Gregorian calendar It also specifies its epact relative to 1 January, in contrast with the Julian calendar, which specified it relative to 22 March. The old date was derived from the Greek system: the earlier "Supputatio Romana" specified it relative to 1 January. During the period between 1582, when the first countries adopted the Gregorian calendar, and 1923, when the last European country adopted it, it was often necessary to indicate the date of some event in both the Julian calendar and in the Gregorian calendar, for example, "10/21 February 1750/51", where the dual year accounts for some countries already beginning their
November (Roman month) have been the most ancient holidays, becoming part of the calendar before 509 BC. Unless otherwise noted, the dating and observances on the following table are from H.H. Scullard, "Festivals and Ceremonies of the Roman Republic" (Cornell University Press, 1981), pp. 196–198. After the Ides, dates for the Julian calendar are given; pre-Julian dates for particular events, when April had one less day, are noted parenthetically. November (Roman month) November (from Latin "novem", "nine") or mensis November was originally the ninth of ten months on the Roman calendar, following October ("octo", "eight") and preceding December ("decem", "ten"). It had 29