316 Mr. Shepard's reply to Prof. Del Rio. 



dom, whereas that of Mohs and Breithaupt accomphshes both 

 objects at the same time. My Treatise has said of its Charac- 

 teristic, that being apphed to an analytical system, " it is intended 

 solely to effect the recognition of minerals and that the student has 

 no interest in the classes and orders or in the succession observed 

 among the species, except so far as they relate to the naming of 

 minerals. To arrange a cabinet of specimens according to a system 

 invented solely to conduct to their names, would be like preserving 

 the staging about an edifice after its construction was completed." 

 (Preface to Treatise p. viii.) This leads Prof. Del Rio to make 

 the remark, that ' this is a solid objection indeed, since by the 

 ftiethod of MoHs and Breithaupt, it is not necessary to destroy 

 the bridge after having crossed the river.' In reply to the figure, it 

 might be enough to say, that the student having crossed the bridge 

 in his onward route to knowledge has no occasion to recross it to his 

 previous state of ignorance ; and therefore, while there is nothing in 

 my system to compel him to blow up the bridge if he could, it must 

 be a matter of perfect indifierence to him whether it remains or not. 

 But to examine the disadvantages the pupil actually incurs by 

 being obliged to acquire a knowledge of the natural system by itself 

 and succedaneously, it is quite certain that he can have as little 

 interest as comprehension respecting the nice affinities of mineral 

 species before he has become acquainted with the majority of them. 

 And although in employing the Characteristics of Mohs or Breit- 

 haupt, he is continually conversant with the classes, orders and ge- 

 nera of the natural system, yet as it is for the single purpose of learn- 

 ing names, the fact that these express the natural alliances of the 

 species is unheeded. It can only happen after he has made the 

 acquaintance of a large number of minerals, that he is prepared for 

 this new view of their relations ; and it makes very little difference 

 whether his attention is directed to it after having learnt the names 

 by an artificial or synthetical system, provided the analytical one 

 does not involve him unnecessarily in the labor of names for its di- 

 visions, which surely cannot be charged to mine, since it does not 

 contain a single new word. How many hours does Prof. Del Rio 

 think it would demand of a pupil of common capacity who had de- 

 termined the names of half the mineral species, completely to put 

 himself in possession of the natural system of Mohs or Breit- 

 haupt ? At any rate, the advantage in facility of determination, of 

 the analytical over the synthetical system, as evinced by the forego- 



