The Perpetual Calendar

A helpful Tool to Postal Historians

On 2000.03.01 we celebrated the
300th Anniversary for the
Gregorian Calendar in Denmark!

Copyright 1995- by Toke Nørby.
This article must not be published without permission from the author
- but you are welcome to take a printout for your personal use ;-)
(Please note that URLs and e-mail addresses can be outdated!)

Updates and Acknowledgements
This document will be updated from time to time and you can click on Updates and Acknowledgements below if you want to see what is different from version to version of this document. Also, on that page I have mentioned all the kind people who have contributed to this article - thanks to all!.

Updates and Acknowledgements

Though, here I would like to thank a few people with some I have had a great calendar/postal history discussion: Bob Track (track@worcester-ma.u-net.com), Mass. USA, for valuable help with many discussions on the calendar-postal history aspects. Also, for valuable help with digging out information from various sources I want to thank Manfred Kiefer (Manfred.Kiefer@t-online.de), Germany. Manfred and I have discussed calendar aspects since 1996.

Last but absolutely not least my warmest thank to my now late e-mail friend Lance Latham (b. 1948.10.25 - †2008.08.12). Lance and I had a long and constructive discussion on many, many calendar aspects although Lance knew that I'm not a calendar expert!

References and Links
As you can see from the "Updates and Acknowledgements"-page there are a nice number of people who have contributed to this article. Information have been gathered from all parts of the world thanks to people who are interested in this subject. You can find valuable references and links to important calendar pages and - to this subject - other highly relevant pages here:

References and Links

If your current printout is "out of date" feel free to take a new printout. The previous update was made on 5 November 1999 ("Version 1999.11.05"). In this Version 2000.02.29 I have made a change in Scheme 2 and 3 as I would like to indicate that the first Day of the week (DOW) is a Monday as it is in Denmark. Second: I have also indicated that the exact cycles in the Gregorian Calendar are 400 years where the so-called year types are repeated - more on that later. Third: - and just to please you (did I? :-) I have made a separate page with perpetual calendar using Pope Gregor XIII's change over dates in october 1582. You will have access to that Perpetual Calendar after the section: "The Gregerian Tip"! And further: You will find that there are a lot of major and minor changes in this version, so you should do yourself a favour and look on my "Updates"-page to see all the changes I have made.

So, please read on and enjoy what I have put together with help from nice calendar friends "out there". Thank you.

Viewing the document
This document contains several schemes (tables) and is tested using Netscape and Microsoft Internet Explorer (Version 4 and higher). Depending on the screen/monitor/printer you are using, you could have some troubles with viewing the schemes but if you ajust your preference scalable/fixed font, a print out should give nice usable schemes with no undesirable extra line breaks.

Introduction
People studying material related to postal history often like to know on what weekday a dated or date postmarked letter (or any other item related to postal history) was cancelled. The need for this could be to find out what way a letter had been sent according to time and/or route tables for ships, trains or other mail carriers in regular service. In such cases this Perpetual Calendar, which covers the Julian and the Gregorian Calendar, can be a valuable tool as most of the postal history material we are concerned about originated from countries with Julian and/or Gregorian Calendars.
    You know, of course, that in old days there were (and in some countries still are) other calendars (non-Julian and non-Gregorian) in use and my advice is: Do not collect postal history material from such countries! (I am just joking ;-)
    As far as I know you can find Perpetual Calendars published in different philatelic magazines. In 1985 I found that I did not quite understand on what calculations The Perpetual Calendar was based and I had some trouble finding out the right weekday for letters from Russia - but more about that later.
    Another problem for me was that most of the Perpetual Calendars did not go as far back in time as I wanted, e.g. I had a Perpetual Calendar covering the years 1900-2200 and this was not satisfactory for me as most of my Danish inland ship letters are from the period 1836-1855. To solve this I sat down and worked out my own Perpetual Calendar.
    In this document I now and then refer to articles etc. (listed in the reference list at the end of this article). So when you in the text see text succeeded by an "active" number in brackets, e.g. "(3)" it means that the information originate from the third mentioned reference in my reference list.
    In the following I shall give a brief description of the background for our present Gregorian Calendar but I will omit many, many special and detailed calculations necessary for the making of The Perpetual Calendar. If you would like to know how a Perpetual Calendar was constructed "in the old days" you can take a look at (1). If you want to see how a modern Perpetual Calendar can be constructed you can consult my old article (2) where the calculations for Scheme 2 and 3 in this document are fully described - in Danish :-)

The Calendar before Julius Caesar's Calendar
Even this calendar not is important to postal historians (!) it is important to know why Julius Caesar introduced his famous "Julian Calendar" in 45 BC. We do not know exactly what happened in the many years before 45 BC but the calendar used had originally commenced in March on the date when the new consul took office. In 222 BC the date of assuming duties was fixed as March 15, but in 153 BC it was transferred to the Kalendae of January, and there it remained. January therefore became the first month of the year, and in the western region of the Roman Empire, this practice was carried over into the Julian calendar (3 - II, p 64).

