Once a great gray brent goose, with black head and staring eyes, approached Thora with a loud, harsh cry, and flapped its wide, outstretched wings against her.  Thora took hold of the rope tightly with both hands, and placing her feet on a narrow ledge of rock, looked round and uttered a shrill, “Tr-r-r-r,” frightening the bird away.

When we got safely down to within a couple of fathoms of the surface of the clear water, we left the rope and made our way along a strip of flaggy gneiss, until we reached an immense boulder which had been detached from the main cliff.  This great rock lay before the cavern in a way that, as we found, not only hid the entrance from view, but also—­except, I suppose, in very stormy weather—­prevented the sea from flowing in.  I crept behind this barrier, holding Thora’s hand, and we were soon at the mouth of the cave.

A slanting ray of sunshine found its way within, illumining the great vaulted roof and the dripping stalactites, that looked like giant icicles hanging above us.  We were able to walk or scramble over the rocks and shingle for a considerable distance.

When we passed into a part of the grotto where the darkness deepened, however, Thora began to show signs of timidity.  She spoke of having heard about many an Orcadian who, in attempting to reach the innermost recesses of such caverns, had been taken possession of by the evil spirits that were commonly believed to inhabit these places; and the strangely-echoing sounds we heard were exaggerated in her imagination, and became to her as the weird voices of kelpies and water nymphs.

I endeavoured to allay her fears as I proceeded to strike a light, and reminded her of the magic stone that I had hanging at my neck; but still she was reluctant to go further.

“Take you the stone yourself then, Thora, if you’re afraid,” I said, as I took the cord from my neck.  “It will keep you from danger.”  And I looped the cord over her head.

Now Thora had an implicit faith in the virtues of that little stone, and when she felt it resting on her throat her fears were at once conquered.

It took some trouble to light our torch, but with the help of some wool from my cap as tinder I set to work with flint and steel, and at last we got the tar rope in a blaze.  Thora took the torch in hand and picked her way over the rocky floor, exploring every nook and cranny of the cave.  So rapidly did she skip from stone to stone and climb over the intervening boulders, that I frequently found it difficult to keep up with her.

We tried to find some traces of the wreck of the Undine, or of anyone having lived there, but we found nothing beyond a great heap of oyster shells that had been thrown into one corner.  But Carver Kinlay might very well have existed comfortably in this immense place, for, besides the dried fish that he was said to have found among the wreckage, there was a fine bed of oysters within easy reach of the entrance to