I don't see how you can claim that they're wrong). Thus I use "AM", although I agree that it's not pretty; that's because it really should be in small caps: "AM".
-- Toby Bartels 00:12, 4 Jan 2005 (UTC)
replies: text: At some point, a Wikipedia-wide style convention was developed, and is recorded in the Manual of Style. The winners were "a.m." and "p.m.". I have updated this article accordingly.--Srleffler 04:39, 8 April 2006 (UTC)
thread_title:  a.m. A.M. am AM & What about p? 

message: Isn't it more widespread than just the U.S.?  I'm pretty sure it's used throughout Canada (except possibly Quebec) as well.
Yes it is widely used in Canada, generally excluding quebec and other French dominated regions such as Northern Ontario
Begging your pardons, but this debate, and the resulting explanation soup of "usage" on the front page of this entry, seems to entirely miss the key point. Which is that the statement "12 PM is not noon" leaves the door wide open for all those less fortunate who will read it and say AHA, so "12 PM is midnight" or so "12 AM is noon" (*tears hair out*). I have visited an optometrist, located in an upscale mall and associated with a national chain, who still proudly displays a sign stating that they are open until 12 AM every Saturday. Yet, they don't understand why they have to keep saying no to Saturday afternoon and evening apointments.
:Please have a signature for your messages. Thank You! --Siva1979Talk to me 04:47, 26 April 2006 (UTC)
thread_title:  "especially common in the USA?" 

message: Can any one explain why certain countries still use the 12-hour clock --AzaToth talk 11:47, 15 November 2005 (UTC)
thread_title:  Reason for use 

message: "Noon and midnight are only infinitely short points in time, and therefore it is not practical to use any other convention than that which also applies immediately afterwards, when the clock still displays 12:00."
Using this logic, the minute hand would never be able to leave the 12:00 position as anything immediately after would also be 12:00...
The fact that a point has no length has nothing to do with it - the 3am point also has no length but it is definitely am.
I believe that the reason that it doesn't make sense to allocate either am or pm to 12:00 is that it is a point that joins two continuiums, am and pm (similar to two rulers, one red and one blue that are laid end to end). The join point (12:00) is neither am or pm, just like the join point of the two rulers is neither red nor blue. User:24.5.38.74
:The point I was trying to make when using the term "infinitely short points in time" could be explained far more precisely, but unfortunately such an explanation would assume that the reader is familiar with the notion of open and closed ends of intervals in mathematics. The explanation could then go like this:
::It is customary that the time interval associated with a given time display is closed at the start and open at the end. For example, the fourth hour of the day, during which a U.S.-style digital clock displays 3:MM:SS am, covers the time interval [03:00, 04:00). Likewise, the first minute , during which a U.S.-style digital clock displays 12:00:SS am, covers the time interval [00:00, 00:01), etc. If we accept that convention, then it only makes sense – in the interest of consistency – to also interpret the time intervals denoted by the "am" and "pm" periods as closed at the start and open at the end. In other words, "am" covers the interval [00:00, 12:00) and "pm" covers the interval [12:00, 24:00). Doing it the other way round would lead to the oddity that a clock would have to flip between am and pm an infinitely short time after it flips from 11 to 12.
:Such an explanation might appeal more to readers with a good background in mathematics, but I don't know whether we can assume that here. (On the other hand, people come to Wikipedia to broaden their mind, so perhaps it is ok to explain first what open and closed interval ends are?) Markus Kuhn 09:47, 26 April 2006 (UTC)
thread_title:  Infinitely short periods in time? 

