Where the "Notes" section describes a date difference
between sources, and that difference is 11 - 12 days then the
most likely reason involves the difference between Gregorian (currently
used in the West) and Julian dates used in Russia until after
the Revolution. At which time the Soviets changed to Gregorian
calendar, and had to drop 13 days from the calendar. The day after
31 January 1918 became 14 February 1918.
Use your browser "Back" button to return to previous page.
Societies need some way to keep track of time, and complex calendars were developed early in human history. The mean interval between successive vernal equinoxes (365.2424 days), is about 11 minutes less than 365 1/4 days; the synodic period of the Moon (the time between successive full moons or new moons) is about 29 1/2 days, and thus 12 months add up to about 354 days. Constructing a calendar that incorporates both the movements of the Sun and Moon is therefore not a simple business. Various solutions have been tried.
We find the seven-day week already in Genesis. The names that we assign to the days have their origin in the division of the day into 24 hours, which originated in Egypt Our division of the hour into minutes and seconds is derived from the sexagesimal system of the Mesopotamians; the division of the day into 24 hours originated with the Egyptians; the seven-day week originated in the ancient Near East, while the names are derived from a Greek convention developed during the Hellenistic period. Our calendar is based on the motion of the Sun alone, but our various religious calendars are based on a combination of the motions of the Sun and Moon. Our civil calendar derives from the Romans with some alterations.
Its origin is described nicely in the "Calendar" article in the 11th edition of the Encyclopedia Britannica (1910), which reads in part:
The civil calendar of all European and American countries has been borrowed from that of the Romans. Julius Caesar abolished the use of the lunar year, and regulated the civil year entirely by the sun. He fixed the mean length of the year at 365 1/4 days, and decreed that every fourth year should have 366 days, the other years having each 365.
In order to restore the vernal equinox to the 25th of March, he ordered two extraordinary months to be inserted between November and December in the current year, the first to consist of thirty three, and the second of thirty-four days. The intercalary month of twenty-three days fell into the year of course, so that the ancient year of 355 days received an augmentation of ninety days; and the year on that occasion contained in all 445 days. This was called the last year of confusion. The first Julian year commenced with the 1st of January of the 46th before the birth of Christ, and the 708th from the foundation of the city.
In the distribution of the days through the months, Caesar adopted a simpler and more commodious arrangement than that which has since prevailed. He had ordered that the first, third, fifth, seventh, ninth, and eleventh months, that is January, March, May, July, September and November, should have each thirty-one days, and the other months thirty, excepting February, which in common years should have only twenty-nine day, but every fourth year thirty days. This order was interrupted to gratify the vanity of Augustus, by giving the month bearing his name as many days as July, which was named after the first Caesar. A day was accordingly taken from February and given to August; and in order that three months of thirty-one days might not come together, September and November were reduced to thirty days, and thirty-one given to October and December. For so frivolous a reason was the regulation of Caesar abandoned, and a capricious arrangement introduced, which it requires some attention to remember.
The additional day which occurred every fourth year was given to February, as being the shortest month, and was inserted in the calendar between the 24th and 25th day. February having then twenty-nine days, the 25th was the 6th of the calends of March, sexto calendas; the preceding, which was the additional or intercalary day, was called bis-sexto calendas,--hence the term bissextile, which is still employed to distinguish the year of 366 days. The English denomination of leap year would have been more appropriate if that year had differed from common years in defect, and contained only 364 days. In the modern calendar the intercalary day is still added to February, not, however, between the 24th and 25th, but as the 29th.
The Julian method of intercalation supposes the year too long by 11 minutes 14 seconds, it could not without correction very long answer the purpose for which it was devised, namely, that of preserving always the same interval of time between the commencement of the year and the equinox. The excess of 365.25 days above a true solar year would amount to a day in 128 years; but in the time of Caesar the length of the year was an astronomical element not very well determined.
The Julian Calendar was adopted by Christian Europe with the Papacy at its head. By about 700 CE it had become customary to count years from the starting point of the birth of Christ. But the equinox kept slipping backwards on the calendar one full day every 130 years. By 1500 the vernal equinox fell on the 10th or 11th of March and the situation was increasingly seen as a scandal. The most important feast day on the Christian calendar is Easter, when the suffering, death, and resurrection of Christ are celebrated. In the New Testament we find that Christ's crucifixion occurred a week after Passover. On the Jewish calendar, Passover was celebrated at the full moon of the first month of spring. In developing their own calendar, Christians put Easter on the first Sunday after the first full moon after the spring equinox. If the equinox was wrong, then Easter was celebrated on the wrong day. Most other Christian observances (e.g., the beginning of Lent, Pentecost) are reckoned backward or forward from the date of Easter. An error in the equinox thus introduced numerous errors in the entire religious calendar.
After the unification of the Papacy in Rome, in the fifteenth century, Popes began to consider calendar reform. In 1582 Pope Gregory XIII (hence the name Gregorian Calendar) ordered ten days to be dropped from October, thus restoring the vernalequinox at least to an average of the 20th of March, close to what it had been at the time of the Council of Nicea. In order to correct for the loss of one day every 130 days, the new calendar dropped three leap years every 400 years. Henceforth century years were leap years only if divisible by 400. 1600 and 2000 are leap years; 1700, 1800 and 1900 are not.
The new calendar was adopted immediately in Catholic countries. Protestant countries followed suit more slowly. Protestant regions in Germany, and the northern Netherlands adopted the calendar within decades. The English retained the Julian Calendar. Further, while others now began the new year uniformly on 1 January, the English began it on 25 March. Now, for example, the date 11 February 1672 in England was 21 February 1673 on the Continent. After 1700 in which the Julian Calendar had a leap year but the Gregorian did not, the difference was eleven days. The English and their American colonies finally adopted the Gregorian Calendar in the middle of the eighteenth century. George Washington was born on 11 February on the Julian Calendar; we celebrate his birthday on 22 February
Julian dates start at noon. Gregorian dates begin at midnight.
Thus there may be 11 or 12 days difference currently between any
given date in the era 1800 -2000 Julian and Gregorian, depending
on whether the reference Julian date event is before or after
noon.