The beautiful weather continued unchanged throughout the afternoon. As the sun declined in the sky there was a perceptible coolness in the air, but the exercise of riding removed all necessity for using their blankets.  
Although the party had been edging toward the foot-hills for hours, it seemed to the boys that they were as far off as ever. They had covered many miles, but those who have travelled in the West know the deceptive character of the crystalline atmosphere, so far as distances are concerned. However, as twilight began closing in they reached a small grove of trees, which was the destination of the guide from the first. It was there he meant to camp for the night, and he could not have selected a better place had he spent a week in looking for it.
 
The grove covered less than an acre, the trees standing well apart, and wholly free from brush and undergrowth. Thus even the horses could pass back and forth freely. Over this shaded space the dark-green grass grew luxuriantly, with a soft juiciness of texture which made it the ideal food for cattle and horses. In the middle of the grove bubbled a spring of clear cold water, whose winding course could be traced far out on the plain by the fringe of deeper green which accompanied it.
 
Saddles and bridles were removed, and the ponies turned free to crop the grass until they were filled, when they would lie down for the night. The blankets were spread on the ground near the spring, and then, at the suggestion of Hazletine, all three joined in gathering dried branches and limbs with which to start a fire. It was now cool enough to make the warmth welcome, while the flame would add to the cheerfulness of the occasion.
 
Jack and Fred had never ridden so far at one stretch, and when they reclined on their blankets to watch Hank start the fire they were thoroughly tired out; but it seemed to them their hunger was more ravenous than ever. Each forbore to speak of it, but the deliberation of their friend in preparing the meal was almost intolerable.
 
The first night spent by the boys in camping out in the wilds of Wyoming was one that can never be forgotten. When the meal was finished and the last vestige of food eaten, the three stretched out where they could feel the grateful warmth of the fire that had been kindled against the trunk of a large oak. Hank had again lighted his pipe, and deeply interested Jack and Fred by his reminiscences of a life that had been filled to overflowing with strange experience and adventure. They listened, unconscious of the passage of the hours, until he abruptly asked:
 
"What time is it?"
 
Each youth looked at his watch, and, to his astonishment, saw that it was nearly half-past ten. They had supposed that it was fully two hours earlier.
 
"One of the rules that must always be follered," said the guide, "when hunting or away from home, is that all the party mustn't sleep at the same time."
 
"Then one has to stand watch?"
 
"It looks that way. Now, we'll divide the time atween us, each taking a part, so that it won't come heavy on any one."
 
"That will suit us," Fred hastened to say, while Jack nodded his head.
 
"All right. You, Jack, will keep watch till twelve—that is midnight; then you'll rouse t'other younker, and he'll stand guard till two; then he'll give me a kick, and I'll run things till daylight."
 
"What are we likely to see?" asked Jack, who naturally desired to learn all the points concerning his new duties.
 
"How should I know?" asked Hank, with a grin. "There may be wild animals, sich as grizzlies, cinnamon or black bears; there may be wolves, or dog Injins looking for a chance to steal our ponies."
 
"Why do you call them 'dog Indians?'"
 
"A dog Injin is a tramp 'mong the other tribes; he don't live much with any of 'em, but sneaks round the country, looking for a chance to steal something, and it don't matter what it is."
 
"Suppose I catch sight of one of the animals you name, or a dog Indian—what shall I do?"
 
"Shoot him quicker'n lightning."
 
This was a startling order, but the guide was in earnest.
 
"Are you afeard to do it?" he asked, half contemptuously.
 
"No; I'll shoot the instant it is necessary, but I don't fancy the idea of picking off an Indian without warning."
 
"If you give him warning you won't pick him off. If you're so squeamish, you might argufy the matter with him."
 
"Leave that to me; I'm on duty now; go to sleep."
 
Without another word the guide wrapped his blanket about him and stretched out in front of the fire, with his feet toward it. Judging from his heavy breathing, it was barely five minutes before he became unconscious.
 