message: Moved from the article:
* Some people claim that changing the notation if the clock destroys cultural identity and abominates the language, because the day begins with midnight and ends right before midnight. In other words, it is customary that the time interval associated with a given time display is closed at the start and open at the end. If we accept that convention, then it only makes sense – in the interest of consistency – to also interpret the time intervals denoted by the period of a day as closed at the start and open at the end. In other words, "day" covers the interval [12:00 AM, 12:00 AM).
* The Sumerians had a sexagesimal or base-60 numbering system. So that explains why there are 60 seconds in a minute and 60 minutes in an hour.. Now look at degrees, notice how 40°12'13" is 40 degrees, 12 minutes, 13 seconds... There are 360 degrees in a full orbit, or 60*60/6. Let's try dividing 60 by 5, we get 12... Why 5? well 60 can be factored these primes 2,3,5 any multiple of them makes a nice simple divisor, so 2,3,5,6,10,12,15,18,30 are your basic options, of those the only ones that make sense here are 3, 5, 6. Why they chose 5 not 3 or 6 I can't tell you, maybe they just thought 15 or 18 hours were still excessive, and 10 too few? Maybe 12 was better because it could be divided twice in half? Note, 24 is not in the list 2,3,5,6,10,12,15,18,30. This is a problim with clocks with analog dials.
I really do not see why the story about Sumerian number systems represents an advantage. If you want to include that story it might perhaps better fit in a "background" or "history" section. Anyway it should be rewritten, as it is rather conversationally formulated, not encyclopedic. And it should be Substantiated with sources, as it looks like original research, which is not accepted in wikipedia.
Similarly, I do not see how the story about half-open intervals presents an advantage. It sounds like a very specific (even personal), not general interpretation of what a clock time is meant to mean.
−Woodstone 07:49, 10 May 2006 (UTC)
replies: text: I agree, but right now it just says "Some people claim that changing the notation of the clock to 24-hours destroys cultural values and identity and abominates the language," which is bewildering.  I think we should remove that too. 132.236.113.119 07:03, 9 July 2006 (UTC)
thread_title:  Sumerians and half open intervals 

message: Can we ensure that there is consistency between 12-hour clock and 24-hour clock? The issues are almost identical but the articles are inconsistent.
Perhaps we should have a single article. bobblewik 07:27, 15 May 2006 (UTC)
thread_title:  Consistency between [[12-hour clock]] and [[24-hour clock]] 

message: We now have a "Use by country" section in both the 12-hour clock and 24-hour clock pages, which will lead to redundancies and inconsistencies. How about moving this entire section into a new separate article Date and time notation by country, were contributors interested in giving a detailed account on the related conventions have all the space they need? Markus Kuhn 13:10, 15 May 2006 (UTC)
thread_title:  Use by country 

message: It is more efficient to split a series up in to two parts. For example we do not have different names for negative numbers; we use the − sign.
I don't understand this sentence, and the use of "we" is problematic. What do negative numbers have to do with time notation? Could someone who knows what the argument is supposed to be rephrase it, and write in a way that doesn't show that the author uses the 12-hour clock? Thanks, PruneauT 12:38, 16 June 2006 (UTC)
replies: text: Since no one seems to answer, i've deleted the sentence. PruneauT 00:29, 20 June 2006 (UTC)
thread_title: Weird sentence

message: "It is unlikely that Australia will never migrate to 24-hour notation." 
What did the author intend to say? I assume it was "...will ever...", but I've nothing to back it up.
:I copied it from 24-hour clock and I was confused by it. Copied question over there. Zginder 13:29, 27 July 2006 (UTC)
thread_title:  Australia - Double negative 

message: Regular editors of this article may be interested in some proposed changes to the use of am/pm/noon etc. in the Manual of Style (WP:DATE), relying in part on this article. See Wikipedia talk:Manual of Style (dates and numbers)#Imporvement about guidelines in Time. — Joe Kress 16:28, 8 August 2006 (UTC)
thread_title:  Manual of Style 

message: I removed two paragraphs from the article.
* From the section Advantages over the 24-hour clock: because this sentence doesn't show an advantage of 12-hour clock over 24-hour clock. Maybe it fits better in another part of the article but it's a claim that would need some citing.
Some people claim that changing the notation of the clock destroys cultural identity and abominates the language.
* From the section Pronunciation: because the paragraph is about the pronounciation of 24-hour times. I'm including this in here: 24-hour clock.
Military circles use the 24-hour clock exclusively and would typically pronounce times ending in :00 minutes as the hour followed by "hundred" with an optional "hours". For instance, 16:00 would be pronounced "sixteen hundred" or "sixteen hundred hours".--Bisco 00:06, 1 October 2006 (UTC)
thread_title:  Removed content 

message: From the Typography section:
hence 5:30 is half past 5 or merely half five
Is this correct? I thought 5:30 would be half six.--Bisco 00:11, 1 October 2006 (UTC)
replies: text: I happened to notice this older remark when inserting mine below. Yes, it is correct. In English "half five" is short for "half past five". There is no expression "half to five" that could be shortened to it (unlike in German). −Woodstone 14:14, 15 October 2006 (UTC)
thread_title:  Typography - half hours 

message: Does anyone know of a clock chiming up to 24 times? It is mentioned in the article, but I doubt if any exist. −Woodstone 14:10, 15 October 2006 (UTC)
replies: text: It was certainly common centuries ago - see striking clock for a quote about a famous example from 14th century. But I very much doubt whether you'd find a similar clock that still does it today, and even in Italy they changed most of their clocks to conventional striking ages ago. Cormullion 15:16, 15 October 2006 (UTC)
thread_title:  Chiming 24 times? 

