As has already been observed at page 223, it is by no means uncommon to find portions of polished celts which, after the edge has been by some means broken away, have been converted into hammers. Very rarely, there is a cup-like cavity worked on either face in the same manner as in the celts shown in Figs. 87 and 88. A specimen of this character, from the neighbourhood of Bridlington, is shown in Fig. 163. It is of close-grained greenstone, and, to judge from the thickness of the battered end, the celt, of which this originally formed the butt, must have been at least half as long again as it is in its present form. The cavities have been worked out with some kind of pick or pointed tool, and from their position so near the butt-end, it seems probable that they did |243| not exist in the original celt, but were subsequently added when it had lost its cutting edge, and was destined to be turned into a hammer-stone. In the Greenwell Collection is a similar specimen, 4 inches long, found at Wold Newton, in the East Riding of Yorkshire. In the celts with cup-shaped depressions on their faces, but still retaining their edge, the depressions are nearer the centre of the blade. This hollowing of a portion of the surface is sometimes so slight as to amount to no more than a roughening of the face, such as would enable the thumb and fingers to take a sufficiently secure hold of the stone, to prevent its readily falling out of the hand when not tightly grasped; a certain looseness of hold being desirable, to prevent a disagreeable jarring when the blows were struck. If, as seems probable, many of these hammers or pounders were used for the purpose of splitting bones, so as to lay bare the marrow, we can understand the necessity of roughening a portion of the greasy surface of the stone, to assist the hold. [Illustration: Fig. 164.—Bridlington. 1∕2] In Fig. 164 I have represented a large quartz pebble found in Easton Field, Bridlington, which has the roughened depression on both faces rather more strongly marked than usual, especially on the face here shown. It is more battered at one end than the other, and has evidently been long in use. It shows some traces of grinding at the lower end in the figure, as if it had been desirable for it to have a sort of transverse ridge at the end, to adapt it to the purpose for which it was used. Canon Greenwell found in a barrow at Weaverthorpe,[920] Yorkshire, a hammer-stone of this kind, but nearly circular in form. It is a flat quartz pebble, about 1 3∕4 inches in diameter, battered all round, and broken at one part, and having the centre of one face artificially roughened.