The Calendar: Story Of Its Development (1959)

[Music] our calendar helps us keep track of time before there were calendars prehistoric men began observing certain Cycles in nature the sun rose and set regularly the cycle of the changing Moon gave primitive man a concept of a longer period of time as agriculture developed Egyptians and other ancient peoples observed the cycle of the seasons later they also observed that from one planting time to the next the moon went through its cycle about 12 times by learning to keep track of the year in this way ancient man began the development of the calendar about 3,000 BC Egyptians made use of an interesting astronomical fact they had observed they knew that each year the bright star we call Sirius reappeared in the sky Just Before Sunrise rise after an absence of 70 days a few days afterwards the Nile River would begin to flood planting time each year began when the water went down again and so the Egyptians had found a basis for a Moon Star calendar which worked something like this their year was 12 lunar months long or about 354 days the months were grouped into three seasons based on agriculture the flooding season the coming forth and the Harvest because their calendar year was about 11 days short of the actual length of time it takes the Earth to make a complete Journey around the Sun every few years a 13th month was added to keep the calendar in closer agreement with the seasons Egyptians found this calendar satisfactory for religious and agricultural purposes it is likely that through many observations of syrius the Egyptians learned that reappearances of the star occurred about every 365 days with this knowledge the Egyptians developed a calendar which was better suited for collecting taxes and carrying on business in the Egyptian 365 day calendar the days of the year were divided into 12 months which no longer had any relation to the cycles of the Moon each month had 30 days for a total of 360 days to give the year 365 days five Festival days were added but because a year is actually about one qu of a day longer than 365 days syrius seem to rise about one day later every 4 years in time the actual seasons did not coincide with the calendar Seasons astronomers of ancient Babylonia are believed to have helped develop the 7-Day week this was probably done by dividing the faces of the Moon into four parts there were about seven days between the new moon and the first quarter seven more to the full moon seven to the last quarter and seven to the new moon again making four weeks in the lunar month and so we can see the beginnings of our modern calendar have come from both ancient Babylonia and Egypt far away in another part of the world the Mayas an ancient people of Central America observed the rising and setting of the sun over fixed landmarks from these observations the Maya developed a 365-day calendar known to have been in use as early as 300 BC the year was divided into 18 months of 20 days each for a total of 360 days five Festival days gave the Mayan calendar 365 days the Romans did not develop an accurate calendar until the time of Julius Caesar before then their year was based on the cycles of the Moon such a calendar was satisfactory for an Agricultural Nation even though it needed an extra month every few years but as the Roman empire grew a standard unchanging C calendar was needed in 46 BC Julius Caesar adopted the basic idea of the Egyptian calendar for the Roman Empire in this new Julian calendar there were 12 months whose names were the basis of those we Ed today there were seven months of 31 days four of 30 one of 28 to make up the year of 365 days but to keep the calendar year from from shifting one day every four years as the Egyptian calendar had done to the month of February an extra day was added every fourth year what we call the leap year so A year had an average length of 365 and a/4 days but the length of the year is actually several minutes less this small error over many hundreds of years became noticed in the date of the Spring Equinox the day when the number of hours the sun is in the sky is equal to the number of hours it is gone the Spring Equinox came on March 25th in Caesar's time but the DAT seemed to be slowly changing according to the calendar the Spring Equinox came on March 21st in the year 325 ad when the Christian Church officially adopted the Julian calendar The Equinox was significant because Easter was determined by it by the year 700 when the Equinox occurred on the 18th of March it was realized that the Julian calendar was going out of adjustment at the rate of 3 days about every 400 years eventually Easter would come in Winter Then Fall then summer and so on this growing error was not corrected until 1582 in that year Pope Gregory I 13th with the advice of astronomers declared that from the month of October that year 10 days should be omitted October 15th followed October 4th this change caused the Spring Equinox the next year to come not on March 11th as it normally would have but on March 21st when the Equinox had occurred in the year 325 then Gregory proclaimed a change and determining leap years to prevent the Spring Equinox from continuing to shift 3 Days Every 400 years until 1582 February was given 29 days in all years divisible by four but with Pope Gregory's change there would be a different rule for Century years according to this new rule while the year 1600 would still be a leap year 1700 would not be nor would 18800 or 1900 00 but the year 2000 would be a leap year only those Century years evenly divisible by 400 would be leap years and so Gregory's calendar had three less days than the Julian calendar every 400 years Rome quickly influenced many countries to adopt the new Gregorian calendar but 170 years passed before it was adopted by England in 1752 to change to the Gregorian calendar from the month of September 11 days were omitted that year in England in 1752 September 14th followed September 2nd that year the American colonies also adopted the Gregorian calendar the calendar we use today perhaps in the future further changes will be made a 13-month calendar has been suggested each month would have 28 days giving 364 days for 13 months a 365th day would be added at the Year's End in leap years an extra day would come after June 28th a given date always would come on the same day of the week according to both this calendar and to one called the world calendar which would make year divisible into four equal parts in each quarter a 31-day month would be followed by 2 30-day months giving a total of 364 calendar days the 365th day would be an extra Saturday following December 30th in leap years there would be an extra Saturday following June 30th though changes in the calendar could make it more convenient in in some ways the calendar we now use is still a practical instrument developed over thousands of years by which time can be reckoned from day to day and over long periods