Does anybody have any idea what this piece of equipment is?
It is precision potentiometer with very low resistance and very high ratio accuracy. It could be used for say in bridge with "zero reading" galvanometer to match 2 currents or voltages. It was possibly marketed for chemical labs doing thermocouples measurements.

I'd estimate it is nearly as good as low-end Kelvin-Varley divider. And can still be very useful and very stable thermally.

One clue comes from googling the "Rubicon Company Philadelhia". There are similar products (from 1960s) like "standard 1 Ohm", potentiometers, galvanometers (with mirror for light beam!) and other high end lab devices of the era.