They are pretty simple. There is a reservoir in the bottom that you fill with fuel. Mineral spirits, or lamp oil seem to burn the cleanest. Lamp oil is pricey refined mineral spirits. There is a fair amount of confusion info about fuels, but if you go to the hardware store and buy unscented mineral spirits, in the paint department, you can't go far wrong.
The lamps have cotton wicks that hang down into the oil and *wick* it up to the tip were you light it. The wick burns down at a slow rate, much like a candle. The knob is for adjusting the wick height. There is a little bit of technique involved in lighting a lamp. Remove the glass chimney. You fill it (if needed) and then turn the wick up just high enough to light it with a match. It will flare initially a bit and I crank it down pretty far into the lamp until the flame tames. Then I put the glass chimney back on and turn it up to the desired level of burn. This minimuzes the soot accumulation in the chimney.
We refill the lamp maybe once a week or a bit more often if we are burning it extra. They get used most nights for a few hours at least.
They need a *cap* or *bell* to divert the heat rising up the chimney. Other wise the ceiling, if it's at all near will get pretty warm. Not catch fire warm, but bubble and ruin the finish warm.
Ours have them incorporated into the hanger. There are many designs of oil lamps, many especially for boats that have the bells and gimbals all ready.
Great information Sarafinadh, thanks for sharing!
Inspired by this post and something I read about a mason jar lamp I just went and got a mason jar, jabbed a hole in the lid with a screw driver, then cut a piece of cloth and put it through the hole. I had some lamp oil here for an emergency lantern, so I just put an inch of that into the mason jar, swished it all around so that the cloth would get oil all over it, then pulled some of the oiled cloth through the hole in the mason jar. Lit it with a lighter, and it works!
You would think the jar would get hot but it really doesn't, even the ring holding the metal jar lid didn't get hot (I did not screw it down in case pressure builds up inside the jar).
The only thing that doesn't work is that the fat flame does smoke a lot, I don't know if that is because of the fuel I used or if it is because of the wick I made, or too much wick, or what the trouble is. Maybe oil lamps just smoke a lot, I don't know.
I would not leave my mason jar lamp unattended, but it would probably serve to heat up a small area while I was sitting next to it, if it just didn't smoke so much!
Edit, it looks something like this except without the fancy lids, and the wick on mine is a lot bigger so the flame is a few inches tall.