(24)

ῶ = ½ ∫ G′ − Gz dt= ∫ z3 (G′ − Gz) / 2An dz,
E − z AE − z √ (2Z)

(25)

an elliptic integral, of the third kind, with pole at z = E; and then

ῶ − ψ = KCH = tan−1 KH/CH

= tan−1 A sin θ dθ/dt= tan−1 √ (2Z),
G′ − G cos θ (G′ − Gz) / An

(26)

which determines ψ.

Otherwise, from the geometry of fig. 4,

C′K sin θ = OC − OC′ cos θ,