The Julian Calendar
In the year of 46 BC Julius Caesar (102-44 BC) decreed a solar calendar with months at fixed lengths after the Egyptian model where one year had 365 days, 12 months and every 4th year was a leap year with 366 days. Caesar also retained 1 Januar as the beginning of the year which - as mentioned - was in troduced in the Roman calender earlier. To get the public feasts back to the correct seasons an intercalary month was inserted in the year of 46 BC which was called the "Year of Confusion" as it consisted of 445 days - and on 1 January 45 BC the Julian Calendar came into effect. (3 - II, pp 75).
    Around the year 527 AD, Dionysus Exiguus suggested counting the years from the "birth of Jesus Christ" on 25 December 753 AUC (Ab Urbe Condita, i.e. since the founding of Rome), making the current era start with 1 AD on 1 January 754 AUC. This means that the 1st millennium cover the years 1-1000, 2nd millennium the years 1001-2000 and the 3rd millennium the 2001-3000 (w1). (Happy New Millennium on 2001.01.01 :-)
    The tradition that the vernal equinox should be fixed to a particular date (21 March), harks back to the first official council of the Christian Churches in 325 AD, at Nicaea. The mean Julian year had 365.25 days; i.e. (365*3 + 366)/4. This actually was a bit over-estimated - and led to the vernal equinox slipping by about a day every 130 years during the Julian calendar period from 325 AD to 1582 AD (w2).

The Gregorian Calendar
To avoid this increasing difference between date and Equinox Pope Gregorius XIII (with the help of the astronomer Christopher Clavius (1537-1612)) in 1582 declared that the day after 4 October 1582 should be 15 October 1582 and then Equinox again would fall on 21 March. Furthermore the rule for leap years (which said that years divisible with 4 should be leap years) was changed so that years, at the end of the century, should be leap years only if they were divisible with 400 (e.g. 1600, 2000, 2400 etc.).
        The papal bull was dated "Anno Incarnationis Dominicae M. D. LXXXI." (In the year of the Incarnation of the Lord 1581 which is the year beginning March 25, 1581 and which corresponds to 1582 in our current year reckoning.)
        Contrary to popular belief, the papal bull did not mandate any particular date as the start of a new year.
        In the Gregorian Calendar there is then 303 years with 365 days and 97 years with 366 days, which gives a mean year of 365.24250 days: 365 days, 5 hours, 49 minutes and 12 seconds. Related to the mean interval between vernal equinoxes this corresponds to a slippage of less than one hour in every 300 years for the foreseeable future - until circa 4000 AD (w2).

To convert from the Julian to the Gregorian calendar:
    From    5 October 1582 JU - 28 February 1700 JU: Gregorian dates = Julian dates + 10
    From 29 February 1700 JU - 28 February 1800 JU: Gregorian dates = Julian dates + 11
    From 29 February 1800 JU - 28 February 1900 JU: Gregorian dates = Julian dates + 12
    From 29 February 1900 JU - 28 February 2100 JU: Gregorian dates = Julian dates + 13
    (Not 2000 JU because of the Gregorian leap year in 2000)

The Calendar Reform in Various Countries
The Gregorian Calendar was introduced at different times at different places. The following three schemes lists countries where I have found sources showing calendar changes from Julian to Gregorian calendar. For postal historians information on calendar changes before 1700 (Julian or Gregorian time) is not especially relevant because there - to my knowledge - do not exist letters from one country with Julian Calendar to another country with Gregorian Calendar - or vice versa - where you are able to see different datings due to the different calendars. At least are such letters not in the hands of collectors. Anyway, it is my hope that you can use some of the information listed.

You should be aware of the fact that some major sources, like (5), say that the Gregorian Calendar was introduced in England in 1753 while other major references, like (4), say 1752, depending on what the changes should have been made before a source say that the shift has taken place. England left out 10 days in september 1752 and this is what this document is concerned about: when the leaving out of the days took place for a certain country/area. So even England "at last introduced the Gregorian calendar by changing the calculation of the easter in the Gregorian way" (5), this document still list the change over in september 1752.

Earlier Calendar Reforms
You must be aware that the territorial division of Europe has changed a lot since the Gregorian Calendar was introduced in 1582. Territories that existed those days do not exist any more, others have changed considerably, and so on. Especially, Germany and Italy used to be a patchwork of bigger and minor states. For Germany you can roughly say that the Catholic territories adopted the Gregorian Reform in the 16th century already whereas the Protestant territories only followed in the 18th century. The situation in Switzerland was similar. Below I have listed information on the Calendar Reform where older territories are placed under the modern states they belong to nowadays - thanks to Manfred Kiefer.

The Change Over in Denmark - The Danish Astronomer Ole Christensen Rømer
Ole Rømer was born on 25 September 1644 in Aarhus (where I live) and although he was very well known as an astronomer in Denmark he became famous all over the world when, on 22 November 1675, he published and proved the velocity of light. Not only did this discovery make him famous, he was also recognized for his invention of the Meridian Circle, the Altazismuth and the Passage Instrument. (The Danish stamp to the left was issued on 25 September 1944 to celebrate the 300 anniversary of his birth) (11).

Later on, at the beginning of 1695, when Ole Rømer presented that year's new almanac to our King Frederik IV, he recommended that Denmark should adopt the Gregorian calendar which was introduced in the Catholic countries more than 100 years before. Rømer's opinion was that if Denmark introduced the calendar, other countries would immediately follow. But from opponents there were suggestions that Denmark should introduce the "New Style" together with Sweden and the Lutheran (Protestant) part of Germany. Therefore the Rømer's recommendation made slow progress and Denmark had to wait until 1700 before we could introduce the "New Style" in 1700 together with the Lutheran part of Germany and her Swedish provinces. Sweden went her own way.

