ABSTRACT
The resistance standard described by James L. Thomas was the result of his extensive effort to develop a new standard by systematically investigating every factor affecting the stability of resistance—time, surface effects, temperature, power, pressure—detectable at the time. Thomas's standard remains the most stable resistor of any available, although two more modern designs are nearly a match in predictability. Much of the research leading to this standard resistor design is described in an earlier paper by Thomas. However, the paper Stability of Double-walled Manganin Resistors is the more popularly known and describes the standard in its final form, after some major modifications in size and connections. An unknown standard resistor is indirectly compared to a reference bank of the same nominal value using the substitution technique, where the unknown and reference resistors are sequentially substituted in the same position of a bridge circuit.
