"I don't believe they are following us," said Dick, as he placed his ear to the ground and listened. All was as silent as the grave. They remained under the rock the best part of an hour, allowing their trusty animals to get back their wind and strength. During this time Wumble walked back a short distance and Tom climbed up to the top of the rock, but neither made any discovery of importance. It was a little after midnight when they moved forward again. Their pace was now little better than a walk, for the trail was a dangerous one, and in many spots they had to leap down and lead their horses. Once they came to a gully six to eight feet wide, without a bridge, and it took a good deal of urging to get Tom's horse to make the leap across. "If a fellow should tumble in there where would he go to?" asked Sam, with a shudder. "He'd go out of sight forever," replied Wumble solemnly. "Some of those cuts are a thousand feet deep." "What a mighty upheaval of nature there must have been here at one time," said Dick. By three o'clock in the morning Tom was completely fagged out and could scarcely keep his eyes open. Gradually he dragged behind the others, his eyes closing every few minutes in spite of his efforts to keep them open. "I wish I had a cup of strong coffee to keep me awake," he murmured. "How much further are you going, Jack?" "A couple of miles or so," answered the old miner. "Want a smoke? You can have my pipe." "Thank you, but I don't smoke, and I guess it would only make me feel worse," answered Tom. He began to drop further and further behind. The other boys spoke to him, but they were in reality nearly as much worn out as their brother, and had all they could do to keep Wumble in sight. At last Tom's head fell forward on his breast, and on the instant he went fast asleep. His horse continued to move forward, but coming to a fork in the trail, took the downward path, that being the easier to travel. On and on went the beast, until striking a smooth road he set off on a gallop. The violent motion aroused Tom, and he stared about him in bewilderment. "Dick! Sam!" he called out. "Where are you?" No answer came back, and he sat bolt upright in alarm. Nobody was in sight, nor could he hear a sound saving the hoof beats of his own horse. He drew rein instantly. "Dick!" he called loudly. "Jack Wumble! Where are you?" Not a sound came in reply--not even the cry of a bird--all was absolutely silent. Tom gave something of a gasp. He realized his position only too well. He was lost in the mountains. CHAPTER XXIII TOM MEETS THE ENEMY "Oh, what a fool I was to fall asleep!" Thus spoke poor Tom to himself, as he continued to gaze around him and call out. To one side was the high mountain, to the other a deep valley filled with giant trees, and on both sides an utter loneliness which seemed to penetrate his very soul.