  Using a data sample with a total integrated luminosity of 10.0 pb$^{-1}$
collected at center-of-mass energies of 2.6, 3.07 and 3.65 GeV with BESII,
cross sections for $e^+e^-$ annihilation into hadronic final states ($R$
values) are measured with statistical errors that are smaller than 1%, and
systematic errors that are about 3.5%. The running strong interaction coupling
constants $\alpha_s^{(3)}(s)$ and $\alpha_s^{(5)}(M_Z^2)$ are determined from
the $R$ values.
