CORRESPONDENCE WITH SCIENTIFIC MEN. 63 



visited Shropshire and Radnorshire, and was then con- 

 vinced that there was a vast extent of what may be called 

 a transition country, that had never been noticed by Wer- 

 ner and the wise ones of that time. Some of my obser- 

 vations I communicated to Dr. Henry, Dr. Holland, and 

 Mr. Greenough,* and gave a short notice of the country 

 in the first edition of my "Geology" in 1813. The latter 

 observations were carped at or disputed by Conybeare, 

 and I have never since had the opportunity of reviewing 

 the country attentively, or even visiting the greater part 

 of it. Mr. Murchison's views confirm all my first conclu- 

 sions. His work is entitled "The Silurian System," (a 

 name I do not much approve) ; it comprises the regions 

 occupied by the ancient Silures (a British nation). The 

 great basis of the country is " transition " between the coal 

 and the most ancient slate rocks, comprising also several 

 coal-fields and insulated portions of secondary formations. 

 This country is singularly broken by the protrusion of 

 remarkable igneous or volcanic rocks of whose nature I had 

 little doubt ; but Dr. Holland, whom I showed specimens 

 to in 1811, although he was just returned from Iceland, 

 declined to give an opinion. I had then never seen a re- 

 cent or acknowledged volcanic rock in situ. Mr. Murchison 

 has kindly presented me with a copy of his work, and if 

 my health and strength permit, I will send a review of it for 

 your Journal (which will probably be the last labor of mine 



in geology) I don't know whether Dr. M. has 



enclosed you a little tract of Horace Smith in favor of 

 railroads. In the conclusion, he says we have been all 

 travelling upon a fine locomotive system, from the day of 

 our birth, 68,000 miles per hour ; the comparison with rail- 

 road speed is striking, yet how few think about it ! Mr. 

 Hazlitt said, justly, the discoveries in astronomy have com- 

 pelled bigots to lengthen Jacob's ladder. Indeed, such 



* Greenough set off immediately to Radnorshire, but brought back nothing 

 but doubts and puzzles. 



