Otto Wolff
fl. 1870 - 1920
Otto Wolff was an electrical instrument maker in Berlin, Germany in the late 19th and early 20th centuries.
In the early 20th century, the firm made Reichsanstalt Type resistance standards in Berlin. These devices were important in the history of the standardization of the Legal Ohm. From 1901 to 1909, a group of Reichsanstalt-type resistance standards made by the firm, embodied the standard measurement of the Legal Ohm. However, the standards were not hermetically sealed and their resistance could change in response to changes in atmospheric humidity.
See also:
Elmquist, Randolph E.; Cage, Marvin E.; Tang, Yi-hua; Jeffery, Anne-Marie; Kinard, Joseph R., Jr.; Dziuba, Ronald F.; Oldham, Nile M.; Williams, Edwin R. "The ampere and electrical standards," Journal of Research of the National Institute of Standards and Technology, January 1, 2001.