"Well, give your hydroplane a spin, Dashaway," suggested Mr. King. "I want to see how she works, and must get back to the hangars on business." The Reliance, the new hydroplane of the Interstate people, was twenty feet long and had a fuel gauge and a bilge pump. Dave got into his seat, and Hiram sat directly beside him. A touch put the machinery in motion. "There's a puffy eighteen mile wind, Dashaway," cried out Mr. King. "Yes, I wouldn't venture too far from shore," advised Grimshaw, a trifle anxiously. The water was quite rough where the flight started. The machine acted all right, however. A crowd had gathered on the beach, and there was some encouraging cheering as the power boat gained good headway. "Whew I what have you invited me to, Dave--bath?" puffed Hiram. Dave had neglected to put in place the rubber cover, so that during the preliminary run along the water the waves drenched both of the boys. Dave stopped the motor and started drifting, at a sudden current or breeze sent the tail before the wind. The rear of the hydroplane was forced under water. "Look out!" ordered Dave sharply. "I see--we're in for an upset," spoke Hiram quickly. The hydroplane was forced over backwards, the tail striking a sand bar. Dave and Hiram were both ready for the tip. They escaped with only wetting their feet, for they climbed upon the bottom of the upper surface as the hydro capsized. The hydroplanes prevented the machine from sinking. Almost at once a boat put out from shore. Once back at the boat house, the damage shown was a slight fracture to the main girder and some of the ribs at the trailing edge, and two broken tail spars. Dave sent Hiram at once to the practice grounds to arrange about the repairs. "It's no weather for a trial, Dashaway," said Mr. King, "I think I would postpone the trial trip until tomorrow, if I were you." Dave did not commit himself. He stayed about the boat house after the airman and Grimshaw had gone away, watching every move of the repair man. "She's staunch and sound as she was at the beginning," the latter declared, when he had completed his work. "Yes, I think that is true," replied Dave. "What's the programme?" inquired Hiram, "for I see you don't intend to give up." "Not until I master the Reliance, just as I did the Baby Racer," declared Dave. "That upset was necessary, I guess, to teach me that I must drive on just as little surface as possible in speeding, and make the wings do one half the work." "Then you are going to try again?" questioned Hiram. "Yes, Hiram. The waves aren't so choppy now, and the wind has gone down a good deal." "It's pretty late for much of a run," replied Hiram. "Oh, we can make the end of the lake and back inside of an hour." "Well, I'm always ready--with you," laughed Hiram gaily.