Vintage/Antique Portable Potentiometer, Tinsley & Co. 3184D, Good Condition

Description

This is an antique potentiometer, Model 3184D, built by Tinsley & Co in Essex, UK. The company still exists and still produces precision instrumentation to this day. This device was originally used to measure and characterize test cells, such as emf (voltage) and internal resistance. Inside the unit is an area for two 3V batteries and a Standard Cell to provide a known emf, by which the measurements on the unknown test cells are made. The actual measurements are made with a deflection meter, the components of which appear completely intact.
The unit is in good shape, as shown in the pictures. These types of devices can be used to measure very small potential differences, down to the microvolts even. A functional schematic is shown, and it appears a previous owner added a toggle switch to one of the power lines, possibly to save battery life when not in use. If you're in need of some spare parts, I'm willing to bet this thing is stocked with precision resistors.
Solid wood case, very sturdy construction, weighs about 22 lbs. The outside has some wear and tear as you would expect from a used piece of equipment, but it's overall quite nice. The top cover is easily removed from its hinges so it would make a great decoration on a bookshelf or in a cabinet.
They really don't make 'em like this any more!