ARCT0W8KI, CHANGES IN DISTRIBUTION OF TEMPERATURE 95 



data, the atmospheric pressure and the velocities and directions of the 

 observed winds. 



In the present state of our knowledge of the phenomena governing the 

 climatical variations, however, it would be most unscientific to try to 

 make seasonal forecastings, since, at present, we see only the possibility 

 of arriving at practical results by pursuing patiently the research work 

 in a well-established direction. With the immense amount of work which 

 yet remains to be done before a clear understanding of the climatical 

 variations will be reached, any test of the method employed, in order to 

 show its practical value, would be completely out of place. 



To show how each step forward leads to new questions to be solved 

 and new research work, having apparently nothing in common with the 

 pursued purpose, I will note a few problems arising from a closer ex- 

 amination of the consecutive maps. 



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

 antipleions displayed a tendency of persistence. Xo seesaw movement, 

 between a pleion and an antipleion, leading to the gradual disappearance 

 of both and then to tlie formation in situ of a pleion on the place for- 

 merly occupied by the antipleion and vice versa, could be traced. Minor 

 seesaw oscillations took place, but they sei-ved simply to increase or de- 

 crease the contrast between the pleions and antipleions without destroying 

 them. Together with a tendency to persist goes a tendency of displace- 

 ment. These displacements are generally gradual and continuous, but 

 sometimes they may be very rapid and in striking contrast to the nearly 

 stationary conditions which preceded or followed the rapid change of 

 position. The problem is, then, to know what makes a pleion remain on 

 the map during several years and what makes the pleion move from one 

 region to another. 



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 Amer- 

 ica is to a great extent a purely N"orth American phenomenon. 



This leads naturally to another question of some importance. The 

 pleions and antipleions seem to be correlated or bound together. One 

 depends on the other, and if one moves the other moves. The area of the 

 North American continent seems not to be wide enough for the simul- 

 taneous presence of many pleions and antipleions. In order to remain 

 on the continent, the motion of a pleion involves a displacement of the 

 antipleion in an opposite direction. A rotaiy movement is the conse- 

 quence. It is a pendulation. 



The following diagram shows in a schematic way the pendulations of 



