Harry's face hardened as he held up a hand for silence. The howling on the banks of the little stream was now almost deafening, and every second there came the thunk of arrows against the boat.

"You see what they would do to us," he said.

"Yes, I know," Jack said, "but we are supposed to be civilized! It would be a wicked thing to do, to murder fifty or a hundred of those savages. Suppose we toss a stick where it will do little damage and still attract their attention from the boat? Then we might get that log out of the way."

"We'll see what show we have for getting it out of the way-the log, I mean," Jack replied.

He cautiously opened one of the lower panels at the rear and looked out. The log which blocked the narrow channel was afloat, for it was the trunk of a dry tree, and the water was deep. What held it in place was the end which lay on the sh.o.r.e. It had been rolled in at a point where the bank was low, and at least two-thirds of it lay on the ground.

"I'd like to know how they got it in there!" Jack said. "It looks too big for a hundred men to handle."

"Anyway, there it is," Frank replied, "and there the propellers are--one of them broken. Can we make speed with that busted wing?"

"We've got to," Harry said. "Just hear the devils! They will rush the boat in about a minute!"

The cries coming from the forest were now blood-curdling in their ferocity. The cannibals were evidently working themselves into a pitch of excitement which would give them courage to charge the Black Bear.

Now and then the frightened howl of some wild beast was heard in the distance, adding not a little to the excitement of the scene. The tree which had been set on fire to attract the attention of the airship still blazed, sending a twist of flame far up into the sky.

In the glare of the fire the savages looked like fiends ready for any act of deviltry. Now and then three figures larger than the rest stood together as if in conference, and then the shouts grew louder, and the line about the boat closer drawn.

"I've got a notion that we can make pretty good speed with that broken wing," Jack mused. "Anyway, we can drift down stream if we can't steam up stream, and that will take us out of this mess."

"Then let's blow that log up with dynamite," suggested Frank.

"Yes," said Jack, "and finish the propellers!"

"Blow up the sh.o.r.e end," continued Frank. "Who can pitch it so that it will knock that blooming dry wood into the stream?"

"I'm willing to try," Harry said. "I used to pitch a tricky ball!

I'll get a fuse ready, open a panel, and give it a throw. While I have the panel open, though, you fellows open up a loophole in front and do some shooting out of it to attract attention. I don't want any poisoned arrows biting me."

This was agreed to, and Harry arranged a fuse and prepared to throw it. When Jack opened a panel in front and sent a volley of bullets ash.o.r.e, the boy pushed open a panel in the rear and, waiting until the attention of the savages was attracted to the front of the boat, tossed out the dynamite.

It hurled through the air, flashing in the red light of the fire, and landed at the very end of the fallen tree, rolling into the angle between the wood and the earth. A fine throw!

Harry yelled to Jack to close his panel, and all three boys stood on the tips of their toes, fingers in ears. In a moment the explosion came.

The Black Bear rocked violently, so that it was with difficulty the boys kept their footing. Wild cries of distress and fright came from the forest, and, in a few seconds, the crash of falling trees.

The dynamite had done its work well, at least, so far as noise was concerned. They could not yet see what effect the explosion had had on the tree.

Had it loosened the obstructing log so that the boat could pa.s.s out into the Beni river? Had the concussion damaged the propellers so that the trip up the valley of the Amazon would have to be abandoned?

These questions were in the minds of all three boys as Jack cautiously opened a rear panel and looked out. The first thing he saw was the log, splintered and broken into half a dozen pieces, floating down stream.

The explosion had whirled the great trunk high up in the air and brought it down, broken, in the channel of the stream. There seemed nothing to do now but to set the motors at work and run out of the dangerous position.

But the motors refused to work. Something more than showed on the surface was the matter with them. Harry looked out at the rear and saw a great red patch of earth without a single human being in sight. The fire was still burning brightly, but there were no savages dancing about in its fierce light.

At the sound of the explosion the head hunters had taken to their heels. At first view, no one seemed to have been injured by the dynamite, but, on giving the scene a closer inspection, the boy saw three bodies lying near where the log had been. They might be dead or only stunned; the lad had no means of knowing.

While Harry watched for some sign of life, the roar of a wild animal came from the forest, and he knew that a tiger cat was approaching.

The humans--if the man-eating savages may be so termed--were still running, it appeared, while the wild beasts of prey were returning to the scene of the explosion.

"Come," Harry cried, "we must get out of this now if we can get the propellers to working. There is no one in sight, only three men lying near where the log lay, and there are man-eating animals coming, so I'd rather not see what takes place next."

Jack threw open another panel and stepped out. The roar in the forest was growing again, but no savage was in sight. He moved to the back of the boat and bent down to look at the propellers.

"I can't see from here!" he shouted, in a moment. "Look out for me, you fellows!"

Like a shot he was in the river, diving under the stem of the Black Bear. Harry and Frank, knowing the rivers of that district to be swarming with caymen, grouped at the rear and watched with anxious eyes for the reappearance of their chum.

In a few seconds Jack's face appeared above the surface of the water. He seized a rope pa.s.sed to him and climbed on board, shaking the water from his clothing like a great dog.

"It is all right," he said, as soon as he could get his breath.

"There was a piece of the log wedged in back of the paddles and I got it out. Get a pole and push. She's in the mud, I guess."

The pole was used before the motors were turned on again, and the Black Bear was soon out of the little creek, sailing slowly down the Beni. However, the boat did not behave well, and it was decided to tie up for a day and go over her carefully. The propellers needed fixing, and there might be some other injury which had not been discovered.

Not caring to strain the weakened propellers, they permitted the boat to drift down stream.

When a mile away the illumination of the fire which had been so injudiciously set could still be seen distinctly, and when the boys listened they could hear the cries of the savages and the fierce howls of the wild beasts.

During the day the boys had pa.s.sed a level plateau on the east bank of the river, and it was decided to float down to that, as they could beach the Black Bear there and work without danger of being attacked from the shelter of a forest.

They gained the spot about midnight and anch.o.r.ed some distance out, resolved to take no chances on the sh.o.r.e that night. The stream was quite wide, and they opened the top panels so as to get what fresh air they could.

Jack was the first one to see the airship hovering over them.

"Look!" he cried. "Look! Look! We've just got to attract their attention in some way! See! They are going away again! Confound the luck!"

The airship seemed about to dip down, then it floated off to the west and whirled to the south.

"They're signaling!" Harry cried.

This seemed to be true, for there were lights moving about in the air in queer combinations.

"Get a gla.s.s!" shouted Jack, in great excitement. "We'll soon see about this!"

But the airship seemed interested in the spot where the fire was burning, and did not remain overhead long enough for the boys to get a good view of her. At last she disappeared entirely.

Although anch.o.r.ed out in the stream, which was at least two hundred feet wide at that point, the lads kept a close watch of the sh.o.r.es that night. Once, just before dawn, they caught the sound of paddles, but the canoe which appeared on the west soon sneaked away.

The hubbub on sh.o.r.e kept up all night long. The beasts took up the chorus when the savage tribesmen retreated.

"Beautiful country this!" Jack said, as the sun rose over the great valley. "I think I'll like to live here always--not!"

"Yes," grunted Frank, whose eyes were heavy with the long watch, "even on the Great White Way, the enthusiasm quiets down after three o'clock."