Historic sewage systems

In the 1800s cholera swept through Cambridge, until the installation of a state of the art steam engines...
25 July 2022

Interview with 

Jinx St Leger, Cambridge Museum of Technology




Rising up from the banks of the River Cam, is