428 THE VOYAGE OF THE VEGA. [chap. 



years of which we knew beforehand that it would be a mini- 

 mum aurora year. It was just this circumstance, however, 

 which permitted me to study, in a region admirably suited for 

 the purpose, a portion of this natural phenomenon under un- 

 commonly favourable circumstances. For the luminous arcs, 

 which even in Scandinavia generally form starting-points for the 

 radiant auroras, have here exhibited themselves undimmed by 

 the more splendid forms of the aurora. I have thus, undisturbed 

 by subsidiary phenomena, been able to devote myself to the 

 collection of contributions towards the ascertaining of the posi- 

 tion of these luminous arcs, and I believe that I have in this 

 way come to some very remarkable conclusions, which have been 

 developed in detail in a separate paper printed in The Scien- 

 tific Work of the Vega Expedition (Part I. p. 400), Here 

 space permits me only to make the following statement. 



The appearance of the aurora at Behring's Straits in 1878-79 

 is shown in the accompanying woodcuts. We never saw here 

 the magnificent bands or draperies of rays which we are so 

 accustomed to in Scandinavia, but only halo-like luminous arcs, 

 which hour after hour, day after day, were unaltered in position. 

 When the sky was not clouded over and the faint* light of the 

 aurora was not dimmed by the rays of the sun or the full moon, 

 these arcs commonly began to show themselves between eight 

 and nine o'clock p.m., and were then seen without interruption 

 during midwinter till six, and farther on in the year to three 

 o'clock in the morning. It follows from this that the aurora 

 even during a minimum year is a permanent natural 

 phenomenon. The nearly unalterable position of the arcs has 

 fui-ther rendered possible a number of measurements of its 

 height, extent, and position from which I believe I may draw the 

 following inferences : that our globe even during a minimum 

 aurora year is adorned with an almost constant, single, double, or 

 multiple luminous crown, whose inner edge is situated at a height 

 of about 200 kilometres or 0'03 radius of the earth above its 

 surface, whose centre, " the aurora-pole," lies somewhat under the 

 earth's surface, a little north of the magnetic-pole, and which, 

 with a diameter of 2,000 kilometres or 0'3 radius of the earth, 

 extends in a plane perpendicular to the radius of the earth, which 

 touches the centre of the circle. 



I have named this luminous crown the aurora glory on account 

 of its form and its resemblance to tjie crown of rays round the 

 head of a saint. It stands in the same relation to the ray and 

 drapery auroras of Scandinavia as the trade and monsoon winds 

 in the south to the irregular winds and storms of the north. The 

 light of the crown itself is never distributed into rays, but re- 

 sembles the light which passes through obscured glass. When 

 the aurora is stronger, the extent of the light-crown is altered : 



