97 



sons present looked at it during some minutes in mute ad- 

 miration. 



In the fig. 10 we have a piclure of it. In the fore- 

 most plan of the figure we see the little cot of branches, in 

 which the galvanometer was installed, to the left an auroral 

 are, of which the south end met the northern slope of the 

 mountain and above the apparatus a very distinct yellow 

 beam painted against a little darker yellow sky, with its 

 breadth slightly increasing upwards. By travelling in an 

 angle of about 90° around the top we could prove that the 

 beam was really rising from above the point-apparatus. 

 Even on this occasion experiments concerning the intensity of 

 the el. air current were made by comparison with a Leclanché 

 element. 



From these two experiments I had received the im- 

 pression that it was very easy to produce these beams, but 

 the following year showed that this idea was not true for only 

 twice the phenomenon was seen, 27 of Februar and 2 of 

 March on the same mountain top. 



The phenomenon in form of beams seems to demand: 

 a clear sky, low temperature and relativety low pressure, 



7 



