This thread reminds me of a story my Dad told me many years ago. Employed as a maintenance fitter in the hospital service, around 1949/1950, he helped the electrician to build some lighting dimmers for amateur theatricals.
The dimmers were based on vertically mounted salt glaze clay drain pipes, filled with brine. A rope and pulley system raised and lowered electrodes. It apparently worked, without harming anyone either electrically, or with boiling brine !
I don't doubt the accuracy of the story as I recall it, nor the ingenuity of the people involved, but I've sometimes wondered if it was a unique and original idea, or as now seems likely a clone of a commercial system.
