As Derrick and Paul realized that they were left alone in the burning breaker, in which the heat was now intense, and that they were cut off from the stairway by the closed and bolted door, they remained for a moment speechless with despair. Then Derrick flung himself furiously against the heavy door again and again, with a vague hope that he might thus force it to give way. His efforts were of no avail, and he only exhausted his strength; for the massive framework did not even tremble beneath the weight of his body. Still he could not believe but that somebody would open it for them, and he would not leave the door until tiny flames creeping beneath it warned him that the stairway was on fire and that all chances of escape in that direction were gone. He tried to make himself seen and heard at one of the open windows, but was driven back by the swirling smoke. Then he turned to Paul, who still sat quietly where he had been left. The crippled lad had not uttered a single cry of fear, though the eager flames had approached him so closely that he could feel their hot breath, and knew that in another minute the place where he sat would be surrounded by them. As Derrick sprang to his side, with the intention of dragging him as far as possible from them, he said, "The slope, Derrick! If we could only get to the top of the slope, couldn't we somehow escape by it?" "I never thought of it!" cried Derrick. "We might. We'll try anyhow, for if we stay here another minute we shall be roasted to death." Stooping, he lifted Paul in his lithe young arms, and with a strength born of despair began to carry him up the long and devious way that led to the very top of the lofty building. He had scarcely taken a dozen steps, and was already staggering beneath his burden, when he stumbled and nearly fell over some object lying on the floor. With an exclamation, he set Paul down and picked it up. It was the crutch, Paul's own crutch; and it was so far above where they had sat at work that it seemed as though it must have been flung there. The boys did not pause to consider how the crutch came to be where they found it, but joyfully seizing it, Paul used it so effectively that they quickly gained the top of the building and stood at the upper end of the long slope. It was a framework of massive timbers supported by high trestle-work, that led from the highest point of the breaker down the hill-side into the valley, where it entered the ground. From there it was continued down into the very lowest depths of the mine. On it were double tracks of iron rails, up which, by means of an immensely long and strong wire cable, the laden coal cars were drawn from the bottom of the mine to the top of the breaker. As a loaded car was drawn up, an empty one, on the opposite track, went down. The angle of the slope was as steep as the sharply pitched roof of a house, and its length, from the bottom of the mine to the top of the breaker, was over half a mile.