Time waits for no man.|
--The earliest known source is from St. Marher, 1225 A.D.
There is some confusion as to whether the Gregorian calendar was adopted in 1751 or 1752 in the English-speaking world.
In fact, Parliament passed a bill in 1751 to implement the new "stile" (as the calendar was then typically called) in two stages. First, the (newly adopted Gregorian) year 1752 was to begin on the old (Julian) January 1st, which by that time was 11 days behind the Gregorian January 1st on continental Europe. (This would make January 1, 1752 in England be the same day as January 12, 1752 on the continent.) Second, the 11-day lag was to be eliminated by designating the day after September 2, 1752 as September 14, 1752, synchronizing the calandars from that date onward. Consequently, Jan. 1 and New Year's Day in England did not coincide with that day on the continent (after the latter's adoption of Gregory's calendar* in 1582) until 1753.
* Even with Julius' leap year, the solar year is still a little over 9 minutes longer than the calendar year. In 1582 A.D. Pope Gregory XIII noticed that this added up to 11 days of lost time, so, on October 5th of that year he simply removed the next 11 days (Poof!). Thus, October 5, 1582 of the Julian calendar was followed by October 15 in the new calendar, correcting for the accumulated discrepancy between the Julian calendar and the equinox as of that date. When comparing historical dates, it's important to note that the Gregorian calendar, used universally today in Western countries and in international commerce, was adopted at different times by different countries. Britain and her colonies (including what is now the United States), did not switch to the Gregorian calendar until 1752. Russia was still using the Julian calandar in 1917 by which time it was 13 days behind!
After this band-aid, the Julian Calendar became known as the Gregorian Calendar. However, the Gregorian calandar additionally contains a minor correction to the Julian. In the Julian calendar every fourth year is a leap year in which February has 29, not 28 days, but in the Gregorian, years divisible by 100 are not leap years unless they are also divisible by 400.
The average length of a year in the Gregorian calendar is 365.2425 days compared to the actual solar tropical year (time from equinox to equinox) of 365.24219878 days, so the current calendar accumulates one day of error with respect to the solar year about every 3300 years.
In recent years this "intolorable" state of affairs caused by precession as well as "that's just the way things are" has been attacked by a series of less drastic corrections in the form of "leap seconds". These are inserted into the calandar as needed and most people are not even aware that it has been done.