66 



BELL SYSTEM TECHNICAL JOURNAL 



A rotation of 90° about x^: 



10 

 10 

 10 

 

 1 

 









 



-1 





 





 

 

 

 



-1 



(21.6) 



A reflection in the plane perpendicular to Xz'. 



'l 



1 



1 

















 

 

 -1 

 

 



(21.7) 



A cyclic interchange where av replaces .vi , etc. : 



(The line making equal angles with .Vi, .vo, and ;V3 is a three-fold axis) 



fO 1 o' 



10 



10 



1 



10 



10 



(21.8) 



A cyclic interchange, where — .V3 replaces .vi, etc.: 



(The line making equal angles with .Ti, .V2, and Xz is a six-fold axis of 



second sort) 



the 



(21.9) 



A rotation of 90° about .V3 combined with a reflection in the ;V3 plane: 



0^ 

 

 

 

 

 0-1 



(21. 



