130 Revieios — O. Poulett Scrope's Volcanos. 



I. — VoLCAKOs : The Chabacter of their Phenomena, their share 

 in the structure and composition of the surface of the globe, 

 and their relation to its internal forces, with a descriptive 

 Catalogue of all known Volcanos and Volcanic Formations. 

 By G. Poulett Scropb, F.E.S., F.G-.S., etc., etc. Ee-issue 

 OF THE Second Edition with Prefatory Eemarks, and a 

 List op Eecent Earthquakes and Eruptions. 8vo. pp. 538. 

 London: 1872. 



THE author of this grand work of reference, finding that a larger 

 number of copies of the Second Edition (published in 1862) 

 had been printed than were as yet disposed of, determined to preface 

 the re-issue of the remaining copies with a short notice of the 

 speculations put forward by various writers during the past ten 

 years ; and also to append a list of the most important earthquakes 

 and eruptions of various degrees of intensity which have occurred in 

 the districts habitually subject to similar occurrences. 



On the subject of the " Assumed igneous fluidity of the interior 

 of the Globe" Mr. Scrope remarks, "in the first place, that these 

 speculations are based on a priori conjectures, not on any recorded 

 facts, and belong moreover to the province of Astronomy rather than 

 of Geology. Secondly (he says), I earnestly protest against the 

 assertion of some writers, that the theory of the present internal 

 fluidity of the globe is or ought to be generally accepted by 

 geologists, on the evidence of its high internal temperature." Mr. 

 Scrope proceeds to point out that the idea " that a molten interior to 

 the globe underlies a thin superficial crust, its surface agitated by 

 tidal waves, and flowing freely towards any issue that may here and 

 there be opened for its outward escape," is an attractive and sen- 

 sational one, but cannot be supported by reasoning based on any 

 ascertained facts or phenomena. Mr. Scrope proceeds to express his 

 opinion that we must give up the idea of a liquid interior to our 

 earth, as unsound, and substitute therefor the theory of the 

 existence of liquefied matter " in pockets or vescicles here and there 

 at varying, but still moderate distances from the outer surface." 

 "This view of the complete, or almost complete, solidity of the 

 subcortical mass of the globe (he adds), is, I think, rendered still 

 more probable when we consider the enormous pressure to which 

 every portion of the heated interior must be subjected, not merely 

 from the weight or contraction on cooling of the outer belt, but still 

 more, perhaps, from the vast internal tension of its every part, 

 owing to the tendency to expansion caused by its intense heat, and 

 this whether that part be in a solid, fluid or gaseous state. More 

 assuredly will this be the case if we suppose, as we reasonably may, 

 that at least the first layers of matter immediately underlying the 

 external crust consist of the same crystalline or granular mineral 

 substances (chiefly felspathic silicates) which constitute the lowest 

 known rocks, granitoidal or porphyritic, portions of which in every 

 part of the globe are known to have forced their way upwards in a 



