we can to extricate
ourselves."

"But how?"

The question came from Rob, whose voice, try as he would, persisted in
faltering. It was an awful feeling to experience, this of being penned
scores of fathoms beneath the ocean's surface in a diving boat.

"Well, I have a plan in mind. It is a desperate one, but possibly it may
work."

"What do you propose to do?"

This time it was the inventor who propounded the query. Clearly enough
Mr. Barr himself could think of no way out of the quandary.

"I don't care to say just yet," responded the naval officer.

"Why not?"

"Because it is a sort of forlorn hope that I don't care to advocate
until absolute necessity arises."

In the dire extremity into which they were plunged, not one of them
cared just then to waste time by asking questions. Clearly Uncle Sam's
officer was at the head of affairs. In silence they awaited his next
word.

"Rob, you must reverse the engines. Give them all the power they will
stand. It's just possible that we may be able to back out without
injury, although I fear that we are pretty deeply buried in this cliff."

Rob, accompanied by Merritt, hastened to obey. Together the two boys
entered the engine room, and Rob at once operated the mechanism which
caused the _Peacemaker_ to go backward.

As he pulled over the lever and the engines began to whirr and buzz,
everyone on the boat waited breathlessly for the result. But the
_Peacemaker_ did not move. Under the strain of her laboring engines the
steel fabric shook and chattered, but not an inch did the diving boat
budge.

Rob and Merritt exchanged despairing glances.

"Can't you get any more power out of her?" asked Merritt anxiously.

Rob shook his head.

"Not a bit more, old man. She's running at her utmost now."

"Then we're stuck?"

"It looks that way."

"And we're doomed to die right here unless the nose of the boat can be
got out of that cliff!"

"Never say, 'die,' Merritt. We've done the best we can, and remember the
ensign said that he had a plan if all else failed."

"Yes, 'a forlorn hope' he called it."

"In a case like this we can endure anything. Desperate situations
require desperate means to solve them."

As the young Scout leader spoke, Ensign Hargreaves burst into the engine
room.

The engines were still whirring and buzzing, and the hull of the
_Peacemaker_ was quivering under their powerful stress.

"Have you developed every ounce of power they are capab