Armed with modern rifles, the Indians would have made short work of the occupants of the Black Bear, but the muskets they used were old and mostly out of condition. The arrows were far more deadly, although they stood less chance of penetrating the tough panels.
"Now," Harry said, as they passed a racing fleet of Indian boats, "we can open up a little and get a breath of fresh air! I'm just about suffocated!"
"Not just yet," Jack, who was at the front, said, "for there's a mess of the black scamps just ahead. They are on the bank, both banks, and seem to be waiting for something to happen. I wonder what it can be?"
"Some trap, I suppose," Harry gritted. "Well, all we can do is to ran on through them, if they come out in boats, and get out of their reach. We ought to be able to be out of this blasted country in a couple of hours."
"That's all right," Jack replied, "but you just listen a moment."
But the racing motors shut out all individual sounds, and Harry shut them down for a minute. Seeing this, Jack dropped an anchor at the prow, and the boat lay pulling at the cable in the current.
"What did you do that for?" asked Frank, addressing both boys from the stem.
"Listen!" commanded Jack.
"Look!" ordered Harry.
What Frank heard was the heavy, continuous roar of a waterfall. What he saw, as he crowded up under the plate glass panel in the top, were the lights of an airship!