message: I regularly look at articles that are in need of citation and find links were I can give it the appropriate citation , thereby making wikipedia more encyclopedic , this article has proved problematic it only has one  tag and when trying to check it out I can get to ISO 8601 and look at it, however ANSI standards seem to be for purchase and I cannot access the relevant info to allow me to remove the citation needed tag, if anyone out there can help out or maybe even look at rewording the article it seems like a simple job to remove this tag and yet without relevant links info etc I cannot do it. So for all those sharp minds out there I hope one or more of you can get on the case thanks --Matt 08:08, 17 January 2007 (UTC)
replies: text: The whole article needs citations so I tagged it. Lots of "Many people" and "common practice" and sentences like "Children learn only the 12-hour analog dial at school." As for access to non-free ANSI standards, can't help you there. Gront 16:16, 24 March 2007 (UTC)
replies: text: The standard can be seen on-line at omg.org. I do not know how legal that is. −Woodstone 17:04, 25 March 2007 (UTC)
thread_title:  Fix Citation needed 

message: : Traffic regulations in San Francisco use 11:59 am and 11:59 pm, for midnight and noon respectively.
This statement appears to be incorrect (at best, midnight and noon are reversed), and since I don't know where to check the facts I have just deleted it. Ray Spalding 22:11, 1 Jan 2005 (UTC)
replies: text: A perhaps more accurate description than "11:59 am = midnight in San Francisco and elsewhere" would be to say that these places never schedule any event exactly at midnight or noon, because they lack a convenient notation for these two points in time. Markus Kuhn 15:52, 1 January 2007 (UTC)
replies: text: I looked up the SF traffic code, the only reference to 11:59 is midnight, which is covered in the article and not unique to san francisco. No mention of any 11:59 of either kind for noon (well, if the quote were correct, this 11:59 pm could conceivably mean noon, except that'd be a funny time for new meter regulations to take effect.) --Random832(tc) 13:42, 31 January 2007 (UTC)
thread_title:  11:59 am = midnight??? 

message: Why did the Sumerians or Egyptians use 12 hour increments? Did this concept of "12" derive from the number of notes in the chromatic musical scale? Or perhaps it has some religious significance relating to astrology?
-- 216.102.9.150.
: The article that I linked above is unclear; but I don't think that the chromatic scale is anywhere near that old. -- Toby Bartels 22:34, 5 Jan 2005 (UTC)
replies: text: 12 hours for daytime and 12 hours for nightime come from the Eqyptians who divided the night and day in that manner. The reason for a base 60 numbering system in Sumeria/Babylonia is unknown, but it was actually a base 6×10 numbering system, so there was a kind of base 10 system within it (see Babylonian numerals). Sumeria/Babylonia never used a 24-hour day or a 12+12 hour day. Instead their day had 12 double hours (each called a beru), similar to the 12 double hours in China. But the basic time unit in Babylonia was not the double hour — it was the time-degree (called an us), the time it takes for the celestial sphere to rotate one degree (1/360th of a rotation) around a motionless Earth (4 minutes), so a beru had 30 us. — Joe Kress 04:02, 13 December 2006 (UTC)
thread_title:  Reason for 12-hour increments 

