H. Arctoioski — About Climatical Variations. 



309 



This is not the case. The variation in New York presents 

 most striking coincidences with the Arequipa variation, and 

 the same may be said about the curve of Kazan, in Russia, 

 and North of Iceland, the observations made on Grimsey Isl., 

 under the polar circle, show also all the crests and depressions 

 of the Arequipa curve, slightly retarded. 



Therefore, the impulse which produces the pleionian vari- 

 ations must be felt simultaneously all over the world, and 



Fig. 2. 



Fig. 2. Pendulations of the pleionian center : 1900-1909. 



then, — just as in the case of a handful of stones projected on a 

 quiet surface of water, — from distant points where the impulse 

 is felt directly, the so produced anomalies propagate themselves. 

 We see now how the conception of thermopleions has to be 

 enlarged. Pleions are not simply the areas occupied by posi- 

 tive departures of temperature and antipleions the areas of 

 negative values. They are thermal waves. It follows that, 

 for practical purposes, it would be best to define a pleion as 

 being the area where the consecutive annual means present a 

 tendency to rise. But then the rise of temperature will be felt 

 all over the area only in the case of stationary pleions. If the 

 pleion displaces itself the rise will be observed on the wave 

 front, whereas on the other side we shall notice a progressive 



