1906.] 



SEE— THE CAUSE OF EARTHQUAKES. 275 



and other related phenomena may not be without interest to investi- 

 gators of the physics of the earth. 



Almost exactly four months after the earthquake of April 18, 

 namely, August 16, 1906, another, much more terrible, laid waste 

 Valparaiso and the surrounding cities of Chili, producing scenes of 

 desolation which are rare — even in South America. The scientific 

 need and the humanitarian demand for an investigation of the cause 

 of these disturbances could, therefore, hardly be greater than it is 

 at the present time. But if it be said that the researches of science 

 are powerless to stay the hand of the destroyer, and only the laws 

 of these terrible phenomena can be discovered, yet even the intelli- 

 gent appreciation of natural laws may greatly mitigate the extent 

 of the disaster and suffering which follow ; and on both humane and 

 scientific grounds, the prospects of extending the domain of useful 

 knowledge furnish a high inspiration for earnest endeavor to pene- 

 trate the mystery of these hidden forces of nature, which so long 

 have baffled the skill of philosophers. 



Earthquakes and volcanoes were among the earliest physical 

 phenomena to receive the attention of the ancients, and they have 

 always occupied a prominent place in natural philosophy. Although 

 the importance of the subject was derived originally from the ter- 

 rible disasters which these mysterious agencies of unknown forces 

 occasionally inflict upon large portions of mankind, in more recent 

 times earthquakes have been studied also as about the only available 

 means of throwing light upon the physics of the globe. No arti- 

 ficial forces at the command of the experimenter are great enough 

 to produce vibrations of the earth's crust or to transmit them through 

 the body of the planet when once established in the surface layers. 

 But notwithstanding all the labor and research which has been 

 bestowed upon the subject, it can hardly be said that we yet have 

 any satisfactory theory of the cause of these phenomena. This -is 

 the more regrettable, because, on the one hand, it places it beyond 

 the power of science to predict earthquakes, or even to foretell 

 the regions of their occurrence, which might afford some measure 

 of security to life and property; while, on the other, it leaves 

 many men of science without adequate hope that the true cause of 

 these phenomena will ever be discovered, and at the same time so 



