Figure 4. Phase perturbation over short paths at night. (After Wait & Spies, 10.2 kc/s.) 



applied. Nonetheless, there Is a rather surprising agree- 

 ment between the computed effects and those actually 

 observed, Charleston, S. C. , is 675 n. mi. (1250 km) from 

 Short path Forestport, while Curacao is 660 n.mi. (1220 km) from 



effects observed Summit, so that measurements at these sites would be expected 



to have +6.5-cec residual discrepancies in table 1. The actual 

 discrepancies average 4.3 cec. The theoretical work indi- 

 cates that an additional delay of 12 cec should be expected over 

 the 395 n.mi. (731 km) path from Forestport to Norfolk, Va. 

 The sense of the measurement indicates that a residual of 

 -12 cec would be expected. The average residual is about 

 -9 cec. Because of the effects of higher-order modes, the 



17 



