We have watched the long succession of varied life on the earth recorded in the rocks, and now we come to the most momentous event of all in the history--the coming of Man. The first certain evidence of the presence of man on the earth is found with the coming of the Glacial Period,--unless indeed the supposed flint implements found by Mr. Reid Moir, under the Crag in Suffolk, should prove him earlier still. It is a rare chance that the skeleton of a land animal is preserved; especially rare in the case of a skeleton so frail as that of man. The best chance for the preservation of bones is in deposits in caves, which were frequently the dens of wild beasts and the shelters of man. But the implements used by early man were happily of a very imperishable nature. His favourite material, if he could get it, was flint. Flint could by dexterous blows have flake after flake taken off, till it formed a tool or weapon with sharp point and cutting edge. The implements, though only chipped, or flaked, were often admirably made. They have very characteristic shapes. Moreover, the kind of blow--struck obliquely--by which these early men made their tools left marks which stamp them as of human workmanship. The flake struck off shows what is called a "bulb of percussion"--a swelling which marks the spot where the blow was struck--and from this extends a series of ripples, producing a surface like that of a shell, from which this mode of breaking is called conchoidal fracture. Often, by further chipping the flake itself is worked into an implement. Implements have also been made of chert, but it is far more difficult to work, as it naturally breaks in an irregular way into sharp angular fragments. Flint, on the other hand, lent itself admirably to the use of early man, who in time acquired a perfect mastery of the material. The working of flints is so characteristic that, once accustomed to them, you cannot mistake a good specimen. Sea waves dashing pebbles about will sometimes produce a conchoidal fracture, but never a series of fractures in the methodical way in which a flint was worked by man. And, of course, specimens may be found so worn that it is difficult to be sure about their nature. Again early man may, especially in very early times, have been content to use a sharp stone almost as he found it, with only the slightest amount of knocking it into shape. So that in such a case it will be very difficult to decide whether the stones have formed the implements of man or not. In later times men learnt to polish their implements, and made polished stone axes like those the New Zealanders and South Sea Islanders used to make in modern times. The old age of chipped or flaked implements is called the Palaeolithic; the later age when they were ground or polished the Neolithic. (Simple implements, as knives and scrapers, were still unpolished.) The history of early man is a long story in itself, and of intense interest.