PART II. POLAR MAGNETIC PHENOMENA AND TEUUELLA EXPERIMENTS. CHAP. 



Current-Arrows for the 1st November 1882. 

 Chart V at 20 h 20 m , 21 1 ' 10 m , and 22 h 20 m . 



361 



Fig. 15'- 



THE PERTURBATION OF THE 14th and 15th FEBRUARY, 1883. 



(PI. XXVIII). 



86. The three preceding perturbations have exhibited a very great resemblance to one another 

 in their manner of occurrence and course. 



It will be remembered that in the last-described of these three perturbations, we found at the close 

 a strong negative area of precipitation in the north of Europe, while at the other stations there were only 

 small perturbing forces. 



This last perturbation, with its rather limited area of precipitation, was of the same type as those 

 we so often met with in Part I. It was this type of perturbation that exhibited the simplest conditions, and 

 that we found was the usual one about Greenwich midnight. At the beginning of the present term day, we find, 

 as the curves show, an exactly similar negative polar storm, whose district of precipitation is also restricted 

 to the very same region. The perturbation is here exceedingly characteristic and well-defined, and the 

 subsequent conditions are very normal, so that the day, on this account, at several places where there 

 are no daily hourly-observations has been of great importance in the determination of the diurnal variation. 

 At the beginning of the period, the storm, in several places, has almost reached its maximum. 



