Page:Encyclopædia Britannica, Ninth Edition, v. 5.djvu/729

Rh  Era of Nabonassar.

This era is famous in astronomy, having been generally followed by Hipparchus and Ptolemy. It is believed to have been in use from the very time of its origin; for the observations of eclipses which were collected in Chaldea by Callisthenes, the general of Alexander, and transmitted by him to Aristotle, were for the greater part referred to the commencement of the reign of Nabonassar, founder of the kingdom of the Babylonians. It is the basis of the famous Canon of Kings, also called Mathematical Canon, preserved to us in the works of Ptolemy, which, before the recent astonishing discoveries at Nineveh, was the sole authentic monument of Assyrian and Babylonian history known to us. The epoch from which it is reckoned is precisely determined by numerous celestial phenomena recorded by Ptolemy, and corresponds to Wednesday at mid-day, the 26th of February of the year 747 before Christ. The year was in all respects the same as the ancient Egyptian year. On account of the difference in the length of the Julian and Babylonian years, the conversion of dates according to the era of Nabonassar into years before Christ is attended with considerable trouble. The surest way is to follow a comparative table. Frequently the year cannot be fixed with certainty, unless we know also the month and the day. The Greeks of Alexandria formerly employed the era of Nabonassar, with a year of 365 days; but soon after the reformation of the calendar by Julius Cæsar, they adopted, like other Roman provincials, the Julian intercalation. At this time the first of Thoth had receded to the 29th of August. In the year 136 of our era, the first of Thoth in the ancient Egyptian year corresponded with the 20th of July, between which and the 29th of August there are forty days. The adoption of the Julian year must therefore have taken place about 160 years before the year 136 of our era (the difference between the Egyptian and Julian years being one day in four years), that is to say, about the year 25 In fact, the first of Thoth corresponded with the 29th of August in the Julian calendar, in the years 25, 24, 23, and 22

Era of the Seleucidæ, or Macedonian Era.

The era of the Seleucidæ dates from the time of the occupation of Babylon by Seleucus Nicator, 311 years before Christ, in the year of Rome 442, and twelve years after the death of Alexander the Great. It was adopted not only in the monarchy of the Seleucidæ but in general in all the Greek countries bordering on the Levant, was followed by the Jews till the 15th century, and is said to be used by some Arabians even at the present day. By the Jews it was called the Era of Contracts, because the Syrian governors compelled them to make use of it in civil contracts; the writers of the books of Maccabees call it the Era of Kings. But notwithstanding its general prevalence in the East for many centuries, authors using it differ much with regard to their manner of expressing dates, in consequence of the different epochs adopted for the commencement of the year. Among the Syrian Greeks the year began with the mouth Elul, which corresponds to our September. The Nestorians and Jacobites at the present day suppose it to begin with the following month, or October. The author of the first book of Maccabees makes the era commence with the month Nisan, or April; and the author of the second book with the first Tishrin, or October. Albategni, a celebrated Arabian astronomer, dates from the 1st of October. Some of the Arabian writers, as Alfergani, date from the 1st of September. At Tyre the year was counted from the 19th of our October, at Gaza from the 28th of the same month, and at Damascus from the vernal equinox. These discrepancies render it extremely difficult to determine the exact correspondence of Macedonian dates with those of other eras; and the difficulty is rendered still greater by the want of uniformity in respect of the length of the year. Some authors who follow the Macedonian era, use the Egyptian or vague year of 365 days; Albategni adopts the Julian year of 365$1⁄4$ days. According to the computation most generally followed, the year 312 of the era of the Seleucidæ began on the 1st of September in the Julian year preceding the first of our era. Hence, to reduce a Macedonian date to the common era, subtract 311 years and four months. The names of the Syrian and Macedonian months, and their correspondence with the Roman months, are as follows:—

Era of Alexander.

Some of the Greek historians have assumed as a chronological epoch the death of Alexander the Great, which took place in the year 325 The form of the year is the same as in the preceding era. This era has not been much followed; but it requires to be noticed in order that it may not be confounded with the era of the Seleucidæ.

Era of Tyre.

The era of Tyre is reckoned from the 19th of October, or the beginning of the Macedonian month Hyperberetæus, in the year 126 In order, therefore, to reduce it to the common era, subtract 125; and when the date is , subtract it from 126. Dates expressed according to this era occur only on a few medals, and in the acts of certain councils.

Cæsarean Era of Antioch.

This era was established to commemorate the victory obtained by Julius Cæsar on the plains of Pharsalia, on the 9th of August in the year 48, and the 706th of Rome. The Syrians computed it from their month Tishrin I.; but the Greeks threw it back to the month Gorpiæus of the preceding year. Hence there is a difference of eleven months between the epochs assumed by the Syrians and the Greeks. According to the computation of the Greeks, the year of the Cæsarean era began in the autumn of the year preceding the commencement of the Christian era; and, according to the Syrians, the 49th year began in the autumn of the first year of the Incarnation. It is followed by Evagrius in his Ecclesiastical History.

Julian Era.

The Julian era commences with the 1st of January, forty-five years It was designed to commemorate the reformation of the Roman calendar by Julius Cæsar.

Era of Spain, or of the Cæsars.

The conquest of Spain by Augustus, which was completed in the thirty-ninth year, gave rise to this era, which began with the first day of the following year, and was long used in Spain and Portugal, and generally in all the Roman provinces subdued by the Visigoths, both in Africa and the South of France. Several of the councils 