  We present results from a measurement of double diffraction dissociation in
$\bar pp$ collisions at the Fermilab Tevatron collider. The production cross
section for events with a central pseudorapidity gap of width $\Delta\eta^0>3$
(overlapping $\eta=0$) is found to be $4.43\pm 0.02{(stat)}{\pm 1.18}{(syst)
mb}$ [$3.42\pm 0.01{(stat)}{\pm 1.09}{(syst) mb}$] at $\sqrt{s}=1800$ [630]
GeV. Our results are compared with previous measurements and with predictions
based on Regge theory and factorization.
