388 B1RKELAND. THE NORWEGIAN AURORA POLARIS EXPEDITION, IQO2 1903. 



Kingua Fjord, it also spreads eastwards towards Cape Thordsen and perhaps farther, and then unites 

 with the western branch ; or the system in America will most rapidly spread on the north of the auroral 

 zone, and will not extend farther south to Ssagastyr until later, or there may be two rather distinct 

 areas of precipitation. 



It is possible, too, that the circle which the negative system of precipiatation appears to form round 

 the pole of the earth, is formed more or less at once, and that the displacement that we find in the 

 deflections is occasioned by the movement and deformation of the entire circle. 



The most probable cause of these phenomena, however, seems to be, that several of them separately 

 exert influence. 



A more or less circular, negative system of precipitation will be formed somewhat rapidly, in 

 which there may be one or several districts in which the strength of the precipitation is greatest. By 

 imagining these maximal zones to be moved from time to time, the differences in corresponding hours 

 that appear can be simply explained. 



In addition to the negative system, there is also, as already mentioned, a positive system in the 

 district from Godthaab eastwards along the auroral zone to Little Karmakul. At these two stations, 

 especially the former, this system is comparatively weaker to begin with; but, on the other hand, at 

 Godthaab, at the end of the section under consideration, we find practically no effects of it, while at 

 Little Karmakul, at the end, it is quite distinct and powerful. 



The effects are strongest at the intermediate stations, Jan Mayen, Bossekop and Sodankyla; and 

 there we find the characteristic condition that we have so frequently met with. 



At first the positive system is at work, being then broken in upon by the stronger negative 

 system, which causes a partial reversal of the direction of the deflection at the time when the storms 

 are at their height. Finally, simultaneously with the decrease in the negative precipitation, the positive 

 forces once more gain the ascendency, and the conditions are again such as would be found in the 

 neighbourhood of a positive district of precipitation. It is interesting to observe the conditions at these 

 stations, and see how they alter the farther magnetically north we go. At the three polar stations, Jan 

 Mayen, Bossekop and Sodankyla, the perturbation-conditions are, on the whole, exactly analogous; but 

 we can trace a continuous variation in them from Jan Mayen, through Bossekop to Sodankyla. 



At the first of these three stations, the negative storm is the strongest, although the positive deflec- 

 tions are at first quite strong. At Bossekop, the precipitation is, on the whole, less, but the positive 

 deflections are more numerous than the negative. Lastly, at Sodankyla, the effect of the negative storm 

 is comparatively slight, and the positive deflections predominate. We can thus trace a continuous change; 

 farther north the negative storm acts the more strongly, farther south the positive. If we look still 

 farther south, at Christiania, the positive storm seems to be acting alone. At the time when the negative 

 storm is at its height, there is a strong deflection there in a positive direction; and the curves are 

 sufficiently jagged to make it probable that this station is not far from the district of precipitation of the 

 positive system. The positive system therefore seems to be somewhat far south in its position. 



If, on the other hand, we go still farther south to Pawlowsk and Gottingen, we seem to have passed 

 the point of divergence, for the forces there, in the horizontal intensity, are in a negative direction, and 

 we thus have a change. It must be principally the positive storm which also acts here, if there are not, 

 at the same time, systems of which the greatest effect is exerted in lower latitudes. 



If we look for some movement of the positive system, we find, at first, that the forces are strongest 

 in the west, but at the close the storm is most fully developed farther east. The positive forces in the 

 horizontal intensity also appear very much earlier at the western stations Jan Mayen and Christiania 

 than farther east. At Godthaab, the effect is of short duration, and the storm is not very clearly 

 developed. This might indicate a movement eastwards, such as we have frequently met with at this 



