Page:My Airships.djvu/152

 instead of pushing it through the air. The new 7 horse-power motor with two cylinders turned it with a velocity of 100 revolutions per minute, and produced, from a fixed point, a traction effort of some 30 kilogrammes (66 lbs.). The pole keel with its cross pieces, bicycle frame, and mechanism weighed heavy. Therefore, although the balloon was filled with hydrogen, I could not take up more than 50 kilogrammes (110 lbs.) of ballast. I made almost daily experiments with this new air-ship during August and September 1900 at the Aéro Club's grounds at St Cloud, but my most memorable trial with it took place on 19th September in presence of the members of the International Congress of Aeronautics. Although an accident to my rudder at the last moment prevented me from making a free ascent before these men of science I, nevertheless, held my own against a very strong wind that was blowing at the time, and gave what they were good enough to proclaim a satisfying demonstration of the effectiveness of an aerial propeller driven by a petroleum motor. A distinguished member of the Congress, Professor Langley, desired to be present a few days