How bright are oil lamps?

This bright!
We had a last minute program change for Scouts and I had to pull activities with a vaguely Arabic theme together with less than 24 hours to prepare.
They had fun. There was hummus, kebabs, and Arabic writing to start with. The Bollywood style belly dancing could potentially have sparked an international incident, so the less said the better!
But experimenting with making vegetable oil lamps in old jam jars was fun. A few jars cracked before we mastered a way to have the salted paper towel wick remain in the middle of the jars. They were bright, but it is tough to imagine relying on them as your source of light.
There's nothing slick and over organised about my scout programme, I have to admit, but lots of chances to work through the ideas and come up with individual solutions. Which they did.