I6 NATURE-STUDY REVIEW 



this is done from a sub-conscious summing up of the known 

 favorable factors, or whether from some special sensitiveness, I 

 do not know. Again, after the aurora has settled into the diffuse 

 form, as it usually does, the sky as a rule becomes clouded. Pos- 

 sibly this is due to moisture condensing on electronic matter. 



Why are the lower edges of arcs, bands, and curtains, usually 

 well-defined? One does not wonder that the upper ends are not 

 clearly marked, but often the lower edges are as clear-cut as if 

 they had been sheared smoothly off. Do the edges represent the 

 division line between two different strata of air? As I have 

 mentioned before, I have never seen color effects except when 

 there was rapid lateral motion; and so far as I have noticed this 

 always and only occurs when there is or has been a strong wind. 

 Can local air currents affect the aurora ? Is it possible that friction 

 between two air strata has an3rthing to do with the phenomena of 

 the Lights ? Why do the displays usually occur between eight and 

 ten o'clock in the evening? Why are the arcs of considerable 

 breadth, while the curtains appear to be but thin films? These 

 and a host of other questions challenge the observer who watches 

 these mysterious lights. I shall be pleased to hear from others 

 their observations, and especially to find if they concur with 

 what I have said in regard to the connection between weather 

 and the aurora, and to wind and color effects. 



As a Nature student I can claim neither extensive observation 

 nor original theory. I can only hope to avoid on the one hand 

 the obvious errors such as those quoted, and on the other hand 

 the extreme of the mathematical physicist who thinks it hardly 

 worth his while to look at the sky at all, since from his inner 

 consciousness he can invoke an algebraic formula that is all- 

 sufficient. Nature has been somewhat less generous with flora 

 and fauna in our great Northland than in some other places, 

 but she has in a large measure compensated us by giving us wide 

 horizons of startling clearness, with rippling lakes that mirror 

 skies of sapphire and opal and rose. To watch these at sunrise 

 and at stmset and through the long nights of winter or the short 

 nights of summer is to feel them and to love them; to attempt to 

 describe them in pale prose seems to border on sacrilege. 