message: In chapter "Confusion at noon and midnight" it says
[begin quote]
Noon and midnight are only infinitesimal points in time, and therefore it is not practical to use any other convention than that which also applies immediately afterwards, when the clock still displays 12:00. This convention is standardized for computer usage in American National Standard ANSI INCITS 310 (which extends the international standard ISO 8601 time notation with a 12-hour a.m./p.m. variant for the U.S.-market).
[end quote]
The version of ANSI INCITS 310 which is currently available at [ansi.org] (go to the shop, search for INCITS 310) does not deal with the 12 hour format at all. It gives some explanation on how to use the 24 hour format in data exchange in the U.S., but no clarification, description or explanation on the 12 hour format.
Where does the information given above come from? Was an explanation of the 12 hour format contained in a different version? Is the reference wrong? Or should the last sentence of this phrase rather be deleted from the article?   Daisy G 12:37, 21 December 2006 (UTC)
replies: text: I recall having found sometimes in 1997 in the standards room of the Purdue University Engineering Library an ANSI standard that looked very similar to a national adoption of ISO 8601, but had also a 12-h notation option as an extention. I do not recall the exact document reference, whether it was "ANSI INCITS 310" or some predecesor of it, or whether what I found then is still a currently active ANSI standard as of 2006. Someone with easy access to a US library with a good ANSI collection might be able to answer this one. (ANSI standards are not easily available here in Britain.) It would be nice to have the correct reference and a description of what that specification did with midnight and noon. Sadly, the web sites of most standards bodies are very bad at providing access to information about historic documents. Markus Kuhn 15:46, 1 January 2007 (UTC)
replies: text: The standard I meant was probably ANSI X3.43-1986 "Representations of local time of day for information interchange" (also FIPS PUB 58-1) or ANSI X3.51-1975 "Representations of Universal Time, local time differentials, and United States time zone references for information interchange" (also FIPS PUB 59), but it seems that these FIPS documents were withdrawn in 1997 . So the only US standard now left for representing time in information interchange is essentially identical to ISO 8601. (Given the various ambiguities inherent to the am/pm notation, that's certainly a wise choice, IMHO.) Markus Kuhn 08:22, 23 January 2007 (UTC)
thread_title:  Phrase needs verification 

message: The article contains this line: 
:Some people dislike the idea that midnight has two different notations in the 24-hour clock, depending on whether it is the beginning (00:00) or end (24:00) of the day.
Under which user 155.208.231.234 added:
:This seems an odd argument to someone growing up with the 24 hour system, as we know that even though it is a TWENTYFOUR hour system, the time will never be displayed as 24. From 23:59:59, the time shifts to 00:00:00. Midnight will never be referred to as "at 24 o'clock" in writing nor in speech. In speech it is always "midnight", in wirting it can be referred to as "midnight" or in the format hh:MM (00:02 for two minutes past midnight).
This comment ignores the fact that written notices often contain 24:00 to explicitly indicate the end of the day. For example in ranges used for opening hours as from 07:00 to 24:00. See also the example of a time table using the 24:00 as well as the 00:00 notation in 24 hour clock. −Woodstone 15:16, 22 December 2006 (UTC)
replies: text:  While I tend to agree that midnight should always be 0000 I have seen 2400 used in many countries, on many clocks and machines and very commonly on timetables (especially in Italy where I am at the moment).  24.00 (and sometimes even 24.05, etc.) is found at the end of timetables because if you need a bus in the late evening you naturally look at the end of the timetable and not the start (where you might normally expect to see 0005, etc.).  As for spoken language I don't really know because most people seem to pronounce the 24h times as 'undici ora' (eleven o'clock) rather than 'ventitre ora' (twenty-three o'clock).--Xania talk 00:55, 31 January 2009 (UTC)
thread_title:  Begin and end of day (24:00 issue) 

message: Is there any information on what the various sources saying that noon should be something other than 12:00 pm, have to say about 12:01, 12:30, etc? --Random832(tc) 13:27, 31 January 2007 (UTC)
thread_title:  12:01 

message: Are there any providers of cable or satellite television that still use the 12-hour notation in their set-top boxes? I ust want to find out which pay television companies have 12-hour time and which ones have 24-hour time. Scott Gall 04:40, 8 February 2007 (UTC)
thread_title:  Digital decoders' time notation 