Probably to avoid a Danish counterpart to what is said to have happened in England in 1752: "Give us back our 11 days" we had a very special situation in February 1700. From my Scheme 1 you can see that in Denmark the last Julian day was 18 February 1700 and the first Gregorian day was 1 March. Now, at that time, the markets were very important events for buying and selling cattle and the Almanacs from that time always listed what time during the months the most important markets took place in Denmark. So if we look at the last page of the Danish Almanac shown here, we can read: "De Marckeder som falder imell: 18 Febr. og 1 Martii holdes i dette Aar efter den gammel Regning" (Those markets which will take place between 18th February and 1st March will take place according to the "Old Style"). Strange situation! (13).

12 Pair of Gloves and the Intercalary Day
I think that you should not miss this very old and special folklore (19): In the old days a women could ask for the leap day off and was allowed to make a man an offer of marriage, so all the spinsters were on the warpath on this special day. Though, the "poor" man could avoid the imminent danger if he gave the woman 12 pair of gloves! According to (w7) this practise originate from Queen Margaret of Scotland who issued a decree about that. At that time the "price" was not 12 pair of gloves but 100 pounds - quite a lot of money at that time (and, just to get things straight: I am already married! :-)

Birthday on 29 February?
You know that Denmark is a tiny country so The Danish Statistical Department informed us that (in 1997) there were 3,783 Danes who was born on 29 February. We are a only a little more than 5,000,000 souls in Denmark.

The Danish Perpetual Calender
The reason why I call it The Danish Perpetual Calendar is that it is constructed to show the Danish change from Julian Calendar to Gregorian Calendar. Do not be "afraid" of this fact, as it can be used for your country too, even if your country changed calendar at a different time than Denmark. I will explain the general use of The Perpetual Calendar just after Scheme 2 and 3.

The use of the Perpetual Calendar
First I will show you the overall use of the Perpetual Calendar so, please forget at the moment all about the fact that different countries introduced the Gregorian Calendar at different times. I will return to that "problem" later.
    Suppose you have a letter from Denmark dated on 23 March 1843 (that is in the Gregorian part of the Danish time). You shall find the year 1843 in Scheme 2 in the column 1801-1900. On the same line, but in the right part of Scheme 2, you find that the Month Adding Number for March this year is "2". Add 2 to the date 23 and you get 25. In Scheme 3 you see that 25 stands on the same line as Thursday. Simple! (You now know that if I was born exactly 100 years before I really was, it would have been on a Thursday! (A very useful piece of information - hmm!)

Jumping back and forth in time - The Gregerian Tip
As Lance Latham discuss in his book (14, pp 249-260) there are 14 types of years ("YT" in Scheme 2) in the Julian and the Gregorian calendars. A Type 1 year is a year that begins on a Sunday (nowadays the European week begin on a Monday so we could also have deemed Type 1 years to begin on Mondays - well, this doesn't matter, though :-)
    A Type 2 year begin on a Monday and so on. The Type 8 year begins as a Type 1 year on a Sunday but is a leap year etc, etc. until we ends with a Type 14 year which like a Type 7 year begins on a Saturday but is a leap year.
    Every type of year has a fixed day of beginning and a fixed duration so years of the same type have the same days of beginning, positions of days and days of the week (DOW).

Julian Period
At first sight it appears that my Danish Perpetual Calendar only cover years from 1601 to "infinity". Suppose you want to find out what day 17 April 852 JU was. You then have to add a number which is a multiple of 28, say 30*28 to the year 852 to get a year you can see in the Julian part of the Scheme 2: 30*28+852=1692. So both these years 852 and 1692 are of the same type, Type 13, and they therefore have the same Month Adding Numbers. For April you see that the number is 4. 17+4=21 which in Scheme 3 shows a Sunday. Still simple!
    The reason behind this method is that in the Julian calendar, every 28 years the days in the week returns to the exact same dates. For 1918.01.01 JU, you can use the tip for Estonia, for example (at that time Estonia still used the Julian Calendar). Subtract 8*28 years from the year 1918, then you get 1694 and find that 01.01 is a Monday! You can go as far back as you want using The Gregerian Tip as I use to call it. Can you imagine why I call this a Gregerian Tip? It is because of my total lack of becoming modesty! (My full name is Toke Gregersen Nørby (15 ;-)

You can use the tip to add or subtract 28-year units, as long as you operate within the Julian calendar. The 28-year rule is not correct for the Gregorian calendar (14 p 249), but you can use a similar tip in that calendar:

The Tip used in the Gregorian period
Suppose you have difficulties finding a Gregorian date in the period of 1582.10.15 - 1700.03.01 as this Gregorian period is not shown in my Scheme 2? (As mentioned, Denmark introduced the Gregorian Calendar on 18 February 1700 JU where the next day was 1 March 1700 GR, more than hundred years after most Catholic countries which immediately followed Pope Gregor XIII's bull). You can't use the 28 year rule that you can use for the Julian period since the Gregorian Calendar has more complicated cycles, owing to the 400-year leap year rule. But, as you can see from Scheme 2, the exact cycles in the Gregorian Calendar are 400 years where the year types are repeated, so you can use a similar Gregerian Tip here, too.
    For example, if you want to know the DOW of 13 January 1583 GR, just add 400 years to the year 1583 and find what DOW 13 January 1983 GR is! The Month Adding Number for January 1983 is 5 so 13+5 = 18, which in Scheme 3 shows a Thursday. Voila!

