The critical temperature has been measured for various magnet conductors as a function of the perpendicular applied magnetic field. The isothermal environment was provided by a variable temperature cryostat which fits into the bore of a 10.0 tesla solenoid. The temperature gradient across the sample volume was measured to be less than 25 millikelvins. The superconducting the normal state transition was measured resistively, using sample current densities from 0.01 to 2 A/cm/sup 2/. The maximum applied magnetic field was 10.0 T and varied less than 0.5% in the sample volume. The critical transport current range of the samples measured was from tens to thousands of amperes in the presence of a 10.0 T perpendicular magnetic field at 4.2K.