At the point where the branch leading to the new chambers left the main heading, Ralph turned in, following his accustomed route. It seemed to him that he ought to go to places with which he was familiar. He trudged along through the half-mile of gang-way that he had always found so lonely when he was at work, stopping now and then to rest. For, although he walked very slowly, he grew tired very easily. He felt that he was not getting into a purer atmosphere either. The air around him seemed to lack strength and vitality; and when, at last, he reached the tier of chambers that it had been his duty to supply with cars, he was suffering from dizziness, from shortness of breath, and from rapid beating of the heart. At the foot of Conway's chamber Ralph found a seat. He was very weak and tired and his whole frame was in a tremor. He began to recall all that he had heard and read about people being suffocated in the mines; all the stories that had ever been told to him about miners being shut in by accident and poisoned with foul air, or rescued at the point of death. He knew that his own situation was a critical one. He knew that, with the shaft crowded full of wreckage and giving no passage to the air, the entire mine would eventually become filled with poisonous gases. He knew that his present physical condition was due to the foulness of the atmosphere he was breathing. He felt that the situation was becoming rapidly more alarming. The only question now was as to how long this vitiated air would support life. Still, his courage did not give way. He had strong hope that he would yet be rescued, and he struggled to hold fast to his hope. The flame of his lamp burned round and dim, so dim that he could scarcely see across the heading. The mule came up to him and put out his nose to touch the boy's hand. "I guess we may as well stay here. Jasper," he said. "This is the furthest place away from the shaft, an' if we can't stan' it here we can't stan' it nowhere." The beast seemed to understand him, for he lay down then, with his head resting on Ralph's knee. They remained for a long time in that position, and Ralph listened anxiously for some sound from the direction of the shaft. He began to think finally that it was foolish to expect help as yet. No human being could get through the gas and smoke to him. The mine would first need to be ventilated. But he felt that the air was growing constantly more foul and heavy. His head was aching, he labored greatly in breathing, and he seemed to be confused and sleepy. He arose and tried to walk a little to keep awake. He knew that sleep was dangerous. But he was too tired to walk and he soon came back and sat down again by the mule. "I'm a-tryin', Jasper," he said, "I'm a-tryin' my best to hold out; but I'm afraid it ain't a-goin' to do much good; I can't see much chance"--