POLAR LIGHT. 149 



frequently simultaneously present; in some rare cases as 

 many as seven or nine are seen advancing toward the zenith 

 parallel to one another ; while in other cases they are alto- 

 gether absent. The bundles of rays and columns of light as- 

 sume the most varied forms, appearing either in the shape of 

 curves, wreathed festoons and hooks, or resembling waving 

 pennants or sails.* 



In the higher latitudes " the prevailing color of the polar 

 light is usually white, while it presents a milky hue when 

 the aurora is of faint intensity. When the colors brighten, 

 they assume a yellow tinge ; the middle of the broad ray be- 

 comes golden yellow, while both the edges are marked by 

 separate bands of red and green. When the radiation ex- 

 tends in narrow bands, the red is seen above the green. 

 When the aurora moves sideways from left to right, or from 

 right to left, the red appears invariably in the direction to- 

 ward which the ray is advancing, and the green remains be- 

 hind it." It is only in very rare cases that either one of the 

 complementary colors, green or red, has been seen alone. 

 Blue is never seen, while dark red, such as is presented by 

 the reflection of a great fire, is so rarely observed in the north 

 that Siljestrom noticed it only on one occasion, f The lu- 

 minous intensity of the aurora never even in Finmark quite 

 equals that of the full moon. 



The probable connection which, according to my views,- 

 exists between the polar light and the formation of very 

 small and delicate fleecy clouds (whose parallel and equiva- 

 lent rows follow the direction of the magnetic meridian), has 

 met with many advocates in recent times. It still remains 

 a doubtful question, however,! whether, as the northern trav- 

 elers, Thienemann and Admiral Wrangel believe, these par- 

 allel fleecy clouds are the substratum of the polar light, or 

 whether they are not rather, as has been conjectured by 

 Franklin, Kichardson, and myself, the effect of a meteoro- 



* Op. cit., p. 35, 37, 45, 67, 481 ("Draperie ondulante, flamme d'un 

 navire de guerre deployee horizontalement et ayitee par le vent^ crochets, 

 fragments d'arcs et de guirlandesy' M. Bevalet, the distinguished 

 artist to the expedition, has given an interesting collection of the 

 many varied forms assumed by this phenomenon. 



t See Voy. en Scandinavie (Aur. Boreal}, p. 523-528, 557. 



j Cosmos, vol. i., p. 200; see also Franklin, Narrative of a Journey 

 to the Shores of the Polar Sea in 1819-1822, p. 597; and Kamtz, Lehr- 

 buch der Meteorologie, bd. iii. (1836), s. 488-490. The earliest con- 

 jectures advanced in relation to the connection between the northern 

 light and the formation of clouds are probably those of Frobesius. (See 

 Aurora Borealis spectacula, Helmst, 1739, p. 139.) 



