t6z Theory of Cryjlallifation. 



not be (imply furrowed by ftrioe, as when the laminae de» 

 creafe towards the ridges. They will be roughened by an 

 infinite number of falient angles, formed by the exterior 

 points of the cornpofing cubes, which is a neceffary confe- 

 quence of the continually angular figure prefented by the 

 edges of the laminae of fuperpofition. But all thefe points 

 being fituated on a level, we may fuppofe the cubes fo fmall 

 that the faces of the folid will appear to form fo many fmooth 

 and continued planes. 



But this will be rendered more ftriking by an example. 

 Let it be propofed to conftruct around the cube ABGF 

 [fig. 29), confidcred as nucleus, a fecondary folid, in which 

 the lamina of fuperpofition {hall decreafe on all fides by a 

 fingle range of cubes, but in a direction parallel to the dia- 

 gonals. Let ABCD {fig. 30), the fuperior bafe of the 

 nucleus, be fub-divided into 81 fmall fquares, reprefenting 

 the exterior faces of as many molecules. What will be faid 

 in regard to that bafe may be applied to the other five faces 

 of the cube. 



Figure 3*1 reprcfents the fuperior furface of the firfl la- 

 mina of fuperpofition,- which ought to be placed above 

 ABCD' (fig- 30), in fuch a manner that the point a' may 

 anfwer to the point a, the point b to the point b, the point 

 c' to the point c, and the point <i' to the point d. It may be 

 readily feeri by this difpofiiion that thefquares A a, B b, Cc, 

 J) d, ( fig. 30), remain uncovered, which will fulfil the law 

 of decrement above described. It is moreover feen that the 

 borders QV, ON, I L, GF, (Jig. 31), projeA by one range 

 beyond the borders AB, A D, CD, B C, (fig. 29), which 

 is neceffary, that the nucleus may be enveloped towards thefe- 

 edoes. For a little attention will fiiew, that if this were 



o J 



not the cafe, that is to fay, if the edges of the lamina rcpre- 

 fented fig. 31 as well as the following, coincided with the 

 lines S T, EZ, Y X, M U, on which iuppofition they would- 

 be on a If. el with AD, AB,CD, B C, (fig. 30), they 

 would form re*enieruig angles towards the analogous parts 



of 



