Iviii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Another remarkable book of a general character which has been 

 recently published is Mohr's * Geschichte der Erde.' The author 

 takes up especially the chemical and physical side of the science, 

 and, following the line of argument adopted by Bischof and Yolger, 

 extends it over sea and land, culling with thorough German in- 

 dustry a rich store of examples from observers of all parts of the 

 earth. But the spirit of his inquiry is eminently aggressive ; and 

 whilst attacking certain commonly received views and many points 

 of doubtful acceptation, his self-sufficiency and flippant tone in 

 dealing with some of the greatest names in science are to be 

 regretted, and will certainly not strengthen his position. I^or will 

 he, I believe, find those geologists who have reviewed the history 

 of the progress of the sciences content to refer every question to 

 the undisputed arbitrement of chemistry taken at a given point in 

 its advancing career, or inclined pedantically to limit nature to 

 the results we have been able to accomplish in our laboratories. 

 The author's own arguments for deriving the origin of our coals 

 from seaweed, for making basalt from watery solutions, and for 

 cavilling at all the recognized geological systems are alone suffi- 

 cient to raise a host of opponents. 



To our distinguished Foreign Member and "WoUaston Medallist, 

 Professor Gustav Bischof, belongs in great part the merit of having 

 first worked out, by investigations extending over many years, a 

 variety of problems on the mode of formation of the crystalline 

 minerals in rocks, showing especially the vast number of conver- 

 sions from one mineral species to^ another which may be explained 

 by the action of water. Most satisfactory were the experiments 

 and examples by which he illustrated the chemical power possessed 

 hj rain-water penetrating downwards into the rocky crust, and 

 the crystallization of almost every well-known species of mineral 

 from watery solution. And even though we may not see in the 

 same light his asserted analogies, or allow ourselves always to be 

 converted by his arguments, we cannot but recognize the justice of 

 the main current of his reasoning, and the occasion for the warmth 

 of the diatribes in which he attacks supporters of opposite views. 

 Ko doubt hypotheses of most unwarrantable boldness had been 

 set up by those who saw igneous action in every httle vein of quartz 

 or gypsum ; and beyond all question many of the phenomena, 

 the causation of which was formerly supposed to need a high tem- 

 perature, might be better accounted for by the less heroic but more 

 time-consuming processes suggested by Bischof. Questioning as he 

 has done, from the year 1843 onwards, many of the palpably rash 

 assertions of the ultra-plutonists, he has himself been followed by 

 a goodly array of scholars, several of them contributing material of 

 the very best order to the general geological fabric, others dashing, 

 a little eccentrically, beyond the limits of their master's conclu- 

 clusions, when these latter are fairly stated. Por, after all, does 

 not the Professor make very free with the statement of the 

 opinions of authors who are more attached than himself to what 

 he terms the Plutonic theory ? and does he not sometimes fabricate 



