"See that you are 'going some' at the finish of the race to-morrow," laughed Roque. "It will be because something breaks if we don't hit the high mark," assured Billy. "Go over and size up your winged steed," directed Roque, pointing to a hangar across the field. "Show them No. 3"--this to one of the attendants. "This is no mosquito," announced Billy, after a view of the fine lines of "No. 3." "Speed there, I tell you, old boy," was Henri's comment as he walked around the rigging, "and carrying armor, too." In an hour the boys had fully comprehended all the new features of this up-to-the-minute machine. They had been builders themselves and knew a good stroke of the business when they saw it. Returning across the field, Billy and Henri were introduced to the rival aviators by Roque. The German airmen were a jolly pair, and showed by the professional courtesy they exhibited to the two of their kind that the coming contest was wholly a friendly one, and the results to be of value to the flying corps. "No. 2 is a little older than your machine," was the greeting of one of the Teuton experts, "but it can hold its own." Roque, speaking for his champions, gaily disposed of this claim: "Keep your eyes open to-morrow, Fritz, or you will get lost somewhere in the rear." "No fear, sir; there are no cobwebs on No. 2." "What are they talking about, Buddy?" asked Billy. "They just think they are going to beat us, that's all," interpreted Henri. A bright clear morning presented itself for the aërial race, and Lake Constance lay like a broad mirror under the sunlight. The course was set due north and straightaway for twenty miles, and the turn fixed at a high point called Round Top, upon which, Roque informed the boys, a tall flagstaff had been mounted. There were no preliminary trials, for both machines had been carefully groomed, and each was as fit as a fiddle. With the aviators up the biplanes scudded down the field for the rise, and got away upon almost equal terms, the German drivers slightly in the lead, through better acquaintance with the lay of the ground. They trailed a yellow streamer, while the boys floated a band of black. The ascent reached 2,000 feet, when the machines darted north like arrows. Roque and a group of officers about him followed the speeders through field glasses. "They would run a swallow to death," remarked the secret agent to the aviation lieutenant at his side. The aëroplanes had dwindled in the vision to mere specks, and there was no telling which was in the fore. "Ah, they are headed back!" cried Roque. "Now for the show-down." The glasses revealed the specks moving twin-like, and such was the terrific onrush that the crowd surging in the field soon caught a view of the contestants in growing size. One enthusiast shouted: "Fritz will shut them out!"