THE PRODROMUS 273 



in Figures 9 and 1 1 not all, but only the opposite sides, are equal ; 

 in Figure 10, any given opposite sides are unequal. 



In Figure 1 2 the plane of the base, which ought to be a hexagon, 

 is bounded by twelve sides. 



Figure 13 shows how sometimes the length and number of the 

 sides are changed in various ways without changing the angles, on 

 the plane of the base, while new crystalline matter is being placed 

 upon the planes of the pyramids. 



