756 REVIEWS 



around the centrosphere in a rather deep portion of the crust rather than 

 directly through the body of the earth. So, too, it is necessary still to speak 

 qualifiedlv, for the chief value of the anticipated seismic contribution 

 depends not only on the verity of the passage of the foremost vibrations 

 through the heart of the earth, but also on the transverse character of the 

 second set of these vibrations; for transverse vibrations are functions of 

 sohd bodies, but not of liquids, and hence their significance relative to 

 the physical state of the interior. WTien it shall- be shown beyond reason- 

 able doubt that the second set of the transmitted seismic vibrations are 

 transverse, and that they have passed through the center of the earth, it 

 will have been shown with equal conclusiveness that the earth is solid 

 throughout, save for such local spots as vulcanism requires, which would 

 not affect the general power of transmission. Major Button brings out 

 the data bearing on this chief point of fundamental interest carefully and 

 conservatively, and makes them readily accessible to the geological inquirer 

 who is not in possession of the special seismological literature. As best 

 interpreted at present, the data seem to indicate not only a thoroughly 

 rigid earth, but one in which there is an increase of elasticity of form toward 

 the center in a ratio at least as high as the increase in density. This last 

 is determined by the speed of wave-transmission, which is made the subject 

 of three chapters. 



While these difficult themes of supreme interest to the student of geo- 

 logical fundamentals are given due place in the later chapters of the book, 

 they are not allowed to displace the more superficial and impressive phe- 

 nomena that have given to earthquakes their universal, if somewhat grue- 

 some, interest. The descriptions of the destructive effects are ample, but 

 always clothed in chaste and sober scientific terms. The illustrations are 

 select, and expressive of definite rather than promiscuous effects. 



Much space is given to the instruments used in the more refined observa- 

 tions that characterize the new seismology, and to the methods by which 

 the science is being advanced. The causes of earthquakes occupy a chap- 

 ter; their distribution and geographic relations occupy two, and the book 

 is closed by a' chapter on seaquakes, the distinctness of which from earth- 

 quakes is usually overlooked. The treatment, while careful and exact, is not 

 mathematical, except in a few cases where accurate expression would 

 otherwise be impossible. The literary elegance which graces all of Major 

 Button's writing finds as large an expression here as the nature of the 



subject permits. 



T. C. C. 



