A shower of sparks and a swirling cloud of smoke enveloped them as they stood upright and began to advance. It cleared away leaving them silhouetted against the leaping wall of flame a few yards in front of them--and a cheer went up from the throats of the crowd below. Not a word passed between the two men. Foot by foot they moved forward, laying the hose in a line behind them to lessen the weight and the side-pull, that at first had called forth all their strength to direct the play of the stream; foot by foot they went forward, closer and closer, perilously close, to the blistering, scorching, seething mass--for neither of them would be the first to hold back. High into the heavens streamed the great yellow-red forks of angry flame, and over all, like a gigantic canopy, rolled dense volumes of gray-black smoke. Came at the two men spurting, fiery tongues, stabbing at them, robbing them of their breath, mocking at their puny might. Another step forward and Regan reeled back, one hand went to his face--and the nozzle almost wrenched itself from the engineer’s grasp. “It’s a grand race!” laughed Gilleen, but the laugh was more of a gasping cough, and the cough came from cracked and swollen lips. “It’s a grand race, Regan; an’ the blood----” With a choking sob, Regan steadied himself and seized hold of the nozzle again. They held where they were now--it was the fire, not they, that was creeping forward, pitilessly, inevitably, licking greedily at the tarred roof until it grew soft beneath their feet and the bubbles puffed up and formed and broke. A cry of warning came from below, and with it came the ominous rending groan of yielding timbers. It came again, the cry, and rang in Gilleen’s ears almost without sense. He could scarcely see, his eyes were scorched and blinded, his lungs were full of the stinging smoke, choking full. Beside him Regan hung, dropping weak. “Get back, for God’s sake, get back! “--it was Carleton’s voice. “Do you hear!” shouted the super frantically. “Get back! The roof is sagging! Run for----” Like the roar of a giant blast, as a park of artillery belches forth in deafening thunder, there came a terrific crash and, fearful in its echo, a cry of horror rose from those below. Where there had been roof a foot in front of the men was now--nothingness. Gilleen, with a shout, as he felt the edge crumple under him, flung himself backward and as he leaped he snatched at Regan. His fingers brushed the master mechanic’s sleeve, hooked, slipped--and he struck on his back a full yard away. He reeled to his feet like a drunken man, and dug at his eyes with his fists. Over the broken edge of the shattered roof, hanging into the black below, was the dangling hose--but Regan was gone. Weak, spent, exhausted, the master mechanic, unequal to the exertion of Gilleen’s leap, had pitched downward, clutching desperately, feebly, vainly, as he went. Regan was gone, and twenty feet, somewhere, below--he lay.