The boys would have been glad to explore the petrified forest that night had it been practicable. They had read of the mysterious stone relics of ancient woods, which exist in the remote Sierras, but they had never dreamed they would stumble upon one so opportunely. However, even had they been less tired, it would have been out of the question to examine the strange place more thoroughly that night.

As there did not seem to be any limit to the place so far as they could see, the boys decided to camp where they were for the night. The auto was stopped and the horse unhitched and turned loose at the end of a lariat to graze, his rope being made fast round one of the more slender stone trunks.

"Feels like hitching him to the pillar of the City Hall at home," laughed Joe, as he formed a double half hitch and left the horse to his own devices, first, however, having watered the animal at a small spring which flowed from the foot of a large rock at one side of the mysterious stone valley.

In the meantime, Cal had built a fire of sage brush roots, for there was no wood about, every bit of it having turned to stone long ages before. The pile, on being ignited, blazed up cheerfully, illuminating the sterile, lonely spot with a merry red blaze. The spider was taken out of the utensil locker, and soon bacon was hissing in it and canned tomatoes and corn bubbling in adjacent saucepans. A big pot of coffee also sent up a savory aroma. Altogether, with canned fruit for dessert, the Motor Rangers and their friends made a meal which quite atoned for the loss of their lunch. Even Ding-dong admitted that he was satisfied by the time Cal drew out a short and exceedingly black pipe. The former stage driver rammed this full of tobacco and then leisurely proceeded to light it. After a few puffs he looked up at the group around him. They were lolling about on waterproof blankets spread out on the rock-strewn ground, a portion of which they had cleared. In the background stood the dark outlines of the auto, and beyond, the mysterious shadows of the petrified forest, the bequest to the present of the long departed stone age.

"I've bin a thinkin'," began Cal, as if he were delivering his mind of something he had been inwardly cogitating for some time, "I've bin a thinkin' that while we are in this part of the country we ought to keep a good look out at night."

"You think that Morello's band may give us more trouble?" asked Nat.

"I don't jes' think so," rejoined Cal earnestly, "I'm purty jes' nat'ly sure of it. They ain't the sort of fellers ter fergit or furgive."

"I guess you're right," agreed Nat, "that man Dayton alone is capable of making lots of trouble for us. We'll do as you say and set a watch to-night."

"I vind und set my votch every night," declared Herr Muller, proudly drawing out of his pocket an immense timepiece resembling a bulbous silver vegetable.

"This is a different kind of watch that we're talking about," laughed Nat.

It was ultimately arranged, after some more discussion, that Joe and Nat should watch for the first part of the night and Ding-dong and Cal Gifford should come on duty at one o'clock in the morning. It seemed to young Bell that he hadn't been asleep more than five minutes when he was roughly shaken by Nat and told to tumble out of the tonneau as it was time to go on watch. Already Cal, who like an old mountaineer preferred to sleep by the fire, was up and stirring. It took a long time, though, to rout Ding-dong out of his snug bed. The air at that altitude is keen and sharp, and being turned out of his warm nest was anything but pleasant to the lad.

"L-l-l-let the D-d-d-d-dutchman do it," he begged, snuggling down in his blankets.

"No," said Nat firmly, "it's your turn on duty. Come on now, roll out or we'll pull you out."

Finally, with grumbling protestations, the stuttering youth was hauled forth, and, while Nat and Joe turned in, he and Cal went on duty, or "sentry go," as they say in the army.

"Now then," said Cal crisply, as the shivering Ding-dong lingered by the fire with his rifle in his chilled hands, "you go off there to the right and patrol a hundred feet or more. I'll do the same to the left. We'll meet at the fire every few minutes and get warm."

"A-a-all r-r-r-right," agreed Ding-dong, who stood in some awe of the stage driver. Consequently, without further demur, he strode off on his post. Having reached the end of it he marched back to the fire and warmed himself a second. Then he paced off again. This kept up for about an hour when suddenly Cal, who was at the turning point of his beat, heard a startling sound off to the right among the tomb-like forms of the stone trees.

Bang!

It was followed by two other shots.

Bang! Bang!

The reports rang sharply, amid the silence of the desolate place, and sent an alarmed chill even to Cal's stout heart. He bounded back toward the fire just in time to meet Ding-dong, who came rushing in with a scared white face, from the opposite direction. At the same time Nat and Joe awakened, and hastily slipping on some clothes, seized their rifles and prepared for trouble.