Well, if you better like a Perpetual Calendar using Pope Gregor XIII's dates I have one here:

The Perpetual Calendar - October 1582.

What about England?
Yes, England (and her colonies) could be a problem! "In the old days" England used the Julian Calendar but as you may know England (from the 12th century) began every new year on 25 March! (before they in 1752 changed from the Julian to the Gregorian Calendar). According to A.D. 1751. Anno vicesimo quarto GEORGII II. CAP. XXIII. - An Act for Regulating the Commencement of the Year; and for Correcting the Calendar now in Use (8):

The change of the beginning of the year in England
.....That in and throughout all his Majesty's Dominions and Countries in Europe, Asia, Africa, and America, belonging or subject to the Crown of Great Britain, the said Supputation, according to which the Year of our Lord beginneth on the 25th Day of March, shall not be made use of from and after the last Day of December 1751;
    and that the first Day of January next following the said last Day of December shall be reckoned, taken, deemed and accounted to be the first Day of the Year of our Lord 1752;

This means that the English year 1751 consisted of days from 25 March to 31 December. A total of only 282 days that year!

The change from Julian to Gregorian Calendar in England
.....And that from and after the said first Day of January 1752, the several Days of each Month shall go on, and be reckoned and numbered in the same Order; and the Feast of Easter, and other moveable Feasts thereon depending, shall be ascertained according to the same Method, as they now are, until the 2nd Day of September in the said Year 1752 inclusive;
    and that the natural Day next immediately following the said 2nd Day of September, shall be called, reckoned and accounted to be the 14th Day of September, omitting for that Time only the 11 intermediate nominal Days of the common Calendar;
    and that the several natural Days, which shall follow and succeed next after the said 14th Day of September, shall be respectively called, reckoned and numbered forwards in numerical Order from the said 14th Day of September, according to the Order and Succession of Days now used in the present Calendar;

I know that genealogists are very much aware of this fact, but normally postal historians does not care much about this as probably only very few letters from before 1752 exist!
    A question arose to me about the English year in 1752. Was that year a leap year? Under the Julian Calendar, a year was a leap year if it was divisible by 4, under the assumption that the year began 1 January. This means that England inserted an extra day in February 1752. (7).

Scotland changed from a Julian to a Gregorian calendar at the same time as England in 1752 AD (1, w4), but had already instituted 1 January as the official New Year's Day, beginning in 1600 AD (10).

What about France?
France changed from Julian to Gregorian Calendar on 9 December 1582 JU where the next day was 20 December 1582 GR. But as you might know France had a special calendar in the period from 22 September 1792 GR to 31 December 1805 GR, the so-called French Republican Calendar (FRC). (1 pp 126-127. w5). This calendar was introduced by legislation on 5 October 1793 but was taken to have begun on 22 September 1792 at autumn equinox and the day of foundation of the French Republic (4). Officially it ceased 11 Nivôse, year 14 (1 January 1806) although it does appear in small measure on letters well into 1809. Furthermore, Lance Latham mentions (e1) that FRC was in use during a brief period of the Paris Commune in May of 1871!!

This decimal-based calendar had twelve months:

Month endings at "-aire" are in Autumn, "-ose" in Winter, "-al" in Spring and "or" in Summer. This calendar had no weeks but every month was divided into three decades with ten days each: from primidi to decadi, which means that they had to add five or six days at the end of every year depending on whether the year was an ordinary year or a leap year. These five or, at leap years, six days were feast days or holidays, the so-called Jours complementaires or the Sansculottides ("the days of the poor") and each day had a name: Jour de la Vertu (Virtue), Jour de Genie (Genius), Jour de Travail (Work), Jour de la Raison (Reason), Jour de la Recompense (Reward) and Jour de la Revolution (e1).

The names of the 3*10 days were:

Vice Versa?
Let us say you send a letter from Denmark 11 July 1795 and two days later (13 July) it is "postmarked" - or at least the Republican day is written on the letter - in France. But what is the French Republican date for 13 July 1795? Find July 1795 in Scheme 5.2 and you see that 19 July 1795 is the same as 1 Thermidor, year 3. As you want the date 19-13=6 days earlier (that is obviously in the month before Thermidor) you get 30 - 6 = 24 Messidor, year 3.

