The instrument is combined potentiometer and double ratio
box. It may be used for measurement of two or four terminals
resistance and metallic bars from 1.1 ohm down to 0.0001 ohm
and arranged on allrotary dial. The slide wire reads resistance
in steps of 0.001 ohm. Knife edged special jockey is provided
for accurate contacts, with the help of double ratio box the
reading can be made form 1.1 ohm down to 0.00001 ohm.