44 Theory of CryfialUzat'ion. 



lamina be compofed only of 40 cubes, 7 on each fide, in fuch 

 a manner that if its inferior bafe be nfg (fig. 8), that bafe 

 may fall exactly on the fquare marked by the fame letters 



Cfc- 7)- 



Above this r I •- * ia let us apply a fecond compofed of 

 25 cubes, five ... h fide, fo that if / m p u (fig. 9), repre- 

 fent its lower bafe, this bafe may be found fituated exactly 

 above the fquare defigned by the fame letters (fig. 7). 



Let us, in like manner, apply a third lamina upon the 

 fecond \ but containing only 9 cubes, three on each fide, fo 

 that v x y z (fig. 10) being the inferior bafe, this bafe may 

 correfpond with the fquare marked by the fame letters 

 (fig. 7). Laftly, on the middle fquare r, in the preceding 

 j lamina, let us place the fmall cube r (fig. ji), which will 

 jeprefent the laft. 



it may be eafily feen that by this operation we fhall have 

 formed upon the face ABCD (fig. 7) a quadrangular pyra- 

 mid, of which this face will be the bafe, and which will have 

 the cube r (fig. 1 1 ) for its fummit. If we continue the fame 

 operation on the other five faces of the cube (fit*. 7) we fhall 

 have, in all, fix quadrangular pyramids, refting on the fix 

 faces of the nucleus, which they will envelop on all fides, 

 But as the different courfes or laminae which compofe thefe 

 pyramids project beyond each other a certain quantity, as 

 may be feen j^. 1 2, where the parts elevated above the planes 

 BCD, oCG reprefent the two pyramids which reft on the 

 faces ABCD, BCGH (fig. 7), the faces of the pyramids' 

 •will not form continued planes : they will be alternately re- 

 entering and falieut ; and in fome meafure will imitate a 

 pyramidal afcent of fteps, which prefents four faces (efcalier 

 h. quntre faces ). 



Let us now fuppofe that the nucleus is compofed of an 

 incomparably larger number of cubes, almoft imperceptible, 

 and that the lamina?, applied on the different faces, which I 

 Iball in future call tdlkind of fuperpofition> go on increasing 

 towards their four edges, by fubtraflions of one range of 



cubes 



