and the actual Forms ()f Inorganic Bodies. 141 



of light displays are perfect exhibitions of symmetry ; and all of 

 them can be well explained, by assuming that there is a ten- 

 dency in those molecules which produce them to group in sphe- 

 roidal assemblages, which, however, they are always prevented 

 from effecting completely by particular forms or attractions, or 

 some such circumstances, in the nature of the molecules of light 

 themselves. 



But let these remarks suffice as to the phenomena of crystalline 

 bodies, in order that we may proceed to state, that it is not in 

 those bodies only where the individualizing power has operated 

 with sufficient force to give birth to crystals, that the tendency 

 towards maximum symmetry may be detected. How often does 

 that structure occur in mineral bodies, though almost in a me- 

 chanical state, to which the name of concentric lamellar is given ? 

 There is scarcely a rock in the whole geological series which does 

 not sometimes display it. Granite, trap, rock-salt, and even sand- 

 stone, on the great scale, and pearl-stone, agaie, and pisolite, on 

 the small scale, either often or always exhibit this structure; 

 and others, in which it cannot be detected when they are newly 

 broke into, display it after being for some time exposed to the 

 weather. It may be said, then, that all inorganic nature sup- 

 plies evidence that the particles of inorganic bodies tend to as- 

 sume the most symmetrical positions, in reference to each other, 

 which circumstances admit of, and to associate in groups of a 

 spherical or tessular contour, as often as some particular cir- 

 cumstance, either connected with the form of the molecules, or 

 their peculiar attraction, does not prevent such a result. 



But while I thus endeavour to shew that one of the elements 

 of physical action is to determine towards the sphere, let it not 

 be thought that there is any thing occult in such a determina- 

 tion. From the nature of matter and motion, it follows neces- 

 sarily that it must be so, in order to perceive which, it is only 

 requisite to attend to the following considerations: — The pro- 

 perties of matter usually enumerated are extension, mobility, 

 elasticity, impenetrability, heat, luminousness, attractibility, 

 elasticity. Now these, when viewed abstractly, and as properties 

 of a single mass of matter, insulated in space, either vanish al- 

 together, or prove themselves to be modifications of these two 

 properties, extension and elasticity ; for in the idea of these two 



