I explored the shores of the island on to the _Ru Stoir_, and thence to the Bay of Laig; but though I found detached masses of the reptile bed occurring in abundance, indicating that its place lay not far beyond the fall of ebb, in no other locality save the one described did I find it laid bare. I spent some time beside the Bay of Laig in reexamining the musical sand, in the hope of determining the peculiarities on which its sonorous qualities depended. But I examined, and cross-examined it in vain. I merely succeeded in ascertaining, in addition to my previous observations, that the loudest sounds are elicited by drawing the hand slowly through the incoherent mass, in a segment of a circle, at the full stretch of the arm, and that the vibrations which produce them communicate a peculiar titillating sensation to the hand or foot by which they are elicited, extending in the foot to the knee, and in the hand to the elbow. When we pass the wet finger along the edge of an ale-glass partially filled with water, we see the vibrations thickly wrinkling the surface: the undulations which, communicated to the air, produce sound, render themselves, when communicated to the water, visible to the eye; and the titillating feeling seems but a modification of the same phenomenon acting on the nerves and fluids of the leg or arm. It appears to be produced by the wrinklings of the vibrations, if I may so speak, passing along sentient channels. The sounds will ultimately be found dependent, I am of opinion, though I cannot yet explain the principle, on the purely quartzose character of the sand, and the friction of the incoherent upper strata against under strata coherent and damp. I remained ten days in the island, and went over all my former ground, but succeeded in making no further discoveries.