CHRONOL'OGY, the science which determines the dates of events, and the civil distinctions of time. The divisions of time are either natural or artificial; the natural divisions of time are the year, month, week, day, and hour, deduced from the motions of the heavenly bodies, and suited to the purposes of civil life : the artificial divisions of time are the cycle or period, the epoch, and the asra or epoch, which have been framed for the purposes of history. In order to ascer tain and register the intervals of time between different events, two things must necessarily he assumed: let, an epochs or fixed point in time to which all events, whether preceding or succeeding may be referred; and 2d, a measure or definite portion of time, by which the intervals between the fixed epoch and other events may be estimated. Of these the first is entirely arbitrary, and the second arbi trary to a certain extent ; for though certain periods are marked out by the recurrence of natural phenomena, yet a choice of these phenomena must be made. It is on account of the arbitrary nature of these two elements, on which all chron ological reckoning depends, that so much confusion and uncertainty exist respect ing the dates of historical events. The diversity of epochs which have been as sumed as the origin of chronological reckoning, is a natural consequence of the manner in which science and civili ration have spread over the world. In the early ages the different communities or tribes into which mankind were divided began to date their years each from some event remarkable only in reference to its own individual history, but of which other tribes were either ignorant, or re garded with indifference. hence not only different nations, but ahinmt every individual historian or compiler of an nals, adopted an epoch of his own. Events of local or temporary interest were also constantly occurring in every commu nity which would appear of greater im portance than those which were long past, and constantly be adopted as new historical dates. The foundation of a monarchy or a city, or the accession of a king, were events of this class; and ac cordingly are epochs of frequent occur rence in the ancient annals. Religion also came in to increase the confusion caused by political changes. Soon after the introduction of Christianity, the various sects began to establish eras, commencing with events connected with the appearance of Christ ; hut no regard was given to uniformity. In like man ner. the Mohammed Ins employ dates having reference to the origin of their faith. All these circumstances have con
spired to render it is task of extreme dif ficulty for modern historians to ascertain the order of the political occurrences of ancient times. But it is not merely the number of chronological epochs and the various origins of eras that have caused the perplexity; the measure by which long intervals were compared varied in different countries, and in different ages, and hence arises another source of confu sion in arranging the order of time. In the scripture history, the lapse of time is frequently estimated by generations or reigns of kings. Some of the histori ans of early Greece reckoned by the suc cession of the priestesses of Juno; others by that of the ophori of Sparta; and others again by the archons of Athens. Even when the length of the solar year began to be used as the measure of time, uniformity was not obtained. The length of the solar year is a fixed element in nature, and liable to no variation. But neither the commencement or termina tion of the year is marked by any con spicuous sign. Its precise length can only be ascertained by a long-eontinued series of astronomical observations. Rude nations were therefore unaeqmtinted with it ; and even when it had become known with considerable accuracy, it was still necessary to form a. civil year, and adapt it to the seasons, the solar year not being composed of an exact number of days. Mast nations had recourse to intercala tions for this purpose. For these rea sons, and numerous others that might easily be adduced, it is very seldom that the precise interval between the events mentioned in ancient. history and modern dates can bo determined with any degree of certainty, and great discrepancies exist among the computations of different chro nologers.
GIIB,ISELEPJlAN'YINF, religious images of gold and ivory. These, the earliest images of the gods in Greece, were of wood, gilt, or inlaid with ivory, whence were derived aerolites, the heads, arms, and feet of which were of marble, the body still of wood, inlaid with ivory, or quite covered with gold. From this arose the chryselephantine statues, of which the foundation was of wood, cov ered with ivory or gold, with drapery and hair of thin plates of gold, chased ; and the rest of the exterior was of ivory, worked in a pattern by the scraper and file, with the help of isinglass. The ivory portion of these works belongs to seulp tore,'and the gold part to toreutie art ; they were long in favor as temple statues, as marble and brass were used for com mon purposes.