TO ON THE PRIMITIVE FORMS OF CRSTALSl 



coinciding with the axis of the rhomboid, and of the 

 same character as the separate axes. The intensity 

 of the resultant axis gradually diminishes with the 

 obtuseness of the rhomboid, and from its maximum 

 intensity of 3f, it descends to 0, its character re- 

 maining always the same. 



When the angle of the rhomboidal planes be- 

 comes 90°, the rhomboid is converted into the cube : 

 The three axes which were formerly inclined to one 

 another at an acute angle, are now perpendicu- 

 lar to each other : Each of the three is inclined 54° 

 44' 8" to the axis of the rhomboid, which is now one 

 of the diagonals of the cube ; and the intensity of 

 the resultant axis is 0, the forces being every where 

 in a state of perfect equilibrium. 



The series of obtuse rhomboids having now ter- 

 minated in the cube, the series of acute rhomboids 

 commences ; and as the angle of the rhomboidal 

 planes decreases below 90°, the three axes become 

 inclined to one another at an obtuse angle ; the in- 

 tensity of the resultant axis begins to increase from 

 0 ; but its character is now changed, and is oppo- 

 site to that of the three axes by which it is produ- 

 ed. 



The acute rhomboids terminate in the hexaedral 

 prism, when the angle of the rhomboidal planes has 

 become 0. The axes are now all in the same plane, 

 and the intensity of their resultant is equal to l^Jl 

 its character being still of an opposite nature. 



