THE AURORA BOREALIS. 



195 



brilliancy of the spectacle that is occasionally pre- 

 sented in the northern skies. 



The most ordinary aspect of the aurora is that of 

 a band of pale-green light extending irregularly 

 over part of the sky, and marked by wavy motions, 

 as well as by varying brightness. Sometimes one 





AURORA BOREALIS. 



part of this band becomes more bright than another 

 part. Sometimes the whole seems to move gently, 

 like the undulations of a flag in a light breeze ; at 

 other times more vigorous action takes place, and 

 pointed tongues of light shoot vividly up into the 



