Neither the ordinary years nor the leap-years have a uniform duration; the former fluctuate between 353, 354, and 355 days; the latter between 383, 384, and 385 days. The following is the cause of this variety: There are certain days in the week which are never made the beginning of the new year (the 1st of Tishri). Whenever the astronomical beginning of the year happens to be on one of these days, a day is added to one year, and taken from the next. The addition in the former case is made in the month of Cheshvan, and the curtailing in the latter case in the month of Kislev. The length of the months is therefore as follows:—Nisan, 30; Iyar, 29; Sivan, 30; Tammuz, 29; Abh, 30; Elul, 29; Tishri, 30; Cheshvan, 29 or 30; Kislev, 30 or 29; Tebheth, 29; Shebhat, 30; Adar, 29, in leap-year 30; Adar-sheni (in leap-year), 29 days. The first day of the month is called New-moon-day ‏חדש‎ [81] or ‏ראש חדש‎, “beginning of the month.” In those months which have thirty days, the thirtieth day is likewise kept as Rosh-chodesh. The beginning of the astronomical month is the moment of the conjunction of sun and moon, [82] when the moon is exactly between the earth and the sun. Nothing is then visible of the moon. Six hours at least later a very small portion of the moon can, under favourable conditions, be seen, and the day on which this takes place is the first of the calendar month. At first, from the earliest days down to Hillel II. (about 360 C.E.), Rosh-chodesh was determined by direct observation. The highest court, the great Sanhedrin, examined the witnesses who had noticed the reappearance of the moon, and accordingly determined the first day of the month by the solemn declaration, Mekuddash, “sanctified;” that is, the day is to be kept as Rosh-chodesh. These proceedings took place on the thirtieth day of the month. If witnesses presented themselves who testified to the appearance of the new moon, and after due examination their statement was found to be correct, the same day was proclaimed as Rosh-chodesh, and the preceding month had twenty-nine days; if no witnesses presented themselves, or the witnesses could not sustain their evidence, the day was added to the expiring month, and the day following was the first of the next month. The decision of the Sanhedrin concerned only the thirtieth day of the month. As soon as their decision was arrived at, Jewish congregations located within a certain distance were informed by signal or by trustworthy messengers which day had been fixed as the first of the new month. The decrees of the Sanhedrin, the highest religious council of the nation, were accepted by all Jewish congregations as law, and the Festivals were celebrated in accordance with the New Moon thus appointed. There were, however, Jewish congregations in distant parts that could not be reached by the messengers in due time, and these were in doubt concerning the day on which a Festival had to be celebrated. Being