96 P. A. ØYEN. 



of increase was, we have no means of actually determining; 

 it is only of the three chief glaciers of Olden that we have an 

 account of the increase down to the year 1873. We are, however, 

 justified in regarding this increase as slight, and its duration 

 as rather short; and it is a fact not to be overlooked, that in 

 the years 1868 and 1869, the weather, in the neighbourhood 

 of the Jostedalsbræ, was unusually wet and cold. This is, how- 

 ever, a phenomenon of great interest, that may also be traced 

 in the Folgefon, the Glacier of Buer here having been reported 

 to have been exposed to a temporary rush of advance during 

 the first half of the decade 1870—1880, a well-marked rush in 

 the general increase of that glacier during the period from 1868 

 to 1893. 



According to my experience, the glaciers of the Jotunheim 

 are the very best indicators of the oscillation of our climate. 

 Having numerous accounts of a continuous decrease of these 

 glaciers down to our own time, continuous with the exception 

 only of a few, but only slight alterations, it is even more 

 remarkable to find such a difference of glacier oscillation as that 

 shown in the above-mentioned increase of the glacier branches 

 of the Jostedalsbræ and the Folgefon. We are under the neces- 

 sity of regarding this aberration of oscillation merely as disturb- 

 ances originating from purely mechanical sources. It must not, 

 however, be forgotten, that this phenomenon may possibly be a 

 slight indication of some differences in the variation of chmate 

 in the interior of our country, as compared with that going on 

 along our western coast. 



We are, however, justified in regarding this phenomenon as 

 partly a mechanical one, and we, shall presently look at some 

 even more striking instances of the kind, when comparing the 

 oscillation of some glaciers belonging to our western Glacier 

 Regions. The facts here observed present a theoretical interest 

 of great importance. We have before us an actual proof of the 

 reality of a phenomenon supposed by Reib to be potential : „Two 



