JEWISH The Jewish Calendar in use to-day is both solar and lunar, the years being reckoned by the sun and the months by the moon. In order to adjust the two systems a month is intercalated in the 3rd, 6th, 8th, 11th, 14th, 17th, and 19th years of a 19-year cycle. For practical purposes, such as the beginning of Sabbath, the day begins at sunset but the calendar day of 24 hours, always begins at 6 p.m. The hour is divided into i,o8o parts (Halaqim) each part (Helaq) being equal to 3.3 sec. The Helaq is sometimes further divided into 76 rega'im. A synodical month is the in terval between two conjunctions (Conjunction = Molad) and amounts to 29 days 12 hours 44 min. 3 sec. The calendar month must, however, naturally contain an exact number of days, conse quently the Hebrew month varies between 29 and 3o days, no month has either 28 or 31. The full (Male) month contains 3o and the defective (Haser) 29 days. The months Nissan, Sivan, Ab, Tishri, and Shebat are always full; lyyar, Tammuz, Ellul, Tebeth and Adar are always defective, while Marheshvan and Kislev may vary.
The number of days in a year naturally changes. The total will be the days in month (29d. 12 h. 44 min. 3 3 sec.) multiplied by 12 in an ordinary year and by 13 in a leap year. But as either process would result in a fractional answer, the ordinary year has 353, 354 or 355 days and the leap year or 385. The New Year begins on Tishri I, but it may be delayed by one or two days for various reasons. Thus, in order to prevent the Day of Atone ment (Tishri io) from falling on a Friday or Sunday, the New Year must avoid Sunday, Wednesday or Friday. Or again, if the conjunction of Tishri takes place after noon, so that the crescent would not be seen on that evening, the New Year is one, or some times two days later. Other causes may also produce delays (dekiiyyoth). A year in which Marheshvan and Kislev are both full, is called complete (Shelemah), and will contain 355 or 385 (if leap) days. In a normal (Ke-Sidrah) year, in which the former month is defective and the latter full, the total of days will be 354 or 384, while in a defective (Haserah) year, when both months contain only 29 days each, the total of days will be 353 or 383. The character of a year (qebiac, lit. "fixing") is described by a group of three Hebrew consonants, the first and third giving the days and the week on which New Year and Passover fall respectively, while the middle consonant is the initial of "normal," "defective" or "complete." There can be only 14 types of qebi `6th, seven in common and seven in leap years.
The mean beginning of the four seasons is called Tequfah (lit. orbit or course), spring beginning when the sun reaches the equi noctial point in Nissan, summer in Tammuz, autumn in Tishri and winter in Tebeth. The length of the seasons was variously fixed by different Rabbis. In the 3rd century A.D. Mar Samuel Yar hinai (165-25o, head of Academy of Nehardea) calculated the interval between tequf 0th as 91 days, 7 hours, 3o min. It was observed that the first tequ f ah always moves forward, year after year, by one day and six hours. The result is that after 28 years have elapsed the Tequfah reverts to the same day and to the same time of day as at the beginning. This orbit is called the Great or Solar Cycle (Mahzor Gadol or Hammah). Samuel's length of the solar year (365 4 days) was emended by R. Adda to 365 days, 5 hours, S5 min., 2557 sec., a total approximating to the Ptolemaic year, but still too great by nearly seven minutes.
In addition to the solar cycle of 28 years, the Jewish Calendar employs, as mentioned above, a smaller or lunar cycle (Mahzor qatan) of 19 years in order to adjust the lunar months to the solar year by means of intercalations. The Feast of Passover, on 14 Nissan could not begin before the spring Tequfah and there fore the intercalary month finally selected was Adar. A regular intercalation was not practised before the introduction of the continuous calendar and the adoption of the Metonic cycle. The Mahzor qatan is based on the equation =12+7, for lunar months correspond to 19 solar years. In order, therefore, to keep 12 months in the year, seven intercalations are necessary : the periodicity of these additions has been given above. The era which is in use to-day is that of the Creation (Anno Mundi, Li yetzirah, see CHRONOLOGY).
The Jewish year 5689 A.M., 1928 in the Christian calendar, be gan on Sept. 15, 1928, and ended on Oct. 4, 1929. It was known as 689 according to the short system (i.e., omitting the thou sands) ; it was a leap year containing 13 months, S5 Sabbaths and 385 days. The qebi'a was Zayin, Shin, he, which indicates that New Year fell on the 7th (Zayin) and Passover on the 5th (he) day of the week and that Marheshvan and Kislev each con tained 3o days (complete, shelemah, shin). 5689 was the 8th year of the 300th lunar cycle since the Creation and the 5th of the 204th of the solar cycle since the Creation.
