CHRONOLOGY, a time-scale, a system of reckoning time massively. In testimony of the social memory and of the classi fication and exploitation of social experiences embedded therein mankind has learnt to recognize the orderly recurrence of natural phenomena and to base thereon his calendar (q.v.).
Every science has now its chronology. The as tronomer reminds us that "looked at in the astronomical time scale, humanity is at the very beginning of its existence—a new born babe, with all the unexplored potentialities of babyhood" (J. H. Jeans in Nature, Supplement, March 1928) ; so that the chronology of the astronomer "uses a clock which does not tick seconds but years : its minutes are the lives of men." It tells us `'that light travelling 186,000 m. a second, takes about 14o million years to come to us from the most remote objects, visible in the biggest telescope on earth" (ibid.).
We turn now from chronology of this vastness—to the chronology of this habitable globe, to the time scale of geology (q.v.) which is based for its larger divisions on the record of physical events, displaying ice-ages, periods of mountain build ing, of tectonic activity. By the aid of palaeontology, smaller divisions are established : yet here again we deal with vast figures.
The earth (q.v.) must be 2,000 million years old and man from the best evidence now available, has existed thereon for something like 300,00o years.* Where then—with a 12 in. measure as our scale—shall we place the beginnings of our race? Each division of an inch stands for 16o,000,000 years, so we divide the last of our inches of our scale by 5o and there place the first appearance of man. Where shall we place the Piltdown man (see MAN), or Heidelberg man? Divide one fiftieth of an inch into tenths and mark the fifth of these divisions as the age of Piltdown man.
Where shall we put the beginnings of the Neolithic age, when agriculture, domestication, settled life, metal lurgy all have their beginning? It is so near us that we can not mark it successfully. We can no longer use our big scale. We must change our scale and take a scale of 12 in. to represent the 300,000 years of man's existence. Each inch stands for 25,000 years and we must place the dawn of what is essential to modern life about halfway in the last or 12th of our inches. Ur and its treasures go to 3500 B.C. or 5,000 years ago and are one-fifth of an inch from to-day. Egypt is but a century or two later. The Indus civilization comes next and then that of China. The archaic cul ture of Central America is 3,00o years old, but by then great empires in the East had waxed and waned and disappeared. Egypt was then old Egypt ; and the Greeks like Herodotus were as children in cultural growth.
History.—Again we must change our scale. If we take the Neolithic age as
years ago, as a basal point (ignoring there by all the Palaeolithic and Eolithic periods), each inch stands for 1,o00 years. The discovery of the New World called America comes half way in the last inch upon this scale and there is so much to cram into the last tenth of the last inch that we are almost tempted to augment our scale once more.
Dynastic Reckoning.—When we come to the great civiliza tions of antiquity in the valleys of the Euphrates, the Tigris and the Nile or in China, we find established the method of chron ological computation by reckoning dynasties of rulers. Social continuity finds its expression and its measure in this development of social organization. But dynasties are human, and disappear. Within the framework of historical chronology we may at will establish periods based on the varying phases and variable ele ments of human culture. The founders of great religions are remembered in the chronologies of their followers. There are great periods in art, in literature, in science, not inaptly recorded and recollected and concentrated by the names of great indi viduals. It is still true that the world forgets. The record of their existence and often their deeds are being revealed to us by archaeology (q.v.) so that we seem to know more of them and *Sir A. Keith places the Piltdown skull as of a million years ago.
their fore-runners than they even knew themselves. Yet in their flourishing days, which by scale of time are so near to us and by scale of culture seem so different, there was behind them a long past, unheeded, ignored, yet potent in their lives as their achieve ments are still potent in and even essential to our lives. (See
