Phil. Mag. Ser. 6, Vol. 21, PI. Y. 



Curves 5. 

















c 



















/ 

















/ 







I 3 



\ 









> 



V 







V 











V 

















/ 



/ 









7 



i 









/ 

















/ 















/ 













3 

 2 







./ 















V 































es 





/ 















"Z. a-y , \-o hsr 5o -2-a~ o-o j-i- ctk 



Curves 6. 



i^e* c^ 



Q ( >>vuc ^a-N-jt'j ^t->- >-« ck» .^ 



