VULCANOLOGY AND SEISMOLOGY. 223 



March appear to be tlie mouths of greatest earthquake activity. A 

 period of earthquake calm is found iu August aud September, coinci- 

 dent with the period of greatest cyclonic activity. 



Prof. J. P. O'Reilly, of Dublin, has prepared an earthquake map of the 

 British Islands. [Trans. Boy. Ir. Acad., xxviii, 285.) It is based upon 

 a catalogue of 53 earthquakes felt in historical times up to 1880, of 

 which 8 occurred previous to the year 1700. These are rearranged 

 and recatalogued with respect to localities and frequency, and the map 

 is shaded accordingly. The most deeply shaded portions, indicating 

 the greatest frequency, are found in Southern Scotland and in the neigh- 

 l)orhood of Bristol Channel, and generally the map shows much more 

 earthquake action in Great Britain than in Ireland ; whence the author 

 infers the existence of some barrier, such as great lines of faulting be- 

 neath the sea, which prevents the extension of seismic action to the 

 adjacent island. He does not, however, allude to what is certainly the 

 fact, that the probability of any slight earthquake passiug unreported 

 would be much greater in Ireland than in Scotland or England. The 

 relationship of the ai^eas marked by frequency of earthquakes to the 

 great coast line directions, described in previous i)apers by this author, 

 is jiiscussed, and also the relation between the coal areas (which are 

 marked on the map) aud the earthquake areas ; and the auggestiou 

 is made that if a similar iu vestigation of European earthquakes on which 

 lie is engaged should confirm the indications of the map of England 

 that coal areas are also earthquake areas, then the earthquake map 

 might be an important aid in the search for concealed beds of coal. 



In a memoir on the earthquakes of July, 1880, in the island of Luzon 

 (Trans. Seis. Soc. of Jap., V, 43), Don J. Centano y Garcia dissents from 

 the conclusions of Father Faura, previously published, which jilaced the 

 (seismic center in an extinct volcano situated between Lepan to and Ben- 

 guet, in the central mountain chain of Luzon. After an extended de- 

 scription of the effects produced by the earthquake, mostly based upon 

 bis own observation, he reaches the following conclusions : All the 

 series of earthquakes from the 14th to the 25th of July, 1880, can be di- 

 vided into three classes, corresponding to the 14th, 18th, and 20th days. 

 The intensity curves for each of these periods, as drawn on the author's 

 map, indicate that the seismic center was in the southern part of the 

 island, near the lake called La Laguna, southeast of Manila, the curves 

 of maximum intensity for the iirst two periods including the region 

 just east of this lake, and for the third period its western shore. 



In an article on Earthquake Disturbances of the Tides on the Coasts 

 of India {l^ature, xxix, 358), we find some results reached by Maj. M. 

 W. Rogers iu a discussion of the earthquake waves which appeared in 

 the Bay of Bengal on December 31, 1881. The probable position of the 

 center of impulse was beneath the waters of the western part of tfee Bay 

 of Bengal, and the velocities deduced lor the sea wave were : To Port 

 Blair, in the Andamans, 360 miles an hour; to Madras and Negapatam, 



