“Oh, say, speaking of the holes leading into the mines puts me in mind of a story,” began Shadow. “Once there were three boys—” He stopped abruptly and looked contritely into the sober faces of his chums. “Confound it, anyway! what business have I got to try to tell a story at such a time as this? Excuse me, fellows. I—I feel just as bad over this as any of you do,” he added, lamely.

“Speaking about holes,” resumed Roger, after an awkward silence, “Phil and I examined two more of them yesterday, but got no trace whatever of Dave. That makes about the tenth time we have been out on a search.”

“And I have been out just as many times,” came from Ben; and Buster and Shadow nodded to infer that they had done practically the same thing.

Several days had passed since our hero’s disappearance, and the time had dragged heavily with his chums. Had it not been for the daily tasks assigned to them, they would have been a most miserable crowd. Even as it was, whenever they were off duty they invariably went on a hunt for their missing friend.

“Have you written anything to his folks yet, Roger, as you spoke of doing?” questioned Phil, a little later, when Shadow and Buster had left the others.

“No, I haven’t, Phil,” was the slow reply. “I can’t pluck up the courage to do it. What Dave’s folks and the Wadsworths will say when the news reaches them is something I hate to think of.”

“I’m with you in that,” answered the shipowner’s son. “I’m sure such bad news will put Jessie Wadsworth to bed.”

“And Laura, Phil. Don’t forget her. She thinks the world and all of her brother.”

“It’s too blamed bad, that’s what it is!” burst out Ben. “Oh, I do wish we could learn what has become of him!”

The young engineers had been kept fairly busy, for the American army and their allies were advancing steadily. The Americans had had one or two hot contests for the possession of several French villages. They had driven the Germans from the outskirts, and then from the villages themselves, and finally into the woods beyond, making an advance of ten or fifteen miles all along the front. The casualties had been heavy, and as a consequence the field hospitals were crowded with the wounded.