^2 Analysis of Scientific Books and Memoirs. 



Art. XXX v.- analysis OF SCIENTIFIC BOOKS AND 

 MEMOIRS. 



Mffnoir o»» the Geology of Central France-, including the volcanic fur- 

 mations of Auvergne, the Velay, and the Vivarais, By G. Poulett 

 ScROPE, Esq. F. R. S., F. G. S. In one Volume 4to, with a Volume of 

 Plates. liond. 1827. 



The subject of volcanos, whether active or exthict, must always be consi- 

 dered as one of the most important in geology. The products of their 

 eruptions are derived from those inner regions of the globe which would 

 otherwise be inaccessible to observation ; and the primary phenomena which- 

 they exhibit, as well as the extraordinary effects by which these pheno- 

 mena are attended, give us the only information which we possess respect- 

 ing those tremendous agents which are imprisoned within the adamantine 

 walls of our planet. It seems scarcely possible to conceive that the study 

 of volcanos could have been set at nought by any person bearing the 

 name of a geologist. Some of the half-taught votaries of the Wernerian 

 School indeed affected to consider them as mere superficial convulsions, 

 which had no effect on the main crust of the globe, and which disclosed 

 none of the secrets of its interior arrangements. Such opinions had no 

 other object but to undervalue the influence of a central heat as one of the 

 leading agents in the induration and elevation of the earth's crust, but 

 though they passed current in that level of intellect for which they were 

 adapted, they at last roused the indignation of the philosophical geologist, 

 and have at last sunk never more to rise, under the the powerful weapons 

 of argument and observation. 



One of the first persons who assailed and overthrew these dogmas of the 

 Wernerian theory, was our distinguished countryman Professor Playfair. 

 In a dissertation on volcanos which he read to the Royal Society of Edin- 

 burgh, and which was intended to form a part of the second edition of his 

 Illustrations of the Btdtonian Theory, he arranged all the facts which cha- 

 racterized the most remarkable eruptions, he traced over the globe the ef- 

 fects of the earthquakes which accompanied them, and he proved by calcu- 

 lations, founded on these facts, that the agent from which they arose 

 must in some cases have been seated at a depth beneath the earth's surface 

 at least § or ^ of its radius. These opinions, though the memoir which 

 contained them was never published, were speedily propagated, and seve- 

 ral of our young geologists, who had not been tainted with preconceived 

 opinions, devoted themselves to the study of the volcanic phenomena. 



One of the most distinguished of these was Mr Scrope, the author of 

 the present work, who explored with his own eyes the volcanos of Italy 

 and Sicily, and whose work on that subject we have already fully analyzed 

 in a preceding number. Not satisfied, however, with the study of active vol- 

 canos, he resolved to examine those which had been long extinct, and 

 whose products, modified by accidental causes, and by the action of diurnal 



