PREVIEW: Epochs #241 | The History of the Steam Engine - Part II
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Summary
Today Alex and I talk about the history of steam and steam engines and all things related to that, including the invention of the first steam engine, the flying scotsman and the development of the modern steam engine.
Transcript
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Hello and welcome back to Epochs. Today we're going to talk again all about the history of
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steam and steam engines and all things related to that and i am joined by alex how are you sir
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hello good afternoon yes yeah i'm very looking forward to this because last time you was on
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yeah we only really scratched the surface didn't we we um yes we went off on uh on quite a tangent
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we talked about all the earlier stuff things like um just the very very earliest concepts of a steam
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cylinder and newcomer and a little bit of james watt didn't we so in other words the very very
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first kernels of the thing you could even a push call a steam engine yes so today we're going to
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try and get a bit more into it and a bit more of a bit more of the history yeah we're going to
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actually get into it because we went off on a massive tangent about what would you do if you
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had a million slaves in in ancient greece and could you could you build a steam powered battle trireme
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which i enjoyed immensely but it didn't quite fit the brief so the thing i had in mind was how do
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we go from sort of a newcomer pump pumping water out of a cornish mine to 120 mile per hour flying
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scotsman in like the 1930s yeah 1920s 1930s yeah like how the history of that the story of that yeah
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it's it's really good to say yeah it's the cornish um because it it really does come down to a cornishman
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richard trevithic who is the inspiration for trevithic day in cambourne which is well worth
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the visit if only once just to see what cambourne's like uh but uh cornwall obviously has a great
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history of mining and mining under the sea go back to the ancient times i mean even the the ancient
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greeks um used to in the bronze age were getting their tin from cornwall um so there's a long history
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of it but mining under the sea water's a very pressing issue so obviously they're quite early
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adopters of of uh atmospheric engines but the thing with that which is the newcom which is the
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newcom and engine uh but they are extremely inefficient yeah very low pressure right very
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low pressure you just can't pump much water very far with it with the best within the world you just
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can't yeah and the the sizes the other thing with a very low pressure engine is if you want large
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powers out of it it has to be enormous right because your only vacuum it is limited by air
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pressure so it's about 14.7 pounds a square inch and if you're going to build a massive one that costs
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uh well too much money it's just not economical yeah yeah so they don't or they never did well
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they did build some but yeah you know the absolute ludicrous ones but eventually you just end up having
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to build two because it's easier to build two than build one massive one right um you you end up at the
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sort of upper limit of the technology but the other thing about the inefficiency is that you've got to
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have the coal and there's no coal in cornwall right so there was a tremendous problem of the coal for
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the engines came from south wales because that was their local supply so it's not a million miles away
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but it's an annoying it's far enough yeah yeah right um and obviously is that why just just put something
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together in my head why in newcastle they could do it yeah because in for a while i think the two main
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places where they were using um engine cylinders to pump out water was cornwall and newcastle yeah
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but of course that in newcastle they're using it to pump out a coal mine so you just bring the coal up
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and chuck it in the in the pump and then whatever's left you sell on whereas the mine captains actually
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have to buy it in and you start getting to the limits of the infrastructure because there were you
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know legends of like thousand horse cart traffic jams on the mud tracks between like new lynn and
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penzance and truro and around here you need an enormous amount of coal relatively enormous amount
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of coal if you're burning sort of the the little one they've got at the moment apparently burns 10
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tons a day well that means 12 that means 10 horse carts a day of coal might take two days to get
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there so you need 20 on the road right you know before in the late 17th century or sorry late 18th
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century early 19th century there would be dozens or hundreds of these in cornwall right yeah so
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right there it's just a silly amount of coal you need yeah right so the the impetus is there to make
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it more efficient and uh richard trevithick who his schoolmaster said is a bit of a loafer uh not good
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inattentive and all the rest of it um has a natural knack an ability with mechanical systems
