i 



12 EARTHQUAKES ON THE PACIFIC COAST 



As many of the earthquakes of California are very local phe- 

 nomena, which depend upon local causes for their production, we 

 cannot expect to obtain very definite laws from a table like this 

 which covers the whole of such a vast territory. Moreover, the 

 facilities for gathering information in the thinly settled portions 

 of the State were imperfect in the earlier years, and even now 

 shocks are not carefully recorded at more than two or three places 

 in the State. For these and other reasons this table can only give 

 approximate results. It does not include every single earthquake 

 set down in the catalogue, since it was compiled before the list 

 was entirely finished. It, however, contains nearly all. It is suf- 

 ficiently full for its purpose, which is simply to show the relative 

 frequency of shocks in the various months. This is for; 



'' January 68 



February 45 |^ ^^^^ ^^^^ Vernal Equinox (1850-1887). 



. ^^?, „, 1 (Rainy Season.) 



April 71 ) ^ •' ' 



^^^^ l^} 1.53, near Summer Solstice (18.50-1887). 



J^f^ ^l\ (Dry Season.) 



July 45 ) ^ • ' 



August.. 53) 22^ ^^^j. Autumnal Equinox (18.50-1887). 



September. . ..85 V ,n a„„„ \ 



„ ' , „„ I (Dry Season.) 



October 88 ) ^ • ' 



November 57 ) ^^g ^^^^ Winter Solstice (1850-1887). 



December ... .83 ;- ' /r> • o „„ \ 



, -- „„ ( (Rainy Season.) 



1^ January 68 ) ^ - ■' 



Eainy season, 390; dry season, 378. Thus for California, Ore- 

 gon and Washington at large, shocks are about equally probable in 

 the wet and in the dry season. Table A includes the data derived 

 from observations at San Francisco. If we form a similar table 

 which includes all the data for California, Oregon, etc., excluding 

 San Francisco, the result will be, for: 



f January 43 



February 33 ) ^^^.^^^^ Equinox. 



March 40 1 ' ,d • o \ 



April 56J (Rainy Season.) 



^^y q! ) 105, near Summer Solstice. 



i S;.: ■.::■.::.■ 331 (Dry season.) 



August. 43 ) ^gg ^^^^ Autumnal Equinox. 



September ... .64 > /rv c? \ 



„ \ , t,., 1 (Dry Season.) 



October 53 ) ^ ■^ ' 



November. • • -SJ ) ^g^ Qg^r Winter Solstice. 

 December ... .61 ;- ' ,t> ■ r.„ „„ v 

 [January 43 i (Rainy Season.) 



Eainy season, 250; dry season, 264. (See the last column of 

 Table B.) 



