Page:Popular Science Monthly Volume 27.djvu/320

304 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 propeller into action, with a velocity of three revolutions per second, and turning the head of the aërostat against the breeze, it was kept motionless for some minutes; but the rudder soon proved to be insufficient to keep the direction constant, flapping like a sail, and at times



leaving. the aëronauts at the mercy of the wind. After stopping the propeller and waiting until the direction of the aërostat 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 aërostat 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 aëronautics 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 danger and without any uncontrollable 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 aërostat 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 aërostat was propelled at a rate about one third greater, so as to make at times very perceptible headway against the wind.