I have already mentioned[1103] that in grinding and polishing the concave faces of different forms of perforated stone axes, it is probable that stone rubbers were used in conjunction with sand. Even the smaller flat and rounded faces may have been wrought by similar means. That rubbers of some kind must have been used, is, I think, evident from the character of the surfaces, especially of those which are hollowed; and the most readily available material for the formation of such rubbers, was doubtless stone. There is therefore an _à priori_ probability of such stone grinding-tools having been in use; and if we find specimens which present the conditions which such tools would exhibit, we are almost justified in assuming them to have served such purposes. Now in the collection of Messrs. Mortimer, of Driffield, Yorkshire, are several pieces of flint and portions of pebbles of schist, flint, and quartz found in that neighbourhood, which are ground at one end into a more or less rounded form, and exhibit striæ running along, and not across, the rounded surface. They have, in fact, all the appearance of having been used with coarse sand for grinding a concavity in another stone, such, for instance, as the concave face of the stone axe shown in Fig. 125. I am indebted to their kindness for the specimen shown in Fig. 183, which consists of a short piece of a conical nodule of flint, the large end of which has been used for grinding in ancient times, the striated face being now considerably weathered. In the Greenwell Collection is a rubber of the same kind from Weaverthorpe on the Yorkshire Wolds. Mr. H. S. Harland[1104] has found other specimens in Yorkshire, of which he has kindly given me several. Polishers[1105] are also found in Scotland. A polisher of somewhat similar character, but made of serpentine, was found in the |267| Lago di Varese, near Como, where a number of stone implements were also discovered. At a later period larger rubbers of the same kind were used to smooth the flutings of Doric columns. I have seen some among the ruins of the temples at Selinunto, in Sicily. Some long narrow rubbers, apparently intended for grinding out the shaft-holes of perforated axes, have been found in the Swiss Lake-dwellings; and I have a slightly conical stone, about an inch in diameter, from Mainz, which may have been used for the same purpose. * * * * * In the barrow at Cowlam, already mentioned, besides the grinding-stones of grit, there was a piece of flint roughly chipped into a cubical form, and having one face partly ground smooth. It may have been used for polishing the surfaces of other stone implements, or possibly merely as a muller. It is shown in Fig. 184. The striæ run diagonally of the square face.