Reflections on some Miner alogical Systems. 421 



posed of two bent faces, but they result from an infinite 

 number of planes. The character of simplicity therefore is 

 totally wanting in this choice. 



Still, however, there are many more objections to this me- 

 thod. There is scarcely any figure which I have not heard 

 considered in several points of view. The dodecaedron with 

 rhomboidal faces has been sometimes regarded asahexaedral 

 prism, terminated at each extremity by a triedral pyramid. 



The hexaedron appears entirely useless, as besides this 

 figure there may be two modes of considering all the cry- 

 stals which belong to it. The cube, for instance, is a hexae- 

 dron, but at the same time it is a quadrangular prism with 

 square faces. The rhomboid is also a hexaedron and a 

 quadrangular prism, with rhomboidal faces; and every te- 

 traedral prism terminated by planes as bases is a hexaedron. 

 Moreover, these figures may be considered as two mutilated 

 triedral pyramids, united, it is true, base to base, with the 

 edge against the face. Here then is a crystal which belongs 

 to three different species of principal forms ; and such is the 

 influence of this character in the specification of minerals, 

 that the same mineral may very weli belong to three species 

 in the oryctognostic system. 



The table is nothing but a prism extremely shortened. 

 The geometer knows as well as any other what a table is : 

 but 1 suspect that from Archimedes to Newton ; from the 

 first who failed in squaring the circle, till the learned Ger- 

 man who told me that he had discovered a fourth dimension 

 in space,^— no geometer has treated it as a geometrical figure. 

 This invention is purely mineralogical. But where does 

 the prism finish, and the table commence ? Is there a point 

 where a crystal being no longer a prism is not yet a table ? I 

 do not see why the table should not be ranked among the 

 imitativeiforms, as the club, bush, comb, mirror, and other 

 usual instruments. 



WERNERIAX PRETENSIONS TO THE DISCOVERY OF THE 

 INTEGRAL MOLECULE. 



There is an article in the external characters of Werner, 

 which at first seems to have some resemblance to the form 

 of Haiiy's integral molecule : I mean what relates to the 

 lamellated fraciure. After having spoken of the perfection, 

 imperfection, ike. of the lamince, their direction and their 

 form, he speaks of the structure of the laminae (lamina- 

 tion), or of the cleavage (durchga?ig der blatier), and says 

 that it may be double, triple, quadruple, and sextuple. If 

 it were wished to enter into all the details of this subject, 



2 D 3 we 



