Therefore, we write our proven integral form for area F (that we of course identify with the area of the ellipse in direction 1) and proceed in the same way with these two quantities like we did before with n_s:

(Fig. 22)

But as V₀ is a variable of , it must be put - for the self-interaction of a particle - under the integral. Hereby the difficulty of the variability of V₀ and, thus, of E has been overcom:

  XLIV  

Now, as usual, we express the elliptical functions by the quantities of the circles: