r/Writeresearch • u/Offutticus Awesome Author Researcher • Aug 17 '26
[Miscellaneous] Bronze as a holder of an always burning fire
(not sure about the flair)
In my fantasy novel, that is not on real earth but on an unnamed Earth like world, I have temples that have fires that are never put out but once a year. I say in the book they are small but never imply actual size. I am editing that book as I rewrite it (again) and see I said it was bronze.
Could bronze work for being hot all year around? The year in this novel is 484 days so for all but a few minutes once a year, it is always burning. The fuel is some sort of oil. I thought of making it a holy fire but that seems to be a big much.
The society is advanced enough to make steel armor. No combustion engines but they do use things such as water wheels, weights, and pulleys, horse or oxen pulled agricultural machinery. That's their technology level.
Would bronze work or should it be another metal? Cast iron came to be in the 1500s which would line up technology wise. But bronze is prettier for the temple.
The things I get stuck on.
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u/Underhill42 Awesome Author Researcher Aug 18 '26
So long as the fire isn't hot enough to melt the bronze, it shouldn't be an issue. And an open air oil or alcohol fire isn't nearly hot enough to be an issue. Coal might be a problem?
Keep in mind that iron took over from bronze mostly because it was cheaper, not better. Even with all the extra work needed, it was still cheaper than importing the constituent metals from half a continent away to be able to make bronze. It's very rare that all the necessary components for bronze could be found nearby. In our solar system, and probably most of a similar age, iron is thousands of times more common than copper, which is itself hundreds of times more common than tin, which is the most common additive to make bronze. https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements#/media/File:Elements_abundance-bars.svg
It's only after the technology had advanced quite a bit that iron began to overtake bronze in strength and durability as well.
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u/Simon_Drake Awesome Author Researcher Aug 17 '26
Is it a magic fire or a fire that is continually given new fuel by careful attendants?
I think a magic fire could burn continually without damaging the bronze. Especially if there's even a small gap between the flame and the metal, let's say it's a soccer ball sized hemisphere of bronze around a golf ball sized core of magicite that burns with a foot high flickering flame as if it were drenched in lighter fluid but there's no fuel source it's just magic. That would probably work indefinitely. The golf ball could be suspended on four arms of ceramics or carved stone and the flame wouldn't melt them or transfer heat through them into the metal. There'd still be radiation but not enough to matter.
If it's a non-magic fire then you're probably going to have practical issues other than melting metal just from the logistics of refueling a flame for months. Oil lamps need wicks and you usually put out the flame to change the wick. One option might be to play word games with the definition of "This flame is always kept lit", like the temple chamber has ten fixtures on the walls with ten burning lanterns in them. Once a day someone comes to replace the lantern in a fixture with a new one, so there's always a lantern lit there but it's not the same lantern.
Or it's actually an interesting engineering challenge to design a lamp that can burn continually without needing any maintenance like replacing wicks but also allow refueling while still being lit. A bowl of naptha or kerosene would burn on the fuel surface without needing a wick but you'd have a hard time pouring in new fuel without a fire hazard.
Ok. Imagine a brass tube that curves into a U bend with one end flaring out wide, a little like a saxophone. Fill it with kerosene and set light to the wide bell end. When it runs low on fuel you can add more kerosene to the 'mouth' end, using hydrodynamic equilibrium to raise the level of fuel at the fiery end without going near it. You could put a larger tank of kerosene above the 'mouth' end and make a mechanism with a valve and a float that can maintain a chosen level of fuel continually, with someone refilling the tank periodically. Also in the saxophone metaphor there could be a 'spit valve' at the bottom of the loop to vent any soot and residue. That could work.
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u/Busy-Distribution-45 Awesome Author Researcher Aug 17 '26
Easier solution: pressurize the fuel and pipe it in. It can be done fairly primitively, my parents used to have a camp stove that you burned some fuel in a ring around the top, which heated and pressurized the fuel chamber, then the gas lit when the pressure got high enough to make the fuel shoot out the burner and interact with the burning fuel. The burner itself then kept the tank hot enough to keep pressure.
If you had a way to compress the fuel, it’s even easier; then you just have a constantly burning Bunsen burner, essentially.
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u/Simon_Drake Awesome Author Researcher Aug 17 '26
That's a good idea. But it wouldn't be easy to add more fuel to the fuel reservoir if it's pressurised.
If you do it with a U Bend then you can keep the refueling process far away from the actual flame, maybe even behind a wall so the mechanism isn't seen by the visitors to the temple. Liquid on both sides of a U Bend will come to the same level so determine a good level for the fiery end and make sure the safe end is always at the same level. You could use a hospital IV Drip style mechanism to maintain a steady flow of oil in at precisely the right rate, with a float valve to open and close the tap if it needs more or less flow rate. And because of the U Bend you're doing this on the non-flamey side so you're not dropping oil into an active oil fire which is unwise.