The French Colony Lousiana
As you may know the US state Louisiana was a French colony in the periods 1699-1762 and 1800-1803 when it was sold to the USA (11). A question arose if the French Revolutional Calendar had been in use in Lousiana in 1800-1803 and on 1999.01.19 Lance Latham told the members of the Calendar List (r1) that he had received an e-mail from Wiilbur E. Meneray (meneray@mailhost.tcs.tulane.edu):
    During the period in which the FRC was used in France, Louisiana was French for just three weeks (November 30-December 20, 1803). Prior to this French Interregnum, Louisiana had been Spanish since the 1760s, and the area became an American territory on December 20. I know of no reason to suspect that the FRC would have been used during the Spanish regime. The Frenchmen who arrived in 1803, however, brought it with them. When they set out from France to reclaim Louisiana, they had no way of knowing that Napoleon would sell Louisiana to the United States in April and that France would govern the province just for that three-week interregnum.
    For an illustration of these points, see "A Guide to the Papers of Pierre Clement Laussat", ed. by Jon Kukla (New Orleans: Historic New Orleans Collection, 1993). (Laussat was the prefect Napoleon sent to govern Louisiana, before he decided to sell it.) The collection includes letters and documents generated during the Spanish period which bear Gregorian dates; those generated during and after the French Interregnum by Laussat bear FRC dates. The proclamations and such that Laussat issued, with FRC dates, pertained to the entire Louisiana Territory, but I have not seen evidence that its use was mandated; probably it was just assumed. I have no information on the extent to which the FRC might have spread beyond the New Orleans area.
    That the French officers continued to use the FRC even after the transfer to the United States is suggested by FRC dates on two pamphlets printed in New Orleans in 1804: "Burthe, contre Laussat" by Andre de Burthe d'Annelet and "Blanque, en opposition a Burthe contre Laussat" by Jean-Paul Blanque.

What about Hawaii?
John Harper (harper@msor.vuw.ac.nz), New Zealand (e14), has kindly sent me the following - with reference to Robert G. Schmitt and Doak C. Cox, "Hawaiian Time", The Hawaiian Journal of History, vol. 26 (1992) p. 207-225.:
Hawaiians' first non-Polynesian contact was Captain Cook's arrival in 1778. He was already using the Gregorian calendar, had sailed east from England, and did not lose a day. If the International Date Line had been in use in his time he would have treated Hawaii as being west of it. European settlers were still doing that in 1816, but Schmitt and Cox (see reference above) could find no record of when Hawaii decided it was east rather than west of the Date Line.
    Schmitt & Cox said that the pre-contact Hawaiian calendar had 12 lunar months (sometimes 13 to keep the year in phase with the seasons). They also say that a letter dated March 3rd. 1810, probably drafted by Captain Spence of the Duke of Portland, was signed by Kamehameha I and sent to King George III of England, and that after 1820, when the first Protestant Mission schools opened, the newly literate Hawaiians quickly adopted Western dating. So - no last Julian Date. First Gregorian Date 1778.01.21.

What about Germany?
The German Newspaper Die Zeit (20) brought in 1999 a story about the problems in the old Germany areas shortly after some areas had switched to the Gregorian calendar while the neighbour area kept the old Julian Calendar:

... Whoever wanted to arrive in the Catholic Bamberg on October 26, 1600, had to start out from the Protestant Erlangen already on October 15, although the journey to Bamberg was only a day trip, but there was a gap of ten calendar days.
    ....That Catholics wrote the 15th of a month when the Protestant calendar showed the 5th was not that bad. But the 15th of August was a holiday, Assumption of the Virgin Mary, for the Catholics, therefore it was not allowed to work on this day. Hence, it could happen - like on the 15th of August 1621 - that during an inspection a Bamberg official saw farmers working in the fields of the Bamberg village of Stepersdorf. The farmers came from Schwarzenbach and were subjects of Bayreuth or Nuremberg, hence Protestants. However their fields lay in the area of Stepersdorf, and that belonged to the Catholic Bamberg. The official therefore had taken their sickles and horses away. And the same could happen, vice-versa, on Protestant territory.

What about Israel?
Amos Shapir (amos@nsof.co.il), Israel (e11), has kindly sent me the following: The official calendar in all state matters is the Jewish one. Of course, all documents are double-dated, but as far as I know the legal status of the Gregorian dates is "for convenience only".
    The strange result is that bills are discussed in terms of Gregorian dates, and when formulated into laws are converted to Jewish dates; thus the Ministry of Transportation may issue a yearly edict that "all trucks should drive with their headlights turned on between 12 Heshvan and 14 Nisan, 5759 (1998.11.01 to 1999.03.31)", or the Ministry of Education announcing that "the next school year shall start on 20 Elul 5759 (1999.09.01)". This requires that such edicts be renewed each year with different Jewish dates!
    Actually, the Gregorian calendar was in official use here by the British between 1917-1948 (Turkey ruled this area before that). Israel had inherited most of the British law, so Gregorian dates may still have some legal value. There is no specific date of conversion in 1917 - maybe the Gregorian calendar was introduced on 1917.03.01 (see Turkey in Scheme 1.3) - I seems the British just used the Gregorian date wherever they went, not caring much what the "natives" did about it.
    The case of 1948 is more interesting. Israel had inherit the British custom that all laws become official only when published in the government's official announcement paper "The Palestine Gaxette" and published in English and Hebrew. In 1948 it was converted to just "The Official Newspaper" by Israel same format, except that the Israeli version did not have the English part.
    The last British edict in the volume of 1984 is dated April 25; the net one is Israel's declaration of independence, dated 5 lyar, 5708 (1948.05.14 GR). All subsequent laws in the book since then are double dated. Many laws in this volume refer to a law called "The Rules of Order of Government " which was probably enacted by the Israeli government to provide legal continuity in the interim period between the UN decision of November 29, 1947 and the official end of the British Mandate over Palestine on May 5, 1948.

