Lilienthal's first experiments were made in 1891 with a pair of semicircular wings steadied by a horizontal rudder at the rear. The whole apparatus weighed forty pounds and had a total plane surface of 107 square feet. He would run along the ground and jump from the top of a hill. He made many good flights, and in 1893 with a new glider averaged 200 to 300 yards and steered up or down or to either side at will. Lilienthal found that the air flowing along the earth's surface had a slightly upward current, as science tells us it does, and that it would carry him upward if the wind was blowing strong enough. Hence he could go forward either up or down in about the same way that a yacht tacks against the wind. But Lilienthal had the same trouble in balancing that the Wright brothers had at first, so he kept an even keel as best he could by swinging his legs and body from side to side as he hung underneath the glider. The "flying man" made about 2,000 flights and then constructed a still more successful biplane glider for which he built an engine. He was killed while making a glide on August 9, 1896, however, and the motor was never used. Several authorities who were in touch with Lilienthal declared that the machine had become wobbly and unreliable. This, they said, was the cause of its collapsing in midair under the heavy strain. Lilienthal's death, though mourned by scientists all over the world, did not interfere with the great work he had started, for his system had many disciples both in Europe and America. Among these, besides the Wrights, were the Americans Octave Chanute and A. M. Herring, and Percy S. Pilcher of the University of Glasgow. Pilcher was killed three years after Lilienthal, September 30, 1899, while trying to make a glide in stormy weather. [Illustration: THE FIRST SANTOS-DUMONT AEROPLANE This was the first successful aeroplane to be flown in Europe, and was quickly followed by others.] [Illustration: THE CROSS-CHANNEL TYPE BLÉRIOT MONOPLANE The Blériot monoplane was the first of the monoplane type to make a success in Europe.] [Illustration: A VOISIN BIPLANE The Voisin brothers perfected the first permanent aeroplane used in Europe. Henri Farman made his first wonderful flights in a Voisin.] [Illustration: GLENN CURTISS ABOUT TO MAKE A FLIGHT] [Illustration: HENRI FARMAN STARTING ALOFT WITH TWO PASSENGERS] [Illustration: LOUIS BLÉRIOT SHORTLY AFTER COMPLETING HIS TRANS-CHANNEL FLIGHT]