“…We consider (2) for the different a^i = 1, 2, , ri), and we put Δa { = ^Qia^, β, τ)0Q(a if β, τ). Now, multiplying by Ja if sum-ming for i form 1 to n, and then carrying out an appropriate limit process, we obtain lim where the second integral of the numerator gives the surface-measure of the intersection of B and σ and, thus, its value equals π according to our condition, provided that | τ\ < ΎJ.…”