For these reasons the history of the early ages of the world is involved in almost impenetrable obscurity, and chronology, comparatively speaking, is only of recent origin. After political relations began to be established, the necessity of preserving a register of passing seasons and years would soon be felt, and the practice of recording important transactions must have grown up as a necessary consequence of social life. But of these early records a very small portion only has escaped the ravages of time and barbarism.

The earliest written annals of the Greeks, Etruscans, and Romans are irretrievably lost. The traditions of the Druids perished with them. A Chinese emperor has the credit of burning “the books” extant in his day (about 220 b.c. ), and of burying alive the scholars who were acquainted with them. And a Spanish adventurer destroyed the picture records which were found in the pueblo of Montezuma.

Of the more formal historical writings in which the first ineffectual attempts were made in the direction of systematic chronology we have no knowledge at first-hand. Of Hellenicus, the Greek logographer, who appears to have lived through the greater part of the 5th century b.c., and who drew up a chronological list of the priestesses of Here at Argos; of Ephorus, who lived in the 4th century b.c., and is distinguished as the first Greek who attempted the composition of a universal history; and of Timaeus, who in the following century wrote an elaborate history of Sicily, in which he set the example of using the Olympiads as the basis of chronology, the works have perished, and our meagre knowledge of their contents is derived only from fragmentary citations in later writers. The same fate has befallen the works of Berosus and Manetho, Eratosthenes and Apollodorus. Berosus, a priest of Belus living at Babylon in the 3d century b.c., added to his historical account of Babylonia a chronological list of its kings, which he claimed to have compiled from genuine archives preserved in the temple. Manetho, likewise a priest, living at Sebennytus in Lower Egypt in the 3d century b.c., wrote in Greek a history of Egypt, with an account of its thirty dynasties of sovereigns, which he professed to have drawn from genuine archives in the keeping of the priests. Of these works fragments only, more or less copious and accurate, have been preserved. Eratosthenes, who in the latter half of the 2d century b.c. was keeper of the famous Alexandrian Library, not only made himself a great name by his important work on geography, but by his treatise entitled Chronographia, one of the first attempts to establish an exact scheme of general chronology, earned for himself the title of “father of chronology.” His method of procedure, however, was usually conjectural; and guess-work, however careful, acute, and plausible, is still guess-work and not testimony. Apollodorus, an Athenian who flourished in the middle of the 2d century b.c., wrote a metrical chronicle of events, ranging from the supposed period of the fall of Troy to his own day. These writers were followed by other investigators and systematizers in the same field, but their works are lost. Of the principal later writers whose works are extant, and to whom we owe what little knowledge we possess of the labours of their predecessors, mention will be made hereafter.

The absence or incompleteness of authentic records, however, is not the only source of obscurity and confusion in the chronology of remote ages. There can be no exact computation of time or placing of events without a fixed point or epoch from which the reckoning takes its start. It was long before this was apprehended. When it began to be seen, various epochs were selected by various writers; and at first each small separate community had its own epoch and method of time-reckoning. Thus in one city the reckoning was by succession of kings, in another by archons or annual magistrates, in a third by succession of priests. It seems now surprising that vague counting by generations should so long have prevailed and satisfied the wants of inquiring men, and that so simple, precise, and seemingly obvious a plan as counting by years, the largest natural division of time, did not occur to any investigator before Eratosthenes.

Precision, which was at first unattainable for want of an epoch, was afterwards no less unattainable from the multiplicity, and sometimes the variation, of epochs. But by a natural process the mischief was gradually and partially remedied. The extension of intercourse between the various small groups or societies of men, and still more their union in larger groups, made a common epoch necessary, and led to the adoption of such a starting point by each larger group. These leading epochs continued in use for many centuries. The task of the chronologer was thus simplified and reduced to a study and comparison of dates in a few leading systems.

The most important of these systems in what we call ancient times were the Babylonian, the Greek, and the Roman. The Jews had no general era, properly so called. In the history of Babylonia, the fixed point from which time was reckoned was the era of Nabonassar, 747 b.c. Among the Greeks the reckoning was by Olympiads, the point of departure being the year in which Coroebus was victor in the Olympic Games, 776 b.c. The Roman chronology started from the foundation of the city, the year of which, however, was variously given by different authors. The most generally adopted was that assigned by Varro, 753 b.c. It is noteworthy how nearly these three great epochs approach each other,—all lying near the middle of the 8th century b.c. But it is to be remembered that the beginning of an era and its adoption and use as such are not the same thing, nor are they necessarily synchronous. Of the three ancient eras above spoken of, the earliest is that of the Olympiads, next that of the foundation of Rome, and the latest the era of Nabonassar. But in order of adoption and actual usage the last is first. It is believed to have been in use from the year of its origin. It is not known when the Romans began to use their era. The Olympiads were not in current use till about the middle of the 3d century b.c., when Timaeus, as already mentioned, set the example of reckoning by them. Of these and other ancient and modern eras a full account is given in the following pages.

