1 24 Reviews — Vesuvius. 



the (so-called) Temple of Serapis, at Pozzuoli, presents a recent 

 minor example. 



In the tenth chapter, the Professor gives a very complete and 

 exhaustive list of the very numerous minerals found in the lavas, or 

 fragmentary ejecta of Vesuvius, the result probably of their long 

 and repeated exposure to fusion, reconsolidation, and chemical 

 changes within the focal reservoir. Speaking generally, the lavas 

 of Vesuvius have always been doleritic (composed of augite and 

 leucite chiefly) ; while those of the Phlegrean fields and Ischia are 

 trachytic (felspar taking the place of leucite) . 



In considering the theory of volcanic excitement (in which that of 

 earthquakes is properly included) , the author leans to the views of 

 those who think the interior of the globe to be in a state of fluid 

 fusion ; and rejecting, with M. Delaunay, the opinion of Hopkins, 

 that proof of its solidity can be derived from the precession of the 

 equinoxes, attributes to the slow contraction by cooling of the 

 exterior crust, the fractures, and local elevations and depressions, 

 which it has evidently suffered; and in some degree also to the 

 change of volume in the subterranean rocky matter, while passing 

 from a fluid to a solid crystalline condition. The particular phe- 

 nomena of volcanoes are ascribed to the penetration of water from 

 seas or lakes, to the heated and liquid interior, through fissures 

 formed during these more general and deeply seated movements. 

 Perhaps the latter is the least satisfactory of these hypothetical 

 agencies. The penetration of water to any great depth loitlun a 

 mass oi fused rocky matter — and it is certain that all the phenomena 

 point to the existence of water (or steam) within, and even below, 

 masses of subterranean lava — seems to us a scarcely conceivable 

 idea. M. Daubree, and, still later, M. Fouque, have broached the 

 opinion that water penetrates everywhere by infiltration, or through 

 crevices to great depths. But this presupposes the matter into which 

 it finds its way to be solid, and, therefore, only subsequently 

 liquified, whether by increase of heat or reduction of pressure. 

 This seems to us the more probable hypothesis ; though, after all, 

 there is perhaps no sufficient reason for the belief that the water 

 present in, and intimately disseminated throughout, the matter from 

 which lavas are formed, did not exist in it ab initio, as one of its 

 component elements, instead of having been introduced ah entra. 

 If this be admitted, local changes of volume, occasioned by the 

 shifting of caloric, will then account for all the phenomena of frac- 

 ture, elevation and depression, as well as for volcanic outbursts, 

 whenever the heated and liquefied matter could force its way 

 through any fissure into the open air, and the contained water 

 consequently flash into steam-bubbles. 



On the whole, the volume of Professor Phillips is an admirable 

 monograph of the great Campanian volcano, and should be em- 

 ployed as a manual by every one who may visit Naples, and desires 

 authentic information on the most interesting feature in its en- 

 chanting scenery. 



The small work of Mr. Lobley contains a lively sketch of the 



