  Using a new second derivative technique and thermometers which enable us to
determine the local electron temperature in a mesoscopic metallic sample, we
have obtained quantitative measurements of the low temperature field and
temperature dependent thermopower of Andreev interferometers. As in previous
experiments, the thermopower is found to oscillate as a function of magnetic
field. The temperature dependence of the thermopower is nonmonotonic, with a
minimum at a temperature of $\simeq0.5$ K. These results are discussed from the
perspective of Andreev reflection at the normal-metal/superconductor interface.
