398 nlRKELAND. THE NORWEGIAN AUKOfcA POLARIS EXPEDITION, IgO2 1903. 



force, which, at io h 2o m in the horizontal intensity, has a negative direction, but is then once more 

 rapidly reversed; and from io h 25 m there are continuous positive perturbing forces, until the equatorial 

 storm is interrupted by the polar storm that occurs during the last part of the period of observation. 

 The course of the horizontal-intensity curve is the same at all three stations mentioned above, the simi- 

 larity being most marked between Christiania and Gottingen. The curves for these places are drawn 

 on the same scale, but in that for Pawlowsk the same serrations are found, notwithstanding that the scale 

 employed is only one fifth that of the other two stations. The positive forces continue moreover all the 

 time, as the storm remains more or less constant in strength. Further, on the most southern station, Gottin- 

 gen, we find, it is true, at first from io h I5 m to about io h 25 some small but very characteristic deflections 

 in D; from that time, however, the declination-curve coincides fairly well with the normal line, until the polar 

 storm sets in at the end of the period. We thus find here the well-known characteristic features always 

 to be found in positive equatorial storms, and there is therefore no doubt that this is one of that class. 



The determination of the normal line for this date is somewhat difficult, on account of the small- 

 ness of the perturbing forces and the length of the perturbation. The uncertainty thus arising is most 

 apparent at the close of the equatorial perturbation. At its commencement, on the other hand, the 

 uncertainty is not great, so that the forces taken out then differ very little, at any rate, from the actual 

 values; and in the subsequent polar storm, the perturbing forces are of sufficient magnitude to make any 

 uncertainty in the position of the normal line less important. 



From Part I it will be remembered that the direction of the current-arrows in the north of Europe 

 was not so nearly due east as at the more southern stations, but was as a rule a little more northerly, 

 as there were also perturbing forces in declination. This is also the case now. At Pawlowsk there is 

 a considerable deflection in the declination curve, whereas at Christiania and Gottingen this deflection 

 in the declination is not so marked. It is possible, however, that there too there are some more power- 

 ful forces than those indicated on the plate, as the normal line is very difficult to determine, on account 

 of the absence of daily hourly-observations. 



At nearly all the polar stations, we find, at io h 20, a rather sudden deflection in the curves, 

 which indicates that the effect of the equatorial storm begins suddenly and simultaneously everywhere. 



At three polar stations in the eastern hemisphere, which are situated to the south of the auroral 

 zone, namely, Bossekop, Sodankyla, and Ssagastyr, there are positive deflections of fairly constant 

 strength in the horizontal intensity, from the beginning of the positive storm until about i6 h 30"". Simi- 

 larly we find in the declination at the first two of the above stations continual westerly deflections of 

 fairly constant amplitude, while at Ssagastyr the deflections in this component amount to almost nothing. 



At Cape Thordsen, the course of the declination-curve shows conditions very similar to those in 

 the south, and is thus evidently due to an equatorial current-system; but polar precipitation makes its 

 influence more felt here than at the stations just considered. This seems to be especially the case at 

 first, when the horizontal-intensity curve has a rather more disturbed character. 



The equatorial character of the perturbation disappears, however, as we go westwards. We also 

 find the first impulse again at the other stations, and it is therefore evident that the perturbations \ve 

 find here are connected with the equatorial storm, while it is equally certain that other effects seem to 

 be present. If we look, for instance, at the conditions in Jan Mayen, we find at first only very small oscil- 

 lations to either side of the normal line. In the horizontal-intensity curve these are principally above the 

 line, thus answering to positive values of PI,, but farther on, at Godthaab, we find deflections which, 

 though inconsiderable as regards strength, are mainly in the opposite direction, representing negative 

 values of PI,. 



Continuing westwards, we come to the station that is the most important in this instance, namely, 

 Kingua Fjord. The disturbances there are evidently of a distinctly polar character; and the uneven 



