That labyrinths of some kind were also known in olden Denmark appears from the works of the seventeenth-century Danish antiquary Olaf Worm, one of whose woodcuts (Fig. 128) shows the symbol engraved on an ancient cross. We see then that John Aubrey (see p. 136) was not altogether speaking at random when he stated his belief that "we received these Mazes from our Danish ancestors." In fact, he based his observations on the works of the Danish and Swedish writers just referred to. If, as the above considerations lead us to guess, the use of labyrinthine figures was a common feature of the northern peoples before the Norse invasion of Britain, we may wonder whether there is any evidence of the use of the symbol by earlier inhabitants of the same parts; are there any indications of this nature to be found among the relics of prehistoric man in the northern countries? Well, there are certain remains which have been held to afford an affirmative reply to this question. The remarkable prehistoric rock engravings in Northumberland and the Borders, first noticed about a hundred years ago and described in detail by Mr. G. Tate in 1864, are very suggestive in this connection. They include many figures of a character closely approaching that of a circular labyrinth, but no actual design of the conventional Cretan type has been discovered. In Figs. 129 and 130 are seen examples found on rocks at Routing Linn and Old Bewick respectively. The engravings are as much as three or four feet in diameter, and in many cases are interconnected by grooves which terminate at their cup-like centres. They often coalesce and interconnect to form mazy patterns of great complexity. The greater number consist merely of a series of concentric circles around a central cup, the circles in some cases being interrupted along a radial line which is generally occupied by a straight groove. Their origin and purpose are very obscure. Very similar rock engravings have been found, though not in such profusion, in other parts of Great Britain, as far north as the Orkneys, and as far south as Devonshire, and also in the south of Ireland. In other parts of Ireland the engravings have chiefly the shape of a simple spiral. [Illustration: Fig. 129. Rock Engravings, Routing Linn, Northumberland. (G. Tate in Proc. Berwick Naturalists' Club, 1864)] [Illustration: Fig. 130. Rock Engravings, Old Bewick, Northumberland. (G. Tate in Proc. Berwick Naturalists' Club, 1864)] There is strong suggestion of the labyrinth idea in the elaborate series of engravings which adorn the stones of a cromlech on the island of Gav'r Innis, off the coast of Brittany. Here the surface of the stones is entirely covered with engraved concentric grooves, which never cross one another, but form systems of whorls very much like those on the skin of human finger-tips. There is, however, nothing that can be fairly compared with the designs of the turf mazes, the stone labyrinths or the coins of Knossos.