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he quite quite quickly um becomes a mine captain as they call it who's a sort of general manager
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slash supervisor chap um and starts to play around with concepts and what he comes up with is is the
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concept of what he calls it strong steam whereas now we call it high pressure steam and even then we're
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talking sort of 25 50 pound a square inch so now that to me sounds a lot yeah in the scheme of
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things though is it in the scheme of things no it's about you convert it back into atmospheres and it's
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about two or three atmospheres so two or three times atmospheric pressure okay um but that in of
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itself so you put that much more you know two or three times atmospheric pressure into the engine
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it means the engine can be a half or a third the size of a of an atmospheric engine to get the
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equivalent power out of it the problem you get them with high pressure steam is that it's really
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quite dangerous all right the thing can blow up it can blow up yeah and you can't the boilers that
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were using at the day that were called a haystack boiler or a box boiler was essentially a a box
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over a fire so you've got massive flat surfaces and the moment you try and put a pressure in it they
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try and balloon it out like a barrel yeah so what trevidic comes up with is the initially he comes up
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with the cornish boiler um which is a big tube full of water with a little tube in it with fire in it
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so once you've got a round shape it naturally self-supports so it's much much more um strong
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and it's much more economical with the material as well it's just it's a better shape and the two m
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plates um you then essentially make them quite thick and then put sort of girders across the back
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of them and a couple of tie rods at each end to hold the two flat surfaces in line i was gonna say
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because one of the one of the uh it's not really the right word to say but like one of the problems
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with that would be um that it needs to be engineered well enough and the materials need to be strong
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enough yeah but when you're dealing with trying to make a business and make a profit yeah then people
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are always going to try and do it for the cheapest way possible right yeah and so in theory it's all well
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good but then people made ones that still just blew up yes yeah right and the metallurgy wasn't there
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at that time and the ability to quality control wasn't there as well so you can't do
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like proper materials analysis you can't take samples away to be tested in any meaningful way they
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you use a local iron founder who has a reputation for having making decent iron and that's it that's
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all you've got to go on yeah it's his reputation and then his plate goes off to your boilersmith who
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also has developed a reputation for not blowing up uh which is quite useful you're just relying on
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that you're just relying on that it's like yeah this guy's built 100 boilers and none of them are
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blown up so he must be doing something correct um he also has to develop if you're working at
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pressures you know how to develop a safety valve so that the boiler runs up to that pressure and then no
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further right um so he develops counterweight safeties um as well which is literally just a
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uh a valve on the top of the boiler with a bar across it and a weight on the end and then by
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adjusting where the weight is you adjust the pressure on the valve and at that pressure it
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just lifts off and that lets out the excess steam um one of the things i say about that though that like
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we just say that in passing but like this is the first people ever to do this yeah like you've had
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all sorts of empires throughout the the millennia yeah and no one's ever done any of this no no it's
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all english one gang well if we just design that and do that then that works yeah and they're the
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first guys to do it ever they're always running up against the limitations i know in our previous one
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we were talking about um hammers and being able to hammer um we were talking about prop shafts at the
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time but in boiler plate so a cornish boiler is about six or seven feet across by about 30 feet long
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so you've got to you got to roll the plate to make the band but they couldn't roll a plate that was
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about at that time it was about 18 inches wide by about three feet long massive so it's you know
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that's that's big for the time and that's it's a difficult process to roll the place a piece of
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plate to a thickness with any degree of accuracy at that time and then because you've got lots of
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plates you've got lots of joints and joints are failure points and all the rivets that hold the
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joints together have got to be closed by hand because you haven't invented a pneumatic rivet gun
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so you've got you know dodgy plate being held together with possibly dodgy rivets that have
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been driven in by hand by a guy who's probably drunk um so there's all these things but some of
