340 UIRKKI.AND. THF NORWEGIAN AURORA I'Ol.ARIS EXPEDITION, 1 gO2 1903. 



A third station, whicli ought to be mentioned in connection witli these two, is Kingua Fjord; for 

 these three stations together form a more or less distinct group, as a negative polar storm is now acting 

 in this district. We have considered the effect of this storm at the two preceding stations, and we 

 found that at the conclusion of this first section, the storm there was over. This is not the case, 

 however, in Kingua Fjord, where the storm continues without cessation into the next section, although 

 for a short time about i6 h io m , the perturbing forces are very small. 



At the time when the curves at Fort Rae and Uglaamie have their maximal deflection, a distinct 

 maximum is also to be found in Kingua Fjord; but the perturbing forces there are considerably weaker. 



It appears, upon the whole, as if the storm-centre must be situated in the district Fort Rae 

 Uglaamie, at first probably nearest to the former; at the conclusion however we find the strongest effects 

 at Uglaamie. 



It is not impossible, therefore, that we have before us a displacement, in a westerly direction, of 

 the area of precipiation ; but the conditions are probably more complicated. 



In these districts then, a negative system of precipitation is acting. 



If we now examine the other curves in this first period, we find at Little Karmakul and Ssagastyr 

 quite distinct, although comparatively slight, effects of a positive system of precipitation. At Cape 

 Thordsen there are also positive deflections in the horizontal-intensity curve at first; but at the time 

 when the negative storm at the American stations is at its height, the curves seem to show that here 

 too there is a negative polar storm which counteracts the effect of the positive, and makes the curve 

 oscillate to the opposite side. The conditions in the declination and vertical intensity also indicate some- 

 thing similar; for at the time when the negative storm here should begin, we find distinct deflections 

 in these two elements, lasting about as long as the negative storm seems to be acting. 



In the district Godthaab to Jan Mayen, there is also a positive storm which continues into the next 

 section, and there attains considerably greater strength. 



We thus find in this perturbation also, the characteristic systems of precipitation, a negative 

 and a positive, of which the first is fairly powerful and very pronounced, while the second is 

 comparatively slight. 



We may now at once look at the first four charts, which represent the perturbation-conditions 

 during this first section. 



Chart I shows the conditions at rj 1 ' 20, that is to say at a time when the negative storm at 

 Fort Rae has about reached its height. For the time before this, in which, as already mentioned, there 

 are fairly powerful forces at Uglaamie, while those at the other stations were comparatively small, no 

 charts have been drawn, as the condition is clearly apparent from the curves. 



The current-arrow at Uglaamie is now directed NNE, and thus indicates that the conditions are 

 somewhat different from those that are usual in the auroral zone during the polar storms in which the 

 current-arrow is directed either westwards or eastwards. In order to explain this condition, it might be 

 assumed, as has previously been done, that there was here a co-operation between a positive and a 

 negative polar storm. 



In the district Kingua Fjord and Fort Rae, there are distinct effects of a negative polar storm, 

 while at the other stations the perturbing forces are very small. 



On the next charts, Charts II IV, for the hours /./' /"', /./' 20'", ij k and //'' 20'", the conditions 

 are but little changed in the main. Now too we find a distinct negative polar system in the north of 

 America; and in the district Godthaab eastwards to Ssagastyr, there occur more or less distinct traces 

 of a positive system. This is most cleary apparent on Chart III, for i4 h 20 and on Chart IV at i5 h . 

 At the latter hour we notice especially strong effects of this system at Ssagastyr. At Cape Thordsen, 

 on the other hand, we find at I4 h 5 m a distinct westward-pointing current-arrow, which should indicate 



