THE CONQUEST OF TIME AND SPACE 



wings and skimming along some distance before they 

 acquire sufficient velocity to mount into the air. A de- 

 scription of a similar action of an eagle in leaving 

 the earth, written by a careful observer a few years ago, 

 has become classic. This huntsman had come upon 

 an eagle which had alighted upon the sandy banks of 

 the Nile, and had fired at it, thus stimulating the 

 bird to its utmost energy in getting into flight. Yet 

 on examining the foot-marks made in the sand it 

 was found that, even under these circumstances, the 

 bird had been obliged to run "full twenty yards before 

 he could raise himself from the earth. The marks 

 of his claws were traceable on the sandy soil," says 

 the writer, "as, at first with firm and decided digs, he 

 found his way, but as he lightened his body and in- 

 creased his speed with the aid of his wings, the imprints 

 of his talons gradually merged into long scratches." 



It is evident that if such a master of the art of flying 

 as an eagle must thus acquire initial velocity before 

 flight is possible, a human novice must do considerably 

 more. The method that would naturally suggest 

 itself would be that of running down the slope of a 

 hillside, and Lilienthal adopted this method, beginning 

 his flights by running down the gentle slope of a hill 

 against the wind, until the requisite momentum was 

 acquired. This was, indeed, a reversion to some of the 

 oldest types of flying-machines, but with this differ- 

 ence — that it was the result of scientific study. The 

 results attained proved that the theory was not vision- 

 ary — that scientists had not dreamed and studied 

 in vain. For, as little by little the experimenter gained 



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