Stacy threw almost the whole force of his weight on the right stirrup to offset the list of the saddle on the other side, where the stirrup had gone down too far for him to reach. And the first hurdle found the lad clinging desperately to the pony's mane with one hand, the jolt of the jump nearly dislocating his neck as the animal took it.

The youthful rider, finding himself safely over, uttered a series of shrill yells and began urging on the pony with quick, short encouraging blows of the quirt, though the blows were not heavy enough to hurt the tough little beast at all. It was used to much more serious treatment.

Somehow the animal seemed bent on doing its best, though the more it strove to reach the goal, the greater was the fat boy's torture.

Stacy Brown's grit was aroused. He seemed to have come into his own at last.

"They laughed at me," he muttered. "I'll show them that Chunky Brown isn't a tenderfoot. Even if I don't win the race, there will be some others who will finish after I get through." He was reasonably certain of this from his present position. "But I hope I don't fall in," he grinned.

By this time the dust caused by their first trip over the course, had settled so that the spectators were enabled to get a view of the last quarter of the race. And they all admitted, without exception, that it was a real race that they were watching.

Over the last hurdle went two ponies in beautiful curving leaps, ahead of all the others. With their cowboy riders they took the obstruction neck and neck. A full length behind them rode Stacy with the rest of the field strung out to his rear.

The spectators were able to identify the black now from their point of vantage, and Stacy could hear their cheers, though unaware that these were for him. Tad Butler, second to him in the race, was getting every ounce of speed from his pony that the animal possessed. Yet instead of feeling chagrin over the fact that his companion was out-footing him, Tad was elated.

"Go it, Chunky! Go it!" he encouraged.

"I am going," floated back to Tad faintly, causing him to laugh so heartily that he was nearly unhorsed when his pony rose to the hurdle.

As Stacy's mount cleared the last barrier, the fat boy fell forward on the pony's neck, which he grasped wildly, for the saddle in that final leap had, with disheartening suddeness, given way beneath him, slipping clear down under the animal's stomach.

Nothing daunted, Stacy, with his newly discovered grit, worked both spurs vigorously, eyes staring straight ahead of him over the head of his fleeing pony.

They were almost at the finish. Now the dust of the two cowboy leaders in the race did not smite him in the face as heretofore. He was too close up with them for that.

All at once the lad realized that he was gaining. Excitement among the spectators ran high. Observing his predicament and understanding full well the grit he was exhibiting, they were yelling like mad. Chunky began to yell also, uttering a series of shrill whoops, using voice and spurs incessantly, urging the pony to the goal.

The black pony, almost gray with the dust that had settled on his sleek, glossy coat, forged ahead in a noble sprint with head on a level with its back, nose reaching for the finish.

A roar of applause sounded in the fat boy's ears. Yells, cat calls and shrill whoops rent the air.

All at once a pistol barked, the black pony's feet plowed the dust, bringing it to a sharp halt.

The suddenness of the movement caused Chunky's feet to rise straight up into the air. For a few brief seconds he was standing on his head on the pony's neck like a circus performer.

Then, as the animal lowered its head, the rider toppled over, still clinging to the neck of his mount. Such a chorus of laughter and shouting the Jessup ranch had never known before.

"How is it, Mr. Umpire?" piped Stacy, releasing one hand from the pony's neck and raising it questioningly.

"This isn't a baseball game, young fellow," jeered the foreman. "This is a hoss race and you've won it. The black wins and you get the rifle."

The grimy hand that the lad had held aloft still clung to the remnants of the roast sandwich that he had carried throughout race.



CHAPTER XVIII

TAD WINS A ROPING CONTEST

In their enthusiasm two of the ranchers hoisted Chunky to their shoulders and marched about singing. Others fell in behind them until fully half the spectators had joined the procession. Chunky leered down at his companions as he passed them and winked solemnly.

"I didn't suppose he could ride like that," marveled Tom Phipps.

"Neither did any of the rest of us," answered Walter.

"I never saw a more plucky piece of work in my life."

Tad came up to where they were, laughing heartily.

"Doesn't that beat all, Walt?"

"It certainly does."

"Our friends who were defeated do not seem to appreciate the humor of it, though," interjected the young engineer.

"No, not very sportsmanlike, is it? Who is that fellow with whom Chunky's competitors are talking?"

"Name is Cravath. Queer sort of a chap."

"Haven't I seen him about the Red Star?" asked Tad.

"Yes, no doubt. He is a checker at the mine. He and his wife and daughter have a cabin out near the Ruby Rock that you are so much interested in. I know very little about him—"

"Don't like his looks at all," decided Tad.

"No, I never warmed up to him very much myself. I understand he is not very popular among the men, either. But I guess that is because he wins their money in games of chance."

"A gambler?" questioned both boys in surprise.

"I wouldn't go far enough to say that. What are they going to do next here do you know?" asked the engineer, changing the subject.

"I believe it is to be a roping contest. That will be a lot of fun."

"You are not going in it, are you?"

"Of course. Why not? I don't know what they are going to rope, but I'll take my chance with the rest of them whatever it is. Guess I'll ride over and ask Mr. Jessup. I see him over there now."

Mr. Jessup when questioned informed the boy that it was to be a most realistic contest in which two men mounted were to try to rope each other. One of the rules of the contest was that the roper, when he caught his opponent, was to drop the lariat instantly so as not to pull his victim from the saddle.

As only two could meet for the prize it was decided that lots should be drawn from a hat. The two who drew slips of paper with the word "rope" written on them, were to have the honor of meeting in a test of skill.

The prize was a Mexican saddle, silver mounted, at which all the cowmen looked with covetous eyes.

"Think you want to take a chance for the saddle, boy?" asked Mr. Jessup.

"That I do," laughed Tad. "That's the saddle I want—I always have wanted one just like it. But I'm afraid I shall not get the opportunity to try for it."

"They are getting ready to draw. You had better go over," advised the rancher.

Tad found that they were not only getting ready, but that most of the men had already drawn. Only one "rope" slip had been taken from the hat, however, so there still was a chance.

He rode up to the foreman, who was holding the hat from which the drawing was being done.

"May I draw?" he asked.

"Do you know how to sling a rope, kid?"

"A little," answered Tad, with an embarrassed smile, for the cowmen were making uncomplimentary remarks about letting babies into a man's game. The boy's face burned, but he gave no heed to their ungentlemanly remarks.

The foreman held up the hat. Tad leaned over and drew from it a slip of paper.

"Next—who draws next?" demanded the foreman.

"If it will save you any trouble, I might suggest that it isn't necessary to draw further," Tad informed him, with the suspicion of a smile on his face.

"What's that?" asked the foreman sharply.

"I have the second slip," was the quiet reply.

The cowboys broke into loud exclamations of disapproval.

"Fair is fair, boys," warned Mr. Jessup. "You all had your chance and you lost."

"Yes, that's right," agreed the foreman. "You fellows will have to swallow your pills without making faces."

The man Cravath was now talking with the cowboy who had drawn the other slip. He was one of the men Chunky had won from, though Tad did not know it at the moment.

Tom Phipps pushing his way up to the lad informed him of this fact, and drawing Tad to one side whispered something to him.

"Is that so?"

