“I don’t understand it,” muttered the Hunter.

“I do,” said Venning, with a shout.  “Hassan has blocked up the mouth of the canon.”

“Nonsense, boy; how could he?”

“Look out of the loophole.”

Mr. Hume put his face to the hole.  “The water has risen, I think, from the noise.”

“You remember what Muata said about the drowning of the valley?  Well, that is what is happening.  The Arab has blocked the mouth by blasting a mass of rock which overhung the river.  That’s what!”

They pondered over this new phase.

“If we had food, this would be the safest place, after all, then.”

“Food, Dick, and a way out.”

“Dick, of course.  Anyhow, sir, it is a relief to have silence; the noise made my head throb so, I did not know what I was doing.”

Before, they had to shout into each other’s ears, now they spoke in low tones, but even so the echoes seemed to people the dark with whispers, and they desisted from talk.  In the silence they heard presently the swirl and lapping of waters out in the canon, then the sound of men talking, and, what was strange, a noise as of paddles, These outside sounds were muffled and indistinct, but as the night went on they heard a laugh ring out from below, loud and shrill, followed by a confused murmuring, which quickly gained distinctness in the form of a wild chant.  The denizens of the underground world were on the move.  Looking down over the parapet they saw a spurt of flame, and as the fire made for itself a ring of red light far down in the dark, they could make out dimly the forms of people sitting round in a circle.  Then the smell of smoke reached them, and, after an interval, the strong odour of burning flesh.

“Go to sleep, lad,” said Mr. Hume; “they will not disturb us.  They have other prey, found, perhaps, on the scene of the fight in the gorge.”

Venning shuddered, and sought his mat, while the Hunter continued to look down on the unholy feast in the bowels of the earth, with an itch to send a bullet smashing into the midst of the circle.

“Come and rest,” said Venning.  “Don’t you ever feel tired?”

“Tired enough, lad; but I don’t like this news about the river rising;” and ha went to the loophole.

“We’re safe enough, sir—­safe enough for to-night.  There are six miles at the back of the dam, and it would take a lot of water to rise a foot an hour in the canon, and we are more than thirty feet above the normal level, I dare say.  Do rest.”

Mr. Hume sat down, and closed his eyes, but when he heard the regular breathing of the tired boy, he was up again.  It was the thought of Dick that filled him with sleepless anxiety, and he leant on the parapet, fuming over plans in his mind with wearying reiteration.  He was staring straight before him, when a light appeared on his own level, accompanied by the ring of metal on rock.  Instinctively his rifle was levelled, and, with his finger on the trigger, he sighted a foot below the light, which was now quite stationary, but, obedient to a sudden overmastering impulse, he as quickly lowered the rifle.