THE AURORA. 13 



stances which give interest and significance to the 

 strange discovery which is the subject of this paper. 



Could we only associate auroras with terrestrial 

 magnetism, we should still have done much to enhance 

 the interest which the beautiful phenomenon is calcu- 

 lated to excite. But when once this association has 

 been established, others of even greater interest are 

 brought into recognition. For terrestrial magnetism 

 has been clearly shown to be influenced directly by the 

 action of the sun. The needle in its daily vibration 

 follows the sun, not indeed through a complete revolu- 

 tion, but as far as the influence of other forces will per- 

 mit. This has been abundantly confirmed, and is a 

 fact of extreme importance in the theory of terrestrial 

 magnetism. Wherever the sun may be, either on the 

 visible heavens or on that half of the celestial sphere 

 which is at the moment beneath the horizon, the end 

 of the needle nearest to the sun makes an effort (so to 

 speak) to point more directly toward the great ruling 

 centre of the planetary scheme. Seeing, then, that the 

 daily vibration of the needle is thus caused, we recog- 

 nize the fact that the disturbances of the daily vibra- 

 tion may be referred to some peculiarity of the solar 

 action. 



It was not, therefore, so surprising as many have 

 supposed, that the increase and diminution, of these 

 disturbances, in a period of about eleven years, should 

 be found to correspond with the increase and diminu- 



