CM, RAVAGE. 



Fig. 81. 



If we cleave an octahedron parallel to six only of 

 its planes, omitting any two opposite ones, as b and e, 

 fig. 84, and if we continue the cleavage until only 

 the central points of the planes b and e remain, a 

 figure of six sides will evidently be produced. 



This figure is a rhomboid whose plane angles are 

 60 and 120. 



Fig. 85. 



Fig. 85 shews the position of this rhomboid in the 

 octahedron, from which it is evident that the cleavage 

 would be continued as far as the lines f k, I m, n o, 

 and those which are parallel to them on the opposite 

 plane. 



