  We used archival ROSAT observations to investigate the X-ray surface
brightness profiles of a sample of 26 clusters in the redshift range
(0.04-0.06). For 15 of these clusters accurate temperature (kT>3.5 keV) were
available from the literature. The scaled emission measure profiles look
remarkably similar above ~0.2 times the virial radius r_V. On the other hand a
large scatter is observed in the cluster core properties. We fitted a
\betamodel (with and without excising the central part) to all the ROSAT
profile to quantify the structural variations in the cluster population,
unraveling a robust quadratic correlation between the core radius r_c and the
slope parameter beta. We quantified the shape of each gas density profile by
the variation with radius of the logarithmic slope, \alpha_n. The bi-weight
dispersion of \alpha_n among the clusters is less than 20% for any given scaled
radii above x=0.2. There is a clear minimum spread at x=0.3, which is related
to the existence of a correlation between r_c and \beta. These ensemble
properties are insensitive to the exact treatment of a possible central excess
when fitting the profiles. On the other hand the scatter is decreased when the
radii are scaled to r_V.
  The regularity we found in the gas profiles at x>0.2 supports the existence
of an universal underlying dark matter profile. It suggests that non
gravitational heating is negligible for clusters with temperature above
~3.5keV. The very large scatter observed in the core properties favor scenario
where Cooling Flows are periodically erased by merger events. Our results are
consistent with the classical scaling M-T relation. Accordingly the spread in
the reduced mass profiles derived from the hydrostatic isothermal betamodel is
small.
