66 ON THE PRIMITIVE FORMS OF CRYSTALS. 



rhomboid is less than 54° 44' 8 /7 ; but they will be 

 of an opposite character at greater inclinations. 



The very same resnlts are true of the Acute 

 Rhomboid, mutatis mutandis. 



In the Hexaedral Prism, the single axis may 

 be resolved into 



1. Three axes, perpendicular to its sides ; or into 



2. Three axes, perpendicular to its edges ; or into 



3. Six axes, j oin in g the opposite angles of its up- 



per and under hexagonal base ; or into 



4. Six axes, joining the opposite edges of its up- 



per and under hexagonal base. 

 In the Ei-pyramidal dodecahedron, the single 

 axis may be resolved into 



t. Three axes, perpendicular to the sides of the 

 hexagonal base, and lying in the plane 

 of it ; or into 



2. Three axes, joining the opposite angles of the 



hexagonal base ; or into 



3. Six axes, parallel to the faces of the pyramids; 



or into 



4. Six axes, parallel to these common sections,. 



In the Octohedron, with a square base, the 

 single axis may be resolved into 



1. Two axes, perpendicular to the sides of its 



square base, and lying in its plane ; or 



into 



2. Two axes, coinciding with the diagonals of its 



square base ; or into 



