312 Geological Society : — 



He was now free with such remaining strength as he could com- 

 mand to re-enter the field of philosophic speculation, in which he 

 had spent his earliest years of mental exertion, and which for 

 nearly thirty years, through all the engrossing attractions of geo- 

 logical inquiry, had never lost its fascination for him. Accordingly 

 he betook himself once more to the study of such subjects as force, 

 matter, causation, determinism, evolution, &c, and proceeded to 

 apply the facts and principles with which he had in the interval 

 been dealing so actively to the problems in philosophy that had 

 aroused his thoughts in the early years of his life. In spite of his 

 increasing infirmity, he persevered in committing to writing the 

 ideas which he had now formed, and he sent to press his last work, 

 ' The Philosophical Basis of Evolution/ " in 1890. (See page 504.) 

 He died December 15, 1890 : aged G9 years. 



XLIII. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 

 [Continued from p. 240.] 



January 6th, 1897.— Dr. Henry Hicks, F.R.S., President, 

 in the Chair. 



THE following communications were read : — 

 1. 'On the Structure of the Skull of a Pliosaur.' By C. W. 

 Andrews, Esq., B.Sc, F.G.S. 



2. ' On the Pembroke Earthquakes of August 1892 and November 

 1893.' By Charles Davison, Sc.D., F.G.S. 



Part I. of this paper deals with the earthquakes of August 1892, 

 of which eleven are recorded, the principal being the third. The 

 author gives an account of the preliminary shocks and after-shocks, 

 and a detailed account of the principal earthquake, describing the 

 disturbed area, the relationship of the earthquake to a north-and- 

 south fault, hading to the west, that of sound to shock, and the 

 occurrence of sea-waves. 



Part II. treats of the earthquakes of November 1893 ; there were 

 four undoubted earthquakes, of which the first was the chief one. 

 Descriptions are given of the phenomena. 



Part III. treats of the origin of the earthquakes and their 

 connexion with faults; and the author points out the possible 

 value of the study of earthquakes in supplementing geological 

 surveys. For more than fifty years prior to the earthquakes of 

 1892-93 there appear to have been no slips of importance along 

 the fault-system of the area. After this prolonged interval of repose, 

 the earlier movements took place along transverse (north-and-south) 

 faults, and the later along longitudinal (east-and-west) ones. The 

 three faults of the latter series which the author connects with the 

 disturbances lie successively one to the north of the other, as if the 

 abrupt displacement of a rock-mass over one thrust-plane impelled 



