VARIATION OF NODE AND INCLINATION. 83 



and eliminating in turn ^- , -^ , by (3), we get 

 d0 7 dy dR . 



^ar^C'-i)-^ 



de dk ^ 



Again, the inclination being small, 

 dR dR dz dR ds dR . 



, dR dR dz dR ds , dR 



and -j- = -=- . -j~ = p -j . -=- = OK -j- cos (6 7) ; 

 ay dz dy r dz dy dz 



, Z7 

 and p -7rA;-j7 = -j-, 



p 



_ 



dk _ 1 no, dR / fi v 



M^k^JT^'dy'' "^'' 



which agree with the known results, & being = tan 7, or sin 7, 

 quam proximd, and 7 being what Mr Pratt denotes by O. (The 

 squares, &c. of 7 are neglected throughout.) 



62 



