50 THE COMING [OH. 



place. It is pleasant to be able to relate that the debt 

 which he owed to Von Hoff was fully repaid by Lyell ; 

 for the learned German's third volume appeared after 

 the issue of the Principles of Geology, and as Zittel 

 assures us ' its influence on Von Hoff is quite apparent 

 in the third volume of his work 39 .' 



At this period, too, Lyell had the advantage of 

 travelling both on the continent and in various parts 

 of Great Britain with the eminent French geologist, 

 Constant Prevost, who had shown his courage by 

 opposing some of the catastrophic teachings of the 

 illustrious Cuvier himself. 



Still more important to Lyell were the oppor- 

 tunities he enjoyed for comparing his conclusions 

 with those of Scrope, who had joined the Geological 

 Society in 1824, and became a joint secretary with 

 Lyell in the following year. From both of them, in 

 their old age, I heard many statements concerning the 

 closeness and warmth of their friendship, and the 

 constant interchange of ideas which took place 

 between them at this time. 



From Scrope, Lyell heard of the occurrence of 

 great beds of freshwater limestone in the Auvergne, 

 on a far grander scale than in Strathmore, with many 

 other facts concerning the geology of Central France, 

 which so greatly excited him as in the end to alter 

 all his plans concerning the publication of his own 

 book. As soon as Scrope's great work on Auvergne 



