Chapter XVI: The Vent Hole in the Wall

The way grew rougher with every yard they traversed. How Spanish Joe had come dashing down over this ground at headlong speed without breaking his neck was a puzzle.

Frank was feeling his way along carefully when he heard Bob call his name. The rattle of falling shale at the same time gave him a pretty strong suspicion as to what had happened.

"Hello! what's the matter Bob?" he cried.

"I slipped, and fell over the edge of some sort of place here," came back the answer. "Luckily I've managed to get hold of a rock and stopped my tumble. But don't waste any time lending me a hand, Frank, because it seems to me I feel the thing move. If another quake comes it'll let me drop; and perhaps the ground may be a full dozen feet below."

By this time Frank had reached the edge of the drop. He remembered skirting it in climbing upward just a minute before; but had been more successful about doing so than Bob, who was less accustomed to this kind of work.

Frank again had recourse to his handy match-safe. Leaning over he struck a match on the face of the rock. Immediately he drew a quick breath. It was not because he could see the face of his chum only a couple of feet away, as the latter clung to a spur of rocks; it was something else that thrilled him.

As far down as his eyes could see there was only a black void! Instead of the simple dozen feet mentioned by Bob, the yawning precipice extended perhaps a full hundred feet downward!

But there was no need of telling Bob that it might alarm the boy and cause him to weaken, so that his grip would give way.

Frank was quick to understand what must be done. He could just touch the hand of his chum by bending far down; but that was not enough. Instantly he wrapped one leg about a sturdy, if dwarfed, little cedar that chanced to grow at that very spot, as if designed for the very purpose to which he was putting it. Then he was able to thrust himself still further down the face of the wall.

"Take hold, and grip like iron, Bob," he managed to say.

He felt the other obeying him, and thus they caught hold of hands.

"Now, try and dig your toes into the face of the wall if you can," Frank went on, calmly, so far as Bob could know. "It'll help me get you up. Climb over me. I've got a leg around a cedar, and nothing can break away. Now!"

"Say, perhaps you'd better let me drop down." said Bob, thinking his comrade was going to unnecessary trouble in order to save him from a little jolt.

"Climb, I tell you!" snapped Frank.

"Oh! all right, Frank, if you say so," and Bob started to obey.

Fortunately he was an agile lad, and a very fair climber, for the task which he had set himself was no ordinary one. But, by wriggling more or less, Bob managed to finally get a grip on the cedar. After that it was easy work; and having succeeded in reaching solid ground himself, he aided the almost exhausted Frank to draw back.

"Whew! that was some work, now, and all because I was so silly as to slip over the edge of that little hole!" remarked Bob, as though disgusted with himself.

"Look here," said his chum; "lean over carefully, while I drop this match down."

As he struck the match, and then cast it from him it went downward twenty, thirty, forty feet before it was extinguished.

"Ugh!" shuddered Bob, "why, it must be all of a thousand feet down to the bottom, Frank! It scares me just to think of the narrow escape I had."

"Well, I reckon it's all of one hundred feet," replied Frank; "and that's enough to settle a fellow. But let's lie back here, and get our breath a bit before going on up. The cave can't be far off now, if what Joe said is so."

Both of the boys were panting after their unusual exertion, and Bob was glad of a chance to rest for even a brief time. Besides, another burst of thunder was starting in, and he fancied that it was louder than any that had gone before; just as if they might be drawing closer to the place from whence all this clamor came.

The cave that Spanish Joe had found and entered--could it have anything to do with the mystery of the mountain? Frank seemed to think so, and was bent upon ascertaining the facts.

"Listen to that, Frank?" shouted the Kentucky lad in the ear of his mate, while the racket was at its height. "I can hear rocks dropping all around, just like the one did where Joe was grabbed by the leg. Do you think this always happens when the old mountain breaks loose; or is this an extra big celebration?"

"I was trying to get that myself, Bob," admitted Frank; "but we can only guess at it, because you see, nobody's ever been up here when the thunder was rocking the whole range, and so we don't know. But, honest, now, I'm of the opinion this happens only once in a great while; else the mountain would have been racked to pieces long ago."

