Abstract: A non-linear scale instrument responsive to a sensor which generates an output signal proportional to the magnitude of a changeable condition. A visible scale includes spaced gradations over the total extent of the scale, with spacings between pairs of scale gradations varying across the scale. A control circuit, in response to the output signal of the sensor, determines the angular position of and drives a rotatable pointer across the scale to the angular position corresponding to the magnitude of the condition measured by the sensor. The control circuit also automatically converts between different measurement units at the user's selection to re-position the pointer corresponding to the measured condition in the selected units.