Antique Thwing Potentiometer Checking and Calibrating Set Patented 1933

Description

Thwing Potentiometer Checking and Calibrating Set
Patented May 30, 1933 by E.J. Albert, Assignor to Thwing Instrument Co. of Philadelphia, Pa.
Potentiometer Device for testing and calibrating meters
In very good condition, looks as if it was refinished. Two original style batteries are included
very nice hard wood case
It has the instructions on the inside of the lid.
This item is sold AS-IS , no returns, I do not know if this works
This was my fathers ,who was an engineer.