In pbar-p collisions at sqrt(s)=1.8 TeV we find jet events with a
rapidity gap topology.  The number of hadrons in the rapidity interval,
delta-eta_D, between leading-jet cones was sampled by cfharged tracks
with P_T > 400 MeV/c.  We find excess trackless events beyond that expected
in a smooth multiplicity distribution.  In a control region outside
delta-eta_D we see no excess.  For delta-eta_D>0.8, the fraction of
excess tracless events, consistent with estimates based on exchange
of color-singlet di-gluons, is

        R(gap)  = sigma_{jet}(gap)/sigma_{jet}
                = 0.0085 +/- 0.0012(stat.) +0.0024 -0.0012(syst.)