"By George! I believe you are right," exclaimed Chester. "I wouldn't have thought of it, and if I had been in your place at the throttle the chances are we would have gone over if such is the case." "Well," said Hal, "I'll climb down, take a walk ahead and investigate." "I'll go with you," declared Chester. "No, you won't. You stay here and watch the engine." "You are right, as usual," said Chester. "But don't be any longer than you can help." Hal agreed, and a moment later Chester lost sight of him in the darkness. Slowly and cautiously Hal made his way along the track. As he moved stealthily around a curve in the road the cause of the explosion became apparent. It was even as he had feared. His quick wit had detected the meaning of the explosion and none too soon. Just ahead, where a short time before had been a bridge spanning a deep chasm, there was now nothing but space. The bridge had been blown up. Had Hal applied the brakes to the engine one minute later, in spite of the fact that it was traveling very slowly, both boys probably would have been carried over the embankment to certain death; for it is doubtful that either, in the darkness, would have noticed the absence of the bridge in time to leap to safety. And now Hal could make out a number of rapidly moving figures. To his dismay, he saw that they were moving in his direction. He turned quickly and ran back to the locomotive, where Chester was anxiously awaiting his return. "Out here, quick!" he cried, and Chester, in response to his command, leaped to the ground. Hal once more jumped aboard the locomotive, unheeding Chester's cry of wonder, released the brakes, and threw the throttle wide open. Then he dropped sprawling to the ground, while the engine dashed madly down the track. Hal was not badly hurt and was quickly on his feet. "What's the matter?" asked Chester in alarm. "Matter is that the Germans are coming this way," answered Hal. "Come, let's get away from here while we have a chance. We may be able to escape in the darkness." "But why did you start that engine down the track like that?" "Well, I couldn't see that it was any use to us any longer, and it may dispose of a few more Germans. They are walking up the track in force." This appealed to Chester. "Good!" he cried, and both stopped in their tracks to listen. A second and there came to their ears a sudden startled shout, followed by a fearful yell, a moment of silence, and then a crash. "Good-by engine," said Hal. "That's a good job done. You perished nobly. Now," to Chester, "let's get away from this spot as fast as we can." They turned their faces in the direction from which they had come, and set out at a brisk pace. They plodded along for an hour through the open country, finally coming to a dense woods. "Guess we had better try and lose ourselves in here," said Chester. "Right you are," agreed Hal.