130 TRANSACTIONS. 1906-7. 



EARTHQUAKES. 



By Otto Klotz, LL.D., F.R.A.S. 



{Read March I, 1907.] 



Destructive and calamitous as has been the San Francisco 

 earthquake, yet from the scientific standpoint it has given a 

 decided impetus to the study of seismology, and it has hastened 

 the day when our knowledge of the interior of the earth will be 

 of a definite character, which it is not now, if we except the com- 

 paratively few feet that we have penetrated into the earth. 



Nature is an aggregation of facts, and it is the sphere of the 

 investigator to correlate these facts and to explain their existence. 

 In the effort to solve the latter advancement is generally gained 

 by the method of elimination. 



As facts do not generally admit of mathematical analysis, 

 theories and hypotheses are advanced for their explanation. 

 These temporary fortresses must then be able to resist the relent- 

 less cannon of observations and of criticism, for the enemy gives 

 absolutely no quarter. Error succumbs to the first broadside; 

 plausibility turns away many a shot and can stand a long siege. 

 It serves a good purpose in permitting the enemy to reinforce its 

 resources to keep up the attack until either 'the fortress is razed 

 or a new one has been built within, built with the impregnable 

 nickel-steel armor of truth. 



Perhaps a brief review of some of the reasons assigned as the 

 cause of earthquakes, leaving out those of supernatural origin, 

 may not be unprofitable. 



We know that there are many sedimentary deposits or forma- 

 tions constituting part of the crust of the earth. We know that 

 they are more or less soluble. We know that the immediate 

 crust of the earth is intersected and traversed by subterranean 

 water-courses. We know that these waters when brought to the 

 surface are more or less charged with salts — such as lime or so- 

 dium — dissolved from the formations through which the water 

 passed. Now let us put two and two together. If a subterranean 

 stream discharges so many cubic feet of water per day, and each 

 cubic foot contains so many grains of lime, how long will it take 



