684 



BELL SYSTEM TECHNICAL JOURNAL 



t + LOG|0 OF 

 SUNSPOT- NUMBERS 



ULTRA-VIOLET RADIATION 



<M (\J - 



i^'* bo 



(\J (\J - - 



FIELD STRENGTH IN DECIBELS ABOVE 

 ONE MICROVOLT PFR METER 



LOGlo OF U| 

 MAGNETIC ACTIVITY 



rj C) <^ (\j rvj (\J 



LOGio OF SOLAR 



LIMB-PROMINENCES 





