Tossing an armful of homework on the right-hand desk, and waving me to a battered chair, he slid into a swivel-seated one behind it. There he sat grinning like an ape, peering at me around three mountains of paper work heaped up in trays marked, “Incoming,” “Outgoing,” and “Hold.” Though still in his early thirties, Leighton had gray splashes around his temples with laugh wrinkles twinkling at the corners of his eyes—those early-bird aviators tended toward premature grayness. Now, clasping his hands behind his head and hoisting long legs so as to rest his feet on the battered old desk, he grinned his pleasure. “Nobody knows the trouble I’ve seen,” he quoted, “but now that I’ve finally got you here, I hardly know where to begin.” “Begin at the beginning,” I countered. “It’s all Greek to me.” “Well, in the beginning of power-driven flight,” he commenced, “before the Wrights could take the hurdle from the glider to the airplane, they had first to find an engine whose weight was light enough, in proportion to its power, to get the contraption into the air. And since nothing suitable existed, they had to design and build their own. Thus from the beginning,” he went on, “the power plant has been the heart of the airplane. Subsequent progress has been almost entirely a matter of getting more horsepower for less weight. When you want to lift yourself up by the bootstraps,” he added with a grin, “you start reducing, and begin exercising your muscles. The history of aviation can be measured by that ratio, pounds per horsepower.” At the turn of the century, Leighton pointed out, gasoline engines were just coming into use. The Wrights, in designing their little 20-hp 4-cylinder model, had naturally followed the current automotive practice. They had arranged the cylinders in line and had cooled the engine with circulating water. “It is only now,” Leighton explained, waving a hand in the direction of the Lawrance air-cooled radial near the door, “that we are spreading our cylinders like the petals of a daisy and cooling them directly by air. And this section,” he added with obvious pride, “is the foster parent of an innovation but recently classified by the engineering intelligentsia as ‘impossible.’ As for that obsolete term,” he went on, “we have a saying in the Section that goes like this: ‘The impossible we do today; the fantastic may take a little longer.’” He grinned as he watched me for the effect of another one of his phrases.