"It strikes me this is rushing things," remarked Jack to Fred, as the two sat beside each other. "Last night the 'V. W. W.' were in the sleeper of the union Pacific; to-night they are looking out for a chance to shoot Indians."
 
"I don't believe there's any likelihood of finding it. I suspect that Hank is having some sport at our expense. If there was any danger he would stay awake himself, instead of trusting two tenderfeet like us."
 
"It may be, but we are in a wild country, where danger is likely to come at any time, and we may have our hands full. It seems to me that it would have been better to let the fire go out, and not attract attention."
 
"He's running this affair; he wouldn't have had so much wood gathered if he didn't mean to keep the blaze going."
 
With this Fred rose to his feet and flung an armful of wood on the flames, which brightened up until their reflection was thrown against the branches overhead and well out toward the edge of the grove. A faint whinny proved that the horses had been disturbed by the increase in the illumination.
 
Before lying down, Fred looked at his chum.
 
"I wonder, Jack, whether there's any risk of your falling asleep?"
 
"There would be if I remained seated on the ground, but I shall not do that."
 
"It will be dangerous to walk back and forth, where the fire shows you plainly."
 
"My plan is to move out in the grove, where the firelight will not strike me, and stand close to the trunk of one of the trees. I have heard of folks sleeping on their feet, but there's no fear of my doing it. Since I am to call you in less than two hours, Fred, you would better get sleep while you can."
 
The younger lad bade his friend good-night and imitated the action of Hank Hazletine, wrapping his blanket around himself and lying down near the fire. He was not quite so prompt in sinking into slumber, but it was not long before Jack Dudley was the only one of the little party in command of his senses.
 
Jack, like his companions, felt the need of sleep, but the fact that he had but a brief while to remain awake, and the consciousness that the safety of others, as well as his own, rested upon himself, made him very alert. He believed he could sit or recline on the ground and retain his wits, but, fortunately, he had too much prudence to run that risk. Sleep is so insidious a foe that we can never recall the moment when it overmasters us, nor can we fight it off when in a prone or easy posture.
 
He adhered to the plan he had formed. Winchester in hand, he moved away from the fire until, by interposing the large trunk of a tree between himself and the light, he was invisible from that direction. He stood erect, taking care not to lean against the trunk for partial support, and concentrated his faculties into those of listening and looking.
 
The stillness was profound. From the distant mountains to the westward came a low, soft, almost inaudible murmur, such as one hears when many miles from the calm ocean, and which has been called the voice of silence itself. In the stillness he heard the faint crackle of one of the embers as it fell apart, and, though the night wind scarcely stirred the leaves over his head, he caught the rustle. The fact that there was nothing from the direction of the ponies showed they had ceased to crop the grass and were lying down. The safety of the camp was in his hands. If he forgot his duty, it might be fatal to all.
 
The sense of this responsibility and the newness of his position made Jack Dudley more wakeful than he could have been under any other circumstances. To these causes, also, was due a suspicious nervousness which made him see danger where it did not exist. The rustling of a falling leaf caused him to start and glance furtively to one side, and at a soft stir of the leaves under a breath of wind, or a slight movement of the sleeping ponies, he started and grasped his rifle with closer grip.
 
All this was natural; but there came a moment, not far from midnight, when there remained no doubt that some person or animal was moving stealthily through the grove, near where he was standing. It will be remembered that his position was such that the trunk of the large oak acted as an impenetrable screen between him and the camp-fire, which was burning so vigorously that its rays penetrated to a greater or less degree beyond him. Thus he could see anything moving within the circle of illumination, while he was as invisible to the keenest-eyed warrior as if the night was without a ray of light.
 
The first warning was through the sense of hearing. He had been deceived so many times that he suspected his fancy was playing with him again, but the faint tip, tip continued until such explanation was amiss.
 