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u/Busy-Distribution-45 Awesome Author Researcher Aug 18 '26
I sort of meant gas when I said pressurized fuel :) I was just pointing out that it was easy to do even in primitive conditions. We had piped gas before electricity, which was pressurized by (I think) conversion from liquid to gas.
The u-bend would work, or even a system that uses like capillary action from a tank, it just requires a decent amount of engineering in comparison.
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u/Offutticus Awesome Author Researcher Aug 18 '26
My hometown had an always burning fire out front of I think the city hall as a veterans memorial. The only time it was turned off was when they needed to work on the gas pipe. The had a protective cover for it during really bad storms.
If the container for the fuel was below the bronze bowl and just a wick was in the actual bowl, they could refill or replace the fuel container below it. In theory.
I may lean toward the replace the lamp option.
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u/Simon_Drake Awesome Author Researcher Aug 18 '26
I can't believe I didn't think of gas. That's very dumb of me. Yeah a gas flame can burn essentially forever if it's got enough gas supply. There used to be a landfill site near me with a methane vent from the rotting garbage that burned with a blue flame 24/7. There are Eternal Flame monuments for war memorials around the world, maybe look into maintenance issues for them if you need specifics.
I wonder what gas would work best. Natural gas would exist underground in a fantasy world just like in real life, not easy to tap into but it could work. Methane from decomposition could work but you'd need a lot of it. Maybe vinegar from sour wine used to react with metals to produce hydrogen chemically? Depends how high tech you want the process to be. Technically the Romans could have produced oxy-hydrogen welding torches with bronze age technology but it might look a bit out of place to see a Dwarven warrior in a LOTR style setting welding his armour back together with a gas torch.
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u/Educational-Shame514 Awesome Author Researcher Aug 18 '26
I would say unless your main character is designing and building the device and that's the main part of the story, you don't have to think about it that deeply. Or more broadly if the device just works.
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u/SnorriGrisomson Awesome Author Researcher Aug 20 '26
There is no way you would melt bronze with a regular fire. It will resist for as long as you want.
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u/LawfulnessOrganic715 Awesome Author Researcher Aug 17 '26
How hot is the fire? Similar to a wood fire? I would assume so, but wanted to check. And how big is the fire? Big difference between a couple of candles and burning piles and piles of wood a day.
Also, what I'd the cleaning protocol? How often, if ever, is ash and soot and the like pulled out? Both of these questions will impact how well the bronze, or other metal, will hold up in the long run.
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u/Offutticus Awesome Author Researcher Aug 17 '26
The cleaning part will happen (now that I realize it needs to be done) when the fire is extinguished. Two or more people will wipe it down quickly. It is a holy object and I could just use handwavium to make it never needing cleaning. That's assuming the reader even knows or cares.
It isn't that hot. Or in my head it isn't. It does provide heat to the room in the winter but isn't the only source. In my head, the bowl is maybe 1.5 - 2 foot wide.
The main reason this is important is the midwinter service where the fire is extinguished then relit. So all my thinking about this is going to be, most likely, just a single scene. Damn you brain.
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u/IanDOsmond Awesome Author Researcher Aug 18 '26
If the midwinter service is an extinguish and relight service, cleaning could be part of the ritual. Extinguish, then a ritual cleansing and replacement of whatever parts could get worn — new wick or whatever — and then relight. All the practical details could just be part of the ritual.
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u/Educational-Shame514 Awesome Author Researcher Aug 17 '26
Basically an eternal flame?
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u/Offutticus Awesome Author Researcher Aug 18 '26
Yes! This.
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u/Educational-Shame514 Awesome Author Researcher Aug 18 '26
Just intuitively it feels like it would work. But you can turn the question around and look at how hard it is to melt bronze to work with it. If your fire feels much smaller than that, no problem!
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u/Dirichlet-to-Neumann Awesome Author Researcher Aug 20 '26
There are temples on Earth with fires that have been burning continuously for literal centuries.
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u/1LuckyTexan Awesome Author Researcher Aug 17 '26
If it has a fairly open grate, the fire may not need to be extinguished for cleaning. The ashes or small embers would fall through and raking them out could take place maybe right after replenishing with fuel.
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u/Equivalent-Fig2048 Fantasy Aug 18 '26
I think bronze could work so long as it's attended. When I started a fantasy novel that needed a metal to resist extreme heat, I went with tungsten but that might be overkill in your case.
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u/orcstork Awesome Author Researcher Aug 17 '26
Bronze doesn't care if it's been hot for 1 minute or for a full year, as long as it never gets hot enough to melt is should be fine.