"Yes, Cravath owns one of the ponies that came near winning the race. He is not a very good-natured man and I imagine they are putting up some plan to get even with you boys," warned Tom.

"I'm not afraid. They won't let them do anything unfair," said Tad. "Besides, I ought to be able to take care of myself, by this time, though I haven't been doing much with the rope of late. Is that chap an expert roper?"

"I couldn't say as to that. But he's big and strong—"

"Which doesn't count for very much in this sort of a contest," laughed the boy.

"Very well, you know best. But keep your eyes on him."

"Are you gentlemen ready to begin?" called the rancher.

"I must go now," said Tad hurriedly.

"Good-bye and good luck," breathed Mr. Phipps, as the lad rode away at the same time straightening out his rope which he allowed to drag behind his pony while he recoiled it, working it in his hands to limber the rawhide.

"It's a good rope," decided Tad.

The foreman halted them for final instructions.

"Now, gentlemen, understand that the rope must go over the head and be drawn taut, after which you are to let go of it. You are to take your places some distance apart—I'll place you—and start at the crack of the pistol, not before. Understand?"

Tad and the cowman opposed to him nodded, the latter with a sarcastic grin on his face.

The miner had lost the rifle which he coveted, and the cowboy did not propose to have the same luck in the case of the saddle, which was very valuable.

The cowboy had his rope in hand ready to begin, while Tad's had been hung over the saddle horn. The lad was sitting in his saddle easily, with a quiet smile on his face, and the spectators noted that he was not in the least nervous.

"I guess that boy knows his business," muttered Mr. Jessup, who had been observing him keenly. "At least he's got the pluck and will give a good account of himself, though he never will be able to win against a professional rope thrower."

In the meanwhile, the foreman had started to place the contestants. Tad had the sun in his eyes, but he made no protest, knowing that he could change his position as soon as they got the word to go.

"Are you ready?"

"All ready," answered Tad cheerfully.

"Yes," said the cowboy shortly.

Tad's rope was now held in his right hand. Both men put spurs to their mounts almost before the report of the revolver had died way. The ponies leaped forward and the two opponents rode straight at each other.

They passed at racing speed, neither making an attempt to cast.

No sooner had they cleared each other, however, than the cowboy pulled up his horse sharply, wheeled and dashed after the Pony Rider Boy. Tad, having foreseen the movement, had likewise stopped his mount, and turned about. But instead of spurring on, he stood still.

The cowboy had hoped to come up behind Tad and rope him as he raced away. He was slightly disconcerted when he noted Tad's position. But the smiling face of the boy angered him, and the cowman's rope squirmed through the air.

Tad ducked, allowing the lariat to shoot on over him. It fell harmlessly on the other side of his pony and a quick pressure of the spurs took boy and pony from under it.

With a "yip-yip" Tad rushed at his opponent. The latter had had no time to gather in his own lariat, but he began shortening it up intending to swing it from where it lay on the ground.

His opponent gave him no time for this.

Tad made a quick cast. The cowboy threw himself to one side, but the loop of the lariat that had been thrown true reached his broad sombrero, neatly snipping it from his head.

The spectators uttered a yell of approval. They shook out their revolvers, sending a rattling volley up into the air.

Tad Butler had scored first.

His opponent was angered almost beyond control. That a mere boy could thus outwit him, which Tad had neatly done, was too much for his fiery temper.

With a growl of rage he drove his horse straight at the lad. It was plain that it was the fellow's intention to ride him down, which Tad circumvented by standing still until the man was nearly upon him, and then driving his pony out of the path of the oncoming horseman.

Each began a series of manoeuvres, the purpose of which was to place the rider behind his opponent, but each proved too wary to be caught in any such way.

The contest was growing hotter every moment, and the spectators were getting worked up to a high pitch of excitement. They had never seen a more interesting roping exhibition than this, and that a boy was one of the contestants gave their enthusiasm an added zest.

The two were, by this time, working far out on the field. Tad realized this and sought to get back nearer to their starting point. He did not, however, understand that his adversary had any object in getting so far away, though the man had a distinct purpose in so doing, as Tad eventually learned.

The foreman was shouting a warning to them, which Tad tried to heed, although his adversary prevented his doing so by blocking the way each time.

Whenever the opportunity presented itself the cowboy would bump his pony violently against the one that Tad Butler was riding, in an effort either to so jar the boy that he could rope him or else possibly to unhorse the lad.

"See here, you stop that!" shouted Tad after the third attempt. "What are you trying to do to me?"

"I'll show you, you freckle-faced tenderfoot!" yelled the cowboy, making a vicious rush. At the same time his rawhide shot out.

Tad narrowly missed being caught that time, and in turn the cowboy was nearly caught by Tad's loop. A lucky sweep of his arm brushed I the lariat away not a second too soon.

Tad observing that his adversary, who was about to cast again, had him at a dangerous advantage, threw himself down on the side of the pony's neck. Both animals were running almost neck and neck at the moment.

With a whoop the cowboy let go. His loop closed around the boy's ankle which from his position on the pony's side, was sticking well up in the air. Tad's opponent, suddenly braced his pony, while the boy's mount raced straight ahead.

The result of this move was that Tad Butler was torn from his saddle, fetching away the stirrup box on one side with him. He struck the ground violently, and for a moment lay still, while the cowboy sat grinning, making no effort to learn how badly his adversary was hurt.

The foreman and several others were rushing to the scene. By the time they reached it, Tad was scrambling to his feet.

"I roped the kid," announced the cowboy, as if it were all finally settled.

"You roped me by the foot," retorted Tad.

"Yes, that was a foul," said the foreman. "I saw it myself. How'd you come to do that, Bob?"

"Mistake," answered the cowboy, thus admitting that they were right.

Tad turned on him sharply.

"Did you say it was a mistake?" he asked with a world of meaning in his tone.

"We will award the prize to you, Butler," announced the owner of the ranch. "That's the usual way when a foul has been committed."

The cowboy glowered angrily.

"I couldn't think of accepting it, Mr. Jessup," answered Tad, straightening to his full height. "I'll go on with the contest, but he mustn't do that to me again or there will be trouble."

Some of them laughed at the boy's veiled threat.

"There certainly will be trouble," agreed Mr. Jessup—"trouble with me. I want you two to keep up the field further so we can see what is going on. Are you hurt, boy?"

"Shaken up a little that's all. Guess my saddle was worse used than I was."

The contestants lined up for another bout, amid the most intense excitement. So closely had the spectators gathered about them that the ropers had no room in which to work, and the foreman found it necessary to urge them back before giving the word to start.

The Pony Rider Boys could scarcely contain themselves. They, too, were worked up to a high pitch of excitement. But Tad Butler, dirty, with clothes torn and grimy, appeared to be the coolest one in the crowd. If he was angry no one would have imagined it from the pleasant expression of his face and almost laughing eyes.

"All ready! Go!"

They went at each other again, the cowboy ferociously—Tad easily, but keenly on the alert, narrowly watching every move of his opponent.

Round and round circled the pair, neither making an effort to cast for at least ten minutes, ducking, side stepping, or as near to this latter as a pony could get, and with movements much like those of boxers in a ring.

The crowd was offering advice and suggestions freely, but both men turned a deaf ear to all of this. Their whole beings were centered on the work in hand.

