"Oh, all right, Tom. I just wanted to tell you that I think I've gotten over that difficulty you found with the big carburetor you were working on. You didn't say what you wanted it for, except that it was for a heavy duty gasolene engine, and you couldn't get the needle valve to work as you'd like. I think I've found a way." "Good, Dad! I'll look at it when I come back. That carburetor did bother me, and if I can get that to work--well, maybe we'll have something soon that will--" But Tom did not finish his sentence, for Koku was getting the aircraft in operation and Mr. Damon was already taking his place behind the pilot's seat, which would be occupied by Tom. "All ready, are you, Koku?" asked the young inventor. "All ready, Master," answered the giant. There was a roar like that of a machine gun as the Hawk's engine spun the propeller, and then, after a little run across the sod, it mounted into the air, carrying Tom and Mr. Damon with it. "Mind you, Tom, no stunts!" called the visitor to the young inventor through the speaking tube apparatus, which enabled a conversation to be carried on, even above the roar of the powerful engine. "Bless my overshoes! if you try, looping the loop with me--" "I won't do anything like that!" promised Tom. Away they soared, swift as a veritable hawk, and soon, after there had unrolled below their eyes a succession of fields and forest, there came into view rows and rows of small brown objects, among which beings, like ants, seemed crawling about. "There's the Camp!" exclaimed Tom. "I see," and Mr. Damon nodded. As they approached, they saw, starting up from a green space amid the brown tents, what appeared to be big bugs of a dirty white color splotched with green. "The aircraft--and they have camouflage paint on," said Tom. "We can watch 'em from up here!" Mr. Damon nodded, though Tom could not see him, sitting in front of his friend as he was. Up and up circled the army aircraft, and they seemed to bow and nod a greeting to the Hawk, which was soon in the midst of them. Tom and Mr. Damon, flying high, though at no great speed, looked at the maneuvers of the veterans and the learners--many of whom might soon be engaging the Boches in far-off France. "Some of 'em are pretty good!" called Tom, through the tube. "That one fellow did the loop as prettily as I've ever seen it done," and Tom Swift had a right to speak as one of authority. Tom and his friend watched the aircraft for some time, and then started off in a long flight, attaining a high speed, which, at first, made Mr. Damon gasp, until he became used to it. He was no novice at flying, and had even operated aeroplanes himself, though at no great height. Suddenly the Hawk seemed to falter, almost as does a bird stricken by a hunter's gun. The craft seemed to hang in the air, losing motion as though about to plunge to earth unguided. "What's the matter?" cried Mr. Damon.