In their researches on the crust of the earth Playfair, Hutton and Lyell did not pursue them by going down a coal mine till they came to the lowest available beds and work upward from these to the highest. Though for purposes of exposition a great geologist, as Sir Archibald Geikie, may expound the making of the earth from the lowest to the highest levels, and Professor Bonney tell us the _Story of our Planet_ from beginning to end as if he had watched it unfolding, Lyell in his _Principles of Geology_ shows how the studies of his great province began. There we have the backward reading of its story pursued by himself and other great ones, and where it led them. Commencing with the Pleistocene period and passing through Neocene and Eocene periods through the Mesozoic Era and its cretaceous, jurassic and triassic systems to the Newer Palæozoic Era and its Permian, carboniferous, and Devonian systems, the older Palæozoic Era and its Silurian Ordovician and Cambrian systems, he reaches the unknown. But before all this patient research and its record is reached he treats, as he must, of consolidation and alteration of strata, of petrification of organic remains, elevation of strata, horizontal and inclined stratification, of faulting, denudation, upheaval and subsidence as they combine to remodel the earth’s crust. The title of his classical work is significant--_An Attempt to Explain the Former Changes of the Earth’s Surface by Reference to Causes now in Operation_ (it may be noted that in 1830 they were fond of capital letters and of underlining their words). If these great men had been condemned to the sole use of the method of the annalist in his treatment of human history, that of the coal mine in geology, this great province of knowledge would never have been what it is to-day. At this point I think it well to state that this illuminating principle of Lyell is pursued in nearly all the matters of fact and their interpretation contained in the following chapters, so that from time to time I shall have to employ the verb, coined for the purpose, when I attempt to “Lyell” them on behalf of Lamarck. Anthropology. The anthropologist could hardly make a start with his research, if, knowing nothing of his own anatomy, physiology, customs and beliefs, he tried to interpret the physical features, habits, manners, customs and rites of an African tribe. Without such prior knowledge he would find it a profitless task to journey to the banks of the Zambesi and bring back any intelligible history of the aborigines. If he did not know the games of a European child how could he understand the variants of them such as the writer of _Savage Childhood_[2] expounds so well? [2] _Savage Childhood_, Dudley Kidd. The Sources of Rivers.