What about Lithuania?
The Gregorian or New Style Calendar was introduced in the Grand Duchy of Lithuania by Steponas Batoras, Grand Duke of Lithuania on 21 January 1584, soon after the calendar reform of Pope Gregory XIII, and replaced the prevailing Julian or Old Style Calendar (9).

When Russia, which still maintained the Julian Calendar, in 1795 took control of the main part of Lithuania (Provinces Vilna, Grodno, Kovno, Mohilev, Vitebsk and Minsk (11)), the Julian calendar was reinstated by the Czar administration on 1 January 1800. The Gregorian calendar was still in force in the southern Lithuania, the region called Uznemune or Suduva as it in 1795 was given to the German Prussia. Suduva became a part of the Grand Duchy of Warszawa in 1807 (11) which from 1814 was controlled by the Russians. The Gregorian calendar was allowed to remain even after the Russians took over the region and in 1867 created the administrative province of Suvalkai (9).

Thus, in Lithuania from 1800 to 1915, two calendars were in force. The dividing line was the Nemunas river. The Gregorian calendar was finally introduced throughout the country during World War I when the Germans occupied Lithuania. The last Julian day in Lithuania was 15 November 1915 and the first Gregorian day was 29 November 1915 (9).

What about Russia?
In the old days Russia used the Byzantine calendar which counted years from the "creation of the world" in the year of 5509 BC (JU). In the year of 7208 AD (1699 JU) the Russian Empiror, Peter I Alexejevitsch (Peter the Great) announced the adoption of the Julian calendar and that the nearest 1 Januar will be 1 Januar 1700 JU and the Julian calendar remained in use until the revolution in 1918 (3).

Even different parts of Russia changed from the Julian to the Gregorian Calendar on different times during and after the revolution most sources refer to the change in February 1918 where 31 January 1918 JU, was succeeded by 14 February 1918 GR (4). This law was signed on 26 Januar 1918 JU (17).
    In 1918 the Soviets were in the middle of a civil war. The "White" forces continued to use the Julian Calendar after the Soviets changed to the Gregorian calendar, so it was mostly a matter of who controlled what territory at a particular date. At least the new law which introduced the Gregorian calendar from 14 February 1918 GR was valid for St Petersburgh and Moscow (17).
    At that time the capital of Kolchak's republic was initially Omsk and the collection of his laws was published on 31 October 1918 JU. This collection includes a law about introducing the Gregorian calendar from 14 October 1918 GR (17).
    The last area of Russia to make the change was the Far East in 1920. This was after Kolchak's forces had been defeated and the Far Eastern Republic was set up under Soviet control (e7).
    You should also be aware that various areas changed hands several times during the civil war. In Ukraine for example, the civil war went back and forth, and Kiev changed hands something like 16 different times during the civil war (e7). I am sure that the postal clerks did not always bother to change their date stamps.

As you can read in various sources the Soviet Union made an attempt to introduce a revolutionary calendar, like the French Revolutionary Calendar, in 1923 (w6) but you must know that it never came into effect (4, 16).
    Later, in 1929, they introduced some very strange "workers' weeks" during the period between 1929-1940. The introduction of these weeks can be seen from time to time in the literature as "a change in calendar in the Soviet Union" - but this is wrong as it was not an attempt to change the public use of the Gregorian Calendar. Actually "workers' week" is a literal translation of a Russian phrase which means "the number of business days in the week" - so the Russian weeks was 7 days long (17).
    At first the Soviets introduced a five-day "workers' week" and later on a six-day "workers' week". I should emphasize that these strange weeks ONLY were introduced to industry and had no connection with the Gregorian Calendar in use in the Soviet Union in this period. The only reason for these "workers' weeks" was to increase production and only plants in Russia were involved in these special "workers' weeks" (16). According to this reference there were at one time about 50 different schedules for workers in production plants - very chaotic, of course. So you would not expect to find any letters from Russia with postmarks which reflect these special "workers' weeks".

Analyzing Russian Postmarks
First, Russian collectors usually use the rule of thumb that, in the 19th century (from 1 March 1800 JU through 28 February 1900 JU), Russian Julian dates are 12 days before the Gregorian dates. In the 20th century (from 1 March 1900 through 28 February 2000 JU) the Julian dates are 13 days behind. (There was a difference of 11 days in the 18th century, but there is not very much 18th century Russian mail around. :)
    So, this means that if you have a Russian letter postmarked/dated on 31 January 1918 you just subtract a multiple of 28 from the year 1918 so you end up with a year you can find in the Julian part of Scheme 2. For example 1918-10*28=1638. At the same line as 1638 you find the Month Adding Number for January to be 0 and 31+0=31 which in Scheme 3 stands on the same line as Wednesday! That is still simple!

Nb. Until 1918.02.24 GR - Estonian Independence Day - Estonia was part of the Russian Empire (e5).

