  The moment of inertia of even-even deformed nuclei which are derived on the
basis of hydrodynamical model yield values that are too small compared with the
experimental [Davidson 1965] ones. We expect that these contradictions come
from the consideration only the first term in $R$- expansion in spite of not
containing parameters indicating deformity of the nucleus, and neglecting all
other terms which include the deformation parameters $\alpha\lambda\mu$. In
this work, the first three terms in $R$- expansion are taken into account. The
results are more realistic and too much better the previous ones.
