PART III.-Chronology.

CHRONOLOGY is that science, which treats of the artificial divisions of time, and teaches us to adapt them to past transactions, in order to illustrate history. Chronology and geography have been termed the "eyes of history." so closely connected are these three branches of knowledge. In order to make any regular progress in learning, some acquaintance with chronology is indispensable. To pretend to read history, the source and treasure of civil as well as sacred knowledge, without attending to chronology, would be to little or no purpose; to chronology, history owes its use and beauty.

CHAP. I.-EPOCHS AND ÆRAS.

TIMES are distinguished under various aras and epochs. An epoch or epocha is a point of time that begins with æras, and concludes with some remarkable change of things. The first epoch of time, for instance, is said to have been that space which intervened between Adam and the flood; the second is from the flood to the days of Abraham.

An ara is a particular date or period, whence a series of years is computed: the word is sometimes also written in antient authors era; its origin is contested, though generally allowed to have had its rise in Spain. Sepulveda supposes it formed from A. ER. A. the note of abbreviation of the words, Annus, ERat Augusti, occasioned by the Spaniards beginning their computation from the time their country came under the dominion of Augustus, or that of their receiving the Roman calendar.-This opinion is rejected by Scaliger. Vossius nevertheless favours the conjecture.

Different epochas or æras obtain in different nations; the understanding of which is indispensable to the student. We shall briefly notice the principal of these divisions of time.

1. The era of the Olympiads.-This method of computation had its rise from the Olympic games, which were celebrated every fifth year, near the city Olympia, in Peloponnesus. The first Olympiad commenced, according to some chronologers, in the year 3938 of the Julian period; the year from the creation 3174, the year before Christ 774, and 24 years, as some will have it 23 years before the building of Rome. The Olympiads were also called anni Iphiti, from Iphitus, who instituted, or at least renewed the solemnity of the Olympic games. We do not find any computation by Olympiads after the 364th, which ended with the year of Christ 440, except that in a charter of our king Ethelbert, the years of his reign are said to be reckoned by Olympiads. This method of reckoning was followed by the antient Greeks.

2. The era of the building of Rome; which took place A. M. (i. e. in the year of the world) 3197, and B. C. (before Christ) 752 or 753. This has also been called the Varronian epocha, being first introduced by Terentius Varro. The antient Roman historians usually follow this epoch, which is referred to thus, A. U. C. (that is, anno urbis conditæ, or the year of building the city.)

3. The era of Seleucus was followed by the Syro-Macedonians; Seleucus the Great having disused the æra of the Olympiads, and reckoned from the beginning of his own reign, which was twelve years after the death of Alexander. The era of Seleucus commences with the retaking of Babylon by Seleucus in the year of the world 3692 and before Christ 312.

4. The era of Dioclesian was introduced in honour of the emperor of that name: it has also been called the aru of the martyrs, from the vast number of Christians who were put to death during the Dioclesian persecution. This æra commenced in the year of Christ 284, and was for a long time followed in the west.

The æras or epochs, however, which are now chiefly in use or referred to, are the following, viz.

1. The epocha of the creation of the world.-The number of years that elapsed from the creation to the birth of our Saviour, has never yet been satisfactorily ascertained by chronologers. It may here suffice to say, that the system now most generally received is that of Archbishop

Usher; who follows the computation of the Hebrew Bible, and fixes the creation of the world at 4000 years before the birth of Christ.

2. The vulgar or Christian æra, (or of A. D.) This was not fully settled till the year 527; when Dionysius Exiguus, a Roman abbot, fixed it to the 4713th year of the Julian period, which was four years too late. It is however now so generally received, that this gross error in calculation is but seldom regarded.

3. The Hegira, or Turkish æra took its rise from the false prophet Mohammed's flight, from Mecca and Medina on Friday July 16, A. D. 622. It is a lunar year beginning with the new moon of that time, which is the reason of the regard for crescents in the east, where they rise on every mosque. In order to know in what year of the vulgar æra any given year of the Hegira falls, the student should reduce the lunar years into solar years, and add the number of 622. Thus, the year 1221 of the Hegira corresponds with the year 1806 of the vulgar æra; it commenced on the 21st day of March 1806, and terminated on the 11th of March 1807.

4. The ora of the French Revolution.-As this æra is constantly referred to, by French writers, during the period that France was under republican government, a few particulars concerning it may assist the reader's historical studies.