Once both men cast and their lariats locked, the cowboy's loop having slipped over Tad's.

The foreman called a halt while he untied the tangle. The instant this had been accomplished, Tad drew in his with one hand, coiling it at the pony's side.

"Remember, I haven't called time," warned the foreman. "You are still roping."

Tad knew that, but he did not wish to take an unfair advantage.

The cowboy looked up with a startled expression on his face, but nodded and began hauling in his rope when he noted that Tad was making no move.

His rope was in.

"All ready," he said.

So was Tad. The boy's lariat shot gracefully through the air, landing neatly over the cowman's shoulders where it was quickly jerked taut before the other fully realized what had happened.



CHAPTER XIX

WRECKED IN AN ORE CAR

It was all the ranch owner could do to keep peace after Tad Butler had so cleverly outwitted his adversary in the rope throwing contest. Yet, though the defeated man was fairly beside himself with rage, the cowboys generally favored fair play.

Their companion had been beaten in a fair contest, principally because his opponent had been quicker witted.

Tad and Chunky, one bearing a rifle, the other a handsome saddle, were proud boys when they rode home with Tom Phipps and their companions that night. The Pony Rider Boys had carried away the real prizes of the cowboy meet. Chunky had few words. He was so filled with self-importance that he could only look his gratification. When part way home, however, he rode up beside Tad, and leaning from his saddle, whispered, "I didn't fall off, did I?"

The news of triumph spread about the mining camp quickly. When the miners learned that Cravath's pony and his man had been defeated, they shouted for joy. From that moment the Pony Rider Boys became persons of consequence in the Red Star mining camp.

It was suggested that evening that the whole party spend the next day in the mine. Tom Phipps had permission to devote the day to them if they wished to go underground.

"That will be fine," cried Tad, to which sentiment all the rest subscribed, except Stacy.

"I'm going hunting," he announced.

"Hunting? What for?" questioned Ned.

"Anything I can see."

"Then, I'm glad we are all going to spend the day underground. It will be about the only safe place around this part of the country."

"Remember, Chunky, that's a powerful weapon of yours and long range," warned Tad.

"And remember to watch out that you don't fall off your new saddle and break your neck," retorted the fat boy.

On the following morning the boys, with the exception of Stacy, reported at Tom Phipps's shack ready for the day's sight-seeing in the zinc mine far underground. The assistant superintendent had made ready a large basket of food, as the party was to dine in the mine.

Professor Zepplin was enthusiastic. It was an opportunity that he had much desired.

"I understand," he said, fixing Tom Phipps with a stern glance of inquiry, as they started for the mine, "that Silurian species have been found in the limestones hereabouts. Also that others believed to be Cambrian have been discovered. Is this in accordance with your experience?"

"I think I understand to what you refer," answered Tom gravely. "I can't say that I am familiar with the species, however."

"If Chunky was here he would want to know if it were something to eat," laughed Ned. "I'm not very certain myself whether it is or not."

"You'll be wiser by-and-by," said Tad.

Entrance to the mine was gained through a shaft leading straight down for a great many feet. A windlass and bucket was employed to carry the miners up and down, while through another and larger shaft automatic buckets raised the zinc ore to the surface.

All of the party could not be accommodated in the passenger bucket at one time, so it was necessary to make two trips, Mr. Phipps returning with the vehicle to see that the rest of the boys got down safely.

Descending into the cool, damp darkness was a new experience for them. And while the sensations were not particularly pleasant, they agreed that it was the most interesting journey they ever had taken.

"How far down do we go?" asked Walter.

"About fifty feet," answered the miner. "Of course the mine is not that far underground all around. Some of the strata of rock we work lead almost to the surface in places."

"Why don't you begin at the top and work down then?" questioned Tad.

"Some of the mines do that. In this case it was deemed best to sink a shaft. Here we are."

From the darkness the boys had suddenly been plunged into a blinding glare of light. It was so intense that at first they were unable to see anything.

"Good gracious," blinked Ned. "This is brighter than the opera house at Chillicothe. It's enough to put a fellow's eyes out. What is it?"

"Electric lights," laughed Phipps. "We don't have many conveniences above ground, but down here we are right up-to-date, as you have observed."

"As I perhaps shall observe when I am able to get my eyes open once more," added Ned humorously.

"Why, the place is full of tunnels!" exclaimed Walter.

"Regular checker-board under ground," agreed Tad. "Where do all those tunnels go to?"

"Under where you have been tramping since you have been in camp."

"To the Ruby Mountain?" inquired Tad meaningly.

"Yes, most probably that far, or pretty close to it, I should say; but I have never made a measurement with that in view, so that I am unable to give you a definite answer. We should have to bore through some pretty solid rock to get under the little red mountain, I'm inclined to think."

"I'd like to go over that way."

"All right, we will visit that part of the drift later," replied Mr. Phipps.

What Tad's motive might have been in wishing to get under the Ruby Mountain, perhaps he himself did not know. But he did know that somehow he felt that before leaving the mining camp he would solve the mystery of the place.

They first followed the drifts to the west where here and there a dull distant report told them the miners were blasting out the rocks with dynamite. After being broken up into large chunks the ore was placed on little cars and run along tracks to the hoisting apparatus from where it was quickly shot to the surface.

It was a busy scene that the Pony Rider Boys found—a different world from the one they had just left above them.

"Do these mines ever blow up or catch fire?" asked Walter a bit apprehensively.

"No, we have no fires of any consequence. We have never had an explosion and I trust we never shall," answered the assistant superintendent gravely. "You see there is not the same danger in this sort of place that you find in a coal mine. I would prefer to work digging out dynamite to mining coal."

"Dynamite? Do you keep much of it down here?" interrupted the Professor.

"Oh, yes, we have to. There is enough down here at this moment to more than blow up the Ruby Mountain. The greater part of it is stored in what is known as the Ozark drift, the drift running to the southeast. I'll show it to you when we go that way."

Now they were nearing the more active operations and the metallic click of the steam drills filled the air as they bored their way through the solid rock, necessitating the raising of voices that the boys might make themselves heard.

"Would you like to take a ride in one little cars?" asked Mr. Phipps.

The boys were quite certain that they would enjoy such a trip.

"Pile into the next car, then. We'll send it through without any ore this time. There would not be room if we were to load the car. I think it will be a novel experience for you."

And Tom Phipps smiled significantly.

Directing the switch man to shift the car back to the return track, the mining engineer told the lads to climb in and sit down on the floor, which they did promptly.

Only the tops of their heads projected above the sides of the ore car.

"Under no circumstances must any of you straighten up unless you wish to get your heads smashed."

"Why, there is plenty of room for our heads here," replied Ned. "We could stand up and yet have some to spare."

"Right here, yes. We shall go through some places that you would not want to stand through, I imagine."

"Are you ready?"

"Yes."

Tom Phipps climbed over into the car.

"All right, Jim," he called.

Immediately the car began to move and in a few moments had attained a high rate of speed.

"Now, boys, remember your heads," cautioned their guide.

Instinctively each crouched lower as their vehicle was all at once plunged into sudden darkness. Drops of water now and then spattered down on their bare heads. The noise of the car in the dark was deafening. The sound was as if many ore cars instead of one were crashing through the dark tunnel. The lads experienced a strange thrill when the realization came to them with its full force, that they were shooting through the earth, far beneath the surface at the speed of an express train.

