  The correlator of heavy-quark currents is calculated in quenched Lattice QCD
on a $16^3 \times 32$-lattice for $\beta= { 6, 6.3 }$. The renormalized charmed
quark mass is extracted from the short-distance part of that correlator:
$m_c^{\overline{MS}}(m_c) = 1.22(5) GeV$. We study the sensitivity of our data
to the strong coupling constant.
