Abstract
A numerical method for interpolating the resistance-temperature relation of a platinum resistance thermometer is given. Calibration at three points such as 20°, 90°, and 273°K is required. The interpolation is then carried out by reference to the complete resistance-temperature relations of two other slightly different thermometers. Limited tests suggest that it is possible to achieve a temperature scale in this way using commercially available thermometers that is reproducible within 0.001 deg, provided the Callendar-van Dusen constants and the residual resistance ratio are sufficiently restricted.