This reminds me of some of the old theatre equipment I worked with some years ago. I used to be involved with a couple of amateur dramatic groups doing the lighting and sound for them. This was back in the early 1980s, and in one village hall we still had a lot of old 1940s/1950s equipment, which I assume had been donated to the village when it was replaced by my modern gear at a big theatre.
We had a whole bank of rheostat dimmers for the lighting, linear arrangements rather than rotary, with the largest master dimmers being almost 3 ft. long as I recall. Everything was installed in the control booth high up at the back of the hall -- A small enclosure which must have been no larger than about 12 x 6 ft.
When the lights were running on reduced power the heat from the dimmer bank was collosal.
