[DaleHCook]

There is no galvanometer and no resistor ?

You are correct - galvanometers are uncalibrated devices with center zero with no current - they are used only to indicate a balance condition when used with an instrument such as a Wheatstone bridge or a laboratory potentiometer. Your 7050 has an ammeter (probably a milliammeter) which is calibrated (however simply) into good and replace zones. That is what has a 220 Ohm shunt resistor across its movement.