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Page history last edited by PBworks 12 years, 11 months ago

 Roman Calendar





An inscription containing the Roman calendar, which predates the Julian reform of the calendar. Observe (enlarged) that it contains the months Quintilis (5th month) and Sextilis (6th month), and allows for the insertion of an intercalary month.



The original Roman calendar is assumed to be borrowed from the culturally advanced Greeks. However, the early calendar was based on 10 months and only 304 days and there were about 61 days of winter that did not fall within the calendar. The remaining 61 days that were later discovered to have been missing, were ignored and occurred sometime during the winter season. The 10 months, beginning in modern March, were named Martius, Aprilis, Maius, Junius, Quintilis, Sextilis, September, October, November, and December. The last six of these months were derivatives from the Latin words for five, six, seven, eight, nine, and ten. According to legend, Romulus, the fist King of Rome, is supposed to have introduced this calendar in the 8th century BC.


  • Martius (31 days)
  • Aprilis (30 days)
  • Maius (31 days)
  • Junius (30 days)
  • Quintilis (31 days)
  • Sextilis (30 days)
  • September (30 days)
  • October (31 days)
  • November (30 days) and
  • December (30 days)


    Cladius Ptolemaeus:

    The ancient Roman calendar was closely linked to the science of astrology, and the teachings of Claudius Ptolemaeus. Ptolemy's work in astronomy and geography have made him famous for the ages, despite the fact that many of his theories were proven wrong or changed in the following centuries. Some of the ideas which Ptolemy presented include expressing locations by longitude and latitude, representing a spherical earth on a flat surface, and developing the first equal area map projection. Ptolemy's accomplishments reflect his understanding of spatial relationships among places on earth and of the Earth's spatial relationships to other celestial bodies. The first person to refute these theories was the Polish astronomer Nicolaus Copernicus (1473-1543) which expounded a heliocentric or 'sun-centred' 'solar-system'.Today, we still use some of Ptolemy's original theories and debate the same problems that he faced. Longitude and latitude are still used to determine precise location on Earth. 





     The Ptolemaic System


    The Division of the Day:

    Like us, the Romans divided each day into 24 hours, and they assigned 12 to the daytime and 12 to the night. However their timekeeping method did not run from midnight to midnight as our modern method of timekeeping does, but from sunrise to sunrise. This means that the length of the Roman hour varied according to the season, so that during the summer solstice around June 21st when the period of daylight is considerably longer than the night, the twelve hours assigned to the daytime would each have to be 1 hour and 16 minutes long. And during the short days of the winter solstice around December 21st, each daylight hour would be only 44 minutes long.


    There were only two days during the entire year when the Roman day contained hours of exactly 60 minutes. These dates occurred during the equinoxes,  when the length of the day is exactly equal to that of the night. The vernal equinox occurred every year around March 21st, and the autumnal equinox occured around September 21st.


    • Our modern calendar is based on the Julian calendar, implemented by Julius Caeser during 46-45 B.C. and amended by Pope Gregory XIII in A.D. 1582.






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  • Comments (3)

    Anonymous said

    at 1:05 pm on Oct 14, 2008

    It is one of the most informational pages i have ever read. I thing you should get a 100

    Anonymous said

    at 12:52 pm on Oct 14, 2008

    Katie, you site is very descriptive. I didn't really find any problems with your site and it really informed me on how the Romans counted their hours. I am able to learn a lot more about our calendar from reading your site than what I already know. Great site!

    Anonymous said

    at 12:37 pm on Oct 14, 2008

    The presentation of this web page, on a scale from 1 to 10, definitely rates as a 10. Not only it provides facts about the roman and the roman astronomical system, this person also ties the past to the future and explains how this ancient calendar influenced the calendars and astronomy in the future. The visuals tie into the topic very nicely and makes the whole page stand out.

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