Science Interviews


Mon, 22nd Jun 2015

London's burning: the Great Fire

Dr James Campbell, Cambridge Universityís Department of Architecture

Listen Now    Download as mp3 from the show Bring out your Dead: Plague and Fire

After starting in a bakery, the Great Fire of London burned for four days, destroying hugeFire by Soreen D areas of the city. Just as infections spread swiftly through crowded areas, the tightly packed houses allowed the fire to travel rapidly. James Campbell is an architect and architectural historian who studies this period. He explained to Chris Smith what London would have looked like at the time of the fire and how the fire changed the face of the London we have today...

 James - Youíve got to imagine Ė we do have some of these kind of buildings still surviving Ė timber frame buildings. They're tall. They're 3 or 4 stories on the big streets and many buildings behind them tightly packed down small alley ways. These timber frame buildings have wattle and daub basket weave and plaster as a front. So, they will burn extremely easily.

Chris - How many people wouldíve been living like that? How big was London at that time?

James - Well, it was a lot smaller than modern London. Of course, after the plague, there were many fewer people. But weíre talking of a city of about 140,000 in the city and then more in the suburbs. But at this time, the suburbs donít stretch very far. Hampstead is still very much a village in the countryside.

Chris - Were fires terribly common at that time? Or had no one really seen a disaster on this scale before?

James - There had never been a disaster on this scale, but fires were common in towns throughout England in this period. But commonly, they only destroy 30 or 40 houses and the only method of firefighting was to pull the houses down in front of the flames so they had hooks and crowbars and things, and they literally demolished the houses.

Chris - Was there a fire service? Today, we dial 999 if we see a fire. Was there any equivalent then?

James - No, not at all. It was reliant on small organisations, parishes to have their own firefighting equipment and that was part of the big problem of course.

Chris - So, there was no sort of joined up system, no one you could rely on to come in an emergency.

James - And often, as happened in this fire, everybody was so busy saving their own property and running away from the fire, that they wouldnít help out anybody else.

Chris - What was the scale of the damage? Weíve heard obviously Pepys saying there were hundreds of houses, but what was the eventual outcome of the fire?

James - It was completely a disaster. So, it starts in Thomas Farrinerís shop, he makes biscuits of all things, and it catches very quickly.

Chris - How do we know it started there?

James - Because there's a large court case afterwards and he admits that it started in his bakerís shop and he clambered out over the roof. Unfortunately, the first casualty of the fire was his maid who was too afraid to cross the roof and escape. Remarkably in this fire which destroyed 13,200 houses and 87 churches, remarkably, only 6 people died which is extraordinary. And they all fled, with what possessions they could carry, to the fields around London and for 4 days, they were camped in tents around London.

Chris - Is that how long it burned for, 4 days?

James - It burnt for 4 days. They were still there 4 days after the fire had died down. It just kept burning because it had been a long hot summer. Everything was tinder dry and there was a nice wind blowing in from across the Thames going westwards.

Chris - Quite literally a perfect storm this, wasnít it? Did it make its own weather as well? Because when weíve seen examples of fire storms in world war II where lots of ordnance was dropped on a city in Germany for example, there were classic cases of this, you end up with a fire thatís so hot, so intense, that itís pulling in so much air it creates an apparent wind that then drives the fire even faster.

James - We donít have descriptions, though we can guess that that must've been what was happening. It was certainly extremely hot, so that it, for instance, catches St. Paulís Cathedral which is a big stone building and wasnít expected to burn, just because there were so many tinders and things flying through the air. And itís only stopped eventually by the king blowing up a large area of London to the west of it and the weather changing. And that means that everything dies down.

Chris - They create a firebreak by literally just wiping out all the potential fuel.

James - They blow it up and they have done the same thing around the Tower of London and this just created an enormous firebreak.

Chris - How enormous?

James - A hundred meter-wide firebreak approximately.

Chris - Thatís a lot of houses, isnít it? And all these people who end up camped out on the fields, what happened to them?

James - Well remarkably, they found lodgings in the next few days. But then of course, they had to rebuild. When we were talking about this overcrowding, this is then when this problem is solved. Firstly of course because nobody is living in the city at all for several years. Really, the building isnít completed until about 1672. So, youíve got quite a long stretch where there's very few people moving back into the city. And then by new building regulations which change the way they build. So, gone are the higgledy-piggledy timber structures which are cantilevering over the roads ,so they jetty out and they almost meet in the middle. You can imagine how good that was for spreading disease and also for fire. And now, you can only build straight, upright, brick buildings with no exposed timber work. So, we get the city which weíre so used to with rectangular windows and brick arches.

Chris - This is the origin of the building regulations that plague us today. Itís the Great Fire of London to thank for that.

James - If you think of building regulations as a plague Chris, yes. Yes, thatís true. This is the origin of the brick built city. Itís not a hygienic city. The sewers and things will come much later, but itís a city where they get away from the overcrowding in the back alleys because they say ďyou can't build very high in back alleys. You can only build high on big wide streets. The narrower the street, the lower you can build, and everything must be in brick.Ē

Chris - You said that it sorted out a lot of the problems, but didnít sort out all of them. There was quite a notable exception of the sewer situation. So, what was life like in London post-fire before the sewers came along?

James - Well, the water came out of the Thames or it came out of streams running down or it came out of wells. The problem is, your sewage went into pits or tanks behind your property and then it was emptied out periodically by people who were employed to do that. Of course, you had basements. That was one thing that came in. And so, very often these pits which held the sewage would leak into the basements. So, you could get whole basements full of sewage and not to mention of course, also into the water supply, which is why in the 17th century, most people drank beer to avoid poisoning from water. Itís really only in the 19th century when the sewage problem gets dealt with in London because the sewage is also going into the Thames. So, your water is coming partly from the Thames, your sewage is going into the Thames, and so, as you can imagine, itís a source of disease.

Chris - I suppose we exchanged one plague for another because then that meant things like cholera became much more common. Is it a myth that the great fire wiped out the plague? Is that true or is that just apocryphal? 

James - The plague had already died down by the time the fire hit. But there is no doubt that if you wanted to completely destroy any vestiges of rats or fleas or anything else then the great fire really did it because it completely flattened everything. And it kept smouldering for weeks, although it started to rain along last and that gradually put the embers out. So people, wandering around the city in the days afterwards described this terrible wasteland of still burning buildings.

Chris - James Campbell from Cambridge University, thank you very much.

Ginny - We know that the great fire started in a bakery and modern bakeries are still surprisingly dangerous places to work. So while open fires are less of a problem, the products they work with like flour and icing sugar can actually be a danger in themselves. And thatís because finely ground substances combust or burn at a much lower temperature than they would if they werenít so finely ground because they're so mixed with the air. And of course, oxygen is one of the things that you need in order to set something on fire. In fact, with some substances, the spark you get when taking off a jumper caused by static can be enough to ignite them if they're suspended in the air. And this is still a problem. In 2008, an explosion occurred in a sugar refinery in Georgia, and there was another in 2010 in a flour mill in Illinois because of these substances suspended in the air, catching fire and burning. Now, I'm going to cause a little fire of my own to show you just how flammable these substances are. Hopefully, it won't be quite as dramatic as the Great Fire of London and I won't burn down all of Cambridge. The first thing I have to do is light by blowtorch. I've got my blowtorch. Weíve got a nice flame coming out of the top. Now what I've got here is a rubber tube and on the end of it is a little kind of container. What I'm going to do is put some corn flour in that container and then I'm going to blow down the tube. And thatís going to cause a cloud of corn flour to go into the air. I'm going to direct that under where the flame is and weíre going to see whether it combusts. So, I've put a teaspoon of corn flour in my container and I'm going to blow down the pipe. Do you want to count me down?

Audience - Okay, ready? 3, 2, 1Ö

Ginny - So, when I blew that cloud of corn flour into the air, youíve got what looks like a kind of fireball coming out of the top of the blowtorch. Youíve got this big kind of ball of flame and that just shows, there wasnít actually that much fuel in that. It was only a teaspoon or two of corn flour. But because itís so well mixed with the air, it catches fire really, really easily and thatís the same thing that can happen in bakeries and factories, working with these kind of powdered substances. And thatís why they have to be really, really careful.


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