206 



Mr. W. Ellis. On the Simultaneity of 

 Table III continued. 





indicates that the direction of first motion was doubtful. 



. . indicates that no information was received, or that there was no record, or (in 

 a few cases) that the change was small. 



to Lady Well, Lewisham (distance between earth plates 3 miles) : 

 these positions being selected in order that the recording apparatus 

 at the Royal Observatory, through which the wires passed, should be 

 nearly in the middle of the straight lines joining the respective earth 

 plates. Now it has been mentioned that the instances of sharply- defined 

 magnetic impulses contained in Table I were all accompanied (in the 

 just-described newer earth current lines) by active earth currents, in 

 themselves just as sharply defined. The distinctive character and 

 generally isolated position of these magnetic and earth current move- 

 ments thus afford a peculiarly favourable opportunity for investigat- 

 ing any relation that may exist between them, much more so than 



