d[phi] dx d[psi]
------ = --[psi] + x------
ds ds ds
dx d[psi] dp
= --[psi] + 2(a² + [lambda])--------- l--, (9)
ds d[lambda] ds
so that the velocity of the liquid may be resolved into a component
-[psi] parallel to Ox, and -2(a² + [lambda])l d[psi]/d[lambda] along
the normal of the ellipsoid; and the liquid flows over an ellipsoid
along a line of slope with respect to Ox, treated as the vertical.