M + [alpha]M´ = c1, M + [beta]M´ = c2, C + [epsilon]C´ = C3, (13)

dU

c1-- - c2 VR = 0, (14)

dt

dV

c2-- + (c1 U + [xi])R = 0, (15)

dt

dR

c3-- - (c1U + [xi] - c2 U)V = 0; (16)

dt

showing the modification of the equations of plane motion, due to the

component [xi] of the circulation.