“All artifacts are the resultant of an interaction between several factors,—character of the rock, need of the worker, form of the blank selected, skill of the worker. If the tool-maker was in a hurry for a utensil he would be likely to choose material easier to work than ordinarily would be the case,—material that he could shape hurriedly. If he were not skilful he would spend time to look for a blank that was a close approximation to the desired tool, that he might be spared the necessity of shaping it with his unskilled fingers. This would often mean the selection of poorer material than might have been the case under different circumstances. Primitive man, as a recent writer has pointed out, had to exercise more real mental acumen and sagacity, had to be more agile and alert and bring into action more varied qualities of mind and body in order to live, than the great mass of our present population. He used his mind and his judgment in the selection of materials, he weighed all of the pros and cons in the choice of materials for artifacts, just as he did in all the concerns of life. A prevailing notion that he picked up any old stray piece of rock that came conveniently to his hand is a mistake; his choices were results of purpose and intellectual effort. To illustrate my position, allow me to select one type of tool, the grooved axe, and discuss the choice of materials for that particular utensil. It must be borne in mind that early man in Wisconsin rarely used quarried material for axes, he sought rather for water-worn or ice-worn cobbles, and made the axe from these partially shaped and polished forms. It must also be remembered that there are three general classes of rocks, viz.: the igneous, clastic, and the metamorphic. The igneous rocks are of two general types, the coarser-grained intrusives, such as the granites, and the finer textured extrusives like basalts and their close relatives the diabases, though the latter is often quite coarsely crystalline. [Illustration: FIG. 256. (S. 1–4.) This illustrates nine grooved objects from the collection of W. A. Holmes of Chicago. The one to the right, lower row, grooved in the centre and either edge sharpened, is of Class “D.” The upper row, second from the right, double-grooved, Class “E.” In the lower row is a large grooved hammer. The two axes in the upper row to the left are highly polished and show evidence of much use. ] “In selecting material for axes the aborigine employed both types of igneous rocks.