"Ah!" It was almost a groan that escaped him. In the few minutes in which he had been engaged in examining his own wheels the runaway train had gained on him by leaps and bounds. He could now hear the roar of its wheels above the rumble and clatter of his own, that and the buzz of the motor so busy beneath the bonnet. He cast his eye on either side, as if to seek safety there, and watched the fleeting banks of the Chagres River, bushes and trees, and abandoned French trucks speeding past. A gang of workmen came into view, and he caught just a glimpse of them waving their shovels. Their shouts came to his ears as the merest echoes. Then something else forced itself upon his attention. It was the figure of a white man, standing prominent upon a little knoll beside the rails, and armed with a megaphone. He had the instrument to his mouth, and thundered his warning in Jim's ears. "Jump!" he shouted. "Jump! She'll be up within a jiffy!" Within a jiffy! In almost less time than that; there were but two yards now between the small inspection car and the line of loaded trucks. Jim could see the individual pieces of broken rock amongst the dirt, could watch the fantastic manner in which they were dancing. He looked about him, standing up and gripping the side of the car. Then away in front, along the clear tracks. He thought of the passenger train, and remembered that he alone stood between it and destruction. "I'll stick to this ship whatever happens," he told himself stubbornly. "If the train strikes me and breaks up the car, the wreck may throw it off the rails. Better that than allow it to run clear on into the passenger train. Ah! Here it is." Crash! The buffers of the leading truck struck the motor inspection car on her leading spring dumb irons, and the buffet sent her hurtling along the track, while the shock of the blow caused Jim to double up over the splashboard. But the wheels did not leave the tracks. Nothing seemed to have been broken. The dumb irons were bent out of shape, that was all. "Jump, yer fool!" came floating across the air to Jim's ear, while the figure of the man with the megaphone danced fantastically, arms waving violently in all directions. But Jim would not jump; he had long since made up his mind to stick to his gun, to remain in this car whatever happened; for the safety of the passenger train depended on him. True, a telephone message might have reached the driver; but then it might not have done so. He recollected that at the switch where this mad chase had first begun there was no telephone station closely adjacent. It would be necessary for the man there to run to the nearest one. That would take time, while his own flight down the tracks had endured for only a few minutes, though, to speak the truth, those minutes felt like hours to our hero.