"They sure do," was the other's response; "smoothly as a Geneva watch."

The boys sat chatting on various matters, and the time flew along rapidly till Rob suddenly looked at his watch.

"Almost two hours. It's time we were rising," he said.

"What do we want to rise for? It's deep enough here, isn't it?"

"That's just it. The ensign says that the chart shows that a sort of submarine cliff looms up right ahead of us somewhere hereabouts."

"Great ginger snaps! I thought the bottom of the sea was as level as a floor."

"Not a bit of it. It's as full of mountainous regions and flat, depressed plains and valleys as the Rockies themselves."

"Gee whiz! I'd hate to hit one of them. I----"

Merritt stopped short. A terrific crash shook the submarine from stem to stern. Rob saved himself from falling into the machinery by seizing a rail.

For an instant the vibration lasted, and then the diving craft came to a dead stop.

The boys gazed at each other with blanched faces.

Did the crash mean that they had actually struck one of the submerged ranges that make deep sea traveling full of dangers? Had Mr. Barr delayed too long in rising?

On the answer to these questions both boys felt that their lives depended.

They were still regarding each other with consternation when the ensign burst into the cabin.

"Shut off the engines instantly!" he ordered.

"What have we struck? That submerged cliff that you feared?" Rob managed to gasp out, while Merritt hastened to obey the officer's command.

"I--I don't know," was the reply, "but I fear that we are in serious danger!"

CHAPTER XXVIII.

THE SUPREME TEST.

"Open the side window panel and turn on the searchlight!"

The order came from Mr. Barr five minutes after the _Peacemaker_ struck.

Naturally enough, everyone on board was seriously alarmed; but in the face of danger the Boy Scouts took their example for action from the naval officer and the inventor.

Although deadly pale, Mr. Barr kept his voice as cool as an icicle.

Ensign Hargreaves, while fully realizing the danger, yet steeled himself to calmness; and both Rob and Merritt simulated the courage of their elders.

Rob hastened to obey Mr. Barr's command. After a few seconds of manipulation the slide drew back, exposing the large plate gla.s.s panel.

To bring the powerful searchlight into play was the work of but a moment.

As its white rays pierced the gloomy depths of the ocean like a scimitar of light, all on board peered intently from the panel and strove to make out what it was that the diving boat had struck.

At first nothing could be seen but the dark water with myriads of fish swarming about the bright light, which appeared to attract them as moths are attracted to an arc light.

"Swing the light," ordered Mr. Barr; "bring it to bear a little more forward."

Rob obeyed, and the ray of light swung in an arc through the obscurity outside of the _Peacemaker_. All at once, with a sharp exclamation, Rob stopped it.

"Look! look!" he cried, pointing from the window.

They looked and saw before them what appeared to be a steep acclivity, ribbed and rocky as a mountain side. It was against this submerged cliff that the _Peacemaker_ had struck.

"That submarine cliff appears to be of a soft formation," declared the ensign after a brief scrutiny; "our bow has driven into it."

"Then we are doomed to remain here?" asked Merritt with a bit of a quiver in his voice.

"Not necessarily. It's up to us now to do all 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.