message: What do people think about changing the section that refers to using a leading zero with the 12 Hour Clock?  In my (completely amateurish) opinion the use of a leading zero in the twelve hour clock is just wrong.  To my eyes writing 09:02 pm is simply incorrect, not as the article seems to suggest merely a matter of style.  Before the arrival of the 24 hour clock would there have been instances of using a leading zero?  I suspect not; using a leading zero in the 12 hour system would presumably only have occured after the 24 hour system came into being, at which point the leading zero may have been erroneously copied to the other format.  In addition I don't think this section uses adequate citation either.  "Some style guides suggest," which style guides?  I also feel the statement of "many digital clocks" is not rigorous enough either.  I have never seen a digital clock that uses a leading-zero when displaying 12 hour format - I'm not making this up to add to my argument, it's just I've never seen this.  Although I'm sure if you looked hard enough you could find some, I'd venture that this probably doesn't count as "many" and those that do use a leading zero are just poorly manufactured (I've got a clock laying in a drawer that seems to reset itself every five days - but that doesn't add evidence to the case that time starts over at the end of every working week - it's just cheap tat that shouldn't have passed quality control).  No offence meant to the original contributor of this piece, I agree with their basic premise and it's probably a better start than I could have made.  But I think in attempting to preserve neutrality they are giving credence to a state of affairs which is more likely to have come about by error or exceptionally rather than deliberately.  Be interested to hear what other people say - I daresay I am now about to be shot down by a whole bunch of people who regularly write 01:30 pm etc... DistractionActivity 14:24, 21 February 2007 (UTC)
replies: text: Seen as I posted this in Feb and no-one has replied, I'm guessing the above isn't controversial.  I'm deleting the leading-zero section.  I think it confuses more than it helps.  DistractionActivity 16:34, 20 July 2007 (UTC)
thread_title:  Leading Zero in 12 Hour Clock  

message: Regarding the section "Advantages of the 12-hour clock", "eleven" is also not a monosyllabic word. - Lake Ontario 12:33, 21 March 2007 (UTC)
thread_title:  [[Monosyllabic]] Words 

message: Combining the number twelve with ante meridiem or post meridiem is ambiguous and incorrect.
The descriptor would be either noon or midnight sans the number.
Garnered from the Physics Laboratory Time and Frequency Division of the National Institute of Standards and Technology
Betwixt Words 19:46, 7 June 2007 (UTC)
thread_title:  Twelve Hour Clock 

message: The Time and Frequency Division, part of NIST's Physics Laboratory, maintains the standard for frequency and time interval for the United States, provides official time to the United States, and carries out a broad program of research and service activities in time and frequency metrology. National Institute of Standards and Technology's Physics Laboratory, Time and Frequency DivisionPlease see NIST's home page.
If this governmental agency maintains the time standard for our country and state that the use of p.m. and a.m. are incorrect when referring to midnight and noon, I feel it a mute point to offer anything else other than suggestions. 
This entire aritcle needs reworking.
Betwixt Words 16:52, 17 June 2007 (UTC)
replies: text: Hey Alan, something we agree on! "it is the opposite of the very common usage of midnight as being at the end of the day." I have been trying to get an answer to whether the use of the word midnight, in speech or writing, to mean the end of the day is disputed or not. Certainly in my whole life as a native English speaker I've not known it used otherwise than the end of the day. Dyaimz 22:17, 27 June 2007 (UTC)
thread_title:  The entire article  

message: In some countries (I know Norway is one example) a phrase such as "half five" is not short for half past five as stated in the article but rather means 4:30 (i.e. half way to five) Does anyone know of other countries where this is true? Seems like it should be mentioned in the article but since so many other people have worked on it I'll let someone else make any changes. 
Kirkmona 16:13, 20 June 2007 (UTC)
replies: text: This is an interesting point. Norway is definitely not the only country where it has this meaning. But as this is the English version of WP should we only be concerned if this usage happened in an English speaking community? Dyaimz 20:22, 22 June 2007 (UTC)
thread_title:  Pronunciation 

message: Betwixt Words, please give me a reference showing that meridiem by itself is actually a word. You can't, because it isn't. It's like 'memoriam". That is not a word either, but 'in memoriam' is (a compound word).
Alan E. Feldman 2007-07-07 00:41 UTC
The root word is only complete with either unhyphenated prefix and does not stand alone. I wish I could take credit for authoring more than two lines in the article, but I can not; therefore the question belongs to someone else. Thank you though Betwixt Words 20:01, 8 July 2007 (UTC)
replies: text: Meridiem is the accusative case of the fifth declension Latin noun meridies (midday or noon). The accusative case is usually used when the noun is the object of a verb. But Cicero did use it with the adjectives ante and post, so meridiem is not used alone. However, the Anglicized form is meridian, which the OED indicates is "long rare" in the sense of noon. Nevertheless, it is used in United States law in the forms ante meridian and post meridian. — Joe Kress 03:49, 9 July 2007 (UTC)
replies: text: Small correction. The ante and post are prepositions (not adjectives) and they always take the accusative case. The normal meaning of meridian in English is the great circle passing through the poles and the zenith at a place on Earth. So ante meridian would mean: before the Sun passes that circle (as originally, when local solar time was used). Admittedly all of this has no real bearing on the article. −Woodstone 20:29, 18 July 2007 (UTC)
thread_title:  There's no such thing as a 'meridiem' 

