What they saw caused their hearts to beat faster and hope to spring up again in their breasts. For, skilled as they were in such matters, they recognized the airplane up above, whose roaring exhaust had first attracted their attention, as one of the Allied type. It was coming toward them at high speed, flying low, and as it rapidly neared them the four friends, forgetting their German captors, waved their hands wildly to the pilot, whom they could see, as the aeroplane came closer, peering down over the side of the body. The Germans, on their part, were so terrified by the approach of this huge enemy machine, that they seemed to forget all about their prisoners, and in fact about everything except their individual safety. With wild yells of terror they scattered this way and that, all except the sergeant. He, seeing his men running in every direction, snarled out a curse, and whipped out his automatic pistol. "I'll do for you Yankees, anyway, he hissed," and leveled the pistol at them. But even as his finger trembled on the trigger, Frank's fist, with the force of a sledgehammer, came with a crashing impact against the point of the German's jaw, and the Hun went down, his pistol exploding harmlessly toward the sky. Frank, with the light of battle in his eye, seized the fallen man's weapon and looked around for the other Germans. But by this time they had all gotten out of effective pistol range, and after emptying the weapon in the direction of the fleeing figures, Frank and the others turned their attention to the aeroplane, which by now was manoeuvring for a landing. The airship came down in great spirals, and finally took the ground with hardly a jar, running along a hundred feet or so and then coming to a halt. As the boys started running toward it, Tom ejaculated: "Say, fellows, my eyes may be playing me tricks, but if that isn't Dick Lever at the wheel you can call me a German!" "I think it is Dick, myself," agreed Frank. "And if this isn't a case of the 'friend in need,' I miss my guess." It was indeed as they thought. The pilot was an old friend of theirs, but one whom they had not seen for some time. Now, as they raced toward the airplane, he in turn recognized them, and raised a delirious shout of joy. "Tumble into this bus just as fast as you can, fellows," he cried, "we've got to get out of this mighty quick. You can explain the mystery of your being here after we get started." "But can you carry the whole bunch of us?" asked Billy. "Easily," replied one of the two observers, who had not spoken up to now. "We've just dropped our load of bombs on a few German supply depots, and now we're running back light."