242 



BRADLEY M. PATTEN 



a 



-6 



I6§ 

 49 



161 

 49 



-9 



11 



161 

 49 



L 



c \ 



25% 

 59 



250/b 

 59 



-121 



25% 



59 



12 



Fig. 11 An average set at 16| per cent difference 

 Fig. 12 An average set at 25 per cent difference 



