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Thursday, January 24, 2013

Light Matters

There was a brief thread on the OD&D forums about handling light. Nothing world-shattering, but since the D&D rules assume anachronistic kerosene oil lanterns, it was pointed out that oil lanterns should burn a long time. Someone posted the duration of a pint of kerosene: 36 hours, ideally, but you could cheat and just call it a day.

That's significantly longer than I figured, but I did think it should be pretty long. It makes sense to assume an oil lantern will burn all night, since that would simplify things for the night watch. If an oil lantern *didn't* store enough oil to burn through the entire night, that would be one of the first improvement people demanded. They would just make the fuel reservoir bigger until it could handle burning all night.

Most medieval lanterns, in the colder climes, at least, were candle lanterns, so they burn as long as a candle. D&D editions which give specific burn times tend to make candles last a very short time and not provide much light; there seems to be no other reason than they think using torches is more iconic, so candles shouldn't be better than torches. The 3rd edition SRD, for example, says a candle burns for 1 hour and only provides 5 feet of illumination. A five-foot radius makes sense for something like a tea candle, but I know from experience that tea candles burn for more than just an hour; these are tiny puck-sized candles, mostly for decoration or atmosphere. Larger candles ought to provide more illumination and burn longer. After all, candles were used in candle-clocks. I think I prefer the standard candle, and candle lanterns, to burn for four hours with a 30-foot radius, compared to a torch, which has a larger flame (60-foot radius,) but burns for only an hour.

This gives me an idea, though: I think the safe movement rate for a given light source should be equal to the radius. This helps eliminate the need for separate rules governing the quality of illumination; just assume that if you move faster than is safe, based on the radius, you may fall into pits, trigger traps, miss secret doors. I'd probably raise the bull'seye lantern to a 120 foot directional beam, to make it easy to remember and useful for those who want fast travel.


  1. If they were worrying about PCs carrying candle lanterns into dungeons at the expense of 'iconic' torches, they should have asked - does a candle lantern work as a weapon; can it set Mummies or ancient tapestries on fire? can it be thrown at something and potentially used again? Does it have a largish open flame that might scare away dungeon vermin?

  2. I really like your idea about safe movement rate equal to radius of the light source. It has a very elegant logic to it.

  3. The anachronism is pretty slight: kerosene (as white naphtha) production methods are described in 9th-century Persian texts.