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BELL SYSTEM TECHNICAL JOURNAL 



The double maximum in virtual height with a minimum between 

 for 2398 and 3492.5 kilocycles ^ is interpreted by us to have been 

 caused by a decrease in ionic density in the Fi region, which resulted in 

 a change in reflection from the Fi to the F2 layer during the central 

 part of the eclipse. 



From the curves of Fig. 1, it is possible to plot the virtual height 

 contour map shown in Fig. 2. Since we know as a result of data taken 



5000 



^. 3500 



3 2500 



a 



2000 



EASTERN STANDARD TIME (PM) 



Fig. 2 — Virtual height contour map drawn from data for Fig. 1, for August 31, 1932. 



on several hundred days that the A'-component curve in Fig. 1 for 

 4797.5 kilocycles is nearly equivalent to the 0-component ® curve for 

 a frequency approximately 750 kilocycles lower (i.e., 4050 kilocycles), 



» Mimno and Wang, Proc. I. R. E., vol. 21, pp. 529-545, April, 1933, and Kenrick 

 and Pickard, Proc. I. R. £., vol. 21, pp. 546-566, April, 1933, obtained similar double 

 maximum curves. 



^ The expressions "0-component" and "X-component " are used in place of the 

 terms "ordinary ray" and "extraordinary ray" used by other writers. 



