266 RELATION OF DECREMENTS TO 



Intermediary decrements. 



General symbol (B P G q B'r : Br G q B' P ), repre- 

 sents the remainder of the series of planes belonging 

 to class b. 



Decrements on the terminal edges. 



p 

 General symbol B. 



If p =. 1, an individual plane belonging to class c 

 is represented, which may be termed 

 the middle plane of the series com- 

 prehended under that class ; and it 

 would intersect the lateral planes in 

 lines parallel to one of their diagonals, 

 p ^>1 3 the symbol would represent that part 

 of the series of class c, which inclines 

 more on the terminal plane than the 

 middle plane does. 



p <^ 1, the same symbol would represent that 

 part of the series which inclines more 

 on the lateral plane than the middle 

 plane does. 



Decrements on the lateral edges. 



General symbol P G P . 



If p =: 1, mod. d is represented. 

 p^> 1) class e is represented. 