"Why don't you have lights in here?" asked one of the passengers.

"Not necessary," said Mr. Phipps. "It is seldom that anyone has occasion to go through this tunnel—practically never unless something happens to a car in here. There are lights along that may be turned on if necessary, but it would be a needless expense to keep them going all the time—"

"What's that loud noise?" asked Tad.

His ears had caught a booming roar that was a new note in the terrifying sounds of the underworld through which they were traveling.

The boys started uneasily.

"It's water," shouted the guide. "A cataract in an underground water course. These courses have cut channels all through the limestone rocks in the Ozark Uplift."

This somewhat calmed the nerves of the lads, though not wholly so. Faster and faster rolled the car and louder and louder grew the roar of the cataract.

"Are we almost out of here?" demanded Walter uneasily.

"Yes. We shall be clear of it in five or six minutes now. You notice that we strike little grades occasionally, which cause the car to slow down considerably and for that reason the journey seems longer than it really is."

"If we have slowed down at any time I have failed to observe it," laughed Tad.

"What if we should jump the track in here?" suddenly suggested Ned.

"But we won't," answered the guide. "We—"

A grinding, crunching sound cut short his words. The car appeared to pause and tremble throughout the length of its frame; then followed a deafening crash, accompanied by the sound of breaking timbers and splintering wood.

A deep silence, broken only by the roar of the cataract, settled over the scene. The ore car lay a broken, twisted, hopeless wreck.



CHAPTER XX

A MESSAGE THAT THRILLED

Out of the silence came the voice of Ned Rector.

"Help, I'm pinned down," he groaned. "Get me out of this awful hole."

"I'm coming as soon as I can get free of what's on top of me," answered Tad. "Is everybody else all right? W-a-l-t! Mr. Phi-ipp-s!"

Tad struggled desperately and in a brief time succeeded in freeing himself. What had happened to the guide and to Walter he did not dare to think.

First upon getting clear of the obstruction that pinned him down, he rushed to Ned Rector and succeeded in releasing him without great difficulty. Neither boy was hurt much.

"Where's the other two?" cried Tad in a voice of anxiety.

"I don't know. Don't know where I am myself," groaned Ned.

"Hurry, help me find them."

Together the boys groped about in the black tunnel.

"I've got one," called Ned.

"Which one?"

"I don't know. Yes, yes, it's Walt. He's breathing. What shall I do?"

"Drag him over to one side. I've got Mr. Phipps here. I'll have him over there in a minute."

Tad began tugging, with hands under the shoulders of the guide, understanding instinctively that he must get him where they could work over him and try to bring him back to consciousness.

Something whizzed by in the darkness, the rush of air nearly knocking both boys over, and leaving them trying to catch their breaths.

"Wh—what's that?" gasped Ned.

"I—I don't know," answered Tad. "Yes, I do too. It—it was a car returning on the other track for a load of ore."

The lad's knees went weak under him when it came to him that he had only a second before dragged the unconscious figure of the young engineer from that very track.

Now still another sound startled them. It was a roar heavier than any that they had heard before, and as near as they could tell, it was from the direction that they had come.

"Hurry, Ned!" shouted Tad Butler fairly electrified by the thought that suddenly flashed over him.

"What is it? What is it?"

"I—I don't know, but I think it's a car of ore rushing down the grade toward us."

"We're dead ones, then!" cried Ned.

"Be quick, Ned! Grab Walt and run as you never ran before!

"On, on! Keep to your right so you don't get on the return track. Oh, Hurry!"

Tad had already gotten into action. Once more grasping the guide by the arms, the lad ran backward with his heavy burden, with almost marvelous speed under the circumstances.

He was none too soon. Back of him he could hear Ned stumbling over rails and ties with his burden. Then came the heart-rending crash.

The car of ore had plunged into the wreck of their empty car, hurling rocks in all directions. Had they remained where they had been, there would have been none left to tell the story of their experiences.

"I guess it's all over," shouted Ned. "But, there will be more, soon, and some of them may hit us."

In obedience to Tad's command, Ned dragged Walter along a few rods further, where on a curve both boys laid down their burdens.

Tom Phipps under the rough treatment that he had received was stirring and making an effort to sit up. Tad helped him along by slapping him vigorously between the shoulders. Ned was shaking Walter almost savagely.

"Wake up, Walt! Wake up! What's the matter with you?"

Walter groaned.

By this time Tom Phipps had partially pulled himself together.

Tad's heart leaped with joy.

"Walt will be all right in a minute, I guess," Ned informed him.

"And so will Mr. Phipps."

"Where am I?" asked the young engineer.

"We've had an accident, Mr. Phipps," replied Tad. "How do you feel?"

"As if I had been put through the ore mill. Did we have a smash?"

"I should say we did?"

"Who's hurt?"

"Walter was knocked out too, but he is coming round now. Ned thinks the boy is not hurt very badly."

"No, I'm half scared to death, but I'm all right otherwise," answered Walter for himself.

"Which track are we on?" demanded Phipps suddenly, trying to locate his position.

"Our own. You nearly got run over on the other. I pulled you off just in time."

"I'll thank you later. There must be a cross cut near here. If we can find it we'll be able to get to a point where I can telephone them to hold back the cars. They'll fill the tunnel before they know anything has happened, if I don't get word to them at once."

"I should think they would miss the cars."

"They should," answered the engineer. "Is your friend able to walk?"

"How about it, Walter?" called Tad.

"Yes, I can run if it will take me out of this terrible place any sooner."

"Then we'll run," decided Tom Phipps. "I must have gotten an awful hit on my right leg, for I can scarcely bear my weight upon it."

"Shall I rub it for you?" asked Tad.

"No, we haven't time. We must look for that cross cut, which leads into the number eleven drift. Keep to your right, boys. We are safe here now, but not on the other track."

"I know that," answered Tad. He shuddered as he recalled the black, projectile-like object that had whisked by him just after he had pulled Mr. Phipps from the return track.

There was still another reason why the assistant superintendent was so filled with anxiety to reach a place where he could notify the terminals to stop the cars. He did not confide this to his young friends, not wishing to disturb them any more than they had been.

All hands started on a trot, now stumbling, now falling, but without a single murmur, or protest.

"You are a nervy bunch of boys. Never saw anything to equal you," gasped the engineer. "I can't forgive myself for getting you into this wretched mix-up."

"You never mind us. We're all right," answered Tad brightly. "I'm sorry you got knocked out so."

"Here's the cross cut," cried the miner. He had paused and was cautiously feeling his way along the wet, slippery wall.

The boys breathed a sigh of relief.

"Now run as if the Indians were after you. I'm in a bigger hurry than I ever have been in my life."

And run they did.

The boys had no idea what Tom Phipps's reasons were for urging such haste upon them, but they knew they must be urgent ones.

Tad found himself wondering what new peril might be facing them. He decided that the assistant superintendent must be seeking to protect the company's property by stopping the sending of more cars through the tunnel. Yet, if this were so, why had the guide urged them to such haste.

"No," said Tad to himself, "it's something that we don't know anything about. But unless I am greatly mistaken we are going to find out pretty soon."

