Science / Tides and Currents / Gregorian Calendar: The modern calendar in which every year divisible by 4 (excepting century years) and every century year divisible by 400 are bissextile (or leap) years with 366 days. All other years are common years with3 65 days. The average length of this year is, therefore, 365 .242,5 days which agrees very closely with the length of the tropical year (the period of changes in seasons). The Gregorian calendar was introduced by Pope Gregory in 1582, and immediately adopted by the Catholic countries in place of the Julian calendar previously in use. In making the change it was ordered that the day following October 4, 1582, of the Julian calendar be designated October 15, 1582, of the Gregorian calendar; the 10 days being dropped in order that the vernal equinox would fall on March 21. The Gregorian calendar was not adopted by England until 1752, but is now in general use throughout the world.
Calendar Noun Synonyms: appointment book, schedule, slate, diary, date-book, law docket
Science / Tides and Currents / Julian Calendar: A calendar introduced by Julius Caesar in the year 45 B.C., and slightly modified by Augustus a few years later. This calendar provided that the common year should consist of 365 days and that every f MORE
Entertainment / Music / Gregorian Chant: Monophonic melody with a freely flowing, unmeasured vocal line: liturgical chant of the Roman Catholic Church. Also plainchant or plainsong. MORE