312 H. Arctowshi — About Climatical Variations. 



I have taken the differences between the highest and lowest 

 departure for each of the 109 consecutive maps, in other 

 words, the total amplitudes between pleions and antipleions. 

 From 1900 until 1906 the reversed curve expressing these fig- 

 ures graphically and the Areqnipa curve are similar. Then, 

 between 1906 and 1907 an interesting anomaly is noticed. 

 Moreover, the Arequipa temperatures decreased from 1900 

 to 1909. In the United States the differences between pleions 

 and antipleions were also decreasing during that period of 

 years. Independently of the pendulations, the Arequipa vari- 

 ation affects therefore the entire system of North American 

 pleions and antipleions. 



I should like now to pass in review some results obtained 

 from the close examination of European rainfall data, for the 

 years 1851-1905, and to other researches I made on the varia- 

 tions of atmospheric pressure and of sunshine records. 



For rainfall and the other meteorological elements the con- 

 secutive curves also show perfectly characteristic crests and 

 depressions. Moreover, the rhythms are absolutely similar to 

 those of temperature. In consequence we shall have to speak 

 of pleions of atmospheric pressure or baropleions, or, to use a 

 simpler expression, of baros and antibaros. And likewise, in 

 the case of rainfall, we shall have ombropleions or ombrons and 

 antiombrons. And in the case of sunshine, we shall have to 

 speak of helions and antihelions. 



It will be necessary to establish the details of all these varia- 

 tions before it will be possible to search for the mutual rela- 

 tionship of therrnopleions, baros, ombrons and helions, and 

 only then will it be possible to examine the role of the centers 

 of action of our atmosphere, and this will lead to the study of 

 seasonal anomalies. 



It is an immense field of research work to be made, but, as 

 will be seen immediately, all this is only one side of the ques- 

 tion of climatic variations. We have indeed to consider also 

 the macropleionian variations. 



2. Macropleionian variations. 



In order to detect these variations it is necessary to form 

 consecutive means of groups of years. It is impossible to take 

 4, 5, or 6 yearly means because then the chances are that the 

 figures will be greatly influenced by the pleions. To eliminate 

 the pleionian variation it is necessary to take 10 yearly means. 

 But even then some predominant pleions may affect the means. 

 On the other hand, it is impossible to take a longer period than 

 ten years, first of all because it is only exceptionally that we 

 have to deal with long temperature records which may be con- 



