148 



MILLIKAN— METEOROLOGICAL WORK 



TABLE V. 



War Department, Signal Corps, U. S. Army, Meteorological Service. 



Station Fort Oglethorpe, Ga. (90th Meridian Time.) 



IVind Aloft Report. 



Time 7 :39 A.M. Date November 29, 1918. 



In order to meet the obvious need of the aviator for a knowledge 

 of upper air currents the Signal Corps in the summer of 191 7 under- 

 took for the first time in history a general program of mapping the 

 upper air currents of the United States, the Atlantic and western 

 Europe in aid of aviation and particularly with reference to trans- 

 Atlantic flight. By the fall of 1918 twenty-six upper air stations, 

 carefully distributed over the United States, were in full operation 

 in place of the one station which has existed before the war. From 

 these stations reports are telegraphed twice daily to the Weather 

 Bureau in Washington. From the pilot balloon observations charts 

 are constructed showing the wind speed and direction at the vari- 

 ous levels : for instance, one chart shows the wind direction and 

 speed near the ground, another chart shows the wind direction 

 and speed 500 meters above the ground and additional charts 

 show the wind direction and speed at the following levels: 1,000, 

 1,500, 2,000, 3,000 and 4,000 meters above the ground. The fore- 