What about Sweden?
As you see in Scheme 1 Sweden changed from the Julian to the Gregorian Calendar in 1753 but the first step to make the change was taken in 1696 where they decreed that the next leap year after 1696 would be in 1744 - a calendar different from both the Julian and the Gregorian Calendar in the period 1700-1740, but actually they did not put it into practice! (Probably because the Swedish king did not have time to be concerned about such a minor problem as he was deeply involved in the Great Nordic War).
    As a matter of fact Sweden only in February 1700 left out the intercalary day so the last Julian day in February 1700 was 28 February but Sweden "forgot" to leave out the leap days in 1704 and 1708. In 1712 Sweden decided to "go back" to the real Julian Calendar. To correct for the lack of the leap day in 1700 they in 1712 added an extra day to February so February in 1712 had 30 days!!! This strange calendar in the period 1700.03.01-1712.02.30 we call "The Swedish Transitional Calendar". Note that it is simply advanced by one day over the Julian calendar. So, for these days, just use the Julian calendar for the day just before the Swedish transitional date. E.g. for the date 1707.01.01, use the date 1706.12.31 in the Julian calendar (e1). The next years until 1753 were then in sync with the Julian Calendar again.
    This means that the normal calculations used for The Perpetual Calendar can be used for the Swedish period 1700.03.01-1712.02.30 only if you subtract ONE day from the Swedish day of which you want to know the week day!. In the period 1712.03.01-1753.02.17 Sweden was back to the normal "Julian" rhythm.

What about Turkey?
In the Ottoman Empire they used the Islamic (Lunar) calendar, which count its beginning from 622.07.16 (JD# 1948440) the so-called Hijra era (12). Later, on 1789.03.01 JU, the Julian (solar) calendar was introduced as a fiscal year (also used by the postal services), but the Islamic calendar remained as a religious calendar and was still used in the legal sphere and especially for all documents issued by the sultan. They did not count this fiscal year from 1 AD but from the Hijra era. A special problem was the religious lunar year was shorter than the Julian solar year. So to bring the years into line again, the fiscal years numbers 1221 and 1255 were skipped (21).
    Of course the discrepancy continued but was disregarded. For the fiscal year in 1917 the Gregorian Calendar was introduced and the beginning of the year was moved to 1917.03.01, leaving out the days 16-28 Shubat (February) 1332. The final adjustment was made, when they changed the beginning of the year to 1918.01.01. So the Turkish fiscal year 1332 had only 352 days and the fiscal year 1333 only 306. The use of the religious Islamic calendar of course continued until the Republic abolished it on 1926.01.01.
    The Ottoman post used the fiscal dates from the beginning in 1840. But the date printed onto the stamps of the sultans visit to Macedonia was logically the religious one (pure hijra date). The Christian era on postal cancellations refers always to the Gregorian calendar. Whether the religious or the fiscal calendar was meant, you can see by the names of the month, since they used the Arab names for the religious and the Turkish names for the fiscal (civil) calendar (e13).

What about Yugoslavia?
Branislav Skrobonja (yuger@eunet.yu - Beograd, Yugoslavia) (e9): In 1912 the situation on Balkan was as follows: There were five independent orthodox kingdoms in which the Julian Calendar were in force: Romania, Bulgaria, Greece, Serbia and Montenegro. Croatia, Slovenia, Bosnia and Herzegovina were part of Austro-Hungarian Monarchy, where Gregorian calendar was valid. Macedonia was part of the Turkish Empire where the official calendar was the Islamic calendar.

A consequence of the wars during 1912/13 was that Macedonia, where orthodox inhabitants were dominant, became part of Kingdom of Serbia. That means that Julian calendar was now effective in Macedonia, too.

First World War 1914-1918
One of results of that war was that Kingdoms of Serbia and Montenegro joined in one - Kingdom of Serbia, where Julian calendar was effective. The other two constituent countries, Slovenia and Croatia, departed from the Austro-Hungarian Monarchy, and on 1st December 1918 GR these two with Kingdom of Serbia made Kingdom SHS, which lasted till 1929 when it changed the name to Kingdom of Yugoslavia. That means that in Slovenia and Croatia Gregorian calendar was in force at the moment they have joined with Serbia.

The Change Over in Yugoslavia
The Kingdom of Yugoslavia got its name on 6 January 1929. Before that, it was known as Kingdom of Serbs, Croats and Slovenians, shortly Kingdom of SHS Kingdom (the name for Croats is Hrvati). As mentioned SHS was established on 1 December 1918, immediately after First World War. As in previous Kingdom of Serbia dates were reckoned according to the Julian Calendar (Old Style), but on 10 January 1919 the royal government of Kingdom of SHS issued a law that the last Old Style date was 14 January 1919 JU and the First Gregorian Day was 28 January 1919 GR. Julian calendar is still in force in the Serbian Orthodox Church.

So actually the Julian calendar were only in use in the orthodox part, namely Serbia, Montenegro and Macedonia. Due to the fact that in other parts, Slovenia, Croatia, Bosnia and Herzegovina in practice was Gregorian, royal government had decided to uniformly use in whole territory Gregorian Calendar according to the law of 10 January 1919.

As you can see the Calendar situation has always been complicated and not easy to explain in a few words. And, the situation is not easier to understand when we read that (3) on page 275 mention that the decision to switch to the Gregorian Calendar was taken on a congress held in Constantinople in May 1923 with delegates from Serbia and Croatia: The calendar accepted was nearly identical to the Gregorian Calendar apart from the rule that secular years divisible with 900 should be leap years if the rest of the divisions are 200 or 600. This means that the years 2000, 2400 and 2900 are leap years. In the Gregorian Calendar the secular leap years are 2000, 2400 and 2800 etc. because of the 400 year rule so in 2800 the two calendars will be out of sync - but (w1) state that the rule is not official.

