  The cluster Abell 2104 is one of the lowest redshift clusters (z=0.153) known
to have a gravitational lensing arc. We present detailed analysis of the
cluster properties such as the gravitational potential using the X-ray data
from ROSAT (HRI) and ASCA, as well as optical imaging and spectroscopic data
from the CFHT. The cluster is highly luminous in the X-ray with a bolometric
luminosity of Lx ~3x10^{45} ergs/s and a high gas temperature of ~10.4 keV. The
X-ray emission extending out to at least a radius of 1.46 Mpc, displays
significant substructure. The total mass deduced from the X-ray data under the
assumption of hydrostatic equilibrium and isothermal gas, is found to be
M_tot(r<1.46Mpc) ~(8.0 +/- 0.8)x10^{14} solar mass. The gas fraction within a
radius of 1.46 Mpc is ~5-10%. The cluster galaxy velocity distribution has a
dispersion of 1200 +/- 200 km/s with no obvious evidence for substructure. The
total mass within 1.46 Mpc, deduced from Jean's equation using the observed
galaxy number density distribution and velocity dispersion, is found to be
\~6.8x10^{14} solar mass to ~2.6x10^{15} solar mass marginally consistent with
the X-ray deduced total mass.
