Maker's Name: 
Paton Elec Pty Ltd
Where made: 
8.5 × 6 × 8 cm

An external heater is placed in series with an electrical circuit. When current flows the heater heats up a bimetallic juction, creating a DC voltage difference in the junction. The junction is connected to the meter, which is a d"Arsonval movement, and deflects the needle. The scale is square-law, as the DC voltage generated is proportional to the square of the current flowing in the external circuit.

This meter and thermo-junction was designed to measure RF current flowing in an aerial feeder.