ROYAL PHYSICAL SOCIETY. 



J'lutt: XIII. 



160 140 120 lOO 80 60 40 20 



100 720 140 160 



A^rr/c 



OF THE 

 ON MERCATORS PROJECTION 



CAPC VO/fM 



OCBA.V 



/i//T/igcr/c c//icie 



AJVTAIi'Cr/C 



orBA.v 



160 HO 120 lOO 80 



40 20 



60 dO lOO 120 140 leo 



S(»H it- VtreiMsou, Eiliiiliiiryh. 