"And just to think, we had the nerve to come here at a time when it was bound to do its worst," said Bob.

"Glad of it," Frank immediately returned. "It gives us a better chance to learn a few things worth while. I always did like to be in where the roping was fastest. Are you feeling better, Bob?"

"Oh! yes, I reckon I'm all right now," returned the other, rising.

"Ready to go on, then?" continued Frank.

"Try me, that's all. If I turn tail and run, don't ever speak to me again," came the steady, but not boastful, answer.

"Good boy! All right, let's be off again; and be mighty careful how you move. There may be more of those drops lying around loose. And next time you mightn't be so lucky about grabbing a spur of rock."

"That's so, Frank. Wow! but it makes me shiver to even think of it. Talk about Joe's narrow squeak, it wasn't any worse than mine," and Bob started to crawl after his better-trained chum.

Two more evidences came to them of the violence of the unseen force that was making Thunder Mountain shake, before Frank stopped to let his chum reach his side, so that he might exchange a few sentences.

"Looks like that might be the hole ahead," he ventured.

"I can see something that seems blacker than the night itself; is that what you mean, Frank?" asked Bob.

"Yes," his chum continued. "When Joe pointed up this way I took note of just the line, and followed it closely. That was why we came so near the precipice. And if that is the opening to the cave, we want to lie here and listen."

"Why, do you really believe the racket comes out of that hole?" demanded Bob, astonished at the very idea of such a thing.

"Wait and see," replied the other, confidently. "In the meantime, here's our opportunity to pick up a few candles that will come in handy."

They had come to a halt directly under a tree; and Bob had already discovered that the ground was thickly strewn with broken branches. Some of these were apt to be fat with the inflammable gum that exudes from certain species of cedar, and would, as Frank said, make splendid torches.

Frank was already on his hands and knees searching for suitable ones; and as Bob grasped the idea he, too, set to work.

"I have four already; how do you stand?" asked Frank, presently.

"Just as many--no, here's the fifth one, and the best of the lot," came the reply from the Kentucky lad, who went into everything with ardor and enthusiasm.

"That ought to do for us," Frank went on. "And now, listen for all you're worth, because the war is on again!"

Lying there, Bob heard what seemed to be the first signal. It was as though some giant hand had tapped the solid rock with his club. Then faster came the blows, and more and more did the din increase, until it was fairly deafening. Only for his intense eagerness to hear every sound Bob might have been tempted to thrust his fingers into his ears in order to shut out the awful clamor.

To him it seemed as though a thousand anvils were being beaten in chorus, with a few other minor chords thrown in for good measure.

And what interested Bob most of all, as he crouched there listening, was the fact that all this dreadful noise seemed to be coming directly from the spot where his comrade had pointed out as the opening of a cave.

There was not the faintest trace of lightning accompanying the manifestation; and this proved, beyond all question of dispute, that the mystery connected with Thunder Mountain had nothing to do with an electrical storm. Possibly the observing Indians had many years ago discovered this same thing; and it had strengthened their belief that the great Manitou spoke to his red children through the voice of the wonderful mountain.

It took longer, this time, for the noise to die away; just as though, whatever its cause, there was increasing reluctance to subside again.

"That was a screamer, sure enough!" said Frank, when he could make himself heard above the declining roar.

"And Bob, you noticed, didn't you, that it seemed to come right out of that hole? All right, it begins to look now as if we were Johnny on the spot, if we've got the nerve to push things. Somewhere in there, Bob, lies the explanation of the mystery. Do we take the dare; or stay out here and wait till the fuss is over before entering?"

Bob possibly swallowed hard before replying. It was no easy thing for him to say the words that would thrust them up against so terrible a thing as this unknown peril awaiting them in the gloom of that crack of the great mountain. But his hesitation was brief. In fact, he only wanted to catch his breath, shut his teeth hard together, and summon his Kentucky blood.

"It's a go, Frank!" he said, with determination in his voice; "the chance may never come to us again. Let's go in, and discover for ourselves the secrets of the Indian god they say is guarding Thunder Mountain. I'm ready, so lead on!"