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Vile
20th May 2003, 22:27
No, I'm not asking about samurai dating geisha ;)

I have a couple of questions about the nengo dates.

I was looking for a couple of dates and I ran into a list in one Java (the programming language) class that had the exact dates for most of the nengo eras, not only years but the very exact gregorian date when the eras have changed.
Sadly the programmers didn't mention their source (or atleast I didn't find it) and the list was missing some eras, like most of the Hokutocho dates during the Nanbokucho era. The dates started from Taika 1 (16.09.645) and ended naturally to Heisei (08.01.1989). Above dates are in dd.mm.yyyy BTW.

Now to my questions: how well are the exact dates of era changes documented (and how old are these documents) and are these dates well established with historians or are there lot of different versions? What started a new era? Death of the old Emperor or "coronation" (or some similar ceremony, if Japanese had any) of a new one? And my main question: any sources for a complete list? I have tried to search the net, but all the lists show "only" years.

I've made a small computer program for converting the dates and now I'd like to make it a little more better and maybe put it available to everyone somewhere in the Internet.

It would also be nice if someone could point me to a good source on classical Japanese calendar. I've understoot that Japanese changed to Gregorian calendar sometime after the Meiji restoration. And I also read somewhere that the old calendar had 12 months, but no mention about how long these months were (just vague hints that they weren't the "correct" length as there was a leap month needed every now and then) or what Gregorian dates they started and ended.

Thank you in advance!

-Mikko Vilenius

Karl Friday
22nd May 2003, 22:55
Originally posted by Vile
I have a couple of questions about the nengo dates. . . .

Now to my questions: how well are the exact dates of era changes documented (and how old are these documents) and are these dates well established with historians or are there lot of different versions? What started a new era? . . .

And my main question: any sources for a complete list? I have tried to search the net, but all the lists show "only" years. . . .

I also read somewhere that the old calendar had 12 months, but no mention about how long these months were (just vague hints that they weren't the "correct" length as there was a leap month needed every now and then) or what Gregorian dates they started and ended.


The traditional Japanese calendar used 12 lunar months, which means that the months shifted a bit, relative to the months of the Gregorian solar calendar, from year to year. That's why the intercalary (Jap.: uruu) months had to be added occasionally--otherwise eventually New Year's Day would have fallen in mid-summer.

The calendar eras of the traditional system are a very tricky thing. Since 1868 (the first year of the Meiji era), the practice has been to make calendar eras correspond exactly with imperial reigns (following the practice adopted in early modern China). This is a recent innovation, however. Before that, calendar era names could be changed for any number of reasons--including the death of an emperor or the ascension of new monarch. Sometimes names were changed in the hope of breaking streaks of bad luck--such as recurring famines or draughts and the like.

The correspondance of these calendar eras to Gregorian years is well-estabished and agreed upon. Almost any historical dictionary or dictionary of classical Japanese, will have a conversion table in it (I usually use the one in Takayanagi Kosu and Takeuchi Rizo's Nihon-shi jiten [Kadokawa shoten]). So do lot's of other sorts of pocket history references. (I've been trying to find a Palm database for this, but so far haven't had any luck). At any rate, I've not noticed significant descrepancies between various sources on what years correspond to what nengo.

The complicating factor, though, is that calendar eras didn't necessarily change at New Year's. More often, they were changed sometime in the middle of a year. The months, however, were not changed--they continued on as before. Thus the (Gregorian) year 1087, for example, was Otoku 3 until the 7th day of the 4th (lunar) month, when it became Kanji 1 (so that 4/6 1087 was the 6th day of the 4th month of the 3rd year of Otoku; while 4/7 1087 was the 7th day of the 4th month of the first year of Kanji).

Some historians writing in Western languages have converted Japanese dates completely to Gregorian ones, but the convention since the 70s, at least, has been to convert only the year, while giving the month and day according to the (original) lunar calendar.

That ought to be enough confusing babble for one post . . .

Vile
27th May 2003, 00:49
Thank you very much for the information Mr. Friday. Your post raised a couple more of question, though. If you are too busy to answer them, could you please point me a good source on the subject (I understood from your post that the book you mentioned "Nihon-shi jiten" is a book about classical Japanese including nengo list, not about the traditional calendar). Preferably in English. Reading Japanese is rather slow for me yet.


Originally posted by Karl Friday

The traditional Japanese calendar used 12 lunar months, which means that the months shifted a bit, relative to the months of the Gregorian solar calendar, from year to year. That's why the intercalary (Jap.: uruu) months had to be added occasionally--otherwise eventually New Year's Day would have fallen in mid-summer.


