326 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 23, 



April 23, 1856. 



Lester Lester, Esq., was elected a Fellow. 



The President read a Letter from the Directors of the New River 

 Company, in answer to a Memorial, signed by many Members of the 

 Society, relative to the Artesian boring at Kentish Town : — the 

 Directors expressed their regret that they did not feel it to be their 

 duty to the Proprietors of the Company to proceed further at pre- 

 sent with the boring. 



The following communication was read : — 



On the Formation of Craters, and the Nature of the Liquid- 

 ity of Lavas. By G. Poulett Scrope, Esq., M.P., F.R.S., 



F.G.S. 



Contents. 

 Introduction. 



I. Formation of Cones and Craters. 



Hypotheses of crater-formation by " Elevation," " Denudation," and 



'" Engulfment." 

 Circular form of Craters. 

 History of Vesuvius. 



II. Nature of the Liquidity of Lavas. 



Plutonic rocks. 



Lamination, cleavage, and foldings of rocks. 



Introduction, — It is now some thirty years since I published two 

 works* upon the Phaenomena of Volcanos, Active and Extinct. I 

 described in them, as accurately as I could, by pen and pencil, what 

 I had observed during a residence of some duration among the vol- 

 canic districts of France and Italy ; and explained, in considerable 

 detail, the laws which, from those observations, I believed to regulate 

 the remarkable developments of subterranean energies usually called 

 volcanic, which have played so important a part in the construction 

 of the superficial crust of our planet. 



The general principle on which I proceeded in the theoretical 

 portion of these works was the same which had been previously em- 

 ployed by Hatton and Playfair, and was subsequently adopted, with 

 signal success, by Sir Charles Lyell, — namely, to refer, so far as is 

 possible, appearances the origin of which has not been witnessed, to 

 such causes as are seen or known to produce analogous appearances 

 in the present day, — instead of resorting for the purpose to imaginary 

 hypotheses. 



In the earlier volume of the two (the Considerations on Volcanos), 

 however, I certainly overstepped this wholesome rule, by entering 

 towards the conclusion of the work upon some rather crude specula- 

 tions on a general theory of the globe ; and this, together with 

 defects of style and arrangement, and likewise of illustration, of 

 which I became sensible only when it was too late to amend them, 



* " Considerations on Volcanos," &c., 1825-6. " On the Geology of Central 

 France," &c., 1826-7. 