message: I am continuing the discussion fund here Talk:12-hour_clock/Archive_1#Translations_of_a.m._and_p.m.
The current translations are ante meridiem (a.m., from Latin, literally "before the middle day", idiomatically "approaching midday") and post meridiem (p.m., "after the middle day").  If I did not participate in the above stated discussion I would have no clue what "approaching midday" means.  We need a translation that people will understand.Zginder 02:02, 26 August 2007 (UTC)
replies: text: My guess is that "approaching/past" were chosen as a mnemonic. The editor looked for words beginning with "a" and "p" to facilitate remembering which is which. Literally "ante" and "post" mean "before" and "after", "meri" is a form of the word "medius", meaning "middle", and "dies" means "day". My favorite translation is therefore "before/after midday". Because latin has no articles, it could equally well be translated as "before/after the middle of the day". −Woodstone 10:36, 26 August 2007 (UTC)
thread_title:  Translations of a.m. and p.m. (2) 

message: Two weeks ago, 204.210.99.14 added the hypothesis that the 2x12 hour clock has been derived from the precession of the equinoxes. The hypothesis doesn't make sense because the true period is 25,765 instead of 24,000. In addition, it is unlikely that ancient civilisations would have been without a timekeeping convention before somebody figured out the precession of the equinoxes and its period. I removed the hypothesis, but Zginder restored it. Why? Ceinturion 20:11, 1 September 2007 (UTC)
replies: text: I restored it because it appears to have a source.  Has anyone checked it? Zginder 02:46, 2 September 2007 (UTC)
replies: text: 204.210.99.14 uses that source only for the statement that a number of ancient cultures knew the precession of the equinoxes. Wikipedia has an article about the book: "When Hamlet's Mill first came out, it was severely criticized for a number of things, such as tenuous arguments based on incorrect or outdated linguistic information, lack of modern sources and an over-reliance on coincidence, and the general implausibility of such a farflung of influential civilization existing and not leaving behind solid evidence, and at best given a grudging sort of praise, especially for its use of linguistic arguments and analyses."  Unless somebody improves this flimsy section, I'll remove it again next week. Ceinturion 08:35, 2 September 2007 (UTC)
replies: text: I have removed it.  Putting below for better reference:
"While no one is certain of the exact origin of the 24 hour day with its two periods of am and pm it does appear to be a microcosm of the mythological cycle of a Great Year. This was the Greek as well as the Chinese term for one precession of the equinox, a period often rounded to 24,000 years, comprised of two 12,000 year phases. According to Giorgio de Santillana, the former professor of the history of science at MIT, and author of Hamlet's Mill, over thirty ancient cultures believed in this cycle of rising and falling ages marked by the slow movement of the equinox through the twelve contellations of the ancient zodiac."  Zginder 01:36, 3 September 2007 (UTC)
thread_title:  Precession of the equinoxes 

message: "end point convention" (last column of chart) is never defined.  I have no idea what it means. Korky Day 18:15, 13 October 2007 (UTC)
thread_title:  end point convention -- meaning? 

message: Is there a need for the P.M. numbers to be complete, when the A.M. section is abbreviated with ellipses? I would like to have a uniform and concise table, and one that would be uniform (if possible) with the chart that would replace the one found at 24-hour clock...--Vox Rationis 00:30, 2 February 2007 (UTC)
thread_title:  Table of Time Values 

