On Crystallography . C3 



it is coticei-necl, by a series of partial lines, with intermediate 

 points, videc^, (fig. 9,) Plate fX., and M R, CM, CK, 

 (fig. 4,) ibid. We should remark upon this same figure, 

 that the upper parts of the lines M 5^ l\u, which are situated 

 in the space, are assenibiagcs of partial lines interspersed 

 with points, while their lower parts, ap[)licd upon the surface 

 of the solid, are composed of partial lines, without interme- 

 diate points. This distribution, for the happy idea of which 

 we are indebted to M. Tremery, mining engineer, will assist 

 the reader in findirlg his way in the assortment of lines with 

 which projections are complicated, bv enabling him to seize 

 at the first glance the various functions of these lines. 



In indicating the measures of angles relative to each va- 

 riety of crystalline form, I shall iwt repeat those which, 

 being common to it with other varieties formerly described, 

 are already indicated by the latter. It will be easy to re- 

 cognise them from the conformity of the letters, .which upon 

 the difierent figures designate the faces similarly situated. 



t^ENERAL IDEA OF MINERALS; 



Tlve name of minerals has been e;iven to bodies which, 

 being placed on the surface or in the bowels of the terrestrial 

 globe, are devoid of organization, and only present assem- 

 blages of similar molecules united to each other by a power 

 ^lled affinity. 



Of this nun)ber are flints, rubies, diamonds, gold, silver, 

 iron, &c. Mineralogy is the name of the science whicli 

 makes us acquainted with all these difil-rent bodies. 



The genera! classification of the bodies which the study 

 of natural historv embraces, considered on a grand scale, may 

 be referred to txvo terms of comparison, wliich are life and 

 spontaneous motion. From iheir union the distinctive cha- 

 tacter of animals is formed: plants live, and yet cannot 

 move spontaneously : miner^iTs are deprived of both faculties. 

 Man, who is alone capable of studying Nature, toweis 

 above all the beings around him, in point of intelligence and 

 teason. 



The three grand classes of which we are about to treat, 

 with the help of an ultftrior and more coniprchen*ivc view, 



Vol. 34. No. 135. July 1509. K maj^ 



