PART II. POLAR MAGNETIC PHENOMENA AND TERRELLA EXPERIMENTS. CHAP. I. 40! 



At the stations in and to the north of the auroral zone, on the other hand, the conditions are 

 somewhat more variable. This is especially the case at Kingua Fjord. This is quite evident on looking 

 at Chart II IV. At n h 2o m the current-arrow seems in a great measure to be due to the equatorial 

 system, although even now polar precipitation is also certainly asserting itself. At I4 h 2o m , however, 

 the polar system predominates, and at 15'' 20'" is still more evident. 



With the exception of the polar storm at Kingua Fjord, there are none of any magnitude before 

 i6 h 30"; but from that hour polar storms begin to be more and more apparent at other stations. At 

 the same time the equatorial storm still continues to act for some time. 



Between 16'' 2o m and I7 h , we find in the horizontal-intensity curve at Gottingen and Christiania 

 a very characteristic wave; and at Pawlowsk exactly the same thing is found, although, as the scale is 

 smaller, it is less distinct. Similar deflections are also found at the same time in the horizontal-intensity 

 curve at Kingua Fjord, in declination and horizontal intensity at Godthaab and in declination and vertical 

 intensity at Cape Thordsen, in Jan Mayen, and at Fort Conger, all of which exhibit so great a resem- 

 blance to one another, that there must undoubtedly be some connection between them. 



In cases such as this, in which there are effects of both polar and equatorial systems simultaneously, 

 the fact of finding conditions which seem to indicate that the two systems at the same time undergo similar 

 changes, is in perfect accordance with what theory would lead us to expect. According to this, all the 

 perturbing systems that appear simultaneously are due to one system of corpuscular rays, which become 

 deformed by terrestrial magnetism, and, in their effects upon the earth, are apparently more or less 

 separate phenomena. This however, it should be remarked, is only apparent. Theoretically there must 

 always exist a genetic connection between simultaneous perturbations of the most varied kinds, both 

 polar and equatorial, south polar and north polar, etc., etc. A connection such as this is often shown 

 during equatorial storms in which, simultaneously with the serrations in the horizontal-intensity curve, 

 there are found in the polar regions of the earth similar serrations or deflections that are too great to 

 be ascribed to changes in the equatorial system, and which are certainly effects of polar precipitation. 

 Another very typical example of this is to be found on this date, at about i4 h , on comparing, for 

 instance, Christiania and Gottingen on the one hand, with Kingua Fjord or Fort Conger on the other. 



We have often before pointed out simultaneous changes in positive and negative polar storms, 

 which of course are also only indicative of the above-mentioned connection between the phenomena. 



The polar storms that occur at the close of the period are both positive and negative. 



The order of these polar storms on this date is the same as that so often found to be charac- 

 teristic of afternoon storms, referred to Greenwich time. 



At the more southern of the arctic stations in Europe, Jan Mayen and Bossekop, we find the 

 effects of the positive storm. The storm occurs a little earlier at Jan Mayen than at Bossekop, as the 

 horizontal-intensity curve at the former station begins, at about I5 h , to increase more or less regularly 

 to its greatest height, which it attains at about i6 h 40. At Bossekop the greater positive deflections 

 do not occur until a little after i6 h ; but the curve there rises somewhat more rapidly, and attains its 

 greatest value at about 17'' 30. After this first maximum has been reached, the positive deflection 

 remains more or less constant in amplitude for some time, until the negative storm breaks in upon it. 



At about ig h the positive deflections in the horizontal-intensity curve for Jan Mayen begin to 

 decrease, but at the same time the deflection in declination increases, thus forming the transition to the 

 last portion of the observation-period, in which, as we see, the negative polar storms predominate. At 

 Bossekop the transition from the positive to the negative storm is considerably sharper, and occurs at 

 about 2o h . 



At the other stations, wherever perturbations of any magnitude occur, we find only negative 

 storms. 



