POTENTIAL AND EARTH CURRENTS. 185 



ering the electric influence of the two bodies, we find 

 that the lunar surface is that of a dead world, abso- 

 lutely quiescent, so far as we know; while the solar 

 surface, to a great depth, is in a state of the most 

 violent agitation. From which we must infer a great 

 difference of electric potential in favor of the sun. 

 And observation indicates that this state of agitation 

 affects the earth's electricity ; while we have no obser- 

 vations of electric effects produced by the moon. 



Certain electric phenomena on the earth are found 

 to coincide with certain solar phenomena. These con- 

 sist in violent oscillations of the magnetic needle 

 during prominent solar disturbances, indicated by the 

 sun spots. And it is found that the periods of max- 

 imum solar disturbance, which occur once in eleven 

 years, are noted for corresponding maxima in those 

 perturbations of 'the magnetic needle. 



To make this clear, it should be stated that magnet- 

 ism is produced, artificially, by the circulation of an 

 electric current around a conductor capable of being 

 magnetized, at right angles to its length; as by a 

 current circulating in a coil of wire, round a bar of 

 iron or steel. And, conversely, a magnet generates an 

 electric current in such a coil. 



It is known that the earth is a great natural magnet; 

 having north and south magnetic poles, which exercise 

 a directive force on the magnetic needle ; and it seems 

 highly probable, that its magnetism is the result of 

 electric waves, or impulses, circulating round it from 

 east to west as has been shown; giving rise to electric 

 currents ; and due to difference of temperature, and to 

 solar and lunar influences : and that the perturbations 

 of the magnetic needle, coincident with solar disturb- 



