310 H. Arctowski — About Climatical Variations. 



decrease of temperature. This, of course, applies to consecu- 

 tive means. 



In order to study the displacements of pleions, I made 

 detailed annual departure maps, for the years 1900-1909, for 

 Scandinavia and Central Europe, for North America and for 

 the Atlantic. I hope to publish these maps as well as the 

 discussion of the results obtained and, at present, I will simply 

 mention some of the interesting points of my investigation. 



The main result gained by the study of the European maps 

 is that, during the years 1900-1909, the pleions and antipleions 

 did not move from the Atlantic towards Asia. On the con- 

 trary : the displacement was from the NE. towards the SW., 

 or from the E. towards the W. Moreover, these displacements 

 did not cross the areas of maritime climate. The big pleion- 

 ian variations of Europe appear to be a purely continental, 

 and perhaps, arctic phenomenon. But, the areas where they 

 are formed, in situ, are probably not always the same. 



For the United States I have utilized, besides the annual 

 detailed departure maps and the consecutive curves of a 

 selection of stations, also consecutive maps obtained from the 

 district means published in the Monthly Weather Review. 1 

 will notice a few problems arising from a closer examination 

 of these consecutive maps. 



Eirst of all, during the years 1900-1909, the pleions as well 

 as the antipleions displayed a tendency of persistence. No 

 see-saw movement, between a pleion and an antipleion, leading 

 to the gradual disappearance of both and then to the forma- 

 tion in situ of a pleion on the place formerly occupied by the 

 antipleion and vice versa, could be traced. Minor see-saw 

 oscillations took place, but served simpty to increase or de- 

 crease the contrast between the pleions and antipleions with- 

 out destroying them. Together with the tendency to persist 

 goes a tendency of displacement. These displacements are 

 generally gradual and continuous, but sometimes they may be 

 very fast and in a striking contrast to the nearly stationary 

 conditions which preceded or followed the rapid change of 

 position. 



Another fact is the tendency of the pleions and antipleions 

 to remain on the continent. In other words, the phenomenon 

 of the variation in the distribution of the anomalies of yearly 

 temperatures in North America, is a purely North American 

 phenomenon. The pleions and antipleions seem to be cor- 

 related or bound together. One depends on the other. If one 

 moves the other moves. The area of the North American 

 continent seems not to be wide enough for the simultaneous 

 presence of many pleions and antipleions. In order to remain 

 on the continent the motion of a pleion involves a displace- 