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them actually managed to do a good enough job that the confidence gets there and they actually um
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actually managed to move forward the on the on the on the other side of it so once you've made your
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steam the other thing he does is he comes up with uh yeah they come up with uh a principle called the
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cornish principle which is a slight improvement on the watt engine but still using atmospheric
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um principles there's a lovely lovely video which for some reason is on the shell is in the oil
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company's youtube channel and it was made in 1948 about cornish pumping engines and they do those
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classic like black and white um cartoony diagrams about how things work it's absolutely lovely but
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essentially you've still got the same problem where your pump rod's gone down which means your pistons
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come up how do you get it back down again and what they did was they actually you close the top of the
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cylinder you put your high pressure steam in the top which then pushes it down yes shut the inlet valve
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and then they have a pipe that goes from the top of the cylinder to the bottom and you open that and
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the weight of the beam transfers the steam from the top of it down into the bottom so now you've got the
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full cylinder on the bottom all right then you open it out to the condenser it sucks it back down
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right once that's going you've then got 25 pound of steam on the top and a vacuum on the bottom
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and that boost gives you much more power out of the out of the engine so the cornish start again no
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one's ever done that before no and it's such a simple it is elegant isn't it it's such an elegant
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way of doing it and and but it's still relatively low relatively low pressures low pressures and
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not fast no so in the flying scotsman you've got the thing going yeah this is going you they've got right
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slow as shit right yeah they've got absolutely beautiful ways of on the pumping engines they
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can actually adjust both the length of the stroke and the stroke rate right and it's all it is is the
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operating rods that operate the valves go down into into the basement under the cylinder and they've
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got it's almost like a car damper so as it goes up it draws water into a into a little cylinder and
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then there's a tap on the side and as the bob comes back down again by adjusting how open the tap is
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you can adjust how quickly it comes back down again so if you open it all the way the thing
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will go like the clappers and if you just have it dribbling it'll just slowly slowly slowly come
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down and then it will repeat and that was again an economy thing because you only want to pump the
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water out that is actually there you don't want it over pumping yes i think it's important to point
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out at this stage because we're still talking about what the late 18th century yeah 1790s into about
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185 yeah so things nearly all things are still handmade right basically yes handmade every
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handmade every every little thing yeah so it's like every everyone is like a bespoke unique yeah
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project almost yeah and these these big engines you know we said about how they'd um we'd managed to
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sort of link them up to spinning mills cotton mills the weaving power loom hasn't been invented yet i
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think it's about 1820 that's invented so we can mass manufacture cotton cotton uh string we can hook
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them up to bellows so we can make we can keep the brass furnaces going so we can make lots of cast iron
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but it comes back to the bottleneck principle so you you've suddenly you can you can mine a lot more
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coal you can make a lot more thread you haven't developed a steam hammer so that limits the size
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of the thing you haven't developed a rolling mill so you can't roll big bits of plate yet you haven't
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all these things start backing up which then means the price of iron and coal have collapsed which then
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means people have got the spare money to develop things to use all the spare iron and coal for
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um trevidic actually he uh he constantly gets hounded by bolton watts lawyers uh and the story goes
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well he they claimed that he was infringing on their patent because of his their bolton and watt patent
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run out in 1801 so before then you know you've nicked my principle of a beam engine or you know strong
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steam is the the classic sort of hate campaign that he deserves hanging for his use of strong steam
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because it endangers the public and all the rest of it all right very much like edison and uh tesla
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you know a hundred years later like when edison and the other yeah yeah sounds like that trevidic
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apparently one of these bailiffs came down to try and uh extract royalties out of him and um trevidic was a
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six foot six cornish wrestler the giant for the time and um he just uh grabbed the guy by his
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ankles and hang him over a over a mine shaft and sort of shook him shook him out and sent him on
