Centennial Light
en.wikipedia.org
en.wikipedia.org
Go experience it for yourself without knowing anything more, if you haven't already.
People talk about it sometimes as if they made bulbs worse, but they didn't.
The cartel tried to set the efficiency figure such that it wasn't worth it to run the bulb at lower efficiencies for longer life.
As much as they are criticized they seemed to have calculated exactly the right figure: Bulbs today at still 1,000 hours. No one wants a lower efficiency bulb, and shorter lifetimes are too annoying.
If you really want to know more, read the wikipedia article someone else linked, then read the sources it's based on.
I don't usually do this, but uh, citation needed?
Higher temperature = higher efficiency, but also lower life.
This bulb produces basically no light, i.e. very poor efficiency, so the lifetime is very high.
1) It's a 30-watt bulb, so I'd be a lot darker than you'd be used to/would be usable
2) It's gotten even darker, so it would be almost completely useless by now.
3) Because of the lower wattage, it's basically been used more gently than any bulb you'd use now-a-days
Basically, you'd probably replace it about as soon as the current ones anyways.
Carbon filament bulbs are still sold for decorative lighting:
https://www.amazon.com/carbon-filament-bulb/s?k=carbon+filam...
Kind of related: an interesting video on how tungsten filaments are made: https://www.youtube.com/watch?v=DIGqBb3iZPo
Like the coils in your toaster basically. And that's also why it's lasting so long - low temperature equals long life.