In this the boy was right. They were to find out what it was that Tom Phipps feared, and in a manner that they would not soon forget.

The narrow cut through which they were now rushing was little higher than their heads, and was very narrow, so that by raising their elbows they could barely touch the sides and keep themselves in the middle of the passage way.

"Look out for a turn just ahead," warned Phipps. "After that it is straight away."

The turn which they made a few seconds later, Tad imagined, led back toward the place where the car had started from. But they came to the end of the passage abruptly.

They caught a faint click, and instantly they were surrounded by dazzling light. As soon as they became used to the brightness they discovered that they were in a sort of chamber which looked as if it had been worn out by constant and long action of water.

Instantly upon switching on the light, the young engineer sprang to a telephone on the wall. Tad observed that the wires from it followed out into the passage through which they had entered.

The assistant superintendent was telephoning now, and the lads listened intently.

"Hello, hello!" called Phipps in an impatient voice. "Yes, who's this? Acomb? Say, Acomb, there's been a wreck on the number one track just west of here. Two cars smashed, one loaded the other carrying myself and some young men, guests of the company. Don't let any more through until the wreck is cleared away. Send an empty along with the wrecking crew so we can get out. What's that?"

Tom Phipps shuffled his feet about nervously on the stone floor.

"Hurry then, hurry! Yes, we're all here, but hurry!"

The boys instinctively drew near. They imagined that they could hear each other's hearts beat, so tense was the silence.

He turned halfway around to glance at the boys.

"Is it anything serious?" asked Ned in a strained voice.

"I hope not. I can't tell you just yet. We shall know in a minute... Well, send some one for him," he snapped, answering something the man at the other end of the line had said to him. "Hello, hello! That you, Bob? Did Acomb tell you of our predicament? Yes. What I wanted to say was don't for goodness' sake send out the red car while the line is blocked."

"The red car," repeated Ned and Tad in one voice. Neither knew what it meant, but impressed them just the same.

"What, gone? gone?" groaned Phipps. "Are you sure? How long ago? Ten minutes? Shut off the current! Quick! I hope so."

The assistant superintendent hung up the telephone deliberately and turned toward them.

The boys observed that his face was white and drawn.

"What, what is it?" asked Tad.

"There's a car of dynamite coming through the tunnel on the number two track," announced the young engineer calmly, thrusting both hands deep into his trousers pockets.



CHAPTER XXI

IMPRISONED IN A MINE

"That—that's the track that the empty cars go back on, is it not?" asked Tad, after an interval of tense silence.

"Yes."

"The wreck was on the other track."

Tom Phipps nodded.

"Then what harm can the red car, as you call it, do?" interrupted Ned Rector.

"That remains to be seen. The chances are that the number two track was blocked when the car of ore was spilled out."

"Which means?" questioned Tad.

"That there may be another collision," smiled the assistant superintendent. His was a wan smile, however, and failed to enliven the Pony Rider Boys.

"Will the dynamite explode?" asked Walter half fearfully.

"Probably not. I hope not. But you can't tell anything about these high explosives. They're very freaky. All we can do will be to remain here and wait for the car either to stop somewhere after the power has been turned off or to rip its way through the wreck we just left. At any rate we are safe in here."

The boys breathed a sigh of relief.

"Then, there is no danger to us?" asked Ned Rector.

"The danger is minimized."

"How far are we from where we started?"

"Probably a couple of miles."

"My! the Professor will be half scared to death when he hears what a fix we are in," half laughed Ned.

"The foreman, Mr. Acomb, said he would telephone to the other end of the drift telling them we were all right and not to worry about us," said Phipps. This relieved the boys' minds of one source of worry.

"Hark!" cautioned the young engineer.

The lads ceased their talking instantly and listened with straining ears.

"What is it?" breathed Tad.

"It's a car going through the tunnel."

"Is—is it the red car?"

"I don't know. It's a gravity car—traveling along down grade by its own weight, so it must be on track two."

"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 prone 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 passed.

"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 appetite," 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 passage.

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.

"That we are imprisoned far under the surface," answered the miner impressively.



CHAPTER XXII

THE BOYS FACE A MYSTERY

"Then how are we going to get out?" asked Ned Rector as the guide's match went out.

"That depends upon how long it takes to dig us out," answered Mr. Phipps.

"Then they know we are here?" questioned Tad.

"Oh, yes. Luckily for us, they do."

"Will they have to dig far—is that pile between us and the railroad very thick?" stammered Ned.

"It looks so. Of course I am unable to say what has taken place on the other side of it. The entire main cross cut may have tumbled in for all I know."

"If it has, what then?" demanded Tad.

"It will take that much longer to get us out. That's all."

"How long?"

"Master Ned, I don't know. No one can answer that question. Perhaps hours—perhaps days," said Tom solemnly.

"But we'd starve in that time," protested Walter.

"One can go without food much longer than one would imagine. People have fasted for more than a month, as you probably are aware. No, boys, they will get us out in time. The only thing that troubles me now is the air," said the engineer.

"What about it?"

"Well, we can't live without air, you know. It seems to be fairly fresh now, but how long it will continue that way there is no knowing. I'll examine the barrier, but keep back out of the way while I am doing so."

The young engineer climbed over the heap of broken rock in front of him, and made a careful inspection of the cave-in that had so effectually imprisoned them in the drift.

He found nothing to encourage him. The condition of the collapse was even worse than he had anticipated.

"Can you pace—measure off by taking a series of long steps?" he asked.

"Yes," replied Tad promptly.

"Then please go back to where the bend in the cut begins, and pace down to where I am."

Tad did so promptly, glad to be able to do something to occupy himself as well as to help relieve the tension for the others.

"Exactly forty paces," he informed Mr. Phipps.

"One hundred and twenty feet, eh?" The engineer made a brief calculation in his mind. "One hundred and twenty feet. H-m-m-m."

"Is it as bad as you thought?" questioned Tad.

"Worse."

"Tell me what you have found?"

"Only forty feet of cave-in between us and freedom. That's all."

"I should say that was enough," muttered the lad.

"Ample."

"Is there anything we can do, Mr. Phipps?" spoke up Ned.

"Not a thing. All any of us can do at present is to wait. Knowing we are here, they will lose no time in attempting to get us out. I wish the telephone were working so we might let them know we are all right. We might as well go back. I'll make a trip out here occasionally to learn if they are making any signals to us. They will do this as soon as they can get near enough to the obstruction to make themselves heard."

"Make signals—how?" questioned Ned.

"We use a code, a telegraph code. They will rap with a hammer then we'll answer them."

"But you have no hammer—"

"No, I'll use a rock to pound with if they get near enough. There's no hurry, however. It will be a long time before there's any occasion to communicate."

Turning back, Tom led the way through the passage to the large chamber which they had but recently left. Arriving there, he directed each of the lads to light a match at the same time so he could make a survey of the room to determine whether it were safe for them to remain there or not.

"See that hole up there?" he exclaimed.

"Yes, what is it?" asked Tad.

"It's a check. You see there must have been a weakness in the strata at that point—perhaps it had already started to check there, when the force of the explosion split it wide open. The opening is large enough to admit a man's body. Hold your lights down here while I examine this rubbish that has fallen through."

They did so, and Mr. Phipps dropping to his knees sorted over the stones and dirt that had fallen from above.

At a muttered exclamation from him, the lads crowded closer.

"Queer, very queer," he mused.

"What's queer?" asked Ned.

"Why, this stuff. It appears to be surface material mixed with pieces of rock of about the same quality as that of which the Ruby Mountain is composed."

"I don't understand—"

"I mean that this material that has fallen in here did not all come out of the solid rock."

"What does that mean?" asked Ned.

"Perhaps nothing so far as we are concerned. I was thinking that if they could not blast through the drift, they might as a last resort, drill down through the surface from above and pierce this chamber."

"How could they locate our position close enough to do that?" asked Tad.

"That would not be difficult. From the maps of the mine Mr. Munson could work out our position as closely as a captain does that of his ship at sea."

It was a ray of hope which the boys grasped eagerly. They tried to forget that they were practically entombed many feet underground, and that days might elapse before they were rescued.

"I'll bet Chunky will hug himself with delight when he finds out what's happened," suggested Walter.

"Yes, he'll probably think it's very funny, our being bottled up or rather down in a corner underground," said Ned somewhat dolefully.

"I didn't mean that. He'll be glad he went hunting instead of coming along with us," corrected Walter.

"Yes, I guess he will," agreed Tad. "He'll have a right to congratulate himself that he has missed an opportunity to fall in."

The lads forgot their predicament for the moment in the laugh that followed.

"I wish we had a light," said one.

"We might build a fire. What's the matter with burning up our hats?" suggested Ned.

"No, we should be suffocated. Don't you know we are sealed up," objected Tad. "We don't want to make any additional trouble for ourselves."

"Yes," agreed the guide. "But it is peculiar that there is so much fresh air here. Now and then I can almost imagine I feel a draft, though I know that is not the case."

"Could we not get a draft through that large crack in the rocks up there?"

"I don't see how, Tad. There is nothing but solid rocks above it."

The lad stepped under the opening, holding up a finger which he had wet between his lips. For a full moment he stood poised like a statue while the other two boys lighted matches that they might the better see what he was doing.

"I don't care what you say, there is air coming from somewhere. There can be no doubt of it. I feel it plainly. Try it and see if you don't agree with me, Mr. Phipps."

The engineer stepped up and went through the same process that the boy had gone through. He repeated the experiment twice more.

"You're right," he exclaimed, letting his hand drop to his side. "Your good sense is worth more than all my technical knowledge and training."

"The next question is to find out where the draft comes from. It must be from the outside somewhere," said Tad hopefully.

"Not necessarily, my boy. Of course it may be drawn down through crevices covering many feet of solid rock before reaching us. Then again, the air may come from some subterranean water course. As you know the mountains are full of them, channel upon channel, some high and broad enough to drive a coach and four through."

"Oh. I hoped—"

"Never mind regrets, boys. Wherever the air comes from makes little difference so long as it really is air. It is saving our lives."

"From what?" demanded Walter.

"From eventual suffocation. Were it not for that we would stand a good chance of dying before they were able to reach us."

The boys were thoughtful for a few moments.

"Hungry?" questioned the engineer.

"Somewhat," admitted Tad.

"We might be more so if we had a chance to think about it," added Ned.

"I've got a package of chewing gum here. Help yourself," offered Mr. Phipps.

The lads were not slow to do so, and in a moment were chewing industriously, laughing and talking at the same time.

"Beats all what a little thing will make a fellow forget his troubles," said Ned. "Now, I remember—"

"Hello, boy!"

"Who said that?" demanded Tad Butler springing up from the pile of rocks on which he had been sitting for some time.

"Said what?" snapped Ned. "I was talking when you interrupted me."

"I thought I heard somebody say 'hello,'" confirmed Mr. Phipps.

"So did I," added Walter.

"And I know they did," said Tad emphatically.

"Hello, boy!"

This time all sprang up, startled.

"Who's playing tricks?" shouted Ned.

"Heard it that time, did you?" asked Walter. "It wasn't I."

"Nor I," chorused Tad.

"Then it must have been Ned or myself," said Phipps. "I'm sure that I am no ventriloquist."

For the moment Phipps wondered if they were all losing their senses. He had heard of men, imprisoned under similar circumstances, imagining they heard voices.

Tad Butler, however, knew that imagination had played no part in this voice. He had heard the voice before. He informed his companions of this fact.

"Heard it before? Where?" exclaimed Ned.

"On top of the Ruby Mountain yesterday," answered the boy.



CHAPTER XXIII

IN THE RUBY MOUNTAIN

Tom Phipps nodded. He recalled his conversation with Tad upon the other's upon his return from his visit to the Ruby Mountain, and the lad's description of the mysterious voice he had heard there. Mr. Phipps did not give very serious consideration to that part of the boy's story at the time. Now, however, he was startled beyond words.

All of them were startled. To hear a strange voice many feet down under the ground, when all supposed they were far beyond the reach of a human voice, was enough to give almost anyone a start.

Yet Tad was not as much surprised as were his companions, for it will be rememberred he already had been through the experience that was so new to the others.

"Who are you?" demanded Mr. Phipps almost sternly.

There was no reply to his question.

"Tad, are you sure that is the same voice?"

"Positive. There can be no doubt. And, besides, she has used the same words."

"But it's impossible," insisted the young engineer. "No one, let alone a woman, could get near enough to this chamber to be heard as distinctly as that."

"I—I think it must be somebody who can go right through a rock," stammered Ned.

"Ghosts," nodded Walter.

"That's what I thought at first. But I knew it couldn't be after I had time to think twice. And I—"

"He-l-l-l-o-o-o!"

"There it goes again," fairly shouted Tom Phipps. "I'm going to find out what this means before I'm another minute older."

Hastily lighting a match he made a tour of the chamber, every corner of which he examined carefully, ending by a long, critical survey of the hole in the roof.

"It is just as impossible for anyone to be up there as it is to expect to see some one walk through the solid rocks here beside us," he decided, throwing the spent match on the floor where it glowed briefly and went out, leaving the darkness more dense than before.

Tad struck a fresh match.

"Hello, what's this?" he cried, reaching for a small package that lay wrapped in a piece of newspaper on the floor near him. "I didn't see that before."

"Doughnuts!" shouted Ned, who had been peering curiously over Tad's shoulder as the latter opened the package.

"Yes, and they are real," exulted Tad. Already one of them was in his mouth, and the others of the party quickly helped themselves. There was just enough to go around.

"I don't care who you are, but we're much obliged just the same," called Ned in a muffled voice.

"Yes, there's nothing ghostly about this 'bear sign,'" added Tad.

As for their companion, Tom Phipps, words failed him.

"I'm sure I'm going crazy now," he said. "If you are real, for goodness' sake tell us who you are and where you are?" he pleaded.

A merry, chuckling laugh answered him.

"She's up there!" said Tad Butler sharply. He had been listening with every sense on the alert, determined to locate the owner of the voice when next she spoke. Now he was sure that he had succeeded. "I know where you are but I don't know how you ever got there."

"Do you know a way out of this?" interjected Walter.

"Of course," answered the girl.

Tad nodded to his companions. They were burning up their matches very fast now in an effort to catch sight of the owner of the voice.

