I didn't think that carbon arc fixtures were made as late. Take a look at the video!

Not to be stupid but what is the point of a Carbon-arc lamp besides light?

Well, today they're often used as searchlights. Xenon arclamps are arguably better, but the bulbs are far more expensive (than a simple rod of carbon) and likely to explode at EOL. Carbon doesn't do that. I believe the efficacy is about the same at ~30lm/W.

Carbon arc lamps were also used in the early days of radio as a broadband noise source, and are probably used as such today, as they generate a high output white noise when fed from very pure DC. Output is basically broadband noise that extends well past the visible part of the radio spectrum.

Interesting, but why would you need a "broadband noise source?"

For measurement purpose...