An initial experimental program was previously conducted to study the problems in using static pressure probes for flow calibration purposes in low- density, hypervelocity wind tunnels with continuous flow. This data is reviewed in the light of more recent data on thermal transpiration. Results indicate that such probes may be used for what might be termed secondary calibrations, but care is required in interpreting the results. The present experiment yielded data which are compared to static pressures calculated from impact- pressure probe calibrations.