  A value of the Hubble constant has been determined from a comparison of the
X-ray properties and Sunyaev-Zel'dovich effect of the distant rich cluster of
galaxies CL0016+16. The cluster, as imaged by the ROSAT PSPC, is significantly
elliptical and we present the techniques we have developed to include this in
our analysis. Assuming a smooth, isothermal gas distribution, we obtain a value
H_0 = 47 (+23, -15) km/s/Mpc, where the errors include systematic and random
uncertainties but are purely observational. Systematic errors in deprojecting
the elliptical surface brightness distribution due to prolate and oblate
geometries as well as arbitrary inclination angles introduce an additional
fractional error of +/-17% in H_0. At the redshift of CL0016+16 (z=0.5455) the
effect of the cosmological parameters on the derived H_0 value is of order
10%-20%; we quote results for q_0 = 0.1. Combining this result with
X-ray/SZ-effect H_0 determinations from seven other clusters and taking account
of systematic uncertainties in our models for the cluster atmosphere, we find
an ensemble value of H_0 = 42 - 61 km/s/Mpc with an additional random error of
+/- 16%.
