142 L« SeluvcncUer— 0« Eartli- Currents, [June, 



not been unveiled by these observations. To solve the problem it would 

 seem that quantitative measurements of other phenomena, directly or in- 

 directly connected with it, were required, and it was most fortunate that at 

 least one such phenomenon not only existed but was even susceptible of 

 accurate measurement : he meant the earth-currents. 



The chances of giving a true physical explanation of any phenomenon, he 

 observed, increased in geometrical progression with the number of phenome- 

 na directly or indirectly connected with the one to be explained, supposing 

 that they were all susceptible of accurate measurement. 



In this particular case he had to deal with two such parallel phenome- 

 na, the magnetism of the earth, quantitatively ascertained for more than 

 40 years past, and " earth-currents,'' sadly neglected. 



He said he was perfectly aware why " earth-currents" had not been 

 measured, and then, after mentioning the special purpose of his paper, i. e, 

 not to start a fresh theory of the earth-magnetism with the scanty and im- 

 perfect material available, but to lay before the Society some more facts con- 

 nected with its parallel phenomenon, the earth-currents in the Telegraph 

 lines, which had been quantitatively measured during the last six years in 

 widely different parts of the empire, Ceylon included, he proceeded as fol- 

 lows : 



" That it was well known that from time to time Telegraph lines, 

 overland, underground and submarine, were affected by what had 

 been called, ' magnetic storms,' i. e. by very strong currents passing 

 through the wires and overpowering entirely those used for signal- 

 ing, with which electrical disturbances co-existed magnetic variations 

 far exceeding the limits generally observed when no such electrical distur- 

 bances exist, and very often accompanied in the northern (and most likely 

 also the southern) part of the planet by vivid auroras. Now these currents 

 observed in the Telegraph lines were ' earth- currents.'' 



" For instance on the 10th November, 1871, and on the 4th February, 

 1872, earth -currents of considerable strength had been observed in all the 

 lines throughout India, and the submarine cables terminating on its shores. 

 These great electrical disturbances were by no means local, but existed 

 almost simultaneously throughout the earth, shewing us a most interest- 

 ing feature of our planet. 



" The fact of the secular changes of the earth-magnetism occupying such 

 -a long period as about 1000 years (the principal magnetic pole moving 

 round the astronomical pole in 1000 years) pointed most probably to a 

 cause external to the planet. If he were allowed to follow his own imagi- 

 nation, he would say, that earth-magnetism, its diurnal and secular variations," 

 aurorae boreales and australes and electrical disturbances, weak or intense, 

 in the planet, were all due to the movement of the earth and of the heavenly 