Well, well. In a later update I will try to find some exact dates for the areas mentioned here!

"GENE rockstar" wrote me:

Dear Toke,
I have noticed some major errors in your callendar information. Here are the errors:

• In your "What about YUGOSLAVIA" section ,you have mentioned that in 1912 "MACEDONIA" was under Turkish occupation where the official callendar was the islamic one.
• Also you have said that in 1912/13 Macedonia became part of the Serbian kingdom...... However, I must assume here that you are talking about the Former Yugoslav Republic of Macedonia and not the ACTUAL AND REAL MACEDONIA....(which is -and always was- located in the northern part of Greece.) You see, before 1947 there was no country called Macedonia, nor was there any reference using the name Macedonia that was ever directed towards that former Yugoslav republic. In fact, throughout history, before 1947 and right back to the ancient Greek world, every reference to the name MACEDONIA was directed towards the geographical area and kingdom of Macedonia which is located in the northern part of Greece and not southern Serbia.
• To make things clear here with some historical facts: The republic that calls itself "Macedonia" now, had a name. Its name was Dardania, or Paeonia (in ancient Greece). That area, which was part of the southern Serbian kingdom, had its name changed in 1947 by the very clever works of the then General Tito who conspired with the rebel communist army of Greece to make an alliance in order to gain control of Greece. The Yugoslavs would provide weapons to the rebels and the reward would be the merging of the northern Greek province of Macedonia with Yugoslavia. To avoid Eurpean and western intervention over this "handover of territory" to a communist country, a clever ploy of renaming the south part of Serbia (which borders with the Greek Macedonia) from Dardania to "Yugoslav Republic of Macedonia" was put in place in 1947. This would have made the "unification" of the two "Macedonias" very easy and acceptable by all. However,there was the problem of language-names-historical facts and so forth. This was easy solved by the invention in Dec 1947 of the "Macedonian" language, the renaming of most roads and the "change over" from Serbian/Bulgarian and Albanian names to a different type of names which are more similar to Russian than were before. The adaptation (or perhaps brainwashing?) of the Greek history and symbols of ancient Macedonia in all schools and so forth.....
• So to correct your history, it would be better to use the REAL names of the places you refair to, and not the "adopted" modern names. Specially when you are refairing to dates and places that predate 1947 in that region. There is of course the offensive side to your notes, which do bring sad feelings to many (like myself) who are from the region of Macedonia and who dont know why anyone with your knowledge of history would make this kind of mistake.
• Simply put, Macedonia has never been a "country" as such, but a name for a city/state. Nor has there ever been a "race" called "Macedonians" ... it was allways just a reference to Greeks from the region of Macedonia, like the Atheneans and Spartans and myceneans and cypriots and cretans.... All these were Greeks from the various city states. (None of which were located in the former Yugoslavia). This is historical fact and not some fundamentalists statement. Greece does not accept the existence of a country using the name of Macedonia, nor do we recognise them. This contradicts history and Greece cannot accept the re-invention of history in order to allow some "phony" republic to gain its independence. Pls feel free to verify all the above, and make the necessary corrections to your site. Feel free to visit the official Macedonian web site and read some of the historical facts (which are also available in every library around the world).The URL is: www.macedonia.com
• Thank you for your time. Kind regards, Gene. PS. Other than this, I found your site to be very informative and quite good.

Other Calendars
As you have noticed I have not dealt much with other calendars like the Islamic (Hijri), Chinese, Indian, Hebrew, Japanese, Mayan etc. etc. If you need to convert dates from some of these calendars into Julian/Gregorian dates, you should take a look at the "CalendarZone" page (r2), where I am sure that you can find the right calendar page for your need.

An On-Line Calendar Program
Maxim V. Kollegov ("http://come.to/vmax/ - Virtual_Max") has kindly allowed me to use his VMaxCalendar in connection to this page. This nice little JAVA applet you can use in many connections, e.g. postal history and if you are a genealogist. From Maxim's page you can (could!) free download the VMaxCalendar (http://www.geocities.com/SiliconValley/Lakes/8620/vmaxcalendar.html). In the version of Maxim's VMaxCalender you find below, I have included all information on calendar reforms listed in my Schemes 1.1-1.3. Please notice that it is a JAVA applet so if your browser do not support JAVA, don't click on my slightly changed version of:

VMaxCalendar

Epilogue
Now I have described a helpful tool saying only little about the dates in the years when the different countries did start their years! This differs from country to country/time to time, especially "in the old days" but as we only are concerned about the weekdays in these years there is no need to dwell on this "problem".
    I hope that this Perpetual Calendar will help you to describe your postal history material in a good way. My guess is that almost ALL your material can be analyzed using the Gregorian Part of Scheme 2. And now you are able to find out whether your letter had been transported by the Thursday mail carrying Ship or with the Stagecoach leaving on Saturdays according to your "route tables"!

I hope you enjoyed the reading. Take a printout of this article, keep it and use it!

Have a nice Postal History/Genealogy/Calendar study!
Toke Nørby