MINERALOGICAL SYSTEMS. 31 



introducing new names, and neverthelefs has been obliged to 

 introduce many, where new fubftances, names capable of 

 giving falfe impreffions, or others void of fignification and un- 

 fupported by long ufage, required it. Hethenfubftituted names 

 taken from the Greek; a language, he fays, that eminently 

 enjoys the faculty of combining feveral words together, fo as 

 to form one reprefenting concifely the objed to be named, — 

 The adjedives ufed in the nomenclature of the cryftals alfo al- 

 lude to forae remarkable circum (lance of the cryftalline form. 



1 fliall now proceed to philofophical cryftallography, which Philofophical 

 might be called the philofophy of mineralogy. It does not "^'^^""g'^^P'^^ 

 confift in fearching for the primary caufes of phenomena, no- * 



thing can be lefs philofophical than fuch a refearch; primary 

 caufes will ever be beyond the reach of the human mind! 

 The immortal Newton was the firft to point out to us by the 

 •method followed in his admirable book of the Principia, that 

 the only true philofophical way of treating a phytical fcience, 

 or of explaining a natural fad, was to demonftrate that it was The true method 



the mathematical confequence of a general law, grounded °f "P. "'f' 



, .\ , ,r 1 1 1. phyfics IS to ihew 



on an aggregate or facts already obferved and capable that the fafts are 



of correal calculation. If any one of thefe conditions are mathematically 

 wanting, we immediately launch out into hypothefis, expla- general law. 

 nations become vague, and however much we may be per- Hypothefis* 

 fuaded of the truth of our aflertions, we can acquire no cer- 

 tainty. 



Let us apply thefe principles to our two writers. De L'Ifle, The method of 

 in declaring that the various forms obferved in cryftals of the ^gJ^J^ to be Sfe- 

 fame fubftance are only modifications of one conftant primitive ficient iacor- 

 form, certainly announced a raoft important truth. It was a'^^"^^^* 

 flalh of genius; but in a philofophical enquiry, to prove it and 

 not limply to fay it, was the necelTary ftep. On the firft in- 

 fpedion of his cryftalloujraphical tables, a ftudent is tempted 

 to think that important truth demonftrated; but on a clofer ex- 

 amination, the impreffion is done away. The fame order per- 

 vades every table. By fligh^ paflages the ftudent is led from 

 the fimpler to the more compound forms, and after every paf- 

 fage, is tempted to fay ; this can only be a modification of the 

 primitive; then when the real cryftals, and the figures of the 

 tables are compared together, and all thofe of the fame fpecies 

 (with a very few exceptions) are fotind in the fame table, 

 how eafy it is to perfuade ourlelves that nature rnuji operate by 



ftmilar 



