weekly with the rotor-part of cluster (M and few $^4$He atoms, -at first position, which interact directly with M) that they do not follow the rotation of the rotor. In a sense the net potential seen by the rotor part of the cluster appears to remain constant with a change in the angular position of the rotor. In other words the rotor (when rotating about its axis) seems to role over a equi-potential surface; else if there are hills and valleys in the surface, the height of hills is much lower than the energy of rotational excitation of the rotor. Although these efforts rendered a satisfying account of the phenomenon, they could not find a clear relation to superfluidity of $^4$He atoms and this motivated us in concluding this model which not only associates an important aspect of superfluid He-II with the non-trivial dependence of $I$ on $N$ but also clarifies how only few $^4$He atoms attached directly to M take part in the rotation and rests do not follow the rotation effectively.

In what follows from the experimentally observed $N$ dependence of $B$ (represented typically by a curve depicted in Fig.(1)), we observe the following:

\(A) $B$ decreases when 