338 APPENDIX- CALCULATION OF THE 



OCTAHEDRON, RHOMBIC B3SE. 



The units of comparison for determining- the laws 

 of intermediary decrements will be the ratios of 

 those edges, of which portions are intercepted by the 

 particular plane we are examining. 



Having determined the unit, and the symbol, and 

 measured the inclination of the modifying plane on 

 one or more of the primary planes, we may proceed 

 to discover the law of decrement by some of the 

 methods already described. 