message: This section of the main article starts with "Many people who grew up with the 24-hour clock see the 12-hour notation as a less practical and outdated convention".
What does this actually mean? You could grow up in many places not seeing a Fahrenheit thermometer or an inch rule, but is it being suggested that some people have never seen an analogue clock face? My point is that most people use 12hour time to read an analogue clock & 24hour time to read a digital clock. The only time when I would do otherwise is if speaking to someone abroad, I would tell them the time as I think they would understand it best.
If I'm stopped & asked the time, I look at my analogue watch & tell the person what I see! If the hand points to 3, I say "3 o'clock" & I expect the person asking to know if it's am or pm. Dyaimz 22:41, 19 July 2007 (UTC)
replies: text: Well, I grew up without a.m./p.m. clocks which means I'm not used to them which in turn means that: I am confused by them, have to recall the meaning of a.m./p.m. every time, can never remember whether 12 a.m. is midnight or noon, hate it to have to read the time twice because only when I stumble upon those strange abbreviations I know what part of the day I have to put the previous numbers into and yes, I do consider the 12-hour notation impractical and outdated for written time (while intuitive for analogue clocks of course). I just can't help finding a system that starts with 12, then resets one hour later to 1, then resets again 12 hours later to 1-but-a-different-1 and ends at almost-12 not the most logical way of counting from 0 to 24. And this mixing up of more or less international digits with some particular language (Latin/English in this case) isn't that elegant either in my opinion. Anyway, I don't even want to discuss the advantages and disadvantages of having the 12-hour system for analogue and the 24-hour system for written time compared to having the 12-hour system for both. I just wanted to provide some source for the sentence from the article. Although I'm not "many" of course ;) --194.97.120.203 (talk) 14:26, 31 May 2008 (UTC)
thread_title: Criticism and practical problems

message: I find the added columns about endpoint convention and ambiguity more confusing than elucidating. The concepts are not wrong, but the term "end point convention" must be considered original research (no relevant hits on Google). It would be better to stick to only a textual explanation of the concept and not mix it in the table. The ambiguity is only real for the term "midnight" itself. −Woodstone 20:18, 15 October 2007 (UTC)
replies: text: "endpoint convention" has 156 hits and "end point convention" has 99 hits on Google.  I did not invent the term. Zginder 22:36, 15 October 2007 (UTC)

text: I was talking about relevant hits. Try {"endpoint convention" p.m.}. Only 9 hits (3 with added space), including an echo of this article. Not significant. But even the 156 mentioned above is rather low. −Woodstone  —Preceding comment was added at 09:49, 16 October 2007 (UTC)
thread_title:  Endpoint convention and ambiguity columns 

message: The notion that clocks show a truncated time representation is in my view the cleanest way to get around the unclarity at midnight. When the actual time is 12:00:00.001 a.m., a 12-hour digital clock in minutes shows just 12:00 a.m. Of course there is an infinitesimal instant where neither p.m. nor a.m. is (should be) shown, but we would never notice that. The talk about endpoint convention never makes this point very clear. −Woodstone (talk) 10:39, 26 December 2007 (UTC)
thread_title:  Truncated time 

message: (Reduplicating post of mine from User talk:Woodstone:)
Sorry if I stepped on any toes, but I was only removing "See Also" listings from where they duplicate links on the template. Many articles have excessively long See Also lists, that append without adequate explanation, and templates seek to address that.
Specifically regarding 12-hour clock and 24-hour clock articles, references to each are in the body of either article, making the See Alsos redundant, even without the Time MEasurement Template. Also, in the 12-hour clock article, Comparison of the 12-hour and 24-hour clocks is linked twice in the article above, in appropriate places, and should probably not be in the See Also list a third time.
In any case, no page has been left unlinked where it was linked before. I'm very careful about that. Cheers. -- Yamara 16:05, 11 January 2008 (UTC)
thread_title: Time Measurement and Standards Topics Template

message: This section has the following text:
"The moment when the Sun is in fact at its highest point in the sky on a particular day, is noon by apparent solar time, also known as true time. This occurs not exactly 24 hours after the previous true noon. Clock time (mean solar time) is based on the average[7] interval in the course of the year between one true noon and the next.[8]"
Well, for one thing, the first comma should be omitted!
This paragraph fails to mention the effects of time zones and daylight time, both of which have, on average, even larger effects on the (civil) time at which the sun crosses the celestial meridian. Local civil time, in the vast majority of cases, is an integral number of hours offset from UTC. And even UTC is not really the same as Universal Time (UT1) (which is the old definition of GMT, and UT1 is corrected for polar motion, making it slightly different from "mean solar time" [UT0]) as it can differ from that by as much as 0.9 seconds. So this paragraph is highly incomplete and misleading and therefore needs to be fixed. If we didn't have the quotation from the National Maritime Museum (which is incorrect as shown by a previously included quote reference to another page in the same site! [It is incorrect because it implicitly equates civil time with apparent solar time]) then the explanatory correcting quote quoted above wouldn't be needed. So either the correction needs to be expanded to be reasonably understandable and complete or both the incorrect quote and the correction should be removed from the article. I prefer removal but if the incorrect quote must stay, a much more satisfactory correction is needed. This entire bit has come from an attempt to tie a.m. and p.m. to when the sun crosses the meridian but because of all these things the sun can cross up to approx. 2 hours or more "later" then civil noon, making the whole point about crossing the meridian somewhat archaic. 71.127.218.88 (talk) 21:16, 13 January 2008 (UTC)
thread_title: Confusing explantion in the "Confusion at noon and midnight" section

