A half-mile below, where the Salmon flung itself headlong against the upper wing of Jackson Glacier, the floating ice was checked by the narrowed passageway. There a jam was forming, and as the river heaved and tore at its growing burden a spectacular struggle went on. The sound of it came faintly but impressively to the watchers--a grinding and crushing of bergs, a roar of escaping waters. Fragments were up-ended, masses were rearing themselves edgewise into the air, were overturning and collapsing. They were wedging themselves into every conceivable angle, and the crowding procession from above was adding to the barrier momentarily. As the passageway became blocked the waters rose; the river piled itself up so swiftly that the eye could note its rise along the banks. But the attention of the crowd was divided between the jam and something far out on the bridge itself. At first glance Eliza did not comprehend; then she heard a man explaining: "He was going out when we got here, and now he won't come back." The girl gasped, for she recognized the distant figure of a man, dwarfed to puny proportions by the bulk of the structure in the mazes of which he stood. The man was O'Neil; he was perched upon one of the girders near the center of the longest span, where he could watch the attack upon the pyramidal ice-breakers beneath him. "He's a fool," said some one at Eliza's back. "That jam is getting bigger." "He'd better let the damned bridge take care of itself." She turned and began to force her way through the press of people between her and the south abutment. She arrived there, disheveled and panting, to find Slater, Mellen, and Parker standing in the approach. In front of them extended the long skeleton tunnel into which Murray had gone. "Mr. O'Neil is out there!" she cried to Tom. Slater turned and, reading the tragic appeal in her face, said reassuringly: "Sure! But he's all right." "They say--there's danger." "Happy Tom's" round visage puckered into a doubtful smile. "Oh, he'll take care of himself." Mellen turned to the girl and said briefly: "There's no danger whatever." But Eliza's fear was not to be so easily quieted. "Then why did he go out alone? What are you men doing here?" "It's his orders," Tom told her. Mellen was staring at the jam below, over which the Salmon was hurling a flood of ice and foaming waters. The stream was swelling and rising steadily; already it had nearly reached the level of the timberline on the left bank; the blockade was extending up-stream almost to the bridge itself. Mellen said something to Parker, who shook his head silently. Dan Appleton shouldered his way out of the crowd, with Natalie at his heels. She had dressed herself in haste: her hair was loose, her jacket was buttoned awry; on one foot was a shoe, on the other a bedroom slipper muddy and sodden. Her dark eyes were big with excitement. "Why don't you make Murray come in?" Dan demanded sharply.