"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 ashore, 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 pass 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.