“Too close for comfort,” Hal agreed.

“I wonder how many we killed back there,” said Chester.

“I don’t know, but I am sure it was enough.  It seemed to be their lives or ours.”

“It’s only a few more gone to the Happy Hunting Ground in a mistaken cause,” said Chester slowly.  “But, as you say, it was either they or us.  There was nothing else we could do.”

“No,” said Hal, “there wasn’t; but, just the same, it gave me a cold chill as they went flying through the air.  It was terrible.”

Both lads were silent for a time, as the locomotive continued on its way.  It was getting dusk now, and Hal was forced to reduce the speed of the engine even more.  They went slowly along, both lads keeping a wary eye ahead for Germans.

Darkness came on, and still they rode along.  Their speed was little better than a walk, and it was well that Hal had decided to discontinue his reckless driving.

From ahead, a sudden red glare went up to the sky, followed almost instantly by a report like that of a thousand cannons.  The locomotive came to a stop with a jolt as Hal applied the brakes.

“What’s up now?” demanded Chester.

“I don’t know; but that explosion sounded to me as if there were something wrong ahead.  I wouldn’t be surprised if the Germans had dynamited the bridge.”

“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.