COLLECTION OF MINERALS. 277 



those which are rare and precious are placed 

 most insight, and those least worthy of attention 

 are on the upper shelves. 



The mineralogical collection occupies the two 

 rooms immediately following those devoted to 

 geology. To examine them methodically we 

 cros sthe first room, and hegin with the first case, 

 at the extremity of the second room, in the cor- 

 ner, by the window. 



This first case contains several instruments for 

 ascertaining the characters of minerals; amongst 

 others the goniometer , by which are measured 

 the mutual inclinations of the faces of crystals. 

 In the space between the windows are several 

 shelves, on which are arranged models in wood; 

 some of which serve to explain the structure of 

 crystals according to the theory of M. Hauy, and 

 others represent the principal varieties of the 

 regular forms of crystallized bodies. Below these 

 models are polished slabs of red porphyry, etc. ; 

 others which are of a rounded form, and which 

 present tolerably regular patterns of that descrip- 

 tion of argillo-ferruginous limestone, generally 

 known under the name of Indus helmontu. Small 

 tablets are made out of it for covering brackets. 



We will return to the first room, which con- 

 tains the two first classes of minerals, the salts 

 and earthy minerals; and beginning with the 



