  We report results of a large set of N-body calculations aimed to study the
evolution of multi-mass star clusters in external tidal fields. Our clusters
start with the same initial mass-functions, but varying particle numbers,
orbital types and density profiles. Our main focus is to study how the stellar
mass-function and other cluster parameters change under the combined influence
of stellar evolution, two-body relaxation and the external tidal field. We find
that the lifetimes of star clusters moving on similar orbits scale as T sim
T_RH^x, where T_RH is the relaxation time, and the exponent x depends on the
initial concentration of the cluster and is around x approx 0.75. From the
results for the lifetimes, we predict that between 53% to 67% of all galactic
globular clusters will be destroyed within the next Hubble time. Low-mass stars
are preferentially lost and the depletion is strong enough to turn initially
increasing mass-functions into mass-functions which decrease towards the
low-mass end. The details of this depletion are insensitive to the starting
condition of the cluster. The preferential depletion of low-mass stars from
star clusters leads to a decrease of their mass-to-light ratios except for a
short period close to final dissolution. The fraction of compact remnants is
increasing throughout the evolution and they are more strongly concentrated
towards the cluster cores than main-sequence stars. For a sample of galactic
globular clusters with well observed parameters, we find a correlation between
the observed slope of the mass-function and the lifetimes predicted by us. It
seems possible that galactic globular clusters started with a mass-function
similar to what one observes for the average mass-function of the galactic disc
and bulge. (Abridged)
