Leeds & Northrup is named in the source as the manufacturer of the type K potentiometer used in Palmer H. Craig's low-field Hall-effect measurements. Craig reported that potentiometer refinements gave readings accurate and reproducible to one-tenth of a microvolt.
See also
Palmer H. Craig, Anomalous Low-Field Hall Coefficient in Bismuth.
Source notes & attribution
- https://rexresearch.com/craig/craig.htm