How long were these months (how many days) and were all months of equal length? How often the uruu months had to be added? Around when (Gregorian date) was New Year's Day usually celebrated?



the (Gregorian) year 1087, for example, was Otoku 3 until the 7th day of the 4th (lunar) month, when it became Kanji 1 (so that 4/6 1087 was the 6th day of the 4th month of the 3rd year of Otoku; while 4/7 1087 was the 7th day of the 4th month of the first year of Kanji).

Some historians writing in Western languages have converted Japanese dates completely to Gregorian ones, but the convention since the 70s, at least, has been to convert only the year, while giving the month and day according to the (original) lunar calendar.


How easy is it to convert the lunar calendar months and days to Gregorian dates? If I've understood correctly the lunar calendar shifted little by little compared to the Gregorian calendar, so this might mean a little more complicated calculating, plus the addition of the uruu every now and then, which seems to make it even more difficult.

I thought first that the dates given for the eras in the list I used were Gregorian dates, but it seems they were traditional lunar calendar dates. The (erroneous) beta version of the little computer program can be found in http://www.cc.jyu.fi/~mijuvi/nengo/
Specs.txt available from the address above (and included in the zip-files) contains information about the program, like the known bugs and info on how it works (or is at least supposed to work). The program gives some warnings with linux, but seems to work properly. Mac version has not been tested.
Any feedback is welcome! The program requires Java Runtime Enviroment, which is installed with some Internet browsers. It can also be downloaded from the Internet. The address for Java RE can be also found in the specs.txt file.
Btw. my program converts 1087 (before 4/6) as Otoku 4, not Otoku three. I was under impression that the Gregorian year 1084 (2/7 onwards) is Otoku 1, 1085 (starting 1/1) Otoku 2, 1086 Otoku 3 and 1087 Otoku 4. Where am I making the error here?



That ought to be enough confusing babble for one post . . .

Indeed it was. Very enlighting, thank you. But as with many other things, the answers raised even more questions.

Karl Friday
29th May 2003, 16:58
Originally posted by Vile
Could you please point me a good source on the subject . . . . preferably in English.

The only treatment of this in English I can think of off-hand is the short section in Miner, Odagiri and Morrell's The Priceton Companion to Classical Japanese Literature. But that doesn't have much more on this particular topic than what I already summarized in my earlier post.


How long were these months (how many days) and were all months of equal length? How often the uruu months had to be added? Around when (Gregorian date) was New Year's Day usually celebrated?

The months were either 29 or 30 days, I'm not sure exactly what the mix was. Intercalary months were added as needed to keep the calendar from geting too far off the solar one; there must have been a specific rule for when and how often this was carried out, but I don't know what it was. The intercalary months weren't always added at the same time (that is, between the same two months). Again, I don't know what the governing rule here was.

The new year began in the spring, and the date varied from year to year against the Gregorian calendar--just like the Chinese New Year still does today.

Converting lunar months and days to Gregorian ones for historical dates involves some pretty extensive--although not particularly difficult--calculations. Basically, you need to determine when the year in question began (according to the Gregorian calendar), and then count days and months forward. I'm sure that there are tables for such conversions out there somewhere, but I've never looked for them.

As I mentioned in my earlier post, historians almost never convert months and days anymore, first, because it is a tedious, time-consuming process; and second, because it yields little particularly useful information (and actually confuses many issues, since the converted months and days in the historian's book or article would then differ from the the numbers given in the original sources).

The only common exception to this is when authors will sometimes remind readers not to confuse lunar months and seasons with solar ones--such as, for example, that an event that took place in the 6th month of whenever would have occurred in mid-summer, not June.

Hope this helps!

Nathan Scott
29th May 2003, 21:48
Hello,

Though this book doesn't have a conversion table specifically, it might not hurt to pick up "The Kodansha Bilingual Encyclopedia of Japan" (Kodansha International, 1998). It's a little pricey, but it does contain a lot of standardized dates and tables that might be helpful for quick reference. I've found it pretty reliable so far.

Regards,

Joseph Svinth
30th May 2003, 03:45
There are books of calendars out there -- check the astrology section of your bookstore. It's not a bad place to spend some time, anyway, if you want to know why a certain date was chosen, or another date was avoided. The fifth day of the fifth month, for instance, was often chosen as the date for important wrestling tournaments, as it was believed to be the most Yang day of the year.

