156 Chemical and Geological Essays of T. Sterry Hunt. 



2. The possibility of converting granite into limestone. 



3. The possibility of converting gneiss into limestone. 



4. The possibility of converting diorite into limestone. 



5. The possiljility of converting granite into serpentine. 



6. The possibility of converting granulite into serpentine. 



7. The possibility of converting gneiss into serpentine. 



8. The possibility of converting diorite into serpentine. 



9. The possibility of converting limestone into granite. 

 10. The possibility of converting limestone into gneiss." 



Bnt the self-sufficiency of the author, and the misrepresentation of 

 the personal views of other individuals, are by no means the only seri- 

 ous objections to the publication. Chapter xv., on the "History of 

 the names Cambrian and Silurian in Geology," is an essay pretending 

 to give the history of these two words, the use that should now be 

 made of them, and the proper credit that should be extended to the 

 authors ; but it omits to mention many of the leading events in the his- 

 tory of the origin of the term Silurian, magnifies, if it does not invent, 

 trifling incidents in the origin of the term Cambrian, and finally ad- 

 vocates the substitution of the word Cambrian for Lower Silurian in 

 American geology, without any good reason and in violation of the 

 established laws of nomenclature. The word Silurian has priority over 

 that of Cambx'ian. It was applied to the rocks after their fossil con- 

 tents had been studied, and after they had been divided into groups, 

 while Cambrian was applied to a series of rocks without any knowledge 

 of their fossil contents. The terms, Upper Silurian and Lower Silurian 

 have been in general use since 1835, in every country Avhere geology 

 has been pursued as a science, while Cambrian has only been applied 

 since 1836, locally in Great Britain, to rocks that have long since been 

 known to constitute part of the Lower Silurian series. A few of the 

 leading facts connected with the history of the terms LTpper and Lower 

 Silurian (nearly all of which Mr. Hunt has omitted from his essay) 

 are as follows : 



On the 17th of April, 1833, Murchison finished the reading of his 

 memoir, commenced at the preceding meeting (March 27, 1833), 

 before the Geological Society of London, " On the Sedimentary 

 Deposits which occupy the western parts of Shropshire and Hereford- 

 shire, and are prolonged from N. E. to S. W., through Radnor, 

 Brecknock, and Caermarthenshires, with descriptions of the accom- 

 panying rocks of intrusive or igneous characters." He separated the 

 rocks, commencing at the base of the old red sandstone, in descending 

 order, as they succeed each other in Shropshire and Herefordshire, into 



