VULCANOLOGY AND SEISMOLOGY. 301 



the origin of earthquakes in relation with the theory of the tetrahe- 

 dral form of the earth i^roposed by Mr. Lowthian Green (Vestiges of 

 the Molten Globe, 1875). According to this theory the four vertices of 

 the terrestrial tetrahedral form are, respectively, in the Austral conti- 

 nent, the Himalayas in Asia, the Alps in Europe, and the Rocky Moun- 

 tains in America, the several faces being occupied by the Indian, the 

 Atlantic, the Pacific, and the Arctic Oceans, and the consequent areas 

 of greatest deformation or lines of fracture should be the theaters of 

 volcanic and seismic action, which indeed seems to be in accord with 

 the physical facts (Compt. Rend., cii, 715). This tetrahedral theory of 

 the earth's form was also dicussed before the Academj^ by M. H. Faye 

 at its next meeting (Compt. Rend., cii, 786). He showed that reasons 

 for rejecting this theory were abundant, drawn from the uusymmetrical 

 j)Ositiou assigned to the tetrahedral vertices and from the evident spher- 

 ical form of the moon and planets. The details of his discussion be- 

 long rather to physical geography than seismology. 



The promised monograph by Dr. Johnston Lavis on the earthquakes 

 of Ischia has appeared during 1886, but as the writer has not yet seen 

 it, nor any review of it, further notice of it must be reserved. 



An important memoir by T. Taramelli and G. Mercalli on tlie Anda- 

 lusian earthquakes of 1884 (Atti R. Accad. d. Liucei, 1886) has also come 

 to the knowledge of the writer too late to receive more than mention. 



In the fifth edition of the Admiralty Manual of Scientific Inquiry, 

 the article on earthquakes, originally prepared by Robert Mallet, is to 

 be revised by Prof. Thomas Gray, now of Glasgow and formerly in 

 Japan. (N"atare, xxxiii, 135.) 



An account of " Earthquakes and earth movements," intended for 

 the non-scientific reader, has been published in the International Scien- 

 tific Series. It was prepared by Professor Milae, of Japan, who has had 

 such a prominent part with Ewiug, Gray, and others in the recent ad- 

 vances in seismology. It forms a book of 360 pages, divided into 

 twenty chapters. It gives an excellent popular account of the subject, 

 especially the part devoted to seismometry, in which are described a 

 variety of instruments, from the simple columns of Mallet and the mer- 

 cury cup of Cacciatore, to the modern seismographs of Ewing, Gray, 

 and Milne. The character of the earthquake motion is discussed both 

 theoretically and experimentally, with reference to Mallet's and Abbott's 

 investigations, as well as to the experimental work done by the author 

 and others in Japan. The effects on buildings are described and rules 

 for building are inferred. In regard to the determination of the cen- 

 trum and epicentrum several methods are given, dependent on the 

 direction of the motion, on the direction of the cracks in buildings, and 

 on time observations. For the latter case he treats mathematically (1) 

 the method of straight lines, (2) the method of circles, (3) the method 

 of hyperbolas, and (4) the method of co-ordinates ; as also the methods 

 of Haughton and of Seebach. The distribution of earthquakes in space 



