ON SEISMOLOGICAL INVESTIGATIONS. 



57 



similar instruments. Most valuable assistance has however been received 

 from the publications of the Earthquake Investigation Committee of 

 Japan, the International Seismological Association, the Commission 

 Sismique Permanente of the Imperial Academy of Sciences of St. 

 Petersburg, the Societe Sismologica Italiana, the K. NatUurkundige 

 Vereeniging in Nederl-Indie, the Bulletins of the Manila Central Obser- 

 vatory, and the weekly, monthly, and other circulars issued by obser- 

 vers in various parts of the world. 



The chief difference between the present map and the four corre- 

 sponding maps already issued by the British Association is that it con- 

 tains more entries and shows more clearly the present-day sites of 

 seismic activity. The small numbers on the map which are underlined 

 refer to earthquakes which have been recorded all over the world, whilst 

 the remainder indicate earthquakes which were recorded over areas 

 which are approximately those of half our sphere. 



Dual or multiple earthquakes are linked by brackets, and the stations 

 used for the determination of their origin are named. 



Compilations referring to the next five years have been completed, 

 but it was felt they could not be entered on the present map for want 

 of space, and are therefore held over for the next Report. 



The number of megaseisms which have taken place in the different 

 regions in the period considered are as follows : A x twenty, A 2 eight, 

 B fourteen, C x thirteen, C 2 five, 1) 1 six, D 2 seven, Ej eighteen, E 2 seven, 

 E 3 twenty-three, E 1!2 , 3 one, F, thirty-three, F 2 ten, F 3 twelve, G x five, 

 G 2 seven, H fourteen, J two, Id ten, Id five, Id ten, K 4 four, K 5 three, 

 K three, Iv 7 two, K 8 nil, L four, M, twelve, M 2 eleven, M 3 two, five, 

 P five, Q five, R nil, B D, two, K 5 G, four, F,M, two, G,G 2 one, P E, 

 one, A 2 B two, Id, 2, 3 five, F,E 3 three, Id, 3 one, FiF 2 one, M 2 E 2 three, 

 K,A, two. Total 313. 



If we draw a circle 70° in radius, with its centre 180° east or west 

 long, and 60° north lat., it will be seen that this passes through the 

 most active seismic regions in the world. This circle is drawn on the 

 map as a line. If it is replaced by a band 40° in width, it contains 186 

 entries out of the 313. 



List of Earthquakes 1899-1903 inclusive. 



