  This paper is concerned with collisionless aspects of the early evolution of
model star clusters. The effects of mass loss through stellar evolution and of
a steady tidal field are modelled using $N$-body simulations. Our results
(which depend on the assumed initial structure and the mass spectrum) agree
qualitatively with those of Chernoff \& Weinberg (1990), who used a
Fokker-Planck model with a spherically symmetric tidal cutoff. For those
systems which are disrupted, the lifetime to disruption generally exceeds that
found by Chernoff \& Weinberg, sometimes by as much as an order of magnitude.
Because we do not model collisional effects correctly we cannot establish the
fate of the survivors. In terms of theoretical interpretation, we find that
tidal disruption must be understood as a loss of {\sl equilibrium}, and not a
loss of {\sl stability}, as is sometimes stated.
