260 RELATION OF DECREMENTS TO 



Intermediary decrements on the lateral solid angles. 



These are of three kinds, and require three general 

 symbols. 



1st. (Bp D q D'q B"r) represents class f. 

 2d. (Dp B q B" q D'r) .... class g. 

 3d. (B P D q D'r B" s : B P Dr D' q B" s ) represents 



class i when p ]> q; 

 The same symbol represents class k when p <^ q. 



Decrements on the edges of the pyramids. 

 General symbol P B P . 



Ifp zz 1, the symbol represents mod. I. 

 p ^> 1 3 ....... class m. 



Decrements on the edges of the base. 



P 



General symbol D 



p 



Ifp = J, the symbol represents mod. n. 

 p ^> 1, ../... class o. 



The Octahedron with a rectangular base. 

 Fig. 311. 



Simple and mixed decrements on the terminal angles of 

 the planes P. 

 p 

 General symbol P. 



Ifp 1, the symbol represents mod. a. 

 p ^> 1, class b. 