Even after the adoption in Europe of the Christian era, a great variety of methods of dating—national, provincial, and ecclesiastical—grew up and prevailed for a long time in different countries, thus renewing in modern times the difficulties experienced in ancient times from diversities of reckoning. An acquaintance with these various methods is indispensable to the student of the charters, chronicles, and legal instruments of the Middle Ages.

In reckoning years from any fixed epoch in constant succession, the number denoting the years is necessarily always on the increase. But rude nations and illiterate people seldom attach any definite idea to large numbers. Hence it has been a practice, very extensively followed, to employ cycles or periods, consisting of a moderate number of years, and to distinguish and reckon the years by their number in the cycle. The Chinese and other nations of Asia reckon, not only the years, but also the months and days, by cycles of sixty. The Saros of the Chaldeans, the Olympiad of the Greeks, and the Roman Indiction are instances of this mode of reckoning time. Several cycles were formerly known in Europe; but most of them were invented for the purpose of adjusting the solar and lunar divisions of time, and were rather employed in the regulation of the calendar than as chronological eras. They are frequently, however, of very great use in fixing dates that have been otherwise imperfectly expressed, and consequently form important elements of chronology.

Chronology has shared with history the fruits of the novel researches and remarkable discoveries in the field of antiquity which have especially distinguished the present century. The memorabilia of early peoples and ages were set down not only in written records but in monumental inscriptions. The latter, graven on stone or metal, could resist the touch of time and the hand of the barbarian better than the former; and although at various times terrible havoc has been made among them, immense numbers are in existence to this day. In Assyria, Egypt, Persia, Greece, and Italy, the practice of monumental inscription was very general. These inscriptions have attracted the attention of learned men from very remote ages. But as contributions to history and chronology, they have within the present century risen into new and surprising importance. By Grotefend’s decipherment of the cuneiform characters, the language of the Babylonian and Persian inscriptions, and by Young’s decipherment of hieroglyphics, the language of the Egyptian monuments, two discoveries made within a few years of each other, new fields of vast extent and unknown richness have been opened to historical explorers. These fields are now being diligently worked by some of the greatest living scholars; and from granite block and fragile papyrus roll results are already obtained of rare value and of rarer promise. The Assyrian inscribed cylinders, disinterred but thirty years ago, are yielding up the secrets of a long-buried past, enlarging the horizon of history, and even furnishing the means of giving a precise chronology to periods where all was vague. The publication of the Assyrian Canon by Sir Henry Rawlinson in 1862, verified as it was by the subsequent discovery of a record of a solar eclipse, must mark an epoch in chronological science. Egyptian researches and interpretations have been of similar service, and have strongly tended, if not to establish the complete accuracy, at least to indicate the credibility, of Manetho’s account of the Egyptian dynasties. The period through which these dynasties apparently reached was so vast, stretching so far beyond the traditionally accepted limits of man’s existence on the earth, that modern chronologers, when they grew critical, could for a long time only shake their heads in profound doubt over Manetho and his vistas of shadowy kings. For Egyptian chronology the discovery by Mariette, in 1864, of the Apis Steloe is one of the highest importance. A flood of light has been poured on some obscure pages of early Persian history by the great cuneiform inscription of Behistun, discovered in 1835 by Colonel Rawlinson, who subsequently copied and translated it,

In the article Calendar (q.v.), that part of chronology has been already treated of which relates to the measurement of time, and the principal methods explained with sufficient detail that have been employed, or are still in use, for adjusting the lunar months of the solar year, as well as the intercalations necessary for regulating the civil year according to the celestial motions. In the present article it is our purpose to give an account (without repeating what has been discussed in full in the article just named) of the different Eras and Periods that have been employed by historians, and by the different nations of the world, in recording the succession of time and events, to fix the epochs at which the eras respectively commenced, to ascertain the form and the initial day of the year made use of, and to establish their correspondence with the years of the Christian era. These elements will enable us. to convert, by a simple arithmetical operation, any historical date, of which the chronological characters are given according to any era whatever, into the corresponding date in our common are of the Incarnation.

Julian Period.

Although the Julian Period (the invention of Joseph Scaliger, in 1582) is not, properly speaking, a chronological era, yet, on account of its affording considerable facilities in the comparison of different eras with one another, and in marking without ambiguity the years before Christ, it is very generally employed by chronologers. It consists of 7980 Julian years; and the first year of the Christian era corresponded with the year 4714 of the Julian period. (See vol. iv. p. 670.)

Olympiads.

