the unpolished condition appear to be relatively more abundant in that material than in other rocks. In the large collection of the Royal Irish Academy there are but few of either class, and I certainly have seen some hundreds of Irish stone celts with the edges ground, for one in which it had been left as originally chipped out.
In France the chipped celts of flint are not uncommon, but those of other materials are extremely rare.
In Denmark, and Sweden also, the unpolished celts of flint are abundant, but principally of a class not found in Britain, with square sides and neatly worked wavy angles. Some of the other forms, however, also occur, as has been already mentioned. In other materials than flint they are almost unknown.
In North America the roughly-chipped hatchets are scarce, but are more common in flint or hornstone than in other materials.
In Western Australia, where the hatchets are made of rough splinters of basalt and of silicious rocks, grinding seems but little practised. Hatchets ground at the edge seem more common in Northern Australia. It is, however, by no means improbable that in many countries the ruder forms of stone implements have to a great extent escaped observation. I much doubt whether the stone blades of the Australian hatchets, one of which is engraved in Fig. 106, would, if detached from their handles, be thought worthy of notice by the large majority of travellers, or even be regarded as of human workmanship.
However this may be, it appears that in Western Europe the practice of grinding the edges of hatchets and adzes was more universal in the case of those formed of other stones than flint, than with those of purely silicious material. This circumstance rather strengthens the probability of some of the flint implements which are found in the unground condition, having been destined for use in that state, as was the case with the North American hoe-like implements already mentioned.
It seems almost demonstrable that some at least of these unpolished celts must be among the earliest of the Neolithic implements of this country; for though, in Neolithic times, some naturally-shaped stones have been sharpened for use by grinding only, yet the art of chipping stone into shape must in all probability have preceded that of grinding or polishing its edges. So far as at present ascertained, the practice of sharpening stone tools on the grindstone was unknown in Palæolithic times; and, assum-
