THE PRODROMUS 239 



1. That the intermediate planes, or the quadrilateral planes, 

 are formed by the bases of the terminal planes, and hence the in- 

 termediate planes are larger in some crystals, smaller in others, 

 and wholly wanting in still others. 



2. That the intermediate planes are almost always striated, 

 while the terminal planes retain traces of the matter added to 

 them. 



Ill 



p. 40. The crystalline matter is not added to all the terminal planes 

 at the same time, nor in the same amount. Hence it comes to 

 pass: 



1. That the axis of the pyramids does not always continue 

 the same straight line with the axis of the prism. 



2. That the terminal faces are rarely of a size, whence fol- 

 lows an inequality of the intermediate planes. 



3. That the terminal faces are not always triangular, just as 

 all the intermediate planes are not always quadrilateral. 



4. That the terminal solid angle is broken up into several 

 solid angles, this being the case frequently also with the solid 

 intermediate angles. 



IV 



An entire plane is not always covered by crystalline matter, 

 but exposed places are left sometimes toward the angles, some- 

 times toward the sides, and sometimes in the centre of the 

 plane. Hence it happens: 



1. That the same plane, commonly so-called, does not have 

 all its parts located in the same plane, but in different planes 

 extending above it in different ways. 



2. That a plane, commonly so-called, in many places is seen 

 to be not a plane but a protuberance. 



3. That in the intermediate planes inequalities rise like the 

 steps of stairs. 



The crystalline matter added to planes upon the same planes 

 is spread out by the enveloping fluid, and gradually hardens, 

 with the result: 



I. That the surface of the crystal comes forth the smoother 

 the more slowly the added matter has hardened, and is left 



