Stability of double-walled manganin resistors

Abstract

The international ohm is now maintained at the National Bureau of Standards by means of double-walled manganin resistors. It is assumed that the ave rage r esistance of a group of 10 standards, selected from a group of 24 constructed in 1933, remains constant with time. No one of the 10 standards has changed in r esistance with reference to their average by more than 1 part in a million in 12 years.