Jack Adeler was the son of a quiet old gentleman who had left him five hundred thousand dollars, a ranch in Mexico, and the kindliest disposition that a man ever had. He had graduated from Yale, then entered the army, and was devoting a great deal of his own private fortune to aviation. He had never made such showy flights as had Captain Welch, and he never advertised his knowledge of aviation as did the Captain, but Hike had the feeling that he really knew about ten times as much about it. He was solidly built and quick and quiet, and he liked to have Hike and Poodle with him, and never was tired of answering their questions. When they found him—playing golf on the Post links—he listened to their tale of Martin Priest and the tetrahedral. He said that he too was a little afraid that Priest was a crank; but he promised to ride down the coast with the boys and look over the machine. They started the next day. When they reached the secret valley beyond Canyon Diablo, the crank aviator was sitting on a soap-box, waiting for them. He had cut his hair, in a rough way, and had changed his crazy-looking white gown for overalls, a blue flannel shirt, and a greasy sweater-jacket. Poodle’s opinion was that he had changed himself from a crazy prophet into a tramp, a hobo mechanic; but both Hike and Lieutenant Adeler said that he looked like an Edison, with his broad forehead, slender hands, and bright eyes. “Well, I wish I could find out all them things, like you high-brows,” sighed Poodle. “I admit that I’m a mutt. I ain’t even sure but what I’m a wutt. So I hope you’ll let me go to sleep on that nice soft grass, and not yell ‘Come on’ too quick.” Martin Priest seemed to have waked up. He spoke quickly and hopefully—just as Hike did when he was interested. He showed them the machine, and told them of the small flights he had taken with his broken-down engine. He explained a hundred devices. For instance, there was the speed changing gear. His aeroplane was the only one that ran on several speeds, like an automobile, so that the aviator could fly at different rates without having to cut down the feed of the engine with the hand-throttle, every second. But there was a hand-throttle, too. Then, there were double control wires, running from the levers to the rudder and the elevating planes, so that, if one wire broke (a thing that has caused many an aviator’s death) another would take its place. For starting the machine from the seat—without having to have some one whirl the propeller till the engine was going—there was an electrical motor, which was a sort of boy of all work. For, when it was through its work as a motor, it became a dynamo, and filled up storage-batteries which worked the big electrical search-light, for use when the machine was flying at night. It also ran a tiny electric stove, placed at the side of the freight-platform, and warmed electric heating-pads placed on the aviator’s seat to keep him warm.