Geology and Mineralogy. 89 



noticeable features of the present volume are charts giving the 

 time, distribution and periodicities of Japanese earthquakes for 

 over a thousand years, and studies in the variations in magnet- 

 ism, latitude and other physical changes as possibly having rela- 

 tions with the occurrence of severe earthquakes. For more than 

 a decade astronomers have been familiar with the fact, rendered 

 evident by long continued and refined astronomic observations in 

 several parts of the world, that the earth's axis of rotation is not 

 absolutely fixed, but that, on the contrary, the poles wander 

 through a period of years in a complex path within a circle of a 

 few hundred feet radius. Among other results the commission 

 has found that the seismic activity of Japan presents a period 

 of six and one-half years, and in the past nine years all the 

 destructive earthquakes occurred exactly or very nearly when 

 the latitude was at a maximum or minimum. j. b. 



5. Earthquakes, in the Light of the JVew Seismology y by 

 Clarence Edward Dfjtton, Major U. S. A. Pp. xxiii + 314, 

 with 63 illustrations. New York (G. P. Putnam's Sons), London 

 (John Murray), 1904. — This is volume 14 of " The Science Series," 

 and while clear and readable throughout, nevertheless enters into 

 all the chief problems related to earthquakes and is a volume 

 which should be read by every teacher of physical geology. 

 Previous to 1870 the studies published were with few exceptions 

 little more than narratives of disasters. Since that time, largely 

 through the labors of Ewing and Milne, who have more recently 

 been joined by many other investigators, the subject has grown 

 into an exact science which not only reveals the location of 

 regions of unstability whether at the antipodes or even under the 

 ocean, but which is throwing light upon such problems as the 

 density and solidity of the earth's interior. 



After discussing the nature and causes of earthquakes, the 

 author devotes 48 pages to the subject of earthquake instruments, 

 obviously an important topic since it is from these refined instru- 

 ments that nearly all of our modern knowledge has come. 

 Following this are 119 pages on the nature of earthquake Avaves 

 and the deductions from them. This statement gives some idea 

 of the complexity r of the record and the involved messages it 

 brings from the earth's interior and which are still far from being 

 completely understood. The last part of the book discusses 

 earthquake distribution and seaquakes. j. b. 



6. Minerals of Japan ; by Tsunashiro Wada, translated by 

 Takudzi Ogawa. Pp. 144 with thirty plates. Tokyo, 1904. — Not- 

 withstanding the comparatively limited extent of Japan and the 

 fact that its resources are as yet only partially developed, the coun- 

 try has afforded a large number of mineral species, many of them 

 of peculiar interest either because of their rarity or of the beauty 

 of their crystallization. The volume before us gives an excellent 

 summary of this subject and deserves careful study by all 

 interested. Concise accounts of the species identified are given, 

 with exact statement of locality and numerous analyses ; a series 



