Geological Society : — Anniversary of 1839. 219 



leaders in this study will be called upon to execute a more weighty 

 and elevated office, in framing the classifications which other 

 observers are to apply ; in drawing the great lines of division and 

 subdivision which fix the form of the subject ; in setting up the 

 type with which examples are to be compared ; in constructing 

 the language in which others are to narrate their facts. Steps of 

 this kind have formed, and must form, the great epochs in the 

 progress of all sciences of classification, and especially in ours ; 

 and I need not remind you how great the importance and the 

 influence of such steps amongst you have been, to pronounce at 

 once upon the success of such steps must always be in some de- 

 gree hazardous ; since their success is in fact this, that they influ- 

 ence permanently and powerfully the researches, descriptions, 

 and speculations of future writers ; and there are few of us who 

 can pretend to the foresight which might enable us to say, in any 

 special case, how far this will be so. Yet the great works of 

 Messrs. Murchison and Sedgwick, tending to the establishment 

 of a classification of the strata below the old red sandstone (works 

 which, on all accounts, we must consider as a joint undertaking), 

 appear already to oflfer an augury which can hardly be doubtful, 

 of this influence and permanence. Mr. Murchison's appellation of 

 the " Silurian System" has already been adopted by MM. Elie de 

 Beaumont and Dufresnoy, who have given it currency on the 

 continent : M. Boue and M. de Verneuil announce the diff"usion 

 of " Silurian" rocks in Servia and the adjacent parts of Turkey 

 in Europe ; our own members, Mr. Hamilton and Mr. Strickland, 

 have extended their range to the Thracian Bosphorus ; M. Forch- 

 hammer, of Copenhagen, visited the " Silurian region" to en- 

 deavor to recognize the rocks of Scandinavia ; and MM. Omalius 

 D'Halloy and Dumont have just explored it, to establish a par- 

 allel between its deposits and those of Belgium. It will be ob- 

 served that some of the districts thus mentioned are out of the 

 limits of our geological Home circuit ; and if the identification be 

 really and permanently established in these cases, will extend the 

 limits within which the parallelism of geological series can be 

 asserted : and this is, in effect, what we have a right to look for, 

 sooner or later, in the progress of geological science. As we must 

 be careful not to apply our domestic types without modification 

 to other regions, so must we take care not to despair of modifying 

 our scheme, so that it shall be far more extensively applicable 



