412 



The force acting at r due to meridional tension is 



The acceleration of the element is 



o:.Kl!-k\-^^^M, 



i (A-6) 



and the mass is 



av*».d(^ = «.c-t9- a j5 r a r a 4> . (A-7) 



Equating the total force and the product of mass and acceleration we obtain 



after division by (A 4* • 



Substituting (A-3), (A-/+), (A-5), (A-6), and (A-7) into (A-8) and 

 taking the vertical ( d^ ) and meridional (a ) components then dividing by v 

 we obtain 



wnc '-e 



r 



(A-9) 

 (A-10) 



(A-11) 



With the aid of Eq. (A-2), the trigonometric functions of i^ may be expressed 

 in the form 



93 