"How did you suppose I got there if I didn't know the way?"

"No ghost about that, I guess," said the boy.

"Will you help us to get out of here?" asked Tom.

"Can't."

"Why not?" demanded Ned.

"Can you climb up here?"

"No, certainly not."

"Well, that's the answer."

They laughed in spite of themselves.

"Will you tell us how you got where you are?" asked Mr. Phipps.

"That's a secret," replied the girl.

"And I presume your name is a secret too?"

"Yes."

"We'll find out who you are when we get out of here. I promise you that," threatened the assistant superintendent.

"Then good-bye."

"No, no, don't go! Don't go!" begged Tad.

"Say you won't tell on her, Mr. Phipps. "Don't you see—"

"All right, girl, I'll promise to keep your secret."

"You'd better," retorted the girl.

"How did you know we were here?" asked Mr. Phipps.

"I didn't. I heard about the explosion, so I came in here to see if my cave had been harmed any."

"You knew we were right under it, then?"

"Of course. How stupid you are!"

"Where is your cave?"

"I'm in it."

"Yes, I understand that, but where?"

"You ask too many questions."

"Say, young lady, can you find a rope that will reach down to us?" asked Tad, who had been turning over a plan in his mind.

"I guess."

"Please do so then. And hurry, won't you?"

"You will ask no questions?"

"Certainly not!"

"You won't try to find out anything about my cave?"

"No, no, of course not," answered Mr. Phipps impatiently.

"And you will do as I tell you?"

"Yes."

"All right. I'll be back in a minute."

Mr. Phipps sat down nonplussed. "I never was so mixed up in my life," he grumbled. "I can't understand it at all. How did she ever get there?"

"She says it's a cave," suggested Tad.

"But I know of no caves about here."

Tad shrugged his shoulders. That there was one and through it a prospect of their being liberated from their unpleasant and perilous position, was enough for him to know.

"Hello," shouted the girl after a few minutes.

"Yes, did you get the rope?" called Tad excitedly.

"Uh-huh."

"Then drop the end of it down."

A heavy coil hit Tad on the top of his head, nearly knocking him down. He scrambled from under while from above there sounded a peal of merry laughter.

"I don't care, so long as we have the rope," laughed the boy.

"Can you fasten the end of the rope to something up there?"

"No."

"Oh, pshaw! that's too bad," grumbled the boy. "But wait a minute."

Striking a match and shading his eyes with one hand, he peered up to the hole in the rocks. He noted a long narrowing crevice extending back from the main opening.

"I'll tell you what to do."

"Yes."

"Draw the rope into that crack as far as it will go, then tie a knot in the rope so it cannot slip through. I'll climb up—"

"You couldn't get up here. The end of the crack is too far from the place you see. Hold on, here's another crack just like it, right here in the rocks by me. I'll fix it. You all promise not to tell on me?" insisted the girl.

"Yes, yes, yes, we promise. We'll promise anything just now," laughed Ned.

An interval of silence followed while the girl was adjusting the end of the rope. Then she called down to them:

"All ready?" asked Tad.

"Yes, try it."

Tad grasped the rope, and swinging himself clear of the floor, jounced up and down several times.

"I guess it will hold. I'll go up first to see that the rope is secure; then the rest of you can follow me up."

"Why, I couldn't climb that rope to save my life," objected Mr. Phipps.

"I'll fix it so you can. I'll tie some knots in it, then climbing will be easy."

With that Tad once more swung clear of the floor and went up hand over hand with amazing rapidity. By the light of their matches they saw him disappear through the hole in the roof of the chamber.

"It's all right, fellows," he called down to the others. "I'll just haul up the rope and fix it for you."

This he did, letting the rope down to them a few moments later. Walter was the first to try the climb.

"I can't do it, Tad. I just can't," he cried, slipping back to the floor where he landed in a heap.

"Hold the rope down for him, then he ought to be able to make it," directed Tad.

Walter, however, had apparently lost his courage and declared that he could not do it.

"Take a hitch under his arms, good and strong. I'll pull him up," he commanded. They did as the boy above directed, then Tad began his pull. It was a fearful task.

"Grab hold of me, put your arms around my waist and brace yourself," he commanded, and the girl with quick wit comprehended what he wished her to do. Slowly, foot by foot Tad hauled the dead weight up. The last few feet of the rope seemed a mile to him.

With a final desperate effort, just as his muscles seemed to be at the breaking point, Tad, hauled his companion safely to the flat rock beside him, then fell on the floor of the cave, gasping for breath.

"Le—let the r-rope down," he said faintly.

The girl obeyed.

Ned shinned it with little difficulty, Tom Phipps insisting that the lad should precede him, though Ned wanted him to go first.

Tad was on his feet again.

"Can you make it?" he called down.

"I don't know. I'm going to make a big attempt at it," answered the miner. They heard the rope creak and knew that he had thrown his weight upon it.

"I'm afraid I can't get all the way up. My arms are giving out," they heard him gasp.

"Don't let go! Don't let go!"

"I'm afraid I can't help it, my muscles won't stand the strain."

"Twist the rope about one leg and rest. You can hang there all day if you'll do that," snapped Tad. "How is it!"

"Yes, that works fine. My arms are all a-tremble. I didn't suppose I was so weak?"

"You are not used to it, that's all. That's right; come along. I'll strike a match to light the way."

Little by little and with frequent rests, Tom worked his way up and up until within reach of Tad's strong arm. The lad grasped him by the coat collar and pulled him clear of the hole, dropping him flat on his back safe and sound on the rock where he had previously dumped Walter.

"Good gracious!" breathed Mr. Phipps. "Boy, you must be made of cast iron. You—you pulled me up here with one hand."

"You're here, that's all we need worry about just now," answered Tad, breathing heavily. "Now, Miss, will you please tell us how to get out of here?"

"Come," she said, taking Tad by the hand. She turned away, the others following in single file.

Almost at once they emerged into a high-ceilinged cave, dimly lighted as if through stained glass windows.

The lads uttered an exclamation of amazement.

"I know you now. You're Rose Cravath, Tom Cravath's daughter!" cried Phipps, striding forward and grasping the girl by the shoulder. "I demand to know what all this means?"

Tad stepped between them, pushing Tom aside.

"Remember your promise, Mr. Phipps," he warned.

"Yes, but do you realize where we are, boys?"

"No, and I don't care."

"We're in the Ruby Mountain."

"Look! Look!" shouted Tad excitedly, grasping the arm of Phipps.

With this, he dashed away to a distant part of the chamber that lay in deep gloom. Phipps looked in bewilderment.

A few moments later, Tad emerged from the darkness leading a broncho.

"Didn't I tell you?" he asked triumphantly. "I knew I'd get him some day—this is my stolen broncho." And then patting the pony's neck affectionately, he added: "Good old fellow. I'm glad to have you again."

He had indeed recovered his pony. Probably awaiting the departure of the Pony Riders from Ruby Mountain, the desperadoes had kept the pony—with two others—secreted in the mountain chamber. The other two ponies did not, however, belong to the Pony Rider Boys, much to the disgust of the latter.

"Just Tad's luck," growled Ned.



CHAPTER XXIV

CONCLUSION

Before the Pony Rider Boys had an opportunity to voice their astonishment, Rose held up a hand for silence. Voices were heard approaching.

