170 



NA TURE 



[December 23, 1897 



the volcanic to the sedimentary rocks. He also con- 

 structed a map which, however, was not published till 

 after his death. He has left many published works 

 which attest his power, his accuracy of observation, and 

 his judgment. 



We have, then, an interesting account of the circum- 

 stances which led to the systematic exploration of Russia 

 and the part played in it by Pallas, who, among other 

 important observations, clearly recognised a geological 

 sequence in passing from the centre to the outside of a 

 mountain chain. 



The rise of the modern spirit of mountaineering is 

 dated from the time of de Saussure, who described so 

 well the geological structure of the Alps, and whose 

 sections of violently folded rocks anticipated so much of 

 the recent work on that region, and whose experiments 

 on the reduction of granite and basalt to a glassy rock 

 by fusion and rapid cooling marked the commencement 

 of experimental geology. 



Our author then traces the development of the doctrine 

 of the geological sequence of rocks as distinguished by 

 their lithological character, towards which much had 

 already been done, especially by the Wernerian school, 

 and also the order of their formation as indicated by 

 the succession of organic life buried in or associated 

 with them, and differing in character at different periods 

 of the world's history. The controversy as to the true 

 nature of fossils, which has been referred to above, shows 

 that importance had long been attached to them as a 

 means of interpreting the history of the earth. 



We have in the third lecture an account of Werner, 

 the eponymous hero of a theory and a time. The great 

 controversy between the Neptunists and the Vulcanists 

 set men to search for facts in support of their respective 

 views ; and though a wrong working hypothesis may 

 often have coloured the vision and warped the judgment, 

 still the indications offered helped other less prejudiced 

 men along lines where inquiry was fruitful. The Wer- 

 nerian saw basalts interstratified with fossiliferous rocks, 

 and apparently forming one member of a fossiliferous 

 series, while others traced lava-flows with columnar 

 structure from the crater to the sea, and saw how they 

 might rest on ancient sediments and be themselves 

 covered by newer deposits. Werner was wrong about 

 his basalt, but he had introduced a greater care in in- 

 vestigation and a greater precision of description, and, 

 above all, had so insisted upon the doctrine of geological 

 succession that he placed geology upon a sounder basis 

 than it had hitherto ever occupied. 



Von Buch did much to free the scientific world from 

 the tyranny of an uncompromising Neptunism by his 

 demonstration of the constant occurrence of earth- 

 movements down to quite recent times, as well as by 

 many other independent researches recorded in numerous 

 memoirs, and embodied in a large geological map of 

 Germany. 



If we give de Saussure credit for originating experi- 

 mental geology, we must give Hutton a foremost place 

 among those who insisted upon the importance of ob- 

 servation in the field. He was a man of wide interests 

 and varied attainments. He realised the importance of 

 Geology to Agriculture, and published works on " The 

 Principles of Knowledge" and " The Progress of Reason 

 NO. 1469, VOL. 57] 



from Sense to Science and Philosophy," this last title 

 reminding us of Agostino Scilla's " Lavana Speculazione 

 disingannata dal Senso." The aims of both writers were 

 the same, though Hutton got nearer the mark than his 

 predecessor. In tracing the history of an idea, how often 

 we find that the man who gave it to the world, in what 

 we may call an available form, was not the man with 

 whom it really originated. Take, for instance, the view 

 that the action of heat in fusing material is directly in- 

 fluenced by the amount of pressure to which the body 

 is subjected. This is quoted now with references to Sir 

 James Hall, to Fairbairn and Hopkins, and others. But 

 it was one of Hutton's fundamental doctrines, and Hutton 

 got it from his friend Dr. Black, a sound chemist and 

 shrewd experimentalist. 



Hutton's first principle was that " no powers are to be 

 employed that are not natural to the globe, no action to 

 be admitted of except those of which we know the prin- 

 ciple, and no extraordinary events to be alleged in order 

 to explain a common appearance." 



There are many men of note in our day who, going 

 with the swing of the pendulum, as it were, believe in 

 the greater intensity of the operations of nature in past 

 ages, and still within the periods of which we have re- 

 cords in the sedimentary rocks. The phenomena which 

 suggest this view may be reconciled to the strictest 

 uniformitarianism by the doctrine that local catastrophic 

 action is not inconsistent with continuity of causation. 



Several distinguished French geologists, about the end 

 of the last and the beginning of the present century, in- 

 sisted upon the doctrine of stratigraphical sequence as 

 fundamental, and this was soon found to involve the 

 opinion that there was a definite order of succession 

 among organic remains also. In England, while Giraud 

 Soulavie was still a child, and before Cuvier or 

 Brongniart were born, John Michell, Woodwardian 

 Professor of Geology in the University of Cambridge, 

 gave a clear account of the stratified arrangement of 

 the rocks of England, and by his illustrations showed 

 that he understood the principles of geological structure. 

 " Let a number of leaves of paper," said he, " of 

 several different sorts or colours, be pasted upon 

 one another ; then, bending them up into a ridge 

 in the middle, conceive them to be reduced again to a 

 level surface, by a plane so passing through them as 

 to cut off all the part that has been raised. Let the 

 middle row be again raised a little, and this will be a 

 good general representation of most, if not all, large 

 tracts of mountainous countries, together with the parts 

 adjacent, throughout the whole world. From this forma- 

 tion of the earth it will follow that we ought to meet with 

 the same kinds of earths, stones and minerals, appearing 

 at the surface in long narrow slips, and lying parallel to 

 the greatest rise of any long ridge of mountains ; and 

 so, in fact, we find them." 



Then came William Smith, wlio based all his classifi- 

 cations on the " strata identified by their organic fossils." 

 Sedgwick, who in early life had been the companion of 

 Smith in some of his excursions in the north of England, 

 was so impressed by the importance of the methods of 

 geological research employed by Smith, that he spoke of 

 him on one occasion before the Geological Society as 

 "the Father of English Geology." 



