304 APPENDIX- 



-CALCULATION OF THE 



THE CUBE. 



Its elements. 



The inclination of any two adjacent planes at their 

 common edge zz 90. 

 Plane angles rz 90. 

 Edges all equal. 



Inclination of an edge to an axis 54 44' 8 /; . 

 Ratio of an edge : \ a diagonal : : 2 : VcJ 

 an edge : an axis : : 1 : Vg t 



Its units of comparison. 

 In reference to decrements on the edges, the unit 



is nz 1. 

 ..... simple and mixed decrements on 



Vo I 



the angles, it is = _ = y=. 



Simple and mixed decrements on the angles. 

 The law of a simple or mixed decrement on any 

 angle of a cube, may be computed by means of an 

 edge of the primary form, and half a diagonal of one 

 of its planes. The diagonal being used to measure 

 the decrements in breadth, and the edge those in height* 



Ing. 331. 



Let us suppose a cube represented by figure 331, 

 and let us jmaginc a simple decrema|it to have taken 



