200 



SYMPOSIUM ON AERONAUTICS. 



Fig. 12. Mean of Wind Observations in "Highs" at 4000 Meters above Sea 



Level, 1907-1912. 



TABLE I. 

 Turning of Wind with Height. 



with those at the one kilometer level. By the time the three kilo- 

 meter level has been reached, it is probable that isobars are no longer 



