There is another common misapprehension that the magnitude scale is itself some kind of instrument or apparatus. Visitors will frequently ask to 'see the scale.'
This is very similar to astronomy where different magnitudes are assigned to the brightness of an astronomical object, depending on the range of wavelengths being measured.
What emerged, of course, was that the magnitude scale presupposed that all earthquakes were alike except for a constant scaling factor. And this proved to be closer to the truth than we expected.
