  Recent experimental data on tau decays are used to reconstruct the difference
in hadronic spectral densities with vector and axial-vector quantum numbers.
The saturation of Das-Mathur-Okubo and Weinberg sum rules is studied. Two
methods of improving convergence and decreasing errors are applied, and good
agreement with the predictions of current algebra and chiral perturbation
theory is observed. The resulting value of the pion polarisability is (2.64 +/-
0.36) 10^-4 fm^3.
