Artificial light sources have a long history, and have made great strides since fire was the primary source of artificial light. Various forms of combustion have been used more recently than you might realize, with gas lamp street lighting commonly used into the 20th century. In the late 19th, with the advent of electricity, electric lights were developed. Electric lighting provided safer and brighter lighting, for many uses, including in theaters.
Theater is of particularly interest to me, as I became involved in technical aspects of theater as teenager. By the time I learned about lighting the fixtures used halogen bulbs, neat and tidy; producing hundreds or thousands of watts. Modern at the time, these lights run on 120 volt electricity, emitting light and heat. While these kinds of light are still in use, they are being replaced by LED fixtures, using about 1/5th the electricity to create a similar amount of light, and much less heat.
Earlier fixtures used carbon arc lamps. I’ve read about these lamps, but hadn’t seen one. Carbon arc lamps run on high voltage, to produce an arc between the electrodes. As the arc burns the electrodes are consumed, requiring the operator to adjust the electrodes to maintain a burning arc.
I was recently at an abandoned theater, I was pleasantly surprised to find a (mostly) intact spotlight, complete with carbon arc electrodes. In the image below, you can see the electrodes, still mounted in the fixture that allows them to be adjusted as the are consumed.
