Fig. 148.—Ornamented Stone Ball found in the Tay near Perth.
A ball of fine-grained claystone, in the Perth Museum (Fig. [148]), which is said to have been dredged up from the Tay, has its surface divided into four circular discs which scarcely project beyond the circular outline of the ball, and impinge upon each other. In one of the discs the ornament consists of projecting knobs, arranged in rows both ways by the channels between them crossing each other at right angles. The knobs rise from a square base, and are rounded at the summits. This is also the character of the prickly ornament of the hemispheres of the terminal bulbs of the penannular brooches of silver found at Skaill, to which the ornament on the disc of this stone ball has a distinct resemblance. The treatment of the segmental spaces between the discs is also seen in the example from Freelands, Glasterlaw (Fig. [144]), and the simply incised ornament of the remaining discs occurs on two other balls (Figs. 149, 150), which have each but one of their discs ornamented.
Fig. 149.—Ornamented Stone Ball found at Inverawe (2⅝ inches diameter).
Fig. 150.—Ornamented Stone Ball found at Loch Lochy (3 inches diameter).
Fig. 151.—Ornamented Stone Ball found in the Isle of Skye (2¾ inches in diameter).
An example from the island of Skye (Fig. [151]) has its surface covered with small hemispherical protuberances. This variety is akin to another which has the whole surface studded with projections of a pyramidal form. Two balls of this latter variety (Figs. 152, 153) were found in one of the chambers of a curious composite structure, or group of structures, situated close to the shore on the south side of the Bay of Skaill, in the mainland of Orkney.[[70]] One of these (Fig. [152]) has the central portion pierced with a hole. The perforation is roughly made, and considerably wider at its external orifices than in the centre, where it is less than half an inch in diameter.