PART II. POLAR MAGNETIC PHENOMENA AND TERRELLA EXPERIMENTS. CHAP. I. 387 



As regards Ssagasiyr, however, there is one thing to be noticed. From I7 h 40 until i8 h 30, 

 the deflections in the horizontal intensity are too great to allow of being observed. The direction in 

 which the needle moved is not given, nor is the character of the curve such as to enable the direction 

 of the deflection to be determined with certainty. Judging from previous experience, however, there 

 would seem to be no doubt that the deflection has been in a negative direction. 



In the first place, we have never met with positive perturbations here that have been powerful 

 enough to make the needle move out of the field of observation. Further, this station lies just between 

 Uglaamie and Little Karmakul, at both of which, it may be seen, the negative storm is very powerful. 

 This is also the case at Cape Thordsen. 



As the negative storm is powerful at all the stations surrounding Ssagastyr, it would be very 

 improbable, judging by all that we have seen previously, that a strong positive system could act at that 

 one station; and moreover, the part of the curve for the time immediately after this interval, indicates, 

 although faintly, that there has been a negative, not a positive, deflection. The current-arrows we have 

 marked, indicate, therefore, that the needle has moved out in a negative direction ; but, in order to indicate 

 the slight uncertainty, we have placed an asterisk by the arrows in question. 



The perturbing forces everywhere are exceedingly powerful; and the storm-centre of the negative 

 storm is in the district from Uglaamie to Little Karmakul, probably about Ssagastyr. 



We think, however, that we can prove a distinct movement of the system. This is developed 

 earliest round Kingua Fjord, where the forces even at i6 u io m , have attained considerable power. The 

 deflections here increase rather rapidly to a maximum. At Fort Rae and Uglaamie, on the other hand, 

 the deflections at first increase more slowly; but, at both these stations the perturbing forces are of con- 

 siderable magnitude as early as 17''. 



At Ssagastyr, the negative deflections do not begin until 17'' 40; but they are then suddenly so 

 strong, that the needle passes out of the field of observation. 



The negative system thus seems to begin in the neighbourhood of Kingua Fjord, developes there 

 with considerable rapidity, and, simultaneously with the extension of the area of precipitation and the 

 increase of the perturbing forces, the storm-centre moves westwards. If we endeavour to trace a similar 

 movement onwards to Little Karmakul and Cape Thordsen, it appears that the same observation may be 

 made with regard to the first of these two stations ; but consideration must be paid to the fact, that this 

 is within the positive system's sphere of operations, and, before the negative storm gains the ascendancy, 

 there are distinct positive forces. This is also the case afterwards. When the powerful, but brief, nega- 

 tive precipitation is over, positive forces appear once more, this time more powerful than before. The 

 powerful negative forces appear a little later than at Ssagastyr, but we must beware of drawing con- 

 clusions from this condition respecting the movement of the system, the more so as there was powerful 

 negative precipitation north of the auroral zone even earlier, as the conditions at Cape Thordsen show. 

 The deflections in the horizontal intensity at the last-named station, resemble, in many respects, the corre- 

 sponding deflections at Uglaamie. At both places we find, at about 17'' or 17'' 30, a secondary maxi- 

 mum, and at about i8 b 30" the true maximum. There is a slight time-displacement, however, especially 

 in the first secondary maximum, so that the deflections at Cape Thordsen come a little later than those 

 at Uglaamie. The similarity of these curves is strikingly evident at the very first glance; but if we look 

 at the declination-curve, we find no particular resemblance, and the deflections in this component will 

 have a greater significance at Cape Thordsen than at Uglaamie. What we will here draw special attention 

 to, however, is that the negative deflections at Cape Thordsen begin rather early, and thus develope more 

 or less simultaneously with those at Uglaamie, possibly a trifle later; and there are thus considerable forces 

 at Cape Thordsen before they appear at Ssagastyr. The explanation of this must be, either, that simultane- 

 ously with the extention of the negative system of precipitation westwards through North America from 



