December 7, 2004
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Dating the Hard Way
At one time, the Romans used a lunar calendar. The beginning of the month would be determined by the sighting of the faint crescent of the new moon, upon which a pontifex would call out that the sighting had been made, establishing the beginning of the month, the Calends, named for the act of calling out and from which we get our word 'calendar'.
The Calends was also the half-month period following the full moon until the new moon, numbered backwards from the first day of the month. For Calends of January, Calends 1 is January 1, Calends 2 is December 31, Calends 3 is December 30, and so on.
The next lunar event was the quarter moon, which would follow about a week later. It was called Nones, and the period of Nones was numbered backwards too, so, using our previous example, January 2 was Nones 4, January 3 was Nones 3, and so on.
The big event of the month, as you might guess, was the full moon or Ides, The period of Ides, which ended on the full moon, was also numbered backwards. The Ides was the last numbered day of any month. The day following the Ides was the first day of the Calends period of the following month.
The Julian calendar was adopted by order of supreme Priest Julius Caesar in 46 B.C. and the beginning of the year 45 B.C. was set for January 1, two months earlier than the previous new year's date of March 1, which is why our ninth month, September, bears the name of the number seven. In 5 B.C., the lunar calendar was abandoned and the Calends, Nones and Ides were given fixed dates in each of the months, counting, as before, from the ends of the previous months. This causes the Ides to fall on the fifteenth (and the Nones on the seventh) in March, May, July and October but on the thirteenth (the fifth for the Nones) every other month.
March 15 is the Ides of March, even when it isn't the full moon. The Ides of April is April 13. That dreaded day of taxation, April 15, is Calends 17 May.
The ancient Romans were constantly counting down to the next lunar event. A count of six or seven from Calends to Nones was reasonable, as was a count of seven or eight from Nones to Ides, but the new calendar allowed a countdown of up to nineteen days from Ides to Calends, impossible with a lunar month of 29 days. Eventually the system fell into disuse and a new system was started where the days were marked cyclically with the letters A through H to mark off marketing weeks.
If Julius Caesar hadn't been assassinated on the Ides of March in 44 B.C., we probably would have completely forgotten about the system.
The Roman day, from sunrise to sunset, was exactly twelve hours long. Likewise, the night, from sunset to sunrise, was divided into four equal watches of three hours each. The length of the hour was changed to make this happen.
We have the technology now to make Roman clocks and calendars and to do calculations using them, but it isn't a simple process. It is much simpler with our modern system of fixed second, minute, hour, etc. and our modern calendars which, awkward as they may seem at times, are simplicity itself compared with what our ancestors used.