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The Working Planetary Pocketwatch

The place where this little adventure started was an ancient calendar system I found out about quite a while ago. To start at the beginning, if you have ever read the Jewish or Christian Bible, this calendar system actually has its origins in the book of Exodus as part of the story of when God took the Jewish people out of slavery in Egypt, and is actually the calendar system God gives them during the story.  It's also well known that this calendar was in use for well over a thousand years by the Jewish people, although not always by everyone because of how many times they were exiled out of the land of Israel, going to other nations that had their own calendar systems, which the people would morph with this calendar.  The last time this calendar was in use was sometime in the 3rd century when the Jewish people were scattered again by the Romans.  Kind of a neat side note though is there actually are a group of Jewish people I mention below who have reestablished the calendar, now that they are back in the land of Israel.


Because of it being so old, and not many people actually care about it anymore, it is quite hard to find anything about this calendar system online.  Most of the things you find are about the modern day Hebrew calendar that was eventually derived from this ancient one. Even so, amazingly there is a group of people called Karaite Jews who, because of how they believe, they did their best to preserve and use the calendar as much as they could throughout the thousands of years it's been around, and have kept the original one intact. Without them, it eventually probably would have been lost to history as it gradually became out of use more and more, and people generally cared about it less and less. So you can still find a little bit about it in this Wikipedia page, in the section labeled 3.1, Karaite Calendar. The only other places I've ever found it is in that story in Exodus where it's originally from, as well as from someone named Michael Rood, who worked with a Karaite Jew named Nehemia Gordon to put together this video series that goes through the whole calendar and the history surrounding it: Ancient Calendar.  If you would like to learn the whole history of the calendar and more detail about it, this is the only place I've ever found that has it, other than the Bible where the original calendar is talked about.  A record of Oral Jewish Rabbi laws called the Talmud also records how the calendar was observed in Israel before the Jews were displaced by the Romans, but I don't know where I could find that to link to.



To give a short summary about it so you don't have to watch all of that if you don't want to :), the way this calendar system worked was that each phase of the moon would tell you what day of the month it was, and also, when the first sliver of a new moon was visible, that was when a new month would start. So say the moon was a full moon that night. You would then know that you were in the middle of the month because the first sliver of the new moon is the beginning of the month, then the moon becomes full in the middle of the month, and finally goes to not being visible again at the end of the month, and the cycle starts over again. Each phase of the moon changes enough each night, that you can also tell what day it is by each phase.

The other piece of this calendar was that it used a certain stage of ripening on the plant named Barley, which is a grain similar to wheat, to tell when the new year would begin. The way it used this was that, if the barley had reached a certain stage of ripening by this certain day in the 12th month, then on the next new moon that would occur, the new year would start. However, if the barley had not reached that certain stage of ripening, then a 13th month would be added to that year, and you would have to wait until the next new moon to start the new year.


The reason for this is very similar to the reason we add a leap year to our calendars every 4 years, and for us, it's because of the way that it actually takes 365.24 days for the earth to go around the sun completely, but you can't add .24 days to a calendar.  So every year, our calendar becomes out of sync with where the earth is around the sun by an amount of .24 days. Then to get closer in sync, we add an extra day every four years. Similar to this, when using the moon to tell when each month starts, the calendar will become out of sync by almost 11 days each year. So if the barley wasn't ripe by that certain date in the 12th month, it meant that the calendar had become out of sync enough that Spring wasn't actually starting yet.  To rectify this, you would add a 13th month to get the calendar back in sync with where the earth was in its orbit around the sun. The beauty of this is that the calendar can never get out of sync by more than about a month’s worth of days.  You can see this more clearly in the above model, as the years go on and the Days Lost tracker disc keeps counting up until the watch has become out of sync by a little more than a month's worth of days, and a 13th month is added.


So hopefully that will all make sense and didn't get too complicated, but you can see how it all works together to form this rather amazing way of keeping track of dates, and a calendar system based on things you can just observe in nature, that could actually go on forever and ever.  This is something that not even our calendar can do because eventually, all of those decimal places we don't add in every 4 years catch up with the calendar, and you would basically have to do a reset of the calendar to get things back in line with where the Earth is in it's orbit around the sun.  One of the things I love about it too is how the whole thing keeps track of itself, and even if you lose track of what day of the month you are in, or even what month you are in, you always have this reset like the New Moon, or the Barley being ripe, that you can get back in line with it.  It's really quite a neat system.  I should also mention that other ancient cultures also had similar ways of keeping their calendars, trying to use the moon and things like that, some also trying to use calculations like we do now, but this particular way of using the barley with it and the 13th month is, as far as I know, unique to the Jewish people and was what I was trying to recreate with the watch.

Lastly, here is the place you can find this calendar in the Bible, in the book of Exodus.  It's a bit cryptic when you read it in there because it's something God is giving them as the events in Exodus are taking place, but when you put it all together, you can see quite clearly how it all worked. 


The place you find it is when Exodus 9:31, 11:2, and 13:4 are read together.  Unfortunately, the English translation loses some of the meaning of the original Hebrew words, so a more literal translation and helpful notes are provided in parentheses to help in understanding.  The verses take place on the first Passover, during the Israelite's exodus out of Egypt.


Exodus 9:31 (This passage talks about the season the story is taking place in, saying the barley was at a certain stage called Aviv) And the flax and the barley were smitten, for the barley was in the head (Aviv) and the flax was in the bud. But the wheat and the spelt were late crops.


Exodus 12: 2 (Talking about when a new month begins and saying the new year begins when this story is taking place as well) 

This month (literally new moon in Hebrew) is to be for you the first month (new moon) for you, it is the first month (new moon) of the year for you.


Exodus 13:4 Today, in the month of Aviv (the name of the first month of the calendar), you are leaving.



Put them together, and it's basically saying the children of Israel were leaving Egypt in the time when the Barley was Aviv, and God tells them that the current New Moon is suppose to be the beginning of the new year and the first month.  So each new moon starts each month, and if the Barley has reached the stage called Aviv, the new year starts as well because during that stage is when God tells them to start the new year.


(Note: Genesis 1, the creation story, also records when each day begins, at sunset.  So days are counted according to complete rotations of the earth from evening to evening, instead of midnight to midnight.

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