392 E S. Ilolden — Earthquakes in California. 



To this number there will yet be added many of the genera 

 and species from Sardinia, and probably a considerable number 

 from Britain and Scandanavia. 



In the second part of this paper the stratigraphical and 

 zoological relations of the Lower and Middle Cambrian faunas 

 will be discussed. 



[To be continued.] 



Art. XLI. — Earthquakes in California, (1888) ; by 

 Edward S. Holden. 



Lsr 1887 I compiled a list of earthquakes which had been 

 recorded in California/ etc., from 1769 to the end of 1887. 

 This was printed by the Regents of the University of California 

 in a pamphlet of 78 pages and widely distributed. The data 

 there given have been discussed in two papers subsequently 

 written. The first is a note on Earthquake Intensity in San 

 Francisco (1808-1888) printed in this Journal for June, 1888 ; 

 and the second has the title Earthquakes in California, Wash- 

 ington, and Oregon (1769-1888) and has been communicated 

 to the California Academy of Sciences. These three publica- 

 tions contain all the data which I have been able to collect, 

 and I believe that no deductions of especial value can be drawn 

 from the data except those which are there given. These 

 statistics could, of course, be tabulated in several different ways, 

 but it is my opinion, from trials, that no important results not 

 already given would follow. 



The examination of past records has naturally led to the 

 consideration of the best manner of making future ones. The 

 object of such records is to bring to light all the general facts 

 as to distribution of earthquake shocks, as to topographic areas, 

 as to time, as to average- intensity, etc., and also to enable a 

 study to be made of particular shocks, — as to velocity of transit, 

 area of the disturbed region, intensity, etc. In order to study 

 any of these questions with profit it is necessary to have some 

 kind of a measure of the intensity of each earthquake shock. 

 The most satisfactory instruments which I have seen for this 

 purpose are those invented by Professor Ewing, F.E..S. These 

 are devised on sound mechanical principles and are well con- 

 structed by the Cambridge Scientific Company. 



It is necessary at the Lick Observatory to keep a register of 

 all earthquake shocks in order to be able to control the positions 

 of the astronomical instruments. Accordingly I ordered a set 

 of Professor Ewing's instruments for the Observatory, which 

 were delivered in 1887. They are described with woodcuts in 

 Yolume I of the Publications of the Observatory, (page 81), 



