# Collier's New Encyclopedia (1921)/Calendar

Edition of 1921; disclaimer.
​CALENDAR, a distribution or division of time into periods adapted to the purposes of civil life; also a table or register of such divisions, exhibiting the order in which the seasons, months, festivals, and holidays succeed each other in the year. The most remarkable calendars are:
1. The Hebrew calendar. The year of the Jews was a lunar one, being composed of 354 days, divided into 12 months, which had alternately 29 and 30 days. In order to make this lunar year accord with the solar year, the Hebrews supplied, seven times in 19 years, an intercalary month of 29 days. Each month was divided into periods of seven days, or weeks, the Saturday being celebrated under the name of Sabbath.
2. The calendar of the Greeks, whose year was likewise lunar, and composed of 12 months, containing alternately 29 and 30 days. To accommodate this year to the solar one, the Greeks added every two years a supplementary month. Each month was divided into three decades.
3. The Roman, or Julian calendar. The Roman year, under Romulus, contained only 10 months, or 304 days. Under ​Numa, however, the year was extended to 12 months, or 355 days; but, although nominally thus defined, the calendar did not in reality fix anything more precise than the commencement of the months and seasons; and through the ignorance or negligence of the priests, the utmost derangement subsequently arose. To obviate this condition, Julius Cæsar, in 46 B. C., effected a reform, by the introduction of the Julian calendar, in which the length of the solar year was fixed at 365 days, to which was added, every four years, a day called bissextile. This calendar was adopted not only by the Romans, but also by all the modern nations, and remained in use until the introduction of the calendar of Gregory XIII. The Roman year had 12 months, each being divided into unequal parts by the Calends, Nones, and Ides.
4. The Gregorian calendar. This mode of distributing time was the result of the reform inaugurated by Gregory XIII. It came into operation in October, 1582. The Greeks and Russians have refused to adopt the Gregorian calendar, retaining the old style, or Julian calendar. Hence it is necessary to deduct 12 days from the new style in order to make it agree with the old.
5. The Ecclesiastical calendar. The adaptation of the civil to the solar year is attended with no difficulty; but the church calendar, for regulating the movable feasts, imposes conditions less easily satisfied. The early Christians borrowed a portion of their ritual from the Jews. The Jewish year was luni-solar; that is to say, depended on the moon as well as on the sun. Easter, the principal Christian festival, in imitation of the Jewish passover, was celebrated about the time of the full moon. Differences of opinion, and consequently disputations, soon arose as to the proper day on which the celebration should be held. In order to put an end to an unseemly contention, the Council of Nice laid down a specific rule, and ordered that Easter should always be celebrated on the Sunday which immediately follows the full moon that happens upon, or next after, the day of the vernal equinox. In order to determine Easter, according to this rule, for any particular year, it is necessary to reconcile three periods, namely, the week, the lunar month, and the lunar year. To find the day of the week on which any given day of the year falls, it is necessary to know on what day of the week the year began. In the Julian calendar this was easily found by means of a short period or cycle of 28 years, after which the year begins with the same day of the week. In the Gregorian calendar this order is interrupted by the omission of the intercalation in the last year of the century. The connection of the lunar month with the solar year is an ancient problem for the resolution of which the Greeks invented cycles and periods, which remained in use with some modifications till the time of the Gregorian reformation. The author of the Gregorian calendar, Luigi Lilio Ghiraldi, or, as he is frequently called, Aloysius Lilius, employed for the same purpose a set of numbers called epacts.
6. New French calendar. A new reform of the calendar was attempted to be introduced in France during the period of the first revolution. This was adopted by a decree of the National Convention of October, 1793. The year was therein divided into 12 months, of 30 days each, 5 complementary, or "sans-culottides" days, being added at the end of each year. The commencement of the year was fixed at midnight of September 22d (the autumnal equinox), and retrospectively, the new year, or Year I. of the Republic, began on Sept. 22, 1792. Fresh names were given to the months and the days, the titles of the months being, for the autumn season, Vendémiaire, Brumaire, and Frimaire; for the winter season, Nivôse, Pluviôse, and Ventôse; for the spring season, Germinal, Floréal, and Prairial; and for the summer season, Messidor, Thermidor, and Fructidor: these names having reference to agricultural labors, or the state of nature in the different seasons of the year. Each month was divided into three decades (10 days each), each day bearing, instead of the name of a saint, that of an agricultural product, implement, or animal useful in cultivating the earth. This calendar remained in force during 13 years, and was abolished by decree of Napoleon I., on Jan. 1, 1806.