“What is it George?” asked Bob Howard, turning his eyes in every direction except the right one. “I don’t see anything strange.”

Still George made no reply. He simply raised his hand and pointed with his finger toward the middle of the valley. Bob looked, and then his own eyes began to open, and his pale face grew still paler.

It did not seem to him that his nerves could possibly stand another test just then, all unstrung as they were by the terrors of that long voyage in the dark; but now he was about to witness an exhibition of the wonderful powers of nature that would have made the heart of the bravest and strongest man beat rapidly with excitement and apprehension.

About three hundred yards from the spot on which he and his frightened companion stood, was something that looked like a long, natural ridge. It arose to the height of thirty feet or more, and was bare of vegetation. Beyond this ridge, extending the whole length of it, and gradually rising into view above the top of it, was an immense body of water, which was broken into innumerable cone-shaped billows, with broad, flat bases, and smooth, round tops.

These billows, which were of enormous size, were violently agitated, and, although they were tossed about in every direction, they did not change their positions, lose their shape, nor run together, each one, apparently, being independent of its neighbor, and owing its existence to a different power.

Slowly and majestically the billows grew in size and height, and still the boys gazed as if they were fascinated. Suddenly, there was another deafening report, which made the ground tremble beneath them, and up from the midst of the troubled mass arose a single column of water about as large around as a hogshead, smooth as glass, and as clear as crystal, and shot toward the clouds.

It went up to an almost incredible height, and stood as motionless as if it were carved out of stone. Then, the power which created and sustained it ceasing to act, it crumbled to pieces, like a column of sand, and fell back among the billows, which, broken by its weight, rolled from one end of the ridge to the other, dashing the spray high in the air.

This continued for two or three minutes, after which the water subsided as suddenly as it had arisen, its disappearance being accompanied by a low, rumbling noise, which sounded like the muttering of distant thunder, and when that died away all was still.

The two boys drew a long breath, looked at each other in silence, and then they seated themselves on the ground again.

“Old fellow,” said Bob, who was the first to recover his power of speech, “we have solved the mystery of Lost River Canyon. That’s a geyser, and it's the grandest sight I ever saw. I have been through the Yellowstone Park with my father—you can count geysers up there by hundreds, you know—but that famed place can’t show anything to compare with this. It was my good fortune to see all the big ones in operation, but none of them equalled this in grandeur, although the ‘Giant’ beat it in duration. I saw it play for three hours, and throw a column of water to the height of two hundred feet.”

“Did they all make such a terrific noise as this one does?” inquired George.

“Some of them did, and some didn’t. The ‘Castle,’ which not unfrequently plays for an hour at a time, and sends up a jet of water two hundred and fifty feet high, shakes the ground like an earthquake, and makes a noise louder than this one. When it gets ready to go to work, it begins to pulsate and throb at the rate of seventy beats a minute, which grow stronger and stronger all the while, and finally culminate in a blast that is almost deafening.”

“Do you suppose that the explosions made by this geyser during its eruptions were the sounds we used to hear so regularly while we were at the ranch?”

“I am sure of it, and, in order to test the matter—Why, George, it is twelve o’clock!” exclaimed Bob, as he drew his watch from his pocket. “What time was it when we started for the lake? It couldn’t have been much later than five o’clock—could it? Then, we must have been in that dreadful canyon almost seven hours. It didn’t seem so long to me.”

“Well, it did to me!” answered George, with a shudder. “I thought we were never going to see daylight again.”

“So did I,” answered Bob, who was fast recovering his usual spirits. “But here we are safe and sound, and none the worse for our terrible fright. More than that, we have solved the mystery which, like the source of the Nile, was ‘so long a hidden thing to earth.’”

“And our discovery will die with us,” said George, looking up at the tall cliffs which surrounded the valley on all sides. “We shall be prisoners here as long as we live.”

“Not by a great sight,” replied Bob, cheerfully. “We may not get out this week, or this month, but we shall get out—you may depend upon that. Now, then, let’s unload the boat, pitch the tent, and get some dinner.”

“I don’t want anything to eat,” said George.

“Neither do I; but I thought that perhaps a cup of coffee and a sandwich would put a little life and strength into us. Besides, if we keep busy at something we shall have no time to think, you know.”

George was fully sensible of that fact, and so, when he saw Bob jump to his feet and start toward the boat, he got up and went with him, although it required the exercise of all the will-power he possessed to enable him to do it.

His courage and fortitude had never before been so severely tested, and if he had been alone he would probably have thrown himself down upon the ground and abandoned himself to despair. But he could not do that while his companion was so sanguine and full of hope.

He lent his aid in pitching the tent on a little natural lawn, a short distance from the river, and it was not long before he became so interested in his work, and in listening to Bob, who kept up an almost incessant talking, that he forgot all about his wild ride through the canyon, and his narrow escape from death.

When the tent had been put up, George lingered to tighten the guys, while Bob went back to the boat again. Presently, he called to his companion, and threw something out on the bank.

“Didn’t I tell you that we were the victims of treachery?” said he. “Just take a glance at the stump of that oar and tell me what you think about it?”

“Who did it?” said George, when he had examined what was left of the oar, and found the marks of a saw upon it.

