Bigley then began to undress rapidly, while I proceeded to work more slowly, being curious to watch what he was doing.

I had not long to wait, for after making fast one end of the thin line to the thwart of the boat he poised the stone on the gunwale, leaped in, and then putting his left arm round the grapnel rope he got well hold of the stone, and drew it over to descend with it rapidly to the bottom.

I crept to the bows and looked over to see his white body far below in the clear water, and then he came up again to rub his eyes, pant, and hold on by the side of the boat.

“Why, what’s the matter?” I said; “seen a shark?”

“No,” he cried, “but I’ve seen something else. Here, haul up the stone.”

“Bother the stone!” I exclaimed, “I came to bathe.”

“Haul it up quickly,” he said; and I obeyed, and afterwards lifted it on to the gunwale.

He seemed very excited, but he would not speak about what he had seen, only beg me to do what he told me, which was to untie the line from the stone and then make a running noose and put it loosely round.

I did all this, wondering at his mysterious way, but only