In tro deletion. 



1. In 5 Terrestrial Magnetism« Professor Størmer has recently ^ given 

 some very nice results from his Second Series of Aurora Photographs 

 taken during some weeks stay at the village of Bossekop, which is now so 

 well known since the expedition of Bravais. 



Størmer was the first to introduce the cinematographic lens for this 

 purpose, and b}- this new simple means, by which he has really obtained 

 most valuable results, more precise and complete than those obtained by 

 direct parallax observations of aurora, it has been as easy to photograph 

 an aurora as to photograph a house, so to speak. 



From the obser\-atory on the Haldde mountain, erected by me, and 

 where m}- former assistant, Mr. Krogness, is now Director, such aurora 

 photographs are taken almost on every occasion when fine auroras are 

 displaying themselves, and this will be continued year after year through- 

 out a whole sunspot period, the result being published by and bv -. 



At the conclusion of his paper Størmer takes up the question, whether 

 the rays of the aurora are produced b}- negative or positive corpuscle 

 rays, and he arrives at the result: It seems thus to be proved that the 

 aurora was caused by positively charged electric particles. 



I think the reasoning by which Prof. Størmer arrives at this result, 

 is certainly incorrect, as we shall see on account of the superficial manner 

 in which he deals with polar magnetic storms. 



I have already discussed this matter on page 609 in my book: »On 

 the Cause of Magnetic Storms and the Origin of Terrestrial Magnetism«. 

 The Norwegian Aurora Polaris Expedition 1902 — 1903. 



I shall later on often have to cite this work, and for the sake of 

 briefness I shall only call it »Aurora Polaris« or »A. P.« 



' March, 1915. 



- Krcgxess und Vegard, Hohenbestiminungen des Nordlichts. Videnskapsselskapets Skrifter 

 No. II. Kristiania 1914. 