message: I'm in the US, and my family and community (in Buffalo, NY) has always used "a quarter to six", and never "a quarter of six." 74.78.98.109 (talk) 18:00, 8 June 2008 (UTC)
thread_title:  informal speech 

message: The article is tagged as needing citations/references, which is reasonable, and there are also -tags here and there, but their distribution seems less reasonable - actually quite random. Given the general tag at top, should the fact tags flag only controversial or particularly dubious claims, or everything that ideally ought to be sourced somehow?--Noe (talk) 06:35, 12 June 2008 (UTC)
thread_title:  Citations needed 

message: In Sweden it is common to use the terms "five-to-half" and "five-past-half" when referring to :25 and :35 respectively. E.g. 6:35 "five past half seven". Would that be of value to add to the article? I'd add it but there might be other countries that use the same notation.  —Preceding unsigned comment added by Poposhka (talk • contribs) 22:08, 4 December 2008 (UTC)
thread_title:  five-to-half 

message: I find the addition of several 01 and 59 minute times around the tricky transitions clarifying. However they make the table too long. How about removing some integral hours in the regular sections. For example suppress 2:00 till 10:00 (and possibly 14:00 till 22:00)? −Woodstone (talk) 21:51, 31 March 2009 (UTC)
thread_title:  conversion table 12 vs 24 hour 

message: It says, "Digital clocks and computers, when set to the 12-hour system, appear to show the times 12 a.m. and 12 p.m., as in this chart." Appear? They DO show 12 a.m. and 12 p.m. Actually, they usually show 12:00 a.m. and 12 p.m., with the a.m. and p.m. usually being implied by a dot which is lit for PM and dark for AM. Please, "appear"? That's like saying the sun appears to rise in the east. --betaneputne  —Preceding unsigned comment added by 71.125.90.46 (talk) 00:35, 9 June 2009 (UTC)
replies: text: I agree with you 100%, you are absolutely correct. They most certainly do and there hasn't been anything shown to the contrary. This content is definitely incorrect. I will go ahead and remove it. Thanks much betaneputne for pointing this out. JackOL31 (talk) 03:00, 15 December 2009 (UTC)
replies: text: Your edit is still not valid. All 12-hr clocks with am/pm indicators show am/pm as the chart indicates. Therefore, you would need to list all types of clocks. Otherwise the  statement implies that some do not, which is incorrect. If you disagree, please discuss. JackOL31 (talk) 12:16, 15 December 2009 (UTC)
replies: text: In the spirit of compromise, I will agree to Woodstone's edit. The entry certainly seems to be redundant an unnecessary, though. JackOL31 (talk) 12:54, 15 December 2009 (UTC)

text: Let me explain my confusion. Saying that a clock set to the 12-hour mode follows the 12-hour system seems unnecessary. It's a bit like saying cars put into drive gear will go forward. If you really take a hard look at that table, are you really contributing to the entry with previously unknown information? JackOL31 (talk) 13:32, 15 December 2009 (UTC)

text: I saw your statement below, The statement for usage of a.m./p.m. at 12 o'clock is only meaningful for digital clocks (not analog ones). Mentioning that specifically is useful information in view of the ambiguity. I don't quite see it that way. As I mentioned below, some analog clocks and watches do keep track of am/pm, depending on the model. Regarding your concern about ambiguity, the table entry states, "12-hour digital clocks with a.m. and p.m." and lists the values 12 a.m. and 12 p.m.. The footnote says digital clocks display 12 a.m. and 12 p.m. as shown in the chart. I don't see the value added.(Sorry for all the replies - I recently realized you were addressing both issues in the below section where I was addressing them separately) JackOL31 (talk) 13:54, 15 December 2009 (UTC)
thread_title:  Bottom of the "Confusion" Table