THE 



AMERICAN JOURNAL OF SCIENCE 



4* 



[THIRD SERIES.] 



€ 



c? 



Aet. XI. — A Solution of the Aurora Problem ; by Prof. 

 Frank H. Bigelow. 



The problem of the Aurora to which reference is made, is 

 the question of the location in space of the visible arch and 

 streamers, referred to the surface of the earth, as seen by an 

 observer. This is becoming a matter of more importance than 

 it once was, because the progress of discovery shows that it is 

 one of the indices of the physical connection between the sun 

 and the earth, as communicated through the medium of the 

 ether. It therefore holds the same relative position that light 

 and heat do to meteorological phenomena, or that induction 

 does to magnetic variations. But it has the peculiarity of 

 marking out the paths of the magnetic and electric forces that 

 enter or depart from the earth, for it will be assumed that 

 observations have already settled the fact that the auroral 

 streamers coincide with the direction of the lines of force sur- 

 rounding the earth, considered as a magnet. If there are any 

 variations from this condition, it will be one of our ultimate 

 objects to discover them, and perhaps the laws governing the 

 same. At present, however, we limit ourselves to the simple 

 case of the problem, namely the heights, and the distance of a 

 ray from the observer. I am sorry to say that, so far as my 

 knowledge extends, after a diligent search, there are no obser- 

 vations on record of the right form, that will enable me to 

 test the theory. It is my object in this paper to explain the 

 solution, and a simple piece of apparatus, in hopes that before 

 long a suitable set of measurements may be made. 



Am. Jour. Sci.— Third Series, Yol. XLI, No. 242.— February, 1891. 

 6 



