history of the
world in the order of their succession, and to ascertain the intervals
of time between them. The term "chronology" is also used of the order in
time itself, as adopted, and of the system by which the order is fixed.

The preservation of any record, however rude, of the lapse of time
implies some knowledge of the celestial motions, by which alone time can
be accurately measured, and some advancement in the arts of civilized
life, which could be attained only by the accumulated experience of many
generations (see TIME). Before the invention of letters the memory of
past transactions could not be preserved beyond a few years with any
tolerable degree of accuracy. Events which greatly affected the physical
condition of the human race, or were of a nature to make a deep
impression on the minds of the rude inhabitants of the earth, might be
vaguely transmitted through several ages by traditional narrative; but
intervals of time, expressed by abstract numbers, and these constantly
varying besides, would soon escape the memory. The invention of the art
of writing afforded the means of substituting precise and permanent
records for vague and evanescent tradition; but in the infancy of the
world, mankind had learned neither to estimate accurately the duration
of time, nor to refer passing events to any fixed epoch.

For these reasons the attempt at an accurate chronology of the early
ages of the world 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 deliberate 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 Hellanicus, the Greek logographer, who
appears to have lived through t