276 POPULAR LECTURES AND ADDRESSES 



storms, no connection, whether of simultaneous 

 occurrence or of distinct physical relationship, has 

 hitherto been discovered between thunderstorms 

 and their accompanying earth currents on the one 

 hand, and the common cause of auroral displays, 

 magnetic storms, and the underground electric 

 storms with which they also are accompanied. 



Still another wonder the sun-spots, and the ten 

 and a half or eleven years' period of their alternate 

 abundance and scantiness. It seems that in the 

 years of most abundant sun-spots the magnetic 

 storms have been greatly above average in 

 frequency and in intensity ; and there have also 

 been unusually brilliant and wide-spread auroral 

 displays. The last year of maximum abundance 

 of sun-spots, 1870, must be remembered by many 

 of the readers of Good Words for brilliant 

 auroral displays. The magnificent red aurora 

 seen on several nights in the autumn of that year 

 in the south of England, lighting up the sky as it 

 might have been by burning cities, were connected 

 in the popular imagination with the horrors of the 

 Franco-German war raging at that time on the 

 other side of the Channel. We are now coming 



