“Now, off!”

Again they pushed off, the boys with their excitement increasing after this interlude, which showed them the imminence of danger.  A few long strokes took the Okapi well out; then she was put about with her nose up-stream.

“The levers now, my lads!”

They perched themselves on the saddle-seats, and at the clanking of the levers the beautiful craft slipped swiftly up-stream.

Then out of the dark there rose the mournful howl of a jackal, almost instantly replied to by a similar call at a distance.

“The chief calling to his jackal,” said Mr. Hume.  “Thank Heaven, he has got away.  Now I will let him know we are also off;” and he, too, gave the jackal hunting-cry.

Back out of the darkness came the chief’s exultant war-cry, and on it a furious shout from the village, followed by the discharge of a rifle, and the rolling alarm of a war-drum.  Then shone out the glare of torches at the river bank, and a savage yell announced that the men had discovered the injury done to the canoes.

One of the purchases made in London had been a lamp with very fine reflectors.  This Mr. Hume fixed on a movable bracket within reach of his arm as he sat at the wheel, and when the lights at the village faded astern, he lit the lamp, in order to thread a passage by its light through the dark waters.  As the noise of shouting, the drumming, and the report of fire-arms died down, other sounds reached their strained hearing—­the booming of the Congo bittern, the harsh roar of a bull crocodile, and the cries of water-birds.

Then Venning laughed—­a little short nervous laugh.  “We have done it,” he said.

“We have, indeed,” said Compton.

“But if we can only pick up Muata and his jackal, we should be all right.  Just a nice party.”

The rudder-chains clanked; the boat set up a heavy wash as she turned from her course.  There was a splashing, and something snorted almost in Venning’s face.

“Nearly ran into a hippo!” sang out Mr. Hume.  “We must keep out into mid-river; it’s too risky inshore.  Tell me when you are tired.”

“We’re quite fresh yet,” replied Compton.  “It is easier than sculling.”

“Moves like clockwork,” said Venning, gaily.  “I could keep on all night.”

“We’ll have to keep on all night and all to-morrow,” muttered Mr. Hume; and in a few minutes he relieved Compton, making him put on a heavy coat before taking the wheel.  “It’s the chill that is dangerous.  In an hour you will relieve Venning.”