Proo. Ray. Soo. Vol/tt.Pl. 2. 



Fi 9 . 1 . 

 SCHEME A 



Fig . 2. 

 SCHEME B 



The. eocLstu^g 



WaUs stop cU,ervM&. 



Pcrrtijan, of Charts. 

 ~beLow L.W.O.S. T. 

 i-s chaJJ 



Fig .3. 

 SCHEME Ba 



