MAG N ETI C S U RVEY _ 6et/r/eev v lAe fuwa//elof ' 40c/l //O mul l/i& ^(^uaJor _ _ %fioc/v 1840-4-5 . ^Xlt'CU^Xt^L, , 
Phil. Trans. 1875 . Plate 28 . 
