270 DESCRIPTION OF THE MUSEUM. 



The systematic collection, at which we are 

 now arrived, is placed in the upper part of the 

 cases which are to the right of the room on 

 entering. It is divided into two sections: one 

 is formed of specimens for study, which are dis- 

 played in a horizontal line of shelves extending 

 throughout this part of the hall, and which 

 divides the height of the cases into two nearly 

 equal parts: these specimens are almost all of 

 the same size. The second section contains either 

 large specimens, which could not he mixt with 

 those for study, because of their disproportionate 

 size, or pieces cut and polished, which shew the 

 different uses made of them in the arts: they 

 occupy the whole of the upper part of the cases. 



The collection is classed according to the cha- 

 racters which each species of rocks derives from 

 its composition, its texture, and its origin, with- 

 out considering the situation which it occupied 

 in the formation of the solid crust of the earth: 

 its object is to furnish the means of recognizing 

 rocks even when they are out of their original 

 position. The outline of this methodical collec- 

 tion was laid down by the late M. Haiiy. It com- 

 prehends five classes, which may be successively 

 examined, beginning at the extremity of the 

 room, and alternately directing the attention to 

 the stages and upper shelves of each case. 