The Olympic games, so famous in Greek history, were celebrated once every four years, between the new and full moon first following the summer solstice, on the small plain named Olympia in Elis, which was bounded on one side by the River Alpheus, on another by the small tributary stream the Cladeus, and on the other two sides by mountains. The games lasted five days. Their origin, lost in the dimness of remote antiquity, was invested by priestly legends with a sacred character. They were said to have been instituted by the Idaean Heracles, to commemorate his victory over his four brothers in a foot race. According to a tradition, possibly more authentic, they were re-established by Iphitus, king of Elis, in concert with the Spartan Lycurgus and Cleosthenes of Pisa. The practice was long afterwards adopted of designating the Olympiad, or period of four years, by the name of the victor in the contests of the stadium, and of inscribing his name in the gymnasium of Olympia. The first who received this honour was Coroebus. The games in which Coroebus was victor, and which form the principal epoch of Greek; history, were celebrated about the time of the summer solstice 776 years before the common era of the Incarnation, in the 3938th year of the Julian period, and twenty-three years, according to the account of Varro, before the foundation of Rome.

Before the introduction of the Metonic cycle, the Olympic year began sometimes with the full moon which followed, at other times with that which preceded the summer solstice, because the year sometimes contained 384 days instead of 354. But subsequently to its adoption, the year always commenced with the eleventh day of the moon which followed the solstice. In order to avoid troublesome computations, which it would be necessary to recommence for every year, and of which the results differ only by a few days, chronologers generally regard the 1st of July as the commencement of the Olympic year. Some authors, however, among whom are Eusebius, Jerome, and the historian Socrates, place its commencement at the 1st of September; these, however, appear to have confounded the Olympic year with the civil year of the Greeks, or the era of the Seleucidae.

It is material to observe, that as the Olympic years and periods begin with the 1st of July, the first six months of a year of our era correspond to one Olympic year, and the last six months to another. Thus, when it is said that the first year of the Incarnation corresponds to the first of the 195th Olympiad, we are to understand that it is only with respect to the last six months of that year that the correspondence takes place. The first six months belonged to the fourth year of the 194th Olympiad. In referring dates expressed by Olympiads to our era, or the contrary, we must therefore distinguish two cases.

1st, When the event in question happened between the 1st of January and the 1st of the following July, the.sum of the Olympic year and of the year before Christ is always equal to 776. The year of the era, therefore, will be found by subtracting the number of the Olympic year from 776.

For example, Varro refers the foundation of Rome to the 21st of April of the third year of the sixth Olympiad, and it is required to find the year before our era. Since five Olympic periods have elapsed, the third year of the sixth Olympiad is 5x4 + 3 = 23; therefore, subtracting 23 from 776, we have 753, which is the year before Christ to which the foundation of Rome is referred by Varro.

2c?, When the event took place between the summer solstice and the 1st of January following, the sum of the Olympic year and of the year before Christ is equal to 777. The difference therefore between 777 and the year in one of the dates will give the year in the other date. Thus, the moon was eclipsed on the 27th of August, a little before midnight, in the year 413 before our era; and it is required to find the corresponding year in the Olympic era. Subtract 413 from 777, the remainder is 364; and 364 divided by four gives 91 without a remainder; consequently the eclipse happened in the fourth year of the ninety-first Olympiad, which is the date to which it is referred by Thucydides.

If the year is after Christ, and the event took place in one of the first six months of the Olympic year, that is to say, between July and January, we must subtract 776 from the number of the Olympic year to find the corresponding year of our era; but if it took place in one of the last six months of the Olympic year, or between January and July, we must deduct 777. The computation by Olympiads seldom occurs in historical records after the middle of the 5th century of our era.

The names of the months were different in the different Grecian states. The Attic months, of which we possess the most certain knowledge, were named as follows :— [table]

Era of the Foundation of Rome.

After the Olympiads, the era most frequently met with in ancient history is that of the foundation of Rome, which is the chronological epoch adopted by all the Roman historians. There are various opinions respecting the year of the foundation of Rome.

lsζ Fabius Pictor places this event in the latter half of the first year of the eighth Olympiad, which corresponds with the 3967th of the Julian period, and with the year 747 B.c.

2c?, Polybius places it in the second year of the seventh Olympiad, corresponding with 3964 of the Julian period, and 750 B.c.

3d, Μ. Porcius Cato places it in the first year of the seventh Olympiad, that is, in 3963 of the Julian period, and 751 b.c. 4íä, Verrius Flaccus places it in the fourth year of the sixth Olympiad, that is, in the year 3962 of the Julian period, and 752 bc. bth i Terentius Varro places it in the third year of the sixth Olympiad, that is, in the year 3961 of the Julian period, and 753 b.c.

A knowledge of these different computations is necessary, in order to reconcile the Roman historians with one another, and even any one writer with himself. Livy in general adheres to the epoch of Cato, though he sometimes follows that of Fabius Pictor. Cicero follows the account of Varro, which is also in general adopted by Pliny. Dionysius of Halicarnassus follows Cato. Modern chronologers for the most part adopt the account of Varro, which is supported by a passage in Censorinus, where it is stated that the 991st year of Rome commenced with the festival of the Palilia, in the consulship of Ulpius and Pontianus.

Now this consulship corresponded with the 238th year of our era; therefore, deducting 238 from 991, we have 753 to denote the year before Christ. The Palilia commenced on the 21st of April; and all the accounts agree in...