[Illustration: Many glider flights at Kitty Hawk preceded the first attempt to fly in a power-driven plane. Here the Wrights are flying a glider as a kite, controlling it from the ground. Later flights were made in man-carrying gliders.] The brothers now began to study wing structure, but hit upon many difficulties. A simple incident set them on the right track. In selling a customer an inner tube for a tire, Wilbur had taken the tube from the pasteboard box and was idly twisting the box back and forth as he talked to the customer. In doing so he noticed that although the vertical sides remained rigid at the ends, the top and bottom sides could be twisted so that they made different angles at the opposite ends. He immediately wondered why the wings of a gliding machine could not be warped from one end to the other in this same way. In this way the wings could be put at a greater angle at one side than the other and there would be no structural weakness. Wilbur explained the plan to Orville and it seemed so satisfactory that they adopted it for their gliders. The Wrights were now glider-conscious. They built a bi-plane kite with a new system of controls. In 1900 the brothers constructed a man-carrying glider. In order to get practice in operation, they decided to fly it first as a kite. For kite flying they required flat, open country; and for gliding, sand hills free from trees or shrubs were necessary. Favorable winds were also needed. From reports received from the Weather Bureau in Washington, the Wrights learned that a place named Kitty Hawk in North Carolina seemed to meet all requirements. So they wrote to the man in charge of the weather station there for further information. On his and other data, the brothers came to the conclusion that Kitty Hawk was suitable for experiments. What was then a tiny spot on the map was to become, in time, a center of world interest. [Illustration: Diary of Orville Wright, showing page recording the first successful flight.] [Illustration: Map of Kitty Hawk area.] Man conquers the air The spot chosen for the Wrights’ experiments was located on a long strip of sandy beach separated from the mainland of North Carolina. At one point was the Kitty Hawk Life Saving Station and alongside, a government weather station. A mile back from the ocean was the tiny village of Kitty Hawk. Four miles south was the Kill Devil Life Saving Station. Altogether, it was a dreary and uninviting area but one where history was to be made.