“Right, sir,” roared Sergeant James.

“Now,” shouted Roby; “see him?”

“No; the water goes down here in a whirlpool, round and round, and I can feel it sucking at me to drag me below.”

“Yes, sir; I can feel it along the rope. Look at my arms,” growled the sergeant.

There was a quick glance directed at the sergeant, and those who were nearest could see that, while his arms jerked and kept giving a little, the rope was playing and quivering in the light.

“Can’t you see anything?” cried Roby wildly.

“Place like a big well ground in the rock,” came up in hollow tones; “the water all comes here, and goes down a great sink-hole. Shall I cut myself free and dive?”

“No!” came simultaneously, in a hoarse yell, from a dozen throats.

“Madness!” shouted Roby. “Look round again; he may be clinging to the rocks somewhere.”

Dickenson uttered a strange, mocking laugh, so loud and thrilling that it made his hearers shudder.