M A (I N E TIC SU K V E V () !•' p E \ \ 8 V L V A \ I \ 



i, 'i 



The trial of an equation of the form, 



/= I Q + i 4- xdL + ydMco8 I. | zd L dMcos L; 



and of the form, 



/= I a + i + xdL + ydMcos I. + qdJiP cos* L 



showed that tin- extent of the survey is nol sufficiently great to admit of the deter- 



