"We're coming into it now," the brakeman went on. "It's about a mile from here. I'll go back, and when you hear five whistles from the engine you'll know it's slowing up and you are to jump off. I know the conductor will do that if I ask him." The brakeman climbed up the ladder on the end of the box car next to the gondola where the boys were, until he reached the run-boards on top. Then he hurried along to the caboose, where the conductor was. "We must listen for the five whistles," said Jack. "Get ready to jump, Mark. Don't forget your baggage." "No danger of that," chimed in the other, falling into the joyful mood of his companion, who never seemed to be cast down for long, no matter what happened. The train was going down grade now, and the speed was much increased. Telegraph poles whizzed past at a rapid rate and the wheels sung a livelier tune as they clipped over the rail joints. "It's a good thing the engineer is going to slow down for us," said Jack. "We'd never be able to jump off at the rate we're going." "Hark!" exclaimed Mark. "There goes the whistle!" The boys listened. A long, shrill blast cut the summer air, and vibrated back to them over the tops of the cars. "That isn't five whistles; it's one!" cried Jack. "It's the call for brakes! I wonder if anything has happened to the train!" There was a pause. Then came another single shriek from the engine's whistle. It sounded appealingly, as if the steam monster was in distress. "Look! Look!" shouted Mark. "We are going much faster than we were!" At the same instant there was a crash and a jolting sound. The train seemed to break in two parts at about the centre. The forward section, drawn by the engine, went one way, and the other part, with the gondola containing the boys, in the lead, took another track. An insecurely fastened switch was responsible for the accident. The locomotive and nearly half the cars of the train took the main track, while the remainder of the outfit swung on to a siding. The section of the train with the boys aboard had become a runaway freight! "What has happened?" cried Mark. "The train's broken in two!" shouted Jack. "Come on! Help twist the brakes!" Both boys sprang to the wheel of the gondola. It was all they could do to give it a few turns, but they managed to make the brake-shoes grip the wheels to some degree, as was evidenced by the shrill shrieking. "Can you climb up to the top of the box car?" asked Jack. "Sure!" shouted Mark. "Go ahead!" Though Mark was thin, he had a nervous strength almost equal to that of his stouter companion. "We must set all the brakes we can!" Jack cried. "That's the only way to stop the runaway train!" With their small arms they twisted the wheel on the box car. They got it as tight as they could, then ran along the top of the vehicle to the next one. About ten cars down they saw their friendly brakeman. "That's the stuff, boys!" he shouted. "There'll be a smash-up if we don't stop the cars!"