ON SEISMOLOGICAL INVESTIGATION. 



70 



1895 to 1898 inclusive, with the registers of earthquakes which during 

 that period have disturbed the whole world, or, at least, continental 

 areas. A suggested conclusion was that when the pole displacements 

 were comparatively great large earthquakes were frequent, and vice 

 versa. The inference to be drawn from the following note is that this 

 same type of earthquake has been frequent when the change in direction 

 of the movement of the pole has been marked. In the following table 

 the years (1892 to 1899) have each been divided into ten parts, and the 

 large earthquakes which occurred during each of these intervals are 

 given by numerals. 



The earthquake registers fi'om which the latter figures have been 

 abstracted are as follows : — 



1. March 14, 1892 to Aug. 7, 1893.— Strassburg and Nicolaiew(see 'Horizontalpendel- 



Beobachtungen,' &c., von Dr. E. von Kebeur-Paschwitz. ' Beitrage zur Geo- 

 physik,' Band II.). 



2. Aug. 7, 1893, to Sept. 12, 1834.— Charkow (see ' Ergebnisse der auf der Charkower 



Universitiltssteinwarte,' mit den v. Rebeur'schen Horizontalpendel angestellten 

 Beobachtungen, v. Prof. G. Lewitzky). 



3. Jan. 1, 1894, to Dec. 31, 1896. — Italian and other stations (see ' Bollettino della 



Society Sismologica Italiana,' 1895. 



4. Jan. 1, 1897, to Dec. 31, 1902. — Registers from stations widely spread over the 



world, published by the Seismological Investigation Committee of the British 

 Association. 



Although these registers are comparable so far as world-shaking 

 earthquakes are concerned, it is evident that in the last list very large 

 earthquakes are included which could not have i-eached stations in 

 Europe. For this reasou, so far as actual frequency is concerned, 

 Registers I., II., and III. are not comparable with No. IV. 



I 



Earthquake figures connected by brackets refer to two periods, each 

 of 36-5 days, when the change in direction of pole movement was 

 marked. In the following table the total number of earthquakes which 

 occurred in each of these two periods is so far as possible compared with 

 the total number of earthquakes which were recorded in equal intervals 

 of time (73 days) before and after the deflection periods. 



Earthquakes before deflection : no obs. 

 Earthquakes during deflection : 22 

 Earthquakes after deflection : 8 



Earthquakes before deflection : 3 

 Earthquakes during deflection : 10 

 Earthquakes after deflection : 12 or 18 