“You tell,” replied Bob. “I didn’t suppose I had an enemy on the ranch; but that proves that there is somebody there who wanted me to go into that canyon, believing that if I did, I would never get out alive. He will find that he reckoned without his host, will he not? Put it away in some safe place, George. We must take it home with us, even if we have to leave everything else behind us in order to carry it there. Now perhaps we had better load our guns, for we don’t know who or what are neighbors are.”

“What do you mean by that?”

“I mean that there must be wild animals of some sort in the valley,” replied Bob. “If they know how to get in, of course they know how to get out again, and all we’ve go to do is to find a trail, put the dogs on it, and let them follow it up. It will be sure to lead to some gulch or canyon that we can’t see from here, and, by using that as a highway, we shall be able to get out.”

“That’s the very idea,” said George, stooping down to caress the setters, which had taken possession of the blanket their thoughtful master had spread upon the ground for their accommodation. “Do you know I had wholly forgotten that we had brought any dogs with us?”

“So had I. I was so taken up with other matters that I didn’t even see them get out of the boat, nor did I notice how they behaved during that eruption. We must take the best of care of them, for they are our sole dependence now. You thought we couldn’t find use for all this grub, didn’t you?” added Bob, surveying the long row of well-filled baskets he had placed upon the bank. “We may go hungry yet before we see home again.”

“How far off do you suppose it is?”

“I will answer that question, if you will tell me how fast our boat traveled when she was shooting through the canyon.”

“She went like a flash of light,” replied George.

“Well, then, seeing that light travels from the sun to the earth—a distance of ninety-one millions of miles—in eight minutes, we must have passed around our little planet a good many times during our seven hours’ ride. But, for all that, I don’t think we are more than sixty or seventy miles from home.”

“That’s far enough,” said George. “We shall be weary and footsore before we get there, I tell you.”

Having loaded their guns and laid them where they could be readily seized in case of emergency, George busied himself in gathering a supply of light-wood, while Bob started a fire and placed a kettle of water upon it.

By the time their provisions and bedding were under cover, the water was boiling and Bob made the coffee, while George unpacked one of the baskets and spread its contents upon a snow-white napkin in front of the tent. He said he wasn’t hungry; but his actions told a different story, and so did Bob’s.

“Now, then,” said the latter, when the last sandwich had disappeared and the coffee pot had been squeezed dry, “we’ll clear away the wreck and take a survey of that geyser.”

“I believe I am as close to it now as I care to be,” replied George. “The old thing might boil over on us.”

Bob laughed, heartily.

“There’s no danger,” said he. “We have a whole hour in which to make our observations. Since we are here and can’t get away to-day, let’s see everything that we can that is worth looking at.”

George lent willing and effective aid in “clearing away the wreck;” but it was with a good deal of reluctance that he shouldered his gun and followed Bob through the mesquite bushes toward the geyser.

He stopped when he reached the ridge, but Bob fearlessly made his way to the top and looked over it.

“Great Scott!” were the first words that escaped his lips. “Come up here, George. This mound is a silicious deposit, which has been thrown up by the spring, and it is as solid as rock.”

“It ought to be,” replied George, “for it is flint.”

“Then what are you afraid of?”

Bob’s companion would have found it hard work to answer this question, for he did not know just what he was afraid of.

Laying his rifle on the ground, he climbed to the summit of the ridge, and saw below him an extensive, oval-shaped basin, partly filled with water, which was so clear that the smallest pebbles on the bottom could be plainly seen.

Its surface was as smooth as a mirror, and there was nothing in or about the basin to tell of the terrible commotion that had taken place there a short time before.

“This bangs the great geyser of Iceland,” said Bob. “That famous spring, in its calm periods, appears to be a circular basin about seventy-two feet in diameter and four feet deep; but this one is two or three hundred feet wide, and the water must be twenty feet deep. Do you see those little holes, about a foot in diameter, that are scattered all over the bottom? There is where the stream comes from that raises these round-topped waves, while the power that threw that huge column of water so high in the air must have come from somewhere over there,” added Bob, jerking a piece of flint as far as he could toward the centre of the basin. “I wish I had pluck enough to put my skiff in here and take a better look at it.”

“Good gracious!” exclaimed George, backing down the mound. “If you do that, you will have to go alone.”

“Why, such things have been done,” said Bob. “The shaft of that Iceland geyser has been measured, and found to be nine feet in diameter and seventy feet deep.”

Bob took another long look at the yawning gulf below him, and then crawled down the ridge and joined his companion. He picked up his gun, and was about to say something more to him, when he noticed that one of the setters had come to a point, and that the other was backing him beautifully.

“A flock of quails for a dollar!” said Bob. “Now look sharp. It is almost impossible to flush them, and so you will have to shoot them running.”

As Bob ceased speaking, his gun spoke twice in rapid succession. No birds arose at the reports, but a couple of mule deer, which had been enjoying their mid-day nap in a thicket not more than twenty yards away, broke cover, and set off toward the farther end of the valley at the top of their speed.

“Don’t shoot!” cried Bob, as George’s light double-barrel arose to his shoulder. “You’ll only wound them, and, besides, we want them to show us the way out.”