[Mike K]

Originally Posted by Jakko Westerbeke

Going by the text on the label, it’s for testing some kind of batteries for electric firing circuits — that is, the wiring needed to set off electric detonators for explosives used in demolitions.

Or, could it be a device for testing electrically fired Artillery pieces ? It appears to be just one part of a multi - unit system , with a battery , the resistor limits the current flow in the circuit.