The man stared at the two heaps of chain, then at Tom Fillot, and then at his young officer, as he uttered a low groan.

“I’ve done it now, sir,” he faltered, in his deep bass. “I did try so hard, sir; oh, so hard, but it come over me like all of a sudden, and walking up and down warn’t no good. I was asleep as I walked, and at last I thought if I shut my eyes a moment—”

Bang!

A sharp flash and a report made all three start back, and spread the alarm, one of the first to run up being the great black, bar in hand, his eyes flashing, his teeth gleaming, and all eager to join in any fray on behalf of those who had saved his life.

“Wish my cutlash had come down heavy on the hand as fired that shot,” muttered Tom Fillot.

“Put out the light,” said Mark sharply.

Tom Fillot drew his jacket over the lantern, and they all stood round ready for the next order.

“Haul back the chain,” said Mark, in a low voice. “Fillot, stand by, ready to cut at the first hand which thrusts out a pistol.” Then going close to the ventilator, he shouted down, “Below there you heard my orders. We shall show no mercy now.”

A shout of defiance came up, followed by another shot, as the chain began to clink and chink while being hauled back and piled round and round from the edge toward the centre.

“Stop!” cried Mark, as a thought struck him. Then in a whisper, “I’ll have an anchor laid on instead of the cable, and then I’ll have that run back into the tier. No: better still. Get up the biggest water cask we have.”