on't risk their own worthless hides, you may be sure of that!"
exclaimed Tom.

"There they go, but they must have left Koku and the others to their
fate!"

"Oh, if they could only get loose and take control now, Tom, they'd
save your tank for you!" shouted Ned.

"Yes; but they can't, I'm afraid. They may be killed, or so securely
bound that they can't get loose!"

"Can't you get the Hawk there in time to stop her?"

"I'm afraid not. By that time she'll have attained top speed and it
would be taking our lives in our bands to try to make a flying jump,
get inside, and shut off the motors."

"Then the tank's got to smash!" said Ned gloomily.

Tom did not answer for a moment. He and his chum watched the fleeing
figures running away from the war engine. What the plotters had done,
as soon as they saw the aircraft and realized that Tom had discovered
them, was to start the motors and leap from the tank, closing the doors
after them. Whether or not they had left Koku and the others prisoners
inside remained to be seen.

But the tank was plunging her way toward the steep bank of the river,
doomed, it seemed, to great damage, if not to destruction.

"Oh, if we could only halt her!" murmured Ned.

Tom Swift was busy with some apparatus on the Hawk. Ned heard the hum
of an electric motor which was connected with the engine, and there
soon sounded the crackle of the wireless.

"What are you doing? Signaling for help from those inside the tank?"
asked Ned, for the big machine was fitted to receive and send messages
of this sort.

"I'm trying something more desperate than that," Tom answered.

Again the wireless crackled, Tom working it with one hand while, with
the other, he guided the aircraft. Ned looked downward with wondering
eyes.

The tank was still plunging her way toward the steep bank of the river.
If she tumbled down this, there would be little left of the expensive
and complicated machinery inside.

"The rascals did their work well," mused Ned. "They've probably gotten
all the secrets they want and now they're going to spoil all Tom's hard
work. It's a shame! If only--"

Ned ceased his musing. Something was taking place down below that he
could not explain. The tank seemed to be slackening her progress. More
and more slowly she approached the edge of the cliff.

"Tom! Tom!" yelled Ned. "You must have waked some of them up inside and
they've thrown the motors out of gear! Hurrah! She's stopping!"