Reviews — Prof. John Milne — Earthquakes. 371 



heartily congratulate its author upon the energy and zeal with which 

 he has performed his self-appointed task, no less than on the character 

 and appearance of the volume in which he has recorded his results. 



II. — Earthquakes and other Earth-Movements. By Prop. John 

 Milne, F.G.S. With 38 Figures. Vol. LVI. of the Inter- 

 national Scientific Series. (Kegan Paul, Trench & Co.) 



SINCE Mallet's " First Principles of Observational Seismology," 

 better known as " A Report on the Neapolitan Earthquake of 

 1857," no book has appeared on this subject comparable in importance 

 to the present volume. This seems indeed to mark a new epoch in 

 the progress of the science, as that book certainly marked a former 

 epoch, which should probably be reckoned the first. A contrast may 

 be drawn between the two. The first is mainly observational, and 

 its observations are made on single great earthquakes ; its names are 

 Mallet and Hopkins ; its region of research is Italy ; and its concep- 

 tion of an earthquake is one or more shocks. The new epoch is 

 experimental as well as observational ; and its observations are made 

 on all, even the minutest tremors ; Ewing, Gray, Milne, are its names, 

 its classic region is Japan ; and it conceives an earthquake as a train 

 of vibrations. Its great advance is due to the introduction of an 

 instrument of exact research, the seismograph properly so called, a 

 seismometer with recording apparatus. All previous means, the 

 author remarks, ought to be classed not as seismometers capable of 

 measuring a disturbance, but as bare seismoscopes indicating only 

 that a disturbance has taken place. 



Our volume presents a full view of the present state of knowledge 

 on this obscure and difficult subject. If any person wonder that 

 so complete a treatise can issue from so remote a region, let him 

 remember that from that region come all the latest additions to our 

 information. Much credit is due to Mr. T. Gray for his revision of 

 the proofs. The correctness shows the pains that must have been 

 bestowed. The only serious error we have noticed is in the equations, 

 etc., of p. 211. Here certainly either explanation or correction is 

 needed. Ought not the index of the second power to be affixed to 

 each letter in these equations ? 



No branch of the study is neglected : all receive attention. Even 

 practical aspects, so often despised by men who suppose themselves 

 scientific, here have a full share of notice. The 'general conclusions ' 

 at the end of Chapter VII. give valuable advice to those who have 

 to build a house in a region exposed to such dangers. There is even 

 a suggestion for the use of Earthquake lamps to extinguish them- 

 selves in the act of being overthrown. The ' Earthquake coats,' 

 described as having pockets ready filled with provisions as preparation 

 at a moment's notice for spending a night in the air, relieve with a 

 little amusement more serious recommendations. Undoubtedly the 

 most important notes of advice are No. 8 : ' Follow one of the two 

 systems for constructing an earthquake-proof building,' and No. 1 : 

 ' In choosing a site, find out the localities which are least disturbed.' 



