did. But, Dick, do you believe this was the cause of that heavy

rumbling we heard some time back?"

"I couldn't say. It may have been, for you remember that the noise seemed to come and go, at intervals."

"And the trembling of the rocks under our feet, too! That must have been caused by something like this. The hot spring where we said we could have cooked an egg, or made our tea, that may have been the overflow from here, or another fountain like it."

"All we know is that those stories told by the Indians had a foundation in fact. And yet, most people will believe we have simply imagined these things when we tell them what we have seen and heard."

"Yes," sighed Roger, "I only wish there was some way to show them. Seeing is believing, mother always says."

But unfortunately this all happened early in the nineteenth century, and the camera, by which those amazing geysers might have been caught in action, and displayed to people at the other side of the world, had not even taken form in the brain of the most advanced inventor.

Slowly the lads walked back to where the guide awaited their coming. Mayhew looked relieved when they rejoined him. Apparently he had been dubious as to whether they would be allowed to return; he may even have suspected that the angry gods who sent that gushing fountain soaring two hundred feet into the air might stretch out their arms and drag the lads into the yawning crater, to be served as a sacrifice.

Which way to head now was rather a difficult question to answer. If it were left entirely to the discretion of Mayhew, Dick feared the guide might take it into his head to veer around and start back toward the camp, believing that in so doing he would be serving the interests of the boys best by possibly saving their lives.

Consequently Dick meant to keep his hand on the helm, and do most of the directing. Captain Clark had instructed the guide to put himself entirely at the disposal of the boys, so that in reality it was Dick's place to do the ordering.

Looking around them, it was hard to tell which way they had better go. Everything was so strange that although, of course, they knew the points of the compass, and in a general way could understand that they must have come in from the east, still who could say whether the beckoning west was their wisest goal, or some other direction?

"We had better try to keep on, and find that valley toward which Jasper Williams was headed," urged Dick, after they had consulted. "He is a stubborn man in his way, and, even though deserted by both his companions, I believe he would push straight on, so that he might boast of having reached the place he started for."

"And if the Blackfeet have failed to capture or kill him," ventured Roger, "we may find him there--of course granting that we reach that Happy Valley ourselves."

That point having been decided, they started. It was not long, however, before they began to realize that amidst those remarkable cones and thickets and rocky defiles it was a most difficult thing to keep their bearings.

"It seems as though we had come over this part of the ground before," admitted Dick, "for familiar objects turn up on every hand; and yet how can that be when we have kept going straight into the northwest for nearly an hour now?"

"There is something wrong about it all, I'm afraid, boys," declared the guide, with a distrustful shrug of his broad shoulders. "I'm thinking we will meet with some queer experiences before we see another sunrise. As for myself, I am wondering whether any of us will get through it alive."

It was not the hostile Indians that caused Mayhew to say this, nor yet the fact that all sorts of wild beasts doubtless roamed these wild places by night. He was accustomed to taking his chances with such ordinary perils, and scorned them as a true-hearted borderer must. But, deep down in his honest heart, Mayhew feared the supernatural. What he could not understand stood for something dreadful, that sent the cold chill of apprehension up and down his backbone.

"Listen, there is the spouting water at it again!" exclaimed Roger.

True enough, they could catch a deep-throated rumbling sound that seemed to make the very atmosphere vibrate. But Dick immediately made a discovery which he voiced in excited words:

"If that be so," he told them, "what miracle is this; for we surely hear that sound ahead of us, and all this while we have been in the belief that the great water-spout lay back yonder toward the east!"

That afforded Mayhew another opportunity to look worried.

"It's black magic, that's what I believe. The east has become the west! We have all been turned around, and right now I cannot say which way I am looking, although I can see the sun hanging up there above that glittering peak."

"Dick, what can it mean?" demanded Roger, uneasily.

"I can think of but one explanation!" declared the other, steadily. "That is not the same spouting water we heard just now! You remember that we decided there might be others of the same kind in this country of wonders."

It almost seemed as though nature took delight in proving the accuracy of Dick Armstrong's surmise; for, hardly had he said this, than they heard once again the remarkable throb of rushing waters pouring forth from a fissure in the crust of the earth and, what was more, it came from some point toward the rear!

Roger smiled faintly, while even Mayhew condescended to let some of the worried look pass away from his face.

"I should not like to roam about this terrible country after nightfall," said Roger, shuddering; "for there is too much danger of stepping into some bottomless pit, or having a deluge of boiling water thrown over your head. It's a question up here in the winter-time whether you are going to be frozen to death in a bitter storm, or roasted by the fires that are under the earth. I think we must be getting pretty close to where the Evil One lives, Dick. His workshop may be around these hills, for all we know."

Dick, however, shook his head. He was proof against all belief in the supernatural. Such wonders as had been encountered on the trip he felt sure were after all but the products of an eccentric nature. Though they might strike one as bewildering at first, familiarity would dull this feeling of amazement, though it could never breed contempt.

"We have a short time still before the sun sinks," remarked Dick; "shall we go on further or spend the night here?"

"I'd rather find a better place if it's the same to you," Roger started to say, when to his astonishment Dick suddenly clutched him by the arm, and started to drag him away.

At the same moment Roger became aware of a peculiar and alarming sound, as though loose rocks and shale were slipping down an abrupt slope.