"It is an Indian or a wild beast," was his belief.
 
The next minute he knew that, whatever it was, its position was between him and the outer edge of the grove. Since the ponies were on the opposite side of the fire, Jack was nearer the intruder than either they or his friends, sleeping by the camp-fire. Recalling that his place was the most favorable possible, he remained as motionless as the tree-trunk behind him, and to which he stood close enough to touch by moving his foot a few inches backward.
 
The situation being thus, it followed that if the man or beast continued its advance it must come into sight, while Jack himself was invisible. He therefore held his Winchester ready for instant use and waited.
 
He was standing in this expectant attitude when a remarkable thing took place. The fire, having remained unreplenished for some time, had subsided to a considerable extent, when one of the embers fell apart and caused such a displacement of the burning wood that the light flared up and penetrated with its former vigor beyond the tree which sheltered the sentinel.
 
Jack was as immovable as a statue, his weapon grasped in both hands, when this sudden brightening occurred. He was peering out among the dark trees, in the effort to identify the danger, when he saw the unmistakable figure of an Indian, hardly twenty feet away.
 
The buck had entered the grove with the silence of a shadow, and was making his way to the camp-fire, when betrayed in this singular manner to the watcher. In the reflection of the firelight, his naturally hideous countenance was repulsive to the last degree. The features were irregular, with prominent cheek-bones, a huge nose, and a retreating chin. Ugly as nature had made him, he had intensified it himself by daubing black, red and white paint in splashes over the front of his countenance. His coarse, black hair dangled loosely about his shoulders, and a single stained eagle's feather protruded from the crown. It was gathered back of the neck by a thong of some sort, so as to prevent the hair getting in his eyes when there was such imminent need for their use.
 
The chest was bare to the waist, and was also fantastically painted. In the girdle which encircled his waist was thrust a knife, whose handle protruded, while the leggings and moccasins were gayly ornamented and fringed. He held a formidable rifle in his right hand, in a trailing position, and was leaning well forward, with his body bent, as he drew near the camp with that stoical patience which the American race shows in the most trying crises. If necessary, he would continue this cautious advance for hours without showing haste, for it is often that his people circumvent and overthrow an enemy by their incomparable caution and care.
 
One peculiar feature of the unexpected flaring-up of the light was that its strongest force impinged directly upon the painted face of the Indian, which was seen as plainly by Jack Dudley as if the sun were shining. The youth felt that he could not forget that countenance if he saw it a hundred years afterward.
 
Had Jack followed the instruction of their guide he would have leveled his Winchester and shot the Indian dead in his tracks. The fellow was stealing into camp in such a manner that there could be no doubt the least crime he meant to commit was to steal. No ranchman or hunter would hesitate a moment, under the circumstances, to give him his eternal quietus.
 
But Jack Dudley could not do such a thing. To him it was an awful act to shoot a person, even though a savage, and his conscience would never permit him to do so until there was no choice left to him. He would much prefer to frighten away this intruder than to kill him.
 
The youth was so confident of his command of the situation that he would have felt hardly a thrill of alarm, but for the fear that the redskin belonged to a party near at hand who had sent him forward as a scout. Manifestly the right course for the sentinel was to discharge his gun, thus scaring the Indian and awaking Hazletine; but, while debating the question with himself, he became aware that the hostile was advancing.
 
The fellow did this with such marvellous cunning that Jack perceived no movement of his legs or feet. The latter were partly shrouded in shadow, but the Indian himself suggested a statue set up among the trees. Nevertheless he was inching toward the camp-fire, and was already a couple of yards nearer Jack than when the latter first noticed him.
 
Had he approached from the other side the youth never would have discovered his danger; but now he had his eye on the enemy, and meant to keep it there until the crisis was over. It was perhaps ten minutes later that the buck was within six feet of the youth, who, noiselessly bringing his Winchester to a level, took one step toward him and asked:
 
"Well, my friend, what do you want?"