14 



2Z x 2dZ 



i + z a ~ (1 + Z 8 ) a 



But 1 - 4rZ a - Z 4 = 1 + 4r a - (2r ♦ Z a ) a = (p a + Z a )(1/p a - Z a ). 

 AV /v _ r>f (1 + 2Z/f + Z a ) dZ . _ 2f T 1 - p a + 2Z/f . 



■ • dT/T " 2f ( P a ♦ z y )d/p» - z a ) - p 8 + 1/p 3 L P* + z a + 



1 + p a - 2p/f , 1 + p 3 ♦ 2p/f ~| 

 2(1 + pZ) 2(1 - pZ) J 



... log T/T » p3 f l/p2 [ i-^ tan" 1 Z/p + -J" lo g (1 + zV P a) + 



^.^H^-f logd-p'Z a )] 



where T is the tension for Z = 0. This last is seen to be equivalent to equation 

 (10). 



