  We have carried out Monte Carlo calculations on two sets of randomly
generated QCD events due to $p\bar{p} \to t \bar{t}$ with top mass $m_t = 170$
GeV, one set leading to $e^+e^-$ or $e^{\pm}\mu^{\mp}$ or $\mu^+\mu^-$ 2jets
(dilepton) and the other leading to $e^{\pm}$ or $\mu^{\pm}$ 4jets (unilepton)
configurations, in order to test the likelihood methods we have proposed for
determining the top mass by analyses of these two sets of configurations. For
the set of unilepton events, our method gives a very efficient and quite sharp
measure of the top mass lying several GeV below the input mass. For the
dilepton set, our method gives a much broader and markedly asymmetric
distribution for the top mass estimates, 75% of them lying below 170 GeV, but
the dilepton data will have much lower background than unilepton data. We then
illustrate these methods by applying them to the data available from CDF in
1995 and discuss the results obtained in relation to the results for the sets
of Monte Carlo events. The dilepton events yield masses spread widely, over 140
to 180 GeV, generally lower than the unilepton events, which cluster around
$175\pm 8$ GeV. In an appendix, we discuss the nature of the additional
``slow'' $\mu^{+}$ observed in one CDF dilepton event, concluding that it is
most probably a ``tertiary lepton'' resulting from the decay sequence $b\to c +
hadrons$, followed by $c\to s \mu^{+} \nu$.
