  The DO Collaboration has measured the inclusive jet cross section in
proton-antiproton collisions at s**2 = 630 GeV. The results for
pseudorapidities -0.5 to 0.5 are combined with our previous results at s**2 =
1800 GeV to form a ratio of cross sections with smaller uncertainties than
either individual measurement. Next-to-leading-order QCD predictions show
excellent agreement with the measurement at 630 GeV; agreement is also
satisfactory for the ratio. Specifically, despite a 10% to 15% difference in
the absolute normalization, the dependence of the ratio on jet transverse
momentum is very similar for data and theory.
