  Recent accurate data obtained for the isomeric cross section of the
$^{197}$Au$(n,2n)$ reaction provide a valuable opportunity to consider the
question of the effective moment of inertia of the nucleus within a local
consistent model analysis of all available reaction data for the $^{197}$Au
target nucleus. Thus, a definite proof of a moment of inertia equal to that of
the rigid--body has been obtained for $^{196}$Au nucleus while an inference of
the half rigid--body value is suggested for the $^{194}$Ir nucleus. The
usefulness of further measurements at incident energies up to $\ge$40 MeV has
also been proved.
