"I'd say not," rejoined the former Air Mail pilot sententiously. "Mum's the word; we've got something here, Buddy. Unless I'm greatly mistaken we'll be consulting with the Patent Office at Washington much sooner than little mother anticipates." He poked Paul in the ribs as he spoke, and both young men gave vent to a low chuckle of intense satisfaction. It was an even greater pleasure to look forward to surprising their mother than to astonishing the world and winning its plaudits. As good an airplane mechanic and flyer as John Ross was, his younger brother was little behind him in the matter of skill in handling a modern machine. It had been John's habit to return to Yonkers every two weeks for a week's lay-off, as customary with other pilots in the Air Mail service. On these occasions he had arrived in his plane, and during the term of his stay had often taken Paul up into the air for pleasure flights, as well as his chum Bob Giddings. Both boys were keen students, and it was not long before John could trust them to operate his big Martin with every confidence. Once, indeed, he and Paul had been caught over Long Island Sound in a bad storm, when the latter was in the pilot's seat, but Paul had brought the craft through like a veteran, winning his brother's unstinted praise and undying respect. CHAPTER III A SUCCESSFUL MODEL Mr. Giddings was glad to accept the invitation to the trial flight. He and his son met the Ross boys at the old race-course Saturday afternoon. This immense, level field, with its one-mile oval and great empty sheds, at one time had been the county's boasted fair-grounds, but two years prior to the opening of our story it had been sold to Mr. Giddings, whose residence property stretched down the side of Shadynook Hill and joined it. New fair-grounds had then been established in another and more centrally located section of the district. In the old grounds the boys of the neighborhood now went to fly their kites and model airplanes, to hold impromptu bicycle and foot races, and to play tag and hide-and-go-seek in the cavernous sheds and around the numerous sagging stables. It was late in the afternoon--just before dusk, when the winds would be at their quietest, and others not likely to be present--that our friends arrived at the field. There was not a soul to be seen. Paul, who had carried his precious Sky-Bird, freed it from the wrapper and held it up for Mr. Giddings to see. The night before he and John had put the finishing touches to the delicate structure by adding another coat of varnish and attaching the little rubber-tired aluminum wheels to the axle. As Paul now held it up before the gaze of the great newspaper man, Mr. Giddings made no effort to restrain his admiration. "What a little beauty!" he cried. "Why, it's almost a perfect mechanical representation of a bird!" "Isn't she a dandy, dad?" put in Bob, his eyes snapping.