MANGANIN WIRE RESISTANCE UNIT, 1930's

Manganin was used in the 1930's as a replacement for Nickel Silver used up until then.
Manganin and Ureka wire was superceded by Nickel Copper and Nickel Chrome Alloys.

Your comments:

• The 'hole' in the middle is for the thermometer. Many of these resistors were in a 'pot' and suitable oil was put in, to keep the coils at a steady temperature (to be stated on the calibration certificate).
  .......... Dave Coomber, Penkridge, 27th of August 2014
  
  

A0334