"Hurry, hurry!" she whispered excitedly, leading the way through a low, narrow opening into another part of the cave.

Tom Phipps's hat was knocked off by the low archway, but not realizing the loss of it, he did not stop. As they entered the second chamber, which was even more brightly lighted than the one they had just left, they heard the sound of water, but were unable to locate the stream which they knew must be near by.

The voices died away to a low murmur and the girl who had been trembling violently, began creeping cautiously toward the opening to reconnoitre when all at once she started back with a little cry of alarm.

Before the eyes of the astonished boys there suddenly appeared two men. Mr. Phipps's hat had warned the men of the presence of strangers in their stronghold. Their faces, therefore, reflected anger instead of surprise.

For a few seconds the newcomers stood glaring at Phipps and the Pony Rider Boys.

"Tom Cravath!" exclaimed the assistant superintendent. "So, you are the mystery, are you?"

"Poaching, eh?" sneered Cravath unabashed.

"What business you got in here?" snapped his companion.

"I might ask you the same question, you fellow and Tom Cravath?" retorted Mr. Phipps, holding the two men with a level gaze. "And what's more I think your peculiar doings will bear looking into. There's something mighty queer about this business. I shouldn't be surprised if we found we'd solved a greater mystery than we thought—"

"You'll solve nothing!" shouted Cravath, suddenly drawing a revolver. His companion did likewise, both men quickly covering Tom Phipps and the boys with their weapons. "You'll find it ain't profitable to meddle with other folks' business."

"Pity you hadn't learned that lesson yourself," jeered Tom.

"It's over the cliff for the whole blooming bunch of you. I'll give you all the mystery you want."

"Father, father," protested Rose, horrified at her parent's cold-blooded threat. "They haven't done anything. They—"

"You shut up!" roared the miner. "Get out of here! Get in under the arch there! I'll attend to you later!"

The girl hesitated, then crept away sobbing as Cravath made a threatening move toward her.

"Now, I'll settle with you and your bunch of meddling tenderfeet," announced Cravath sternly. "Right about face!"

They hesitated, then turned in obedience to his command. There seemed nothing else for them to do, for both men were fingering their weapons suggestively.

"These boys have done nothing to harm you, Cravath," protested Mr. Phipps. "And no more have I. Mark me, you'll pay for this indignity, and dearly too."

"You don't say?" sneered the miner.

"I suppose this is where you hide the ponies you have been stealing," said Phipps boldly, a sudden thought having come to him.

"Forward march!" roared the enraged miner.

"Not—not over the cliff—you—you can't mean it?" begged Phipps, his face going suddenly pale.

"That's what I mean. You fellows are supposed to be buried in the mine down there. It'll take 'em months to blast into the place where they think you are, and when they reach the place you all will be gone a long time."

Cravath laughed harshly.

"Come now, over you go, unless you prefer to stand there and take your medicine."

"Hold on there a minute. I guess if anybody does the leap for life, it'll be you that does it," shouted a voice behind the two desperate men.

A second dynamite explosion could not have surprised them more. The men wheeled like a flash.

From the shadow of the archway, through which they had just entered, protruded a rifle barrel. The Pony Rider Boys who had also turned sharply at the interruption, observed that the gun barrel had a telescope attachment. Their eyes following further back, observed something else, too.

"Chunky!" gasped the lads in one voice.

Cravath made a move to level his weapon at the boy who had interfered with his plans thus unexpectedly.

"You stop that, now! I've got six bullets in this gun. If you get me excited I may press too hard on the trigger, and—well, maybe you'll think you've stepped into a hornets' nest. Drop those pistols!"

The muzzle of the repeating rifle never wavered. Behind the sights, the eyes of Stacy Brown had contracted into two narrow slits.

The desperadoes hesitated, measuring their chances shrewdly. They must have considered that these were not worth the taking, for they permitted their fingers to relax, the weapons falling to the floor with a clatter.

Chunky lowered his rifle ever so little, and the Pony Riders uttered a yell of triumph.

For one brief instant Chunky was off his guard. In that second he lost his prisoners.

With a bound the two men cleared the intervening space that lay between them and the cliff. They reached it at a point near the corner of the chamber some distance from where they had attempted to drive the boys over. Throwing themselves flat on their faces, they wriggled over the edge and disappeared. A faint splash below, a few seconds later, told the lads that their desperate assailants had reached the water.

"They'll drown, they'll drown!" cried Walter.

"No such luck," growled Tom Phipps. "They've got away, that's all. They know what they're doing."

Chunky swaggered to the edge with rifle dropped over his left arm, and peered over.

"Guess I'll hurry 'em along," he announced, clearing his weapon for action.

Tad sprang forward and forced the barrel up.

"Chunky, Chunky!" he warned.

"I was just going to scare 'em, that's all," grinned the fat boy, lowering his rifle.

At that moment the boys fell upon Chunky, fairly hugging him in their delight. After the keen edge of their excitement had worn off, they pressed him for the story of how he had happened to find his way into the Ruby Mountain at that time.

The lad explained that having been hunting in that vicinity and becoming tired out he had sat down to rest. While thus engaged the men had come along. They were talking of the explosion, and from them he learned that the drift in which the Pony Rider Boys were imprisoned was immediately beneath their hiding place in the Ruby Mountain.

Interested at once, the lad followed them into the mountain.

"But, how did they get in here?" demanded Tom.

"Through a hole in the rocks, that went straight in."

Phipps insisted on being taken to the place at once. He found that entrance had been made through an abandoned shaft that extended into the mountain a short distance on the level. A door had been skilfully constructed, shutting off the entrance to the cave itself. Years before a notorious band of outlaws had been known to have a hiding place somewhere in the vicinity. Tom Cravath and his associates had come upon it and used it for their own nefarious purposes.

"I think we'll find we've come upon a very important discovery," decided Mr. Phipps after listening to the fat boy's story. And so it proved.

Cravath had been at the head of a band of thieves, who made way with their plunder through the Ruby Mountain. A large quantity of it was found there on the following day. As for the stock which they stole, this was led into the mine entrance, down into a subterranean water course along which it was directed for several miles along towards the Indian Territory where it was eventually sold by other members of the gang.

No trace of any of the desperate band was ever found. Eagle-eye, the missing Indian guide, was discovered bound and gagged in a remote chamber in the Ruby Mountain, weak from loss of food. He had caught some of the band stealing the ponies and they had taken him prisoner.

It was proved, however, that neither Rose Cravath nor her mother had any knowledge of the transactions of the desperate band.

Great was the rejoicing in the mining camp when the news of the discovery became noised about. The lads were made heroes by the enthusiastic miners. But this did not bring back the lost ponies. Rather than purchase others for the brief time they would be in the Ozarks, it was decided to close the trip and continue their journeyings amidst other scenes.

On the second morning after their exciting experiences in the mines they rode away, bound for the nearest railroad station, all anticipation at the prospect of a sojourn on the great Nevada desert, of which they had heard so much. How they lost themselves there, their efforts to extricate themselves from the desert maze, attended by a remarkable series of strange happenings, will be told in a following volume entitled, "THE PONY RIDER BOYS IN THE ALKALI."

THE END