There is no cache at the published coordinates!
One of the accomplishments of Julius Caesar was a major reform of the Calendar (see Beware the Ides (and the Nones and the Kalends) for details of the calendar of the Roman Republic, which was in use prior to the introduction of the Julian calendar). The Julian calendar introduced by Caesar is the basis of the Gregorian calendar we use today (the only difference being a small change to the leap year rule).
Calendar reform was sorely needed. During the civil war few leap months had been added to the calendar (which in non-leap years contained only 355 days), and by the time Casear returned to Rome after the civil war the calendar was running well out of synch with the seasons. The (northern) spring equinox was supposed to be on a.d. VII Kal. Apr (March 25), but by the end of the civil war was actually in late Maius. The calendar of the Roman Republic relied on bureaucrats to insert leap months to keep the calendar synchronised with the seasons. Uncertanties around whether a leap month would be inserted made planning very difficult, not to mention problems caused by prolonged periods where no leap months were included. Caesar wanted an absolute set of rules, with no room for discretion by fallible humans!
Towards the end of the civil war, Caesar had spent several months in Egypt (and got to know Cleopatra very well along the way). The Egyptians knew that the year was very close to 365.25 days (in fact it is a little less than that, but that can keep for a later cache). The Egyptians had good reason to be interested in exactly how long a year was, as the Nile flooded at the same time each year.
Caesar used what he had learnt in Egypt in devising his new calendar. The 12 months of the calendar of the republic were retained. However, month lengths were adjusted to give 365 days in a normal year. Martius, Maius, Quintilis, and October continued to have 31 days, and Februarius continued to have 28. The other 7 months had 29 days in the old calendar. Januarius, Sextilis and December were changed from 29 days to 31, and the other four months from 29 days to 30.
Every 4th year a leap day was added to Februarius (not at the end, but in the same place as where the leap month Mercedonius used to inserted) to give 366 days in a leap year. This means on average, over the 4 year cycle, a year had 365.25 days.
It may surpise cachers who have done Beware the Ides (and the Nones and the Kalends) that the "count down" method of numbering the days of each month continued to be used in the Julian calendar, with the timing of the nones and ides as per the Republican calendar (the new 31 day months still had the nones on the 5th and the ides on the 13th, whereas in the original 31 day months these happened on the 7th and the 15th).
The count down method made it possible for the leap day to be part way through Februarius (and not at the end). According to Wikipedia "The new leap day was dated as ante diem bis sextum Kalendas Martias, usually abbreviated as a.d. bis VI Kal. Mart.; hence it is called in English the bissextile day. The year in which it occurred was termed annus bissextus, in English the bissextile year." It is unclear as to exactly when the leap day was observed in the early days of the Julian calendar was, but within a couple of hundred years leap day was the day before a.d. VI Kal. Mart (and so came after a.d. VII Kal. Mart.). With the adoption of the modern way of numbering days of the month in the middle ages, it was obvious to regard February 29 as leap day (as it is the day added in leap years), rather than a day towards the end of February.
Caesar wanted his calendar to have the spring equinox on its traditional date of a.d. VII Kal. Apr (March 25). To do that, the year before the Julian calendar had the leap month Mercedonius plus two extra months (to make up for all of the leap months that should have been added in the preceding years). He called this mammoth year "ultimis annis confusionis" (the last year of confusion). Most of his subjects omitted the word ultimis from this phrase. As an aside, Christmas takes its date from an older festival of the winter solstice. In Roman times the winter solstice was around December 25, not December 21/22 as it is today. The reasons for this discrepancy will appear in a future cache.
Caesar was murdered in the second year of his new calendar, before the first application of the leap year rule, so was not around to make sure that the formula was applied correctly. How hard can every 4th year be? Well, too hard as it turned out. Romans used "inclusive counting", and would have said our week was an 8 day cycle: Sat, Sun, Mon, Tue, Wed, Thu, Fri, Sat. So, for the first three decades of the Julian Calendar, leap years were observed too frequently.
After a period of instabililty following Caesar's murder, Augustus became emperor, and order was restored. Augustus eventually realised that the leap year rule had been wrongly applied, and around 9BC suspended leap years until the calendar had caught up. There is debate as to exactly which years were leap years in the early years of the Julian calendar, but by 8AD leap years had resumed and this time they were observed every 4 years (for the next 1600 years or so).
In 44BC the month of quintilis becme Julius (Caesar was born in July) and in 8BC Sextilis became Augustus (Augustus won a number of key victories in August). Later emperors tried further month name changes, but none stuck.
So, by 8AD (at the latest), we have a calendar with month names and lengths we use today, and a leap year rule that is still pretty much the same. We have a month named after the person who introduced the calendar, and another named after someone who sorted out an error with how the leap day rule was being applied.
The cache is hidden at South 43 AB.CDE East 172 AB.EDB
A = years between leap years in early years of the Julian calendar
B = Number of days added to November.
C = S + T + 1
D = W + X
E = Z - Y
ST = day of February (using our day numbering) on which Romans observed leap day
WWX = number of days in ultimis annis confusionis
YZ = year number (BC) of ultimis annis confusionis
The cache is not hidden in any foliage, and is in a pretty obvious spot (best spotted by looking down from above). Muggles will be a problem at certain times of the day. Be careful repacking the container (bit of a tight fit).
Post review note: reviewer does not want cachers loitering at GZ, so will just add don't go at start or end of school day, side street, magnetic.
This is the third cache of a series on history of the calendar. The caches in the series are:
- A week of it!
- Beware the Ides (and the Nones and the Kalends)
- Veni, vidi, kalendri
- Monk-eying with the Calendar
- Give us our eleven days