Thirlwell saw the danger. So long as the prop slanted, it would not support the beam, and if the beam gave way, the roof would fall and crush them before they could get from underneath. He thought he had a few moments to hammer the prop straight, and swung the ax savagely while the sweat ran down his face. He dared not look up again, but the ominous cracking went on and while he wondered what was happening, Driscoll ran past. A big stone fell beside the man as he seized another prop and with a tense effort jambed it under the beam. "I'll take some weight off her while you shore her up," Driscoll gasped. He had brought a heavy mallet, but before he used this he dragged the foot of the timber round, bending his body forward while his arms got stiff and hard, as if carved from wood. His sullen face was darkly flushed and the swollen veins stood out from his forehead. Thirlwell saw him for a moment as he lifted his ax, and remembering the scene afterwards, thought the fellow had looked a model of savage strength. It was obvious that he had no fear. In the meantime, he was vaguely conscious that Driscoll had saved his life. He and Scott had stayed too long, and could not have fixed their prop before the beam gave way had not the other come to help. For that matter, they were not out of danger yet. Unless they could wedge the timber in the next few moments, the roof would come down. There was not room to swing the ax properly, his body was cramped from bending, and he could not lift his head. Stooping in the low tunnel, he nerved himself for a tense effort and struck several furious blows. The prop quivered, groaned as it felt the pressure from above, moved an inch or two, and stood upright. Then Thirlwell dropped his ax and staggered back. He felt limp and exhausted, and wanted to get away. The beam would hold the roof for some minutes and might do so for a time. "You can let up now, Driscoll," Scott called out when they stopped a few yards off. "We'll see if the prop will stand before we do anything else." "Guess I'll fix the other," Driscoll replied. "Come out," Scott insisted. "You don't know if it's safe." Driscoll glanced round for a moment. His hat had fallen off and the miner's lamp flared and smoked in the water at his feet. His hair was wet with the drops from the roof, and a thin streak of blood ran down his face from a cut a falling stone had made. But his heavy eyes had a fixed, obstinate look. "You hired me to mind the timbers; it's my job." Scott acquiesced with a gesture and he and Thirlwell watched. There was a risk that in wedging the extra prop the man might loosen the first; and then, if neither was able to bear the load, the rock above would fall and bury him. For all that, Driscoll looked undisturbed and did not stop until he had carefully driven the timber into its proper place. Then he turned to Scott and his glance was slow and dull. "I want you to send two of the boys along." "Why do you want them?"