"What can we do?" asked Ned.

"Not a thing, my boy, only keep cool. It will not help matters any to get excited."

"We are not!" replied Ned firmly. Each of the other two boys protested that they had never been less excited, which brought an approving smile from their guide, who was filled with admiration for the plucky lads. The fact is, his admiration had been steadily growing since he had seen their achievements from the time Tad Butler had first staggered into the Red Star mining camp a few days before.

"I guess the car is going through safely. I am glad--"

Tom Phipps did not finish the sentence. He was interrupted in a way that shook all the speech out of him, as it did from the rest of the party.

There occurred a sudden sharp tremor of the rocks about them; then the stones beneath their feet seemed to heave up and down. Their little universe was being turned topsy-turvy, it seemed to them.

At the first tremor, the Pony Rider Boys were thrown p.r.o.ne upon their faces on the rocky floor, partially stunned by the sudden shock. A distant boom, like the report of a cannon sounded in their ears, then all at once a terrifying rending of the rocks about them, accompanied by loud crashes.

"Are you all right?" shouted Mr. Phipps after the deadening effect of the shock had pa.s.sed.

"I'm all right," returned Ned Rector. "Can't anything kill me now.

I'm proof against bullets, wrecks and earthquakes."

"Was that an earthquake?" questioned Walter weakly.

"Dynamite. The red car exploded when it was wrecked," explained the mining engineer. "That was what I feared. Is Master Tad hurt?"

"No, he's all right, I guess," answered Tad for himself. "All the lights have gone out. Can't we turn them on again?"

"I'm afraid not. The wires undoubtedly have been torn and twisted apart in many places. There will be no more light in this drift for some time to come, I reckon."

"Think anyone was killed?" asked Walter apprehensively.

"Oh, no. There was no one near the explosion, except ourselves, and luckily we are safe and sound. I'll try the telephone."

Mr. Phipps spun the handle of the telephone, but without result.

"Like the lights, it's dead," he said.

"What was that crashing noise in here? Was that what did it?"

questioned Tad.

The miner struck a match.

"Look!" he exclaimed.

In the center of the chamber was a heap of rocks, weighing probably a ton or more. These had been wrenched from the roof of the place and dropped into the room where Phipps and the lads were waiting.

"Somehow, I'm feeling a goneness under my belt," spoke up Ned. "Let's get out of here."

"My goneness is in my knees," Walter Perkins informed them.

"Either place is bad enough," returned Ned.

"Do you think it safe for us to leave here now?" asked Tad.

"I have been waiting until I thought it was," answered the guide. "Of course, I have no means of knowing how much the explosion has loosened the rocks further out, near where the blast was fired."

"That's so," agreed the boys.

"We may have to face still other dangers, but I think we had better make a start. I am not sure that these rocks over our heads are any too secure, either. Have you boys any matches?"

"Yes, I have some," replied Tad.

"I'll use mine first, then. We'll need all we have before we get out into the car tunnel," said Tom. "Are you getting hungry?"

"To tell the truth, I for one haven't had time to think about my appet.i.te," laughed Ned.

"Yes, I guess our minds have been so full of other things that our stomachs have not had a chance to make their wants known," said Tad.

"How about you, Walt?"

"What I want most of anything in the world just at this minute, is to see daylight. Isn't night outside yet, is it?"

"No, it is only just past noon," the miner informed him.

"Always have a total eclipse of the sun down here," muttered Ned humorously, but no one paid any attention to his feeble joke.

"If you are ready we will be going now," announced their guide. "Fall in behind me and go very carefully. You are liable to stumble over fallen rocks and break some bones. That's almost as bad as being hit on the head by one, eh?"

"Well, hardly," laughed Ned. "I've got that experience coming to me still, and I'm in no hurry to meet it."

"Keep as far to the side of this chamber as possible," directed Mr.

Phipps. He proceeded ahead of them, lighting the way with matches, which served to relieve the darkness a little, casting weird, flickering shadows on the damp walls and ceiling of the narrow pa.s.sage.

To the miner's gratification, the tunnel appeared not to have been harmed at all, not a stone having been jarred loose so far as he was able to observe.

"I guess we are in luck, boys," he said in a relieved tone. "All clear so far. We shall be out in the main tunnel in a few minutes now. There will be a car along to pick us up very shortly after we get there."

"Hurrah!" shouted the lads joyously, hurrying forward in their anxiety to be clear of the place as quickly as possible. "Can you see the end of the place?"

"No, not yet."

They had just rounded the bend in the tunnel and were heading for the exit into the main cut. Drawing near to it, they observed that Tom Phipps hesitated, then began picking his way along with more caution than before.

"Anything wrong?" asked Tad, who was close behind him.

"I don't know. Be careful. There's a lot of rubbish under foot ahead. I don't like the looks of it at all. Stand where you are."

After proceeding a few paces, their guide halted, holding a match high above his head. He turned toward them slowly.

"The rocks have caved in, boys. There's a solid wall in front of us."

"Which means," asked Tad hesitatingly.