The shaft, the drifts, the crosscuts, and the tunnels all act as flues to suck the flames into them. At Piodie, as at Virginia City, the danger was intensified by the great quantity of fuel with which these natural chimneys were lined. In the Katie Brackett whole forests were buried. Every drift and tunnel was braced with timbers. Scores of chutes, with vertical winzes, all made of wood, led from one level to another. The ore chambers were honeycombed with square sets of timber mortised together and wedged against the rock walls and roof. Upon each set floors of heavy planking were laid. In these were trap doors, through which steps ran leading from the lower level to the one above. The fire was in the north drift. Carstairs led the men forward cautiously. Already their eyes were inflamed from the smoke that rolled out at them. As they moved forward heat waves struck them. The rock walls were so hot that the rescuers could with difficulty keep going. Hugh was at the nozzle of the hose they were dragging. He kept a stream playing on the rock and the charred timber. Presently he fell back, overcome by the intense heat, and Carstairs took his place. Byers succeeded the superintendent at the apex of the attack. Steam, sulphur, fumes, and gas released from the minerals swept the rescuers back. The air was so foul that the workers could not breathe it without collapsing. An air pipe was led in from the main blower above, and the volunteers renewed their efforts. At times the swirling smoke was too much for them. It either drove them to the shaft or it forced them to lie with their faces close to the ground where the air was purer. Farther down the tunnel they could see red tongues of flame licking at them. The roar of the fire as it leaped forward was far more appalling than that of any wild beast could have been. The faces of the firemen were smoke-blackened and grimy. Already several had collapsed from the intense heat. These were helped back to the shaft and sent up. Others came down to take their places. Hugh’s eyebrows crisped from the heat. The men were all naked from the waist up. Below this they wore only cotton overalls and boots. These were licked to a char thin and fragile as paper. The skin peeled from Hugh’s body in flakes where anything touched it. From above came an ominous sound. “Back,” ordered Carstairs. The roof came down, an avalanche of dirt and rock and timber. So close was McClintock to it that the air shock almost knocked him down. Before the dust had settled Carstairs sent his sappers at the job of clearing out and timbering the tunnel.