Reviews — Italian Seismological Society. 275 



The diagrams show the alumina to be nearly constant, only 

 slightly diminishing towards both extremes. The soda is also 

 tolerably constant, diminishing slightly at both ends. The potash 

 is decidedly stronger at the acid end, whilst the other oxides 

 increase from left to right so as to show quite a fan-like expansion 

 from the acid end towards the basic end. 



The diagrams show also that the arbitrary boundaries between 

 acid, intermediate, and basic rocks are very suitably chosen. 



I^ E "VI E "V7- S. 



BOLLETTINO BELLA. SoCIETA SlSMOLOGIOA ItALIANA, Vol. V 



(1899-1900). 



EXCLUDING two bibliographical notices, the present volume 

 contains nineteen papers, of which all are interesting and one 

 is important. In addition, is the catalogue of earthquakes recorded 

 in Italy during the year 1898, compiled by Dr. G. Agamennone and 

 his successor Dr. Cancani. The value of this work is abiding, and 

 increases with every fresh year of its existence. 



If we may judge from this volume, the recent energies of Italian 

 seismologists have been directed less to the invention of new 

 instruments and more to the study of their records. Nevertheless, 

 Drs. Vicentini and Pacher have made an important addition in the 

 form of a vertical component microseismograph. The paper in 

 which it is described, and the representations of some of its records, 

 are most interesting. Dr. G. Agamennone has devised a new 

 seismoscopic clock, and Dr. G. Pericle one more seismoscope. 



Professor A. Ricco, of Catania, gives a summary of a report on 

 the destructive earthquake of November 16, 1894, in Calabria and 

 Sicily, and on its relations with the earthquakes of 1783. From the 

 same writer we have also an account of the Etnean earthquake of 

 May 14, 1898. Dr. Agamennone describes the Balikesri (Asia 

 Minor) earthquake of September 14, 1896, the Apennines earthquake 

 of March 4, 1898, and the Modena-Bologna earthquake of 

 February 2. 1900 ; while Dr. Cancani studies the Latian earth- 

 quake of July 19, 1899. In connection with barisal guns 

 Professor Issel's supplementary paper on the Umbria Marches 

 earthquake of December 18, 1897, is deserving of study. 



Professor Mercalli contributes observations on Vesuvius (July- 

 December, 1898), and Mr. R. V. Matteucci others on the Italian 

 volcanoes generally. On July 19 and 25, 1899, violent explosions 

 occurred in the central crater of Etna ; these are carefully described 

 by Mr. S. Arcidiacono, and their effects on the condition of the 

 orater by Mr. A. Mascari. C. Davison. 



