THE CONQUEST OF TIME AND SPACE 



the air, and it is for this reason that the many members 

 of the balloonist school advocate the inflated bag in 

 place of the aeroplane. The argument advanced by 

 them is that since man has no chance naturally to ac- 

 quire familiarity with balancing in the air, the simplest 

 and best way for him to acquire it is by making balloon 

 ascensions. When he has acquired sufficient skill he 

 can gradually reduce the lifting part of his flying- 

 machine, or gas-bag, gradually increasing the aero- 

 plane or other means of propulsion and lifting, until 

 the balloon part of his device can be dispensed with 

 entirely. 



In short, this argument of the balloon advocates is 

 comparable to two schools of swimming- teachers, one 

 of whom advocates the use of sustaining floats until the 

 knack of swimming is acquired, the other depending 

 upon the use only of muscular movements and quickly 

 acquired skill. In this comparison the aviators have 

 all the best of the argument; for it is a common ob- 

 servation that persons who attempt to learn to swim 

 by the use of floats of any kind acquire that art slowly 

 if at all; while those who plunge in boldly, although 

 they run more risks, quickly learn the art that seems 

 ridiculously easy when once acquired. 



The great German scientist, Helmholtz, after years 

 of careful study, finally reached the conclusion that 

 man would never be able to fly by his own power alone. 

 But, as we have seen. Professor Langley had shown that 

 in these mysterious questions pertaining to flight even 

 a Newton could be wrong; and why not Helmholtz? 

 Otto Lilienthal, also a German, thought that his 



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