Is T c(P) for lead suitable as a low-temperature manometer?

The superconducting transition temperature of lead has been reexamined as a function of pressure to 17 GPa (170 kbars). Tc(P) determined with helium as the pressure medium differed from that when 4:1 methanol:ethanol was used. The disagreement is particularly net in the fcc phase and can be ascribed to a sensitivity of Tc to the state of shear stress. This implies that Tc(P) for Pb is unsuitable as a manometer. The possibility that the hcp phase, occurring above about 14 GPa, may be useful as a manometer is discussed, but a definite conclusion cannot be reached at the present time.