Before returning to Dayton, the brothers were determined to try gliding on the side of a hill with a man on board. Four miles south of their camp was a magnificent sand dune about 100 feet high, covering 26 acres, called Kill Devil Hill. They carried their glider to this hill where they made about a dozen free flights down its side. To take-off from the hillside, one brother and an assistant holding the ends of the glider ran forward against the wind, while the brother who was to operate it ran with them until the machine began to “take hold” of the air, or was airborne. Then the operator jumped aboard and glided free down the hill for 300 or 400 feet, usually gliding only 3 or 4 feet above the soft, sandy ground. The Wrights repeatedly made landings on sledlike skids while moving at a speed of more than 20 miles an hour. The glider was not damaged, nor did the brothers receive any injury. “The machine seemed a rather docile thing,” Orville wrote to his sister, from Kitty Hawk, “and we taught it to behave fairly well.” Wilbur and Orville had misread the weather charts they had studied when choosing Kitty Hawk as the location for their experiments. The charts had listed monthly averages, while the day-by-day weather proved to be less than ideal. On some days tests could not be made because of a dead calm; other days the wind blew too strong—up to 45 miles an hour. Orville wrote about the strong winds that blew: A little excitement once in a while is not undesirable, but every night, especially when you are so sleepy, it becomes a little monotonous.... About two or three nights a week we have to crawl up at ten or eleven o’clock to hold the tent down.... We certainly can’t complain of the place. We came down here for wind and sand, and we have got them. [Illustration: Fellow campers at Kill Devil Hills, August 1901. From left: E. C. Huffaker, Octave Chanute, Wilbur Wright, George Spratt.] Even though the Wrights had only brief spells of favorable weather for practice, they learned much from their experiments. They were pleased with the efficiency of wing-warping to obtain lateral balance, and the horizontal rudder for fore-and-aft control worked better than they had expected. Though Wilbur and Orville believed that fore-and-aft balance and lateral balance were equally important, they were gratified that fore-and-aft balance was so easily attained. They made careful measurements of lift, drag, and angle of attack. The main defect of the glider was its inadequate lifting power. This might be due, the brothers conjectured, to insufficient curvature or camber of the wings which did not have the curvature used by Lilienthal, or perhaps even the Lilienthal tables of air pressure might be in error.