HEAVY-QUARK-MESON MASS GAP FROM SPECTROSCOPY

Using a quite accurate flavour-independence of nS-level mass differenc es in heavy quarkonia and a corresponding quasiclassical expression fo r the heavy quark binding energy, one shows that experimental data on masses of mesons with heavy quarks allow one to make the estimate <(La mbda)over bar> = 0.63 +/- 0.03 GeV.