TERRESTRIAL, MAGNETISM. 235 



great electric movements above the atmosphere, it would be diffi- 

 cult to place these in the category of galvanic currents ; for 

 although everything seems to indicate that we shovdd regard 

 galvanic currents as electricity in motion, yet every movement of 

 electricity is not a galvanic cvirrent — it is so only when the move- 

 ment forms a circle returning back into itself. As it is only un- 

 der this condition that it is allowable to make the often-mentioned 

 substitution of separated magnetic fluids instead of the galvanic 

 current, then, in the hypothesis mentioned, our relations between 

 the components would no longer apply ; that is to say, the second 

 case would actually present itself. Even the certain establish- 

 ment of this important circumstance would be in itself of great 

 interest, and by that time we may hope to possess such extensive 

 and accurate observations as may make it possible to trace both 

 the source and the nature of the causes. G. 



