When we went along the passage, where on the first occasion I had found the water rise nearly to the roof, we had to wait; a little way ahead of us, where the cave dipped to its lowest, the water was still touching the top. We possessed our souls with what patience we could, and in about half an hour's time we were able to pass. We were quite wet, however, for only our faces and our lamps were above water; with the exception, of course, of the tin box with the candles and matches and our provisions, which I took care to keep dry. Marjory's delight at the sight of the huge red cave was unspeakable. When I lit one of the red lights the blinding glow filled the place, exposing every nook and corner, and throwing shadows of velvet blackness. The natural red of the granite suited the red light, the effect being intensely rich. Whilst the light lasted it was all like a dream of fairyland; and Marjory hung on to me in an ecstasy of delight. Then, when the light died down and the last sparks fell into the natural darkness, it seemed as if we and all around us were steeped in gloom. The little patches of faint light from our lamps seemed to our dazzled eyes to openly emphasise the surrounding blackness. Marjory suggested that we should explore the great cavern before we did anything else. I acquiesced, for it was just as well that we should be thoroughly acquainted with the various ramifications of the cave. I was not by any means sure as yet that we should be able to get to the cave of the treasure. Here, all around us, was red; we were entirely within the sienite formation. When I had been first in the cave I had not seen it lit up. Only where the comparatively feeble light of my bicycle lantern had fallen had I seen anything at all. Of course it may have been that the red light which I had burned had misled me by overwhelming everything in its lurid glow. So this time I got a white light out of the box and lit it. The effect was more ghastly and less pleasant. In the revealing glare, the edges of everything stood out hard and cold, and so far repulsive that instinctively Marjory drew closer to me. While the light remained, however, I was able to satisfy myself of one thing; all around was only the red granite. Colour and form and texture all told the same thing; we had passed the stratification of gneiss and entered on that of the sienite. I began to wonder and to think, though I did not at once mention the matter to Marjory. The one guiding light as to locality in the Don's narrative was the description of the cave "the black stone on one hand and the red on the other." Now at Broad Haven the gneiss and the red sienite join, and the strata in places seem as if welded together or fused by fire. Here and there can be found patches in the cliff where it is hard to say where one class of rock ends and the other begins. In the centre bay, however, to the north of my house, there is a sort of dip in the cliff covered deep with clay, and bright