"Those men are undoubtedly spies," he declared. "They most certainly had designs upon my biplane, which they evidently knew had been completed. I shall turn them over to the military authorities."
He left the house, and in a few moments returned with a squad of soldiers, who took the assailants in charge. Fritz explained to the officer how the two men had been captured, and the German officer complimented the boys highly for their prompt action.
After the two prisoners had been led away, Hal bethought himself of the remark Fritz had made concerning his biplane.
"Do you mean to say your aeroplane is ready for use?" he asked.
"Yes; I am going to make a short flight this afternoon. Would you care to watch me?"
"Would we!" exclaimed Hal. "You can just bet we would!"
"All right, then; come on."
The two lads followed Fritz to his workshop. Inside the boys approached the large aircraft, which rested lightly on its wheels at the end of the speedway. The huge planes which served as wings stretched out on either side like two great box kites, while underneath the aviator's seat the gearing could be plainly seen.
The aviator looked at the machine with great pride, and spoke of the improvements he had made in the propellers and in the system of power transmission. He explained to the boys that, by this direct system, he had gained twenty per cent more velocity; and, now that the war had begun, he hoped to be able to prove this to the army experts.
The boys helped Fritz push the machine out into the open, and watched intently while he tested the steering gear and tried the ignition. After some further tinkering, Fritz finally took his seat, pulled a lever, and, after skimming the ground for a few rods, the machine rose gracefully into the air.