The ara in question was substituted for the vulgar or Christian æra, in all public and civil instruments, by virtue of the decree, issued by the National Convention, on the 5th October, 1793. It commenced with the epocha of the foundation of the republic, i. e. on the 22d of September, 1792 of the vulgar æra; on the morning of which day the sun arrived at the true autumnal equinox, at 18 minutes and 30 seconds past nine o'clock. (Paris time.) This æra was abolished by Buonaparte, and the Christian æra has been re-established since the commencement of 1806.

CHAP. II-DIVISIONS OF TIME.

CHRONOLOGERS have made use of two different sorts of years, the one taken from the course of the sun, the other from that of the moon. The first, called a solar

year, is again divided into two; one of them is exact, and measures the entire course of the sun; it is called a tropical year, because it begins with the solstice (called rgos) and determines in 365 days and the fourth part of a day nearly. The other is called a civil year, less accurate than the former, and subservient to popular uses.

The lunar year contains 354 days. This kind of year is now in use among the Arabians, Turks, and Saracens.

There are other marks and characters of time, or chronological terms which ought to be explained, as cycle, epacts, &c. on account of their frequent use in history.

A CYCLE is a perpetual circulation and recurrence of the same parts of time. The origin of cycles-was thus:The apparent revolution of the sun round the earth has been arbitrarily divided into 24 hours; the basis or foundation of all our mensuration of time. Civil use knows none but hours; or rather multiples of hours, as days and years. But neither the annual motion of the sun, nor that of the other heavenly bodies, can be measured exactly, and without any remainder, by hours, or their multiples. That of the sun, is 365 days, 5 hours, 49 minutes, nearly; that of the moon, 29 days, 12 hours, 44 minutes. . Hence, to swallow up these fractions in whole numbers, and yet in numbers which only express days and years, cycles have been invented; which comprehending several revolutions of the same body, replace it, after a certain number of years, in the same points of the heavens, whence it first departed: or, which is the same thing, in the same place of the calendar.

Such is the famous cycle of 19 years, called also the Cycle of the moon, or lunar cycle, a period of 19 solar years; equivalent to 19 lunar years, and 7 intercalary months: in which time, the new and full moons are supposed to return to the same day of the Julian year.

This is also called the metonic period, from its inventor Meton, the Athenian; and the golden number.-Though, in propriety, the golden number is rather the particular number which shows the year of the lunar cycle any given year is in. This cycle of the moon only holds true for 312 years: for though the new moons do return to the same day after 19 years; yet not to the same time of the day, but near an hour and a half sooner: which error, in

312 years, amounts to an entire day. Yet those employed in reforming the calendar, went on a supposition of the lunations returning precisely from 19 to 19 years, for ever.

The use of this cycle in the antient calendar, is to show the new moon of each year, and the time of Easter. In the new one, it only serves to find the epacts; which show, in either calendar, that the new moons fall 11 days too late.

Cycle of the sun, or, Solar Cycle, a revolution of 28 years; beginning with 1, and ending with 28; which being elapsed, the dominical or sunday-letters, and those that express the other feasts, &c. return into their former place, and proceed in the same order as before. It is called solar cycle, not with regard to the sun's course, which has nothing to do herein; but from sunday, antiently called dies solis, the day of the sun: because the dominical letter is principally sought for from this revolution; the dominical letters, of which are the first in the alphabet, having been substituted in lieu of the nundinal letters of the Romans.

The reformation of the calendar under pope Gregory, occasioned a considerable alteration of this cycle; in the Gregorian calendar, the solar cycle is not constant and perpetual; because every fourth secular year is common; whereas in the Julian, it is bissextile. The epocha or beginning of the solar cycle, both Julian and Gregorian, is the ninth year before Christ.

To find the cycle of the sun for any given year: add 9 to the number given, and divide the sum by 28; the number remaining will be the number of the cycle, and the quotient the number of revolutions since Christ. If there be no remainder, it will be twenty-eight, or the last year of the cycle.

JULIAN YEAR, is a solar year, containing, commonly, 365 days; though every fourth year, called bissextile, contains 366. The astronomical quantity, therefore, of the Julian year is 365 days, 6 hours, which exceeds the true solar year by eleven minutes; which excess, in 131 years, amounts to a whole day. And thus the Roman year stood, till the reformation made therein by pope Gregory.

For this form of the year we are indebted to Julius