Thus we arrive at a state of the arts in which we may suppose man to be able to construct a tool by means of a single blow. By constantly striking in the same direction, flakes would be produced; and by still further repeating the same motions, it would at last be found that by means of many blows a stone could be chipped to an edge or a point so as to form a very efficient tool.
But this continued chipping of the stone in order to produce a tool, implies a considerable mental advance upon the effort of mind necessary to construct a tool with one blow.
It implies continued attention directed by the will to the accomplishment of an object already conceived in the mind, and its subsequent application to another object which must also have been conceived in the mind before the tool was begun.
Now we know from all experience, and from all evolution which we can trace with certainty, that progress moves on in an accelerating ratio, and that the earlier processes take longer than the later ones.
But the implements of the drift, which are the earliest relics of human workmanship as yet recognized, are most of them multi-flaked tools, such as the implements figured on Plate XII, Nos. 1-10, requiring a considerable time to construct, and the use of innumerable blows in order to trim to a point at one end.
It appears therefore evident that in the natural course of events the drift period must have been preceded by an earlier period of considerable extent characterized by the use of single-flaked tools. And we may therefore consider it probable that should any evidences of man be hereafter discovered in miocene beds, they will be associated with such large rude flakes as those now exhibited, which require a feebler effort of attention and of reason to construct.
If we examine the forms of the flint implements of the drift, we find that out of many intermediate shapes we may recognize three in particular, which have been minutely described by Mr. Evans in his valuable work on the stone implements of Britain[9]: (1) a side-tool, consisting of a flint chipped to an edge on one side and having the natural rounded outside of the flint left on the other side, where it appears to have been held in the hand; (2) a tongue-shaped implement chipped to a point at one end, and having the rounded surface for the hand at the big end; and (3) an oval or almond-shaped tool, which is often chipped to an edge all round.