rs were initally stepped, all beautiful brass and mahogany. This was because resistive tracks were very rough and electrically noisy; and continuous wire wound tracks were usually of an inconveniently low resistance [and in my experience scratchy anyway]. The quadrant fader was initially stepped too. Modern ones could be geared to a pot. The advantage of quadrant is that they may be conveniently mechanically grouped and mastered.
I remember the rheostats we had on the stage lighting at school. Big devils the size of an electric fire, due of course to the heat dissipated. I could work three at a time. One with each hand and one with my foot! Never managed four.
Of course before these modern objects we had home made liquid dimmers: vertical pot drainpipes filled with Glauber's Salt solution; and lead electrodes moved by strings. You could work ten of these together! At max brightness you had to short them in case they boiled.
Life was interesting, although hazardous. You had to watch out for the live puddles on the wooden floor from the leaking dimmers.
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