A. W.Jackson — Nomenclature of Crystal! h< f Hod*. 127 



confusion in the science ; and that we can only hope for a satis- 

 factory, unii r nomenclature when based upon 

 mineralogical grounds alone. It is only thus that an exact 

 system of names can arise that can give worthy expression to 

 the exact work that is now being done in this department of 

 geology. Until some such uniform system is .established we 

 must continue to waste our energies in struggling to understand 

 one another when the real difficulty is not with the facts but 

 with the terms in which we express them. The energies ex- 

 pended in this effort would be far more profitably utilized in 

 advancing our knowledge of the facts themselves. 



Justin Roth says that Petrography as a descriptive science 

 loses all significance.* True, but it must be remembered that 

 the purely descriptive stage of a science must always precede the 

 alter stage is only possible after 

 the former has become exact. W to exactness 



of expression in descriptive petrography will add greatly to the 

 scientific usefulness of this branch of -eulogy in helping to solve 

 many of the profoundest problems that engage the attention of 

 the geological thinker of the present day. 



Chapter II. 



It will be observed that I refrain from any attempt to frame 

 a system of names in accordance with the principles [ have laid 

 down. I do this because I think that no new name should be 

 introduced into a science unless it is tolerably sure of being 

 accepted in the sense in which it is proposed. Names are used 

 to promote clearness and not coii/hsin/t and unless this end can 

 be attained it is better to refrain entirely from their introduc- 

 tion. The reformation of the entire nomenclature of a science 

 is a task that should be attempted only by one who has gained 

 authority by h.i j y<- rs "1 special work, by one who is univer- 

 sally recognized as fitted for the undertaking. There are but 

 one or two men living who could hope to succeed. 



All that can be hoped for under the circumstances is that 

 every writer should use the same nomenclature; uniformity, 

 even if based upon principles that all will not accept as valid, 

 is of the first importance. It is better that each should forego 

 the luxury of insisting upon individual idiosyncracies, which 

 in the majority of cases can never hope to become currently ac- 

 cepted than that by so doing he should add to the existing con- 

 fusion. Just as strongly as Capt. Datton f would insist upon 



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