It was some time before, in the plan for the sham battle, the enemy was expected to approach this copse of woods, and, with sentries posted, to detect and give warning of an approach, the rest of the men had been permitted to break ranks and do as they pleased. Some had thrown themselves on the ground in all sorts of sprawling attitudes, others were smoking and chatting together, while still others wandered to the edge of the woods and gazed over the broad plateau that stretched for more than a mile to the left of the woods. The sky was cloudless and the sun was shining brightly. The monotonous boom of the distant guns, sounding like the roar of waves upon a beach, kept up unceasingly, but the boys had got so used to it that they scarcely noticed it. But suddenly, among these bass notes came another sound, or series of sounds, sharp, shrill, metallic, which they had already learned to identify as the popping of anti-aircraft guns. "That sounds as though they had sighted one of the Hun aeroplanes," commented Frank. "More likely it's part of the practice," remarked Tom, carelessly. "Look at those shrapnel puffs over there," cried Bart, pointing toward the sky. High up in the air, following one another in quick succession, were light, bluish streaks, that after reaching an enormous height, suddenly burst in a cloud of white. "They're certainly firing at something," remarked Billy, "but for the life of me I don't see what it is." "I do," cried Bart. "Look! just at the edge of that fleecy cloud. It's so white you can hardly tell it from the cloud itself." They strained their eyes in the direction where Bart was pointing. High up in the air, miles, it seemed, was a long, silver streak, shaped like an immense cigar. At that height it seemed almost to hang in the atmosphere, so gliding and imperceptible was its motion. And yet the boys knew that it was really shooting along with the speed of an express train. "A Zeppelin!" they shouted, in chorus. "A super-Zeppelin, or I miss my guess," observed Frank. "Look at the size of it." "Oh, if the guns could only reach it!" exclaimed Bob. "No such luck," groaned Billy, "it's too far up. See! the shrapnel puffs are half a mile below it." "It's on its way back to the German lines," remarked Frank, "and I guess there's nothing to stop its getting there." "Been on a baby killing trip to Paris, I suppose," said Tom, bitterly. "More likely London, judging from the direction," estimated Billy. They watched the monster as it sailed swiftly on, until it was lost to sight. "I'd have given a year of my life to have seen that thing brought down," said Bart. "Can't you see the crew of it gloating over the women and children they've killed, and boasting about it when they get back to their lines?" "Well, you know the Indians used to scalp women and children just as eagerly as they did men," remarked Billy, "and those Boches can give the Indians cards and spades and beat them out."