690 



BELL SYSTEM TECHNICAL JOURNAL 



transmission from Rugby to Houlton were obtained but are not 

 reproduced. (It will be observed that the antenna current to which 

 the data are corrected is different for different years. This basis 

 results in a convenient spacing of the distribution curves to prevent 



5 10 15 20 25 30 35 



RADIO FIELD STRENGTH IN DECIBELS ABOVE ONE MICROVOLT PER METER 



Fig. 7— Cumulative distribution of daily averages of long-wave radio field strength 

 on days of magnetic calm and on days of magnetic disturbance. Daylight trans- 

 mission path, WNL. 



overlapping.) The year 1930 was magnetically more disturbed than 

 1933. Because of the few days' lag (Fig. 5) of the increase in daylight 

 field strength behind magnetic storms, the full effect that accompanies 

 magnetic disturbances is not revealed by these curves. 



No consistent relationship between night-time long-wave fields and 



