Calmly, Priest stopped the engine. The silence sounded louder than the motor had, for a minute, and Hike yelled “Ouch!” clapping his hands to his ears. Laughing at him, Martin Priest went on, “This bar at my feet controls the engine-feed—if you take your feet off, the feed’s shut off. There aren’t any ailerons, and there aren’t any wings to warp, for lateral stability. (Aren’t we sinking down pretty though?) Don’t need them to keep from tipping, with all these little planes. The rest of the engine-control—spark and so on—is like the engine you learned on a Jolls biplane. That’s enough for a first lesson. Now try her.” He started the engine, stepped back to a passenger-seat, and apparently went to sleep. Hike pushed the right lever cautiously forward, and up shot the machine—up, up, easily, swiftly, the trees and houses, spread out beneath him, fading into a mist. Then he turned in a long awkward circle, and planed easily down. He quivered as he felt the aeroplane obey him. He wanted to go on forever. He wanted to try to make a landing. But he wouldn’t take any chances on wrecking the tetrahedral on her first trial trip. So he motioned to Martin Priest to take control again, and settled back into a passenger-seat, whistling his happiness. They landed in a field outside of Monterey. The ranchero who owned it came rushing up—and in less than ten minutes Lieutenant Adeler had bought that field from him, for an aviation-course. Before nightfall, the Lieutenant had telegraphed to San Diego for the two hundred and thirty horse-power Kulnoch engine which, he told Martin Priest, a crank aviator down there had for sale. The lieutenant sent Hike to buy the lumber for an aerodrome, and led Martin Priest to a barber, to get his hair cut. (But Priest refused to get any better clothes. “Let all the rest of the money you want to spare go in on the tetrahedral,” he said.) Within a week, the new engine had arrived and been put into the aeroplane, while a rough shed had been built. Then Hike heard that Captain Willoughby Welch was going to leave in a couple of days, though it was nearly a month before he was due to report to the Army Board of Aviation—which would spend a million on purchasing some sort of aeroplane. Hike and Jack Adeler had told the Captain nothing about the arrival of the Priest tetrahedral yet, wishing to surprise him after the new engine was installed. But now Hike rushed over to the Captain’s quarters, and begged him to take a look at the _Hustle_. The Captain refused, laughing in his face. The most that he would promise was to come back and take a look at her before going on to Washington. He would have to be back for a day or so, anyway, he said. Hike was much discouraged. But he went on working with Priest and the Lieutenant. It was Hike who suggested a spring for the throttle-foot-bar, so that the aviator could take his feet off the bar, if he wished.