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THE POPULAR SCIENCE MONTHLY 



on reaching a height of sixteen hundred feet the wind was blowing at 

 the rate of rather more than six miles an hour. On putting the pro- 

 peller into action, with a velocity of three revolutions per second, and 

 turning the head of the aerostat against the breeze, it was kept mo- 

 tionless for some minutes ; but the rudder soon proved to be insuffi- 

 cient to keep the direction constant, flapping like a sail, and at times 



I'issandier's Balloon, 18^. 



leaving. the aeronauts at the mercy of the wind. After stopping the 

 propeller and waiting until the direction of the aerostat coincided with 

 that of the wind, the action was renewed. A marked acceleration in 

 speed was the immediate result, and deviations from the line of the 

 wind were secured by very slight motion of the rudder, the aerostat 

 keeping its stability perfectly. The descent was safely accomplished 

 after remaining in the air a little more than an hour. 



This first experiment in the use of electricity in practical aeronau- 

 tics was about as successful as that of Giffard with steam in 1852, so 

 far as relates to the attainment of speed ; but it showed that such 

 speed could now be secured without clanger and without any uncon- 

 trollable variation in the weight of the mass propelled. Tissandier 

 did not expect the attainment of complete success in a single trial ; 

 such as he did attain was enough to convince not only him but others 

 that he had opened out a pathway which could be followed with en- 

 tire confidence. He had not the means at hand sufficient to enable 

 him to keep his aerostat inflated, so as to repeat his experiment on the 

 first favorable day after imposing such modifications as were suggested 

 by the experience of the first ascent. It was not until September 26, 

 1884, that this opportunity was presented. The velocity of the wind 

 was about the same as during the first ascent, but the aerostat was 

 propelled at a rate about one third greater, so as to make at times 

 very perceptible headway against the wind. 



