  We present a spatially resolved map of intracluster gas temperatures in the
rich cluster Abell 2255, using ROSAT PSPC data. The intracluster gas is
strongly non-isothermal and the temperature distribution supports the
conclusions of Burns et al. (1995) that Abell~2255 is currently undergoing a
merger. The hottest regions are near the core, northwest of the center. A map
of the ratio of softer to harder X-ray photons reveals an anomalously soft
region northeast of the center, coincident with a radio ridge discovered by
Burns et al (1995). We suggest that this cooler region is associated with an
infalling group of galaxies which is giving rise to the radio ridge. Meanwhile,
a much more substantial recent merger between comparably sized subcluster
components can account for the more global merger signatures, which include the
extensive central radio halo, the large scale gas temperature variations, the
pair of central dominant ellipticals, elliptical X-ray isophotes offset from
these dominant galaxies, and the very high velocity dispersion of galaxies in
the cluster.
