On the 17th of September the tragic accident that put a stop to the flights occurred. Orville Wright was flying about 75 feet high with Lieutenant Selfridge as a passenger when one of the propellers hit a stay wire which coiled about the blade, breaking it and making the machine unmanageable. The aeroplane plunged to the ground, throwing the occupants forward. Lieutenant Selfridge suffered injuries from which he died within three hours, while Wright suffered several broken bones. This occurred while Wilbur Wright was at Le Mans, France. The year before Dr. Alexander Graham Bell, the American inventor, had invited Glenn Curtiss, a bicycle and motor manufacturer, to aid him in equipping with power the fliers that he was constructing with the help of Lieutenant Selfridge, F. W. Baldwin, and J. A. D. McCurdy. They formed the Aerial Experiment Association, which later became famous, and early in March, 1908, began the test of their first aeroplane, which they called the _Red Wing_. The machine was tried over the ice of Lake Keuka, near Hammondsport, N. Y., and before its makers were ready to fly it went into the air and sailed 300 feet. The _Red Wing_ was of biplane type and mounted on skids, with the propeller and vertical direction rudder at the rear. The horizontal elevating rudder was at the front. The notable feature was the curve of the planes. The upper plane curved from the centre downward, while the lower plane curved from the centre upward, so that the two planes, if they had been a little bit longer, would have met. This curvature was expected to give automatic stability, but the machine was never a great success. The next machine made by these experimenters was called the _White Wing_, and made some fair flights. The next was the famous _June Bug_ which was designed by Curtiss and entered by him to contest for the _Scientific American_ Cup for a flight of one kilometre. The test, which was held on the 4th of July, 1908, near Hammondsport, was the first official flight for a prize in America, and was successful in every way, winning the cup with a flight of 200 yards. This biplane had the three-rudder control--that is, a tail at the rear shaped like a box kite to steer it from right to left, two small parallel planes in front to steer it up or down, and a system of flexible wing tips which enabled the operator to maintain a side to side balance. In 1909 Curtiss made some important improvements over his machine of previous years by replacing the flexible wing tips with ailerons. This was the first time these devices were used in this country, but they had already been introduced in Europe on several machines. There are many kinds of ailerons, but on Curtiss's biplane they were two small horizontal planes fixed between the outer tips of the upper and lower planes. They could be turned so as to keep the aeroplane balanced when making a sharp turn or when struck by a gust of wind.