W.Bodiford
4th June 2003, 01:10
The traditional calendar used in Japan is the luni-solar calendar developed in China. It was intended to give precise lunar and solar information and to predict celestial events. Many different complex formulae were combined together to make these predictions. Over the centuries, as actual observations proved those predictions to be incorrect, the formulae for calculating the calendar would be revised. Usually Chinese court astronomers adopted the revisions first, and then after a few years or decades they would be adopted by Japanese court calendar makers. Sometimes, though, revisions were adopted first by private calendar makers and only later accepted by the Japanese court. In other words, the structure of the calendar evolved over time and different versions of the calendar could be in use at any one time. Moreover, era designations usually changed in the middle of a year and were adopted on different dates in different locations.

For these reasons, it is almost impossible to calculate how to convert dates from the Japanese calendar to a European one (e.g., Roman, Julian, or Gregorian). The well-known guidebook, Research in Japanese Sources: A Guide (by Herschel Webb, with the assistance of Marleigh Ryan; first published by Columbia University Press in 1963 and reprinted by the University of Michigan, Center for Japanese Studies, in 1994) contains numerous errors in its sample exercises in which it attempts to show how dates should be converted. Thus, even the standard textbook is wrong!

The simplest approach, therefore, is to rely on a conversion chart. Fortunately, excellent charts are readily available at any major university research library. Since the information in these charts is largely numerical and re-cycles a relatively small number of standard Chinese glyphs, they can be used even by people whose reading skills are rudimentary. These charts could be converted to digital data with simple OCR software or by means of rote copying. No fancy skills are required. One merely needs patience, for there exists quite a lot of data to copy.

Conversion charts can be found in:

Otani Mitsuo ‘å’JŒõ’j et al., editors. 1992-1995. Nihon rekijitsu soran “ú–{—ï“ú‘?æT. (English Title: The Japanese Luni-Solar Calendar.) 20 vols. Tokyo: Hon-no-Tomosha, 1992-1995.

Library of Congress Call Number: CE15 .N556

These 20 volumes contain conversion charts for every day of every year from 501 to 1500. They provide the following kinds of information for each day: era designation (nengo); cycle of 60 celestial stems and branches (i.e., asterisms) for that year; lunar month (identified as lesser or greater or intercalated); cycle of 60 stems and branches for that lunar month; lunar day; cycle of 60 stems and branches for that day; gods governing that day; lucky and unlucky directions for that day; that day's planet (i.e., days of the week); the Japanese solar seasons; the solar day; celestial events; corresponding dates according to well-known private calendars; corresponding date according to the European Julian calendar and according to the European Gregorian calendar; as well as detailed Chinese astrological data. The detailed information in these charts enable one to determine the entire system of fortune-telling associations that governed which days were to be feared and which ones were to be celebrated and why.


Simpler charts can be found in:

Kakura Kozaburo ‰Á“‚‹»ŽO˜Y. 1992-1993. Nihon in'yo rekijitsu taishohyo “ú–{‰A—z—ï“ú‘Î?Æ•\. 2 vols. Tokyo: Nitto Publications.

Library of Congress Call Number: CE61.J3 K35

These 2 volumes contain conversion charts for every day of every year from 445 to 1872. They provide the following kinds of information for each day: era designation (nengo); cycle of 60 celestial stems and branches (i.e., asterisms) for that year; lunar month (identified as lesser or greater or intercalated); lunar day; corresponding date according to the European Julian calendar and according to the European Gregorian calendar.


For explanations of the luni-solar calendar used in Japan, see the following links.

==========================

Calendary Links by Steve Renshaw
http://www.math.nus.edu.sg/aslaksen/calendar/links.shtml

Lunar Calendar in Japan by Steve Renshaw and Saori Ihara
http://www2.gol.com/users/stever/calendar.htm

National Diet Library: Japanese Calendar (historical overview)
http://www.ndl.go.jp/koyomi/e/

Wikipedia: Japanese Calendar
http://www.wikipedia.org/wiki/Japanese_calendar

Mathematics of the Chinese Calendar by Steve Renshaw
http://www.math.nus.edu.sg/aslaksen/calendar/chinese.shtml

Calendrical Calculations (and conversions) Web site
http://emr.cs.iit.edu/home/reingold/calendar-book/Calendrica.html

Chinese Lunar Calendar
http://lunarcal.tripod.com/

Chinese Calendar through the Ages
http://webexhibits.org/calendars/calendar-chinese.html

Chinese Lunar Calendar - Programming and Astronomical Data
http://www.chineseastrologyonline.com/clc/default.htm

Japan Guide: Calendar
http://www.japan-guide.com/e/e2272.html

===============================

Good luck!

Vile
9th June 2003, 23:13
Thank you all for your replies!