242 BEACH GRASS 



but at other times their wings appear motionless 

 save for slight adjustments from time to time, 

 yet in a mysterious way the great birds rise higher 

 and higher. How can these things be? How 

 can a bird defy gravity and sail upwards without 

 muscular effort on its part other than the great 

 strength needed to keep its wings ext€nded'? 



Watch a hawk or a gull or a pigeon gliding on 

 outstretched wings in its descent towards the 

 ground. Is it not evident that if the wind, into 

 which it generally glides should be deflected up- 

 wards, the glide could be continued in the same 

 horizontal plane or turned even slightly upwards'? 

 Such indeed is often the case. Watch an aero- 

 plane with engine shut off gliding against a wind 

 to a landing. How slowly it approaches the 

 earth! and we are told by aviators that if an in- 

 equality in the ground causes an upward deflec- 

 tion of the wind that the descent is even more 

 gradual. One does not need to be an aviator 

 to understand these things.^ 



^ Since this was written there have been some remarkable 

 instances of human gliding and soaring, dependent on the 

 use of up-currents. These confirm the statement I have 

 made that "there is no mystery about it" 



