"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.