the Olympiads, and of the Building of Rome. I made use only of the two most famous, that is to say, that of the World, and that of Jesus Christ. Every body knows, that the Olympiads derived their origin from the Olympic games, which were celebrated in Peloponnesus, near the city of Olympia. These games were so solemn, that Greece made them her epoch for computing her years. By an Olympiad is meant the space of four years complete, which is the time that elapsed between one celebration of the games and another. The first used by chronologers begins, according to Usher, in the summer of the year of the world 3228, before Christ 776. When the time in which an event happened is reckoned by Olympiads, authors say, the first, second, or third, &c. year of such an Olympiad; which being once known, it is easy to find the year of the world to which the same fact is to be referred; and in like manner, when the year of the world is known, it is easy to find that of the Olympiad which agrees with it. Rome was built, according to Varro's Chronology, in the year of the world 3251, and the 753d before Jesus Christ. Cato dates the foundation of that city two years later, in the year of the world 3253, before Jesus Christ 751. I shall follow the opinion of the latter in my Roman history. The years reckoned from this epoch are called indifferently years of Rome, or years from the foundation of the city. The Julian period is also a famous era in chronology, used principally for reckoning the years before Christ. I am going to explain, in a few words, wherein this period consists, and its use; but first I must give the reader an idea of the three cycles of which it is composed. By the word cycle, is understood the revolution of a certain number of years. The Solar cycle is a term of twenty-eight years, which includes all the variations that the Sundays and days of the week admit : that is to say, at the end of twenty-eight years the first seven letters of the alphabet, which are used in the calendar for noting the day of the week, and which are called Dominical letters, return in the same order in which they were at first. To understand what I have now said, it must be observed, that if the year had only fifty-two weeks, there would be no change in the order of the Dominical letters. But as it has a day more, and two in leap-year, that produces some variations, which are all included in the space of twenty-eight vears, of which the solar cycle consists. The Lunar Cycle, called also the Golden Number, is the revolution of nineteen years, at the end of which the moon returns, within an hour and a half, to the same point with the sun, and begins its lunations again in the same order as at first. We are indebted for the invention of this cycle to Meto, a famous Athenian astronomer. Before the invention of the epacts, it was used for marking the days of the new moon in the calendar. Besides these two cycles, chronologers admit a third also, called Indiction. This is a revolution of fifteen years, of which the first is called the first indiction, the second the second indiction, and so on to the fifteenth, after which they begin again to count the first indiction, &c. The first indiction is generally supposed to have begun three before the birth of Christ. years If these three cycles, that is to say, 28, 19, and 15, are multiplied by each other, the product will be 7980, which is what is called the Julian period. One of the properties of this period, is to give the three characteristic cycles of each year, that is to say, the current year of each of the three cycles; for example, every body knows that the vulgar era commences at the year 4714 of the Julian period. If that number be divided by 28, what remains * after the division shows the solar cycle of that year. In the same manner the lunar cycle and the indiction may be found. It is demonstrated, that the three numbers which express these three cycles cannot be found again in the same order in any other year of the Julian period. It is the same in respect to the cycles of other years. If we trace this period back to its first year, that is to say, to the year when the three cycles, of which it is composed, began, we shall find it precede the creation of the world 710 years; supposing the creation to precede the vulgar era only 4004 years. This period is called Julian, because it is made to agree with the years of Julius Cæsar. Scaliger invented it to reconcile the systems that divided chronologers concerning the length of time elapsed since the beginning of the world. There are some who believe that only 4004 years of the world are to be reckoned before Jesus Christ. Others give more extent to that space, and augment the number of years of which it consists. These variations disappear when the Julian period is used, for every body agrees in respect to the year in which that began, and there is nobody who does not allow, that the first year of the vulgar era falls in with the 4714th of that period. Thus in the Julian period there are two fixed points, which unite all systems, and reconcile all chronologers. It is easy to find the year of the Julian period, that answers to any year whatsoever of the vulgar era of the world. For as the beginning of the Julian period precedes that era 710 years, by adding that number to the year proposed of the era of the world, we have the year of the Julian period that answers to it. For instance, we know that the battle of Arbela was fought in the year of the world 3673. If to that number we add 710, it will be 4383, which number expresses the year of the Julian period to which the battle of Arbela is to be referred. The reader knows that hitherto I have not entered into chronological discussions, and undoubtedly does not expect that I should do so now. I shall generally follow Usher, whom I have chosen for my guide in this subject. * I say, what remains, and not the quotient, as some authors do; for the quotient expresses the number of cycles, elapsed since the beginning of the period, and what remains after the division shows the year of the current cycle. |