PART II. POLAR MAGNETIC PHENOMENA AND TERRELLA EXPERIMENTS. CHAP. I. 35! 



pronounced positive storm at Cape Thordsen; and we now find simultaneously with the storms in Ame- 

 rica, very strongly marked effects of a negative polar storm of very considerable strength (compare 

 Plates XXVI, XXV and XXIII). If we go on farther, to Fort Conger, we find there, too, quite distinct 

 effects of a negative storm as the declination-curve there, just at the period under consideration, in 

 which the negative storm occurs, exhibits a very distinct, well defined, westerly deflection of the decli- 

 nation curve of very considerable amplitude. As previously remarked, current-arrows directed westwards 

 answer to a westerly deflection such as this. 



It would appear, therefore, that this is an effect of more or less the same system as that acting at 

 Cape Thordsen. At Kingua Fjord also, there seems to be a negative storm, judging from the deflection 

 of the horizontal-intensity curve; but it is difficult to decide so directly here, as the absolute value of 

 the declination in this case is fairly great, thus giving the deflections in the declination curve greater 

 importance than at those stations at which the declination-value is only small. It seems, however as if 

 this too were principally the effects of a negative storm, and if so, one of longer duration than at the 

 other stations; but these conditions will be better studied by the aid of the charts. 



In addition to this, or these, negative area or areas of precipitation, we find in the region about 

 Godthaab, Jan Mayen and Bossekop, a distinctly positive system of precipitation. The effects of this system 

 are most clearly apparent in Jan Mayen, where the positive deflections in the horizontal-intensity curve are 

 of considerable amplitude and very well defined. The deflections, however, as already remarked, do not 

 terminate at the conclusion of the first section, but continue, without great alteration in strength, directly 

 into the next section. This is at any rate the case as regards Jan Mayen and Godthaab, where the 

 storm is most powerful. At Bossekop the perturbing forces are only small, and here we find a distinct 

 strengthening of the positive deflections, just at the time when the negative storms are at their height. 

 Here too, however, the absolute value of the forces is not particularly great. 



A positive area of precipitation such as this, was also one of the peculiarities of the first section 

 of the two preceding storms. The position here, however, is a little different from what it was earlier; 

 but the only way in which it differs from that of the other storms is that the area of precipitation does 

 not extend so far eastwards as before. 



At Little Karmakul, there are no perturbing forces, in this first section, of sufficient magnitude to 

 warrant the supposition that they are due to the effect of systems of precipitation in the vicinity of the 

 place. In declination, however, we find at about I5 h , that is to say, just at the time when the negative 

 polar storm has its maximum, a very well defined deflection, though of comparatively little strength. 

 In the horizontal intensity, on the other hand, the conditions during this deflection are more or less 

 normal, and it is not until a little later that we find perturbing forces here too, and these in a negative 

 direction. 



In the vertical intensity the conditions here are interesting. Simultaneously with the deflection in 

 declination, there is a corresponding negative deflection here. Immediately before this, there is a deflec- 

 tion in the opposite direction. As these deflections are very well defined, it is possible to attribute some 

 importance to them, notwithstanding their comparatively small strength. It seems reasonable to suppose, 

 both on account of the quiet character of the curves, and the small strength, that the conditions are due 

 to the effect of a system that is not in the immediate vicinity of the place. The direction of the current- 

 arrows that we find here is northerly, and will thus answer to conditions in the eastern part of an area 

 of convergence. The vertical arrow, in accordance with this, is directed upwards. It must thus be either 

 the negative system with district of precipitation in the neighbourhood of Cape Thordsen, which pro- 

 duces these characteristic perturbation-conditions at Little Karmakul or the southern positive system, 

 which has its area of convergence to the north of the main axis, or perhaps both these two in co- 

 operation. 



