According to the usual custom, Peter went on board to test the controls. He was rather a long time--not that the testing was a lengthy affair. As soon as he gained the for'ard motor-room, he proceeded to enclose the magneto of each of the two for'ard motors with sheets of pure Para rubber, making a tight joint to each of the high tension and "earth" wires. The mechanic watched him curiously, but, having been given to understand that certain experiments were to be carried out, he took the unusual procedure with equanimity. "Now," thought Peter, "won't Uncle be surprised if he succeeds in only cutting out the after-engines. We'll see if his secret ray will penetrate this insulated screen. I don't fancy it will." He made his way back to the pilot's seat and gave the recognized signal that everything was O.K. The rest of the crew swung themselves into the observation saloon, while the ground attendants removed the chocks from the massive, tyred landing-wheels. Peter depressed the switch controlling the four electric starters. Instantly the propellers revolved and the flying-boat quivered as if eager to soar into her natural element. A very short run--barely thirty yards--was enough for the machine to acquire momentum sufficient to part company with Mother Earth. With the planes tilted to their maximum angle, the flying-boat almost leapt upwards. The British pilot let her climb steadily, until the altimeter registered 1800 metres. Then he flew steadily eastwards until the flying-boat was immediately over the spacious lake of Sta Estralloda. If the electric current were cut off and a hitch occurred whereby Peter would be unable to restart the motors, the flying-boat could descend and take the surface with little risk. A forced landing on unsuitable and unyielding land might end disastrously. With frequent glances at the clock on the dashboard, Peter kept the flying-boat soaring above the sheet of water. Although he did not turn his head, he knew that curious eyes were watching him through the window between the saloon and his "office". Ostensibly, the experiments were to prove the efficacy of a loud-speaking wireless telephone that claimed to be proof against atmospherics and "cutting in". It was sheer bluff on Brian Strong's part, but it sufficed to allay suspicion as to the real nature of the test. The hands of the clock simply crawled round until they indicated 10.15--the pre-arranged time for the liberation of the secret ray. Nothing happened! The motors continued to purr with their usual rhythm. It made no difference that the magnetos of the for'ard pair were insulated and those of the after engines were not. On the face of things, Uncle Brian's experiment was a failure. Another minute elapsed. Peter continued to keep the flying-boat circling, at the same time descending to 1500 metres.