Abstracts of Technical Articles by Bell System Authors 



Notes on the Time Relation between Solar Emission and Terrestrial Dis- 

 turbances} Clifford N. Anderson. Although the correlation between 

 general solar activity and terrestrial disturbances is quite evident, the 

 association of individual storms with specific sunspot groups has never 

 been very satisfactory. Disturbances sometimes have occurred when no 

 sunspots were visible and at other times large sunspots have been unaccom- 

 panied by any abnormal disturbances. A possible explanation of such 

 anomalies may lie in longer transit times for the disturbing solar emission 

 than is usually assumed. Some indication is given in this paper that these 

 transit times may range from periods as short as only one or two days to 

 as much as three months. The corresponding velocities for the above 

 transit times are of the order of 2000 and 20 kilometers per second. 



Curves show the approximate relation between the angle of emission, 

 velocity, day of emission, and the days intervening between the passage of a 

 spot through the central meridian of the sun and the corpuscular encounter 

 with the earth. 



The Ejfect of the Earth's Curvature on Ground-Wave Propagation.^ 

 Charles R. Burrows and Marion C. Gray. Curves are presented for 

 the rapid calculation of the ground wave for radio propagation over a 

 spherical earth of arbitrary ground constants, antenna heights, and polari- 

 zation. 



Based on the pioneering work of G. N. Watson, a rigorous theory of the 

 propagation of electromagnetic waves round a spherical earth has been 

 developed in the past twenty years. Watson developed his method in 

 detail only in the limiting case of an earth of infinite conductivity, but his 

 work has since been extended by various authors to cover other values of 

 the earth's conductivity. Theoretically, therefore, solutions are available 

 for any values of the earth's constants (dielectric constant and conductivity) 

 and for either vertically polarized or horizontally polarized waves. In 

 practice, unfortunately, the computations required are lengthy and in- 

 volved, and for the most part the recent theoretical papers have confined 

 their calculations to a few specific values of the earth's constants. The 

 present paper attempts to summarize the results so far obtained in a manner 



1 Proc. I.R.E., November 1940. 

 ^Proc. I.R.E., January 1941. 



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