Marheshvan: 22, 25 and 29, First Monday, Thursday and Sec ond Monday, Fasts (in 1928).
Kislev: 25, Hanucah (Feast of Dedication) begins.
Tebeth 2, Hanucah ends; Io, Fast of Tebeth (II Ki. xxv. 1: Zech. viii. 19).
Shebat: 15, New Year of Trees.
Adar: 13, Fast of Esther ; 14-15, Purim.
(TV e-Adar; Second Adar, intercalated month) .
Nissan: 15-22, Passover.
lyyar: 13, 17, First Monday, Thursday and Second Mon day, Fasts (in 1928).
Sivan: 6, 7, Pentecost.
Tammuz 17, Fast (Zech. viii. 19).
Ab: 9, Fast (II Ki. xxv. 8, and Zech. viii. 19).
Ellfll.
The Mishnah already knows of casual intercalations and in Nedarim viii. 5, the second Adar is mentioned as the month to be added. The Jews did not, however, derive the cycle of 19 years from the Babylonians, who did not possess a system of interca lation. The dates in the Assouan Papyri, and Talmudic evidence, make it clear that Jewish intercalation was empirical and irregular. In the beginning of the 2nd century Aqiba reckoned three suc cessive years as intercalary.
The calendar was originally fixed by observation, and ultimately by calculation. Up to the fall of the Temple (A.D. 7o), witnesses who saw the new moon came forward and were strictly examined and if their evidence was accepted the month was fixed by the priests. Eventually the authority passed to the Sanhedrin and ultimately to the Patriarch. When necessary, a second Adar was inserted in order that the reaping of the corn should come at Passover. Gradually observation gave place to calculation. The right to determine the calendar was reserved to the Patriarchate; the Jews of Mesopotamia tried in vain to establish their own cal endar but the prerogative of Palestine was zealously defended. So long as Palestine remained a religious centre, it was naturally to the homeland that the Diaspora looked for its calendar. Uni formity was essential, for if different parts had celebrated feasts on different days confusion would have ensued. It was not until the 4th century A.D. that Babylon fixed the Calendar.
The Book of Jubilees, written in the 2nd century B.C., contains a peculiar calendar, evidently based on a desire to reckon time in a distinctively Jewish way. Every event from the Creation to the beginning of the Exodus is dated in Jubilee periods of 49 years and in the heptads. The author uses a solar year of 364 days, or 52 weeks, divided into four quarters of 13 weeks. The calendar has been well described by Moore as a reaction against Hellenism. That it ever was used is more than doubtful.
The Qaraites (q.v.) opposed the Rabbanites on no point more vehemently than on the calendar; they regarded calculations as impious and useless and sought to reintroduce observation. In this matter they were victorious over the Great Rabbanite champ ion Sa`adya (892-942), whose theory that calculation pre ceded observation they could easily disprove. By the end of the 15th century necessity forced the Qaraites to adopt calculation. Sa`adya was more successful in his defence of the Jewish Exilarch against Ben Meir who, in 921, initiated a great controversy on the calendar. Ben Meir claimed to be a descendant of the Patri archs, and hence asserted his right to fix the calendar. His main point was that New Year is not to be deferred unless the Molad takes place iso of an hour after midday.
The Talmud speaks of various New Year's days. It may be regarded as certain that in Palestine the New Year began in Nissan (cf. Exod. xii. 2) and in Babylonia in Tishri.
For roughly turning years Anno Mundi to Anno Domini, the number 240 should be added and the thousands neglected. Thus (5) 689 A.M.= (I) A.D. 929. Conversely, (I) 929-240=(5) 689. Since the Jewish year begins about September, consequently between September and December 31st, a difference of one may have to be adjusted. For more exact work by far the best tables are those of Schramm (Kalendariographische Tafeln, Leipzig, 1908).
See the articles and bibliographies in the Jewish Encyclopaedia and in Hastings Encycl. of Religion and Ethics. For the Calendar in the Book of Jubilees cf. G. F. Moore, Judaism, vol. i., pp. 193 seq. (1927).
(H. M. J. L.)