VULCANOLOGY AND SEISMOLOGY. 223 



March appear to be the mouths of great<'st earthquake activity. A 

 period of earthquake calui is fouud in August aiul September, coin ci- 

 <leut with the i)erio(l of greatest cyclonic acti\ity. 



Prof. J. P. O'Keilly, of Dublin, has prepared au earthquake map of the 

 British Islands. {Trans. Roy. Jr. Acad., xxviii, 285.) It is based upon 

 a catalogue of 0;> eartlniuakes 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 deei)ly shaded portions, indicating 

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

 borhood 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 

 iieath 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 nuy slight earthquake passing unre[)orted 

 would l)e much greater in Ireland than in Scotland or England. The 

 relationship of the areas marked by frequency of earthquakes to the 

 great coast line directions, described in previous papers by this author, 

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

 marked on the map) and the earthquake areas ; and the ouggestion 

 is made that if a similar investigation of European earthquakes on which 

 he is engaged shoukl 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 i)laced the 

 seismic center in an extinct volcano situated between Lepanto and Ben- 

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

 scription of the effects i)roduced by the earthquake, mostly based upon 

 his 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 i)eriods, 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 first 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 {Xafurc, xxix, 358)^ we find some results reached by Maj. IM. 

 W. Rogers in a discussion of the earthquake waves which ai)peared in 

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

 €enter of impulse was beneath the waters of the western ])art of t^e Bay 

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

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



