ARCT0W8EI, CHANGES IN DISTRIBUTION OF TEMPERATURE 71 



September, 1903-Augiist, 1904. Consequently, consecutive maps would 

 show that the formation of the pleion began in the north and extended 

 progressively south or southeast. 



The map of 1904 (Fig. 16) shows a distribution of the equideparture 

 lines similar, to a certain extent, to that of 1901 ; but the sign of the 

 departures is reversed, since we have now an antipleion where we had a 

 pleion in 1901. The consecutive curves are again a great help towards 

 the understanding of what liappened. If we consider this depression 

 of temperature as being due to the same cause as that of Arequipa, we- 

 may say that in Kazan the reaction is felt first, then in Warsaw and 

 finally in Bucarest, where it is very much retarded. 



In Scandinavia the phenomenon appears to be more complicated. 

 There we have two distinct depressions. One is coincident with that of 

 Arequipa, as the curve of Vesterwig shows, and the other is greatly re- 

 tarded. It may be that the second depression of Haparanda and Sydva- 

 ranger is due to a propagation of the antipleion first formed in Eussia. 



The map of 1905 (Fig. 17), if considered from the same point of 

 view, represents the formation of a pleion and that of 1906 shows the 

 same pleion after the maximum of its development. 



The most important crests on the curves of Kazan and Bucarest occur 

 between 1905 and 1906 and correspond to an Arequipa crest. In War- 

 saw we notice fluctuations ; the same in Scandinavia, where they are even 

 more pronounced. This pleion must have been Asiatic. 



In 1907 (Fig. 19), there are residual pleions over Scandinavia and 

 central Europe and an antipleion over Russia. 



Between 1907 and 1908 the curves of Warsaw, Bucarest and Geneva 

 show the Arequipa crest. 



This fact demonstrates that the Russian antipleion did not spread out 

 progressively over central Europe, as a comparison of the maps of 1907 

 and 1908 seems to indicate. On the contrary, an important interruption 

 occurred, during which a brachypleion (corresponding to the Arequipa 

 crest of 1907-1908) came from the south and invaded southern and west- 

 ern Europe without affecting the Russian antipleion. Finally, this Rus- 

 sian antipleion of 1908 went west in 1909 (Figs. 20 and 21). The con- 

 secutive curves, the curve of Geneva in particular, leave no doubt about 

 this fact. 



The main result gained by the study of the maps is that, during the 

 years 1900 to 1909, the pleions and antipleions did not move from the 

 Atlantic across Europe towards Asia. On the contrary, the displace- 

 ment was from the northeast towards the southwest, or from the east 

 towards the west. Moreover, these displacements did not cross the areas 



