XXXVIII SCIENCE PROGRESS. 



hundred pages, is devoted to a general sketch of modern volcanic action 

 and a comparison of ancient volcanoes — as illustrated by their denuded 

 relics embedded among the sedimentary deposits of past ages — with 

 those of the present day. The author then proceeds to sketch 

 successively the evidences of volcanic action in the British Islands, in 

 Pre-Cambrian, Cambrian, Silurian, Devonian and Old-Red-Sandstone, 

 Carboniferous, Permian and Tertiary times. Convenient as is this 

 strictly chronological order from many points of view it is attended 

 with the disadvantage that the writer is compelled to proceed " from the 

 unknown to the known " — from the study of the much altered and 

 greatly denuded fragments of old volcanic rocks, in which the relations 

 with modern deposits are often very obscure to the comparatively fresh 

 and well-preserved relics of Tertiary Volcanoes, in which the analogies 

 with existing volcanic masses are so clear that they cannot be misunder- 

 stood. Apart from this obvious objection to his method, however, all 

 geologists must feel indebted to the author for the way in which he 

 has succeeded, by weaving together facts and observations from sources 

 new and old, in giving a connected and up-to-date account of all that 

 is known concerning the volcanic history of Britain during each of 

 these ancient periods. 



The last chapter of the work, consisting of about a dozen pages, 

 is devoted to a "summary, and general deductions". It is here, if 

 anywhere, that the reader may perhaps experience some little disap- 

 pointment. In the various memoirs on volcanic phenomena — the 

 publication of which has extended, as the author reminds us in his 

 preface, over a period of nearly forty years — it naturally happens that 

 we are able to trace many changes of opinion or rather developments 

 of the author's knowledge ; there is indeed very little in common 

 between the conclusions arrived at by him during the first half of that 

 period and those expressed during the latter half. As Sir Archibald 

 Geikie has frequently to admit in the course of the work, the views he 

 now expresses are, on many points, strikingly divergent from those 

 which he formerly maintained, while certain of those views are in not 

 less marked conflict with the conclusions of some of his contemporaries. 

 Many geologists will, we think, demur to the new analysis and classi- 

 fication of volcanic phenomena presented in the pages of this his latest 

 work. But concerning the great value of the book — embodying as it 

 does a vast amount of original observation, patiently collected by him- 

 self and numerous fellow-workers in the same field, and skilfully woven 

 into a connected and amply illustrated narrative of the succession of 

 events in past geological times — there cannot be two opinions. Apart 

 from all theoretical considerations, the author must be congratulated 

 upon having produced a treatise which will be of great and permanent 

 value as a book of reference, and, at the same time, of a literary master- 

 piece which cannot fail to add to his already high reputation as an 

 exponent of science. 