"What's the matter?" demanded Cal, in sharp, crisp tones, of the frightened sentinel.

"Indians!" was the gasped-out reply, "the p-p-p-place is f-f-f-full of them."

"Indians!" exclaimed Cal, hastily kicking out the bright fire and leaving it a dull heap of scattered embers, "are you sure?"

"S-s-s-sure. I s-s-s-saw their f-f-f-fif-feathers."

"That's queer," exclaimed Cal, "I never heard of any Indians being in this section before. But come on, boys, it's clear the lad here has seen something and we'd better get ready for trouble."

An improvised fort was instantly formed, by the boys crouching in various points of vantage in the automobile with their rifles menacingly pointed outward. Herr Muller snored on serenely, and they allowed him to slumber.

They must have remained in tense poses without moving a muscle for half an hour or more before any one dared to speak. Then Nat whispered,

"Queer we don't see or hear anything."

"They may be creeping up stealthily," rejoined Cal, "don't take your eye off your surroundings a minute."

For some time more the lads watched with increasing vigilance. At length even Cal grew impatient.

"There's something funny about this," he declared, and then turning on Ding-dong he demanded:

"Are you sure you saw something?"

"D-d-d-didn't I s-s-s-s-shoot at it?" indignantly responded the boy.

"I know, but you actually saw something move?" persisted Nat.

"Of c-c-c-course I did. You didn't think I was go-go-going to s-s-s-shoot at a put-put-petrified tree, did you?"

"We'll wait a while longer and then if nothing shows up I'm going to investigate," declared Cal.

"I'm with you," agreed Nat.

As nothing occurred for a long time the Motor Rangers finally climbed out of the car, and with their rifles held ready for instant action, crept off in the direction from which Ding-dong's fusillade had proceeded. Every now and then they paused to listen, hardly breathing for fear of interrupting the silence. But not a sound could they hear. However, Ding-dong stuck stoutly to his story that he had seen something move and had fired at it, whereupon it had vanished.

"Maybe it was Morello's gang trying to give us a scare," suggested Nat.

"Ef they'd ever got as close to us as this they'd hev given us worse than a scare," confidently declared Cal.

By this time they had proceeded quite some distance, and Cal stopped Ding-dong with a question.

"Whereabouts were you when you fired?"

"I-I do-do-do-do-don't know," stuttered the lad.

"You don't know?" indignantly echoed Nat, "you're a fine woodsman."

"Y-y-y-y-yes I do t-t-t-too," Ding-dong hastened to amend, "I was here—right here."

He ascended a small knoll covered with grass, at the foot of one of the stone trees.

"Which direction did you fire in?" was Nat's next question.

"Off t-t-t-that w-w-w-w-w-way," spoke Ding-dong. "Wow, there he is now!"

The boy gave a yell and started to run, and the others were considerably startled.

From the little eminence on which they stood they could see, projecting from behind one of the pillars, something that certainly did look like two feathers sticking in an Indian's head dress. As they gazed the feathers moved.

"Shoot quick!" cried Joe, jerking his rifle up to his shoulder, but Cal yanked it down with a quick pull.

"Hold on, youngster. Not so fast," he exclaimed, "let's look into this thing first."

Holding his rifle all ready to fire at the least alarm, the former stage driver crept cautiously forward. Close at his elbow came Nat, with his weapon held in similar readiness.

"There is something there—see!" exclaimed Nat in an awed tone.

"Yes," almost shouted the guide, "and it's that Dutchman's old plug!"

The next instant his words were verified. The midnight marauder at whom Ding-dong had fired was nothing more dangerous than the horse of Herr Muller. It had broken loose in the night and was browsing about when the amateur sentry had come upon it. In the moonlight, and when seen projecting from behind a pillar, its ears, which were unusually long, did look something like the head dress of an Indian.

"Wow!" yelled Nat, "this is one on you, Ding-dong!"

"Yes, here's your Indian!" shouted Joe, doubling up with laughter.

"Whoa, Indian," soothed Cal, walking up to the peaceful animal, "let's see if he hit you."

But the merriment of the lads was increased when an examination of the horse failed to show a scratch or mark upon it.

"That's another on you, Ding-dong," laughed Nat, "you're a fine sentinel. Why, you can't even hit a horse."

"Well, let the Dutchman try and see if he can do any better," rejoined Ding-dong with wounded dignity.