In 1903 a 16-horse-power engine and twin-screw propellers were applied to the navigable glider at Kitty Hawk, as shown in Plate XX. The power machine weighed 750 pounds, and was usually started by aid of a tow line and falling weight which helped the craft to acquire headway. After many trials and modifications, the first successful launchings, four in number, were made on December 17th. The first flight lasted 12 seconds, the next two a little more, the fourth lasted 59 seconds, covering a distance of 852 feet over the ground in the face of a twenty-mile wind. To the superficial observer these performances did not seem a very remarkable advance on the flights of Ader, but they had in them greater promise and potency of practical flight. They were the first flutterings of a fledgling endowed with the chief essential organs of aërial locomotion—an awkward but healthy creature that had been evolving steadily for several generations. It would grow rapidly, and ere another half decade, increase the 59 seconds to so many minutes. PLATE XX. [Illustration: FIRST WRIGHT AËROPLANE (REAR).] [Illustration: FIRST WRIGHT AËROPLANE (SIDE).] The experiments were continued during the next two years with increasing success. During the season of 1904, on a field near Dayton, one hundred and five flights were made, some short, others covering the entire circuit of the field no fewer than four times, the two largest measuring each nearly three miles, each accomplished in about five minutes. Various improvements were made in the propelling and steering mechanism, and increased skill in maneuvering was gradually acquired. In 1905 the flights were resumed with a new machine embodying some changes dictated by experience, particularly in the method of control. Forty-nine landings were made involving seven breakages, but no personal injury. On September 26th a flight of eleven miles was achieved. This was followed, within the next nine days, by flights of twelve, fifteen, twenty-one and twenty-four miles, at a usual speed of 38 miles an hour. After this the field practice ceased for more than two years, and the machine was dismantled to preserve secret its mode of construction till the patents could be disposed of. As these performances and those preceding are of unusual interest, a fuller account is given in Appendix IV.