TABLE OF SECONDARY FORMS. 



221 



Secondary forms. 



CONTAINED WITHIN TWEN- 

 TY-FOUR PLANES. 



a. The planes being isos- 

 celes triangles. 



Fig. 296. 



I. The planes being equal 

 trapezoids. 



Fig. 298. x 



'How they may be derived. 



From the cube. Modification 



regular tetrahedron, 

 Modification d. 



regular octahedron, 

 Modification c, 



rhombic dodecahe- 

 dron, Modification b. 



cube, Modification 



regular octahedron, 



Modification f. 

 rhombic dodecahe- 

 dron. Modification/. 



cube, Modification 



b. 



regular octahedron, 



Modification b. 

 rhombic dodecahe- 

 dron, Modification c, g, or 



