“I wonder why Dave doesn’t come back?”

“He must have taken quite a walk, Roger.”

“I should think, Phil, that he would be too tired to go very far; we’ve had quite a strenuous day, if you’ll remember.”

“I don’t have to remember! My back keeps reminding me of it all the while,” said the shipowner’s son. “I’ll tell you what—being a working engineer in the army is no fool of a job!”

The two chums had finished the letters they had spoken of writing, and along with several of the others were taking their ease in that portion of the abandoned mines which had been turned over to them for quarters. Not far away Ben and Buster were sitting beside a small nail keg, playing a game of checkers on a home-made board with some French coins for men. Close at hand sat Shadow, telling one of his innumerable stories to some of the other engineers.

“What do you say if we go out and meet him?” remarked Roger, after a pause.

“Suits me,” responded Phil. And a moment later they were on their way.

Outside the moon still shone brightly, so that objects could be seen for quite a distance. They looked up and down the path through the trees, but, of course, saw nothing of the young lieutenant.

Presently an officer approached them who proved to be Captain Obray.

“Out a little late, aren’t you?” said the captain pleasantly, as they saluted. “I thought all you fellows were pining for sleep after such a hard day’s work.”