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his merry way um so yeah he wasn't he wasn't one for the authorities um but he he takes this
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the concept of high pressure steam and he's like well if i forgot high pressure steam
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the engine for a given power output can get smaller and smaller so there must come a point
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where it's small enough and powerful enough to drive itself right you put it on some sort of platform
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put it on some sort of platform and and away you go and what he comes up with was the puffing devil
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in 1801 and there is a um replica of it built by the trevidic society it sort of runs up and down
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campbell neil every year um it was at uh stythians rally this year actually fascinating little thing
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because there's so many little problems he had to work out um to make an engine unit because nobody
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had ever built a unit before you had your boiler was in one building and then there was a whacking
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great pipe that went through the wall and then a beam engine sat in another building it was over three
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stories so you know you had all the control gubbins in the in the in the basement and then the
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cylinder on the first floor and then you had the um beam up the top in the roof so how do you how do
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you make some of that onto something you can even put in a cart chassis um and what he does is he he
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makes a boiler he then puts a return flue in it um just to try and increase the heating uh space
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he puts the cylinder in the boiler to keep it nice and toasty so that's that and then he
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has a vertical beam at the top a cross beam and then just some coupling rods down to the wheels
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and then it sort of they turn an axle that the wheels sit on and then you can put pins in and
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then that actually engages the conrod into the wheels and then along you go all right uh some sort
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tiller steering arrangement um just to point on rails no this is a road vehicle blimey this is a road
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vehicle yeah uh and uh that's where the the old cornish song about going up cambourne hill coming
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down comes from all right uh i think it was christmas eve 19 uh 1801 him and his mates you know they've
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just they've just built this thing and they uh they go for a drive up cambourne hill to the to the pub
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at the top as you do thoroughly impressed with the with the engine's performance as it roared up the
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hill they all decamped to the pub and leave it in a barn get drunk have a roast goose completely forget
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about the engine all the boiler all the water boils away and apparently it uh it then uh blew up and set
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part of the building it was in oh so yes oh dear oh dear they haven't haven't quite got the concept
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of no once you put a fire in it you kind of have to stick around it that was the one thing i was
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going to say it all sounds well and good but isn't it even like modern i say modern even like mid 20th
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century steam engines right is it not the case that um let's say like a 1920s 1930s or the flying
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scotsman say you have to keep the fire burning the whole time because if it goes out and the thing
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gets cold it's dead yeah until you re-fire it again and of course once you've you've put a fire
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in it and it is hot it does have you do have to keep an eye on it yeah well yeah um you can't well
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you can just you know leave them if you if you've got it you know ram full of water and it's 100 pound
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down or whatever it is and the fire's dying you can you can leave it it's pretty safe but yeah you
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come back and it's cold and you've effectively got to start again and isn't it also like you know uh any
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rocket engine like solid fuel rocket or anything like that you light it or you get it going rather
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one way or another and that's it you're then a passenger till the fuel's burnt isn't it not is
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there an endless like not exactly that in any way but an element of that that once it's hot and it's
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going you could put the fire out if you want by i don't know throwing cold water on it or something
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but assuming you don't do that it's going and yeah it's going to keep going the the thing i always
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say about steam steam engines like steady state right once yeah once they're up to temperature
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they want to go right um and actually i was i was driving one of the engines back from uh a christmas
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thing this this on sunday and you can feel it in the engines you know you'll you'll get them up to
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temperature and she'll i don't know how that roller she must be part mountain goat or something but
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she was going up a hill and you could hear you know chuffing away really really enjoying it and you get
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over you get over the top of the hill and the fire's really hot and all the water you've got's
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really hot and then the safety valve starts screaming off because you're you're just making
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steam she's like no no i want to go i want to go i want to go it's like no actually i've got to go
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back down the other side you fill them back full of cold water and you've sort of got to start again
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again there's a thing just a slight aside before we carry on with the narrative there's a thing a lot
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of people say about steam people actually really work on them like you do
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and really genuinely make them work and make them go um that it feels like it's something that's
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alive oh they are yeah that it's really alive and you're keeping it alive with how you're tinkering
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with it as you go along yeah they do and actually i've read um scientific analysis on um steam engines
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and the best comment that was in the introduction they said they were like frustratingly biological
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which is a wonderful way of saying that yeah they are because particularly a solid fired solid fuel
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fired engine when you're getting down into the really nitty gritty tech you know really trying
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to measure of course in an experiment you're trying to replicate the results
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and with a steam engine fired on coal no two bits of coal are exactly the same size
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right the air pressure outside is no and the air temperature and the humidity is never going to
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be quite the same there's never quite the same amount of soot in the tubes or in the firebox
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so there's you know the the boiler plate is never quite the same temperature and the
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properties in the water are never quite the same and there's so they they do they've there's a mood
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there are if you get bad coal they can be a complete bitch really it's really really bad or for some
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reason you haven't fired it quite properly and and the the great clinkers up and then you just can't
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get them to work and and at a certain point you've just got to admit defeat and start again and i have
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done it we've had we've had um we had a load from south africa and a third of it was rocks didn't
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help yeah right um and it was really horrid stuff it didn't it didn't burn like any coal i've ever
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seen before um very very fine ash it was almost like talcum powder the ash it was very light and it
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was very very fine but it gummed up the tubes if you left it for any length of time it would just
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immediately clinker over what's that mean which is clinker is actually molten ash all right and if
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you've got very high ash content in the in the coal obviously when you're chuffing away you're
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pulling air through so you get the fire really really really hot and if you then stop you end up
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with a layer of ash because the fire continued continually burns so you've got a layer of ash over the top
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but over the top of really hot fire and it fuses into this solid layer of very brittle
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it does actually look like slag and it's got the sort of mechanical properties of like set plaster
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okay it feels like that and all that does is of course it chokes the air off right right and then
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it gets worse because it's poison it's absolutely poison for the fire and it you end up with
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these little holes where there isn't any clinker and then the fire is trying to pull all the air
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through that tiny hole which then pulls a hole in your fire which then means there's no coal in that
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hole which then means you're pulling cold air through all right so that comes back to it being a living
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thing yeah of but you'll you'll do it the next day and that won't happen right for some reason
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yeah you'll just you'll fire it in a slightly different way so the thickness of the fire bed
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will be slightly different and you'll you'll have the you know the lumps will be slightly bigger which
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means that the the structure of the fire has got some more holes in it which gives the ash somewhere
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to go so it can go down into the grate or it'll burn slightly slower which so it doesn't get quite as
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hot but the gas flow is still there so it means it can pull it out over the top things like that
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so that's why an experienced steam engine driver and engineer yeah it is there is an element of an art
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to it oh yeah that they see what the coal they're working with know it inside out like looking at the
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fire all the time checking it all the time all the things you just mentioned and much much more yeah
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and there's an art to that yes it'll take years to feel and just know intuitively or very quickly at
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least what's going on and why it's gone wrong in any given way um fascinatingly i mean you know
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jumping ahead into the sort of big four days the great western and we're sat here in swindon which
00:24:49.880
is the hallowed ground of great western steam that they bought all of their coal from south wales
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right and south wales coal is soft anthracite so it's it's quite and it is soft i mean you you
00:25:07.100
muck it about too much and it just dissolves into dust so you've got to be very very gentle with it
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and in fact western locos were always cold by hand they never used mechanical coaling because it just
00:25:17.760
used to pound it up into dust but it's got a very very high carbon content it's about 95 98 percent
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carbon what that means is that it burns very cleanly but ironically it's actually quite difficult
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to set on fire okay because what you usually do in coal very much like wood is that as you heat it up
00:25:38.180
the gases in it evaporate off that then forms flames the flames get the carbon hot enough for it to start
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to decompose into carbon monoxide and then you burn the carbon monoxide into carbon dioxide and that's
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where most of the heat comes from right so western engines because you were running very very low
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volatiles in in the in western coal they never had wide fire boxes and you could run a very very deep
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fire and there's there's a typical western fire and you see in um in the museum here there's like king
00:26:14.100
george of fifth you've got a you've got a fire bed that's 11 and a half feet long from the from the
00:26:20.720
door to the front of the fire box is 11 and a half feet okay it slopes down i think it's about two feet
00:26:27.080
it goes down but it's only four feet wide this is the bit where you see someone with a shovel shoveling
00:26:33.780
into a hole yeah and you you go you have quite a few feet long yeah so you've got to go in with
00:26:40.880
the with the shovel and hoik it so as it goes in through the hole which is only about this big you
00:26:46.660
can put it perfectly on a on a corner 11 and a half feet away but you run a very very thin fire at the
00:26:52.760
front and it comes back and it and it basically comes up to the door so at the back the fire's about
00:26:57.880
this deep right very very deep fire and it almost acts as like a gas gasifier essentially and you can
00:27:05.820
you can run it like that because what western engines were good at because of the way the
00:27:09.960
great western was built was they do very very long runs so moderate power for a long time and then
00:27:16.800
there's a nip where you've got to get up like two miles of one in 80 or something like that and you
00:27:21.340
suddenly put an explosive demand on the engine right but it's only for about 10 minutes or so okay and
00:27:26.980
then you're up over the top of the hill and then you're away again so that's that like the chilton
00:27:31.540
what hill what the i thought it was extraordinarily flat from london out to bristol london to bristol's
00:27:37.100
all right okay the bristol to exeter run you go up wellington bank okay and i think it's white ball
00:27:43.060
hill and somebody in the comments will correct correct me because it never really won't be sorry
00:27:46.560
but it it goes from flat as you come across the levels the somerset levels then it starts to go up to
00:27:52.660
about one in 150 and then it which is still pretty flat which is quite flat it's that steep for a
00:27:57.940
railway okay and then it and then it peaks at about one in 80 but that's one in 80 in the tunnel
00:28:03.040
right and then you go through the tunnel and then you back down the other side then you just follow
00:28:07.100
the x all the way down to exeter so that that's what it is there's there's like spurts and south
00:28:13.940
wales has got quite a lot of them cornwall's got quite a lot of them um as well where you do that
00:28:19.200
whereas um if you're burning northern coal which is hard coal which has got a much more um volatiles
00:28:27.240
in it the northeastern railways you see the even back to the great northern atlantics and the and
00:28:34.580
the gresley's engines big wide firebox letterbox to try and get everything through but you get with a
00:28:42.160
hard coal you get a much much bigger flame length all right so you need a much a wide box brick arch
00:28:49.680
combustion chamber and they they ran such a thin fire apparently that you could see the coal dancing
00:28:58.020
on the grate as it's pulling it's literally making the one bit yeah and then as it comes up burns away
00:29:05.120
and you end up with a hole you just put the next one in so they're constantly constantly just guys
00:29:10.600
constantly yeah but it's like half a dozen lumps at a time you just go oh it's going and it goes
00:29:16.080
brighter and it does that as it gets thinner the air comes through it faster and faster and faster
00:29:19.900
it gets hotter and hotter and hotter and then and then you've burnt it it's gone okay so you just
00:29:23.260
see these hot spots you go and and then it goes black next one right and then next one and that's
00:29:31.940
that's what you're doing there's a big thing in like the preserve scene now because we've been
00:29:35.340
using soft welsh coal from fozzy frown for years and everybody's got used to it the mine's shut and
00:29:41.080
we suddenly had to look for other coal and everybody's going you know oh this this stuff's rubbish you
00:29:45.380
know i can't do anything with it it's like no it's just different it's just different right and
00:29:49.680
you're gonna have to learn to be an actual proper fireman not fill the box up and then run it on the
00:29:55.660
damper essentially because most people most people wouldn't know any of that no i didn't know any of
00:30:02.120
that hardly any of that anyway yeah there was different that yeah there would be different um
00:30:07.780
things that if you had to do on different times but i didn't know like the deepness of the coal bed
00:30:13.920
mattered and all that sort of thing and they had to be thicker at the at the far end and all that
00:30:18.840
sort of thing it's fascinating to me yeah and uh one thing before we go back to traumatic and stuff
00:30:25.060
um you're talking about how you put a tremendous strain on the engine having to go up a hill
00:30:31.800
the first thing that popped into my mind was something in bloody india or somewhere where it's
00:30:39.520
a really steep incline really steep you're going up a mountain you've got a steam engine and you're
00:30:44.040
trying to get it up a mountain so like you would be put absolutely insane amounts of
00:30:50.380
yeah you're asking it to do something massive yes yeah so you end up you end up with these engines
00:30:57.740
that have huge boilers right tiny wheels right so that the the leverage from the cylinders onto the
00:31:05.300
wheels is is enormous very slow speeds yeah running shorter distances as possible because they're
00:31:13.740
consuming vast amounts of water of water yeah but then because you've got to get it so hot
00:31:19.540
that it's just it's gonna okay okay i get it and you're just using a lot of steam so you need if
00:31:25.880
you're using lots of steam you need lots of water um but and you probably have like two or three
00:31:30.740
coolies in the tender chucking lumps down to the guy who's actually doing the firing right and
00:31:36.520
he'll be doing it just continuously um so yes but anyway going back to see yeah so trevidic has
00:31:44.540
blown up his first end we hope you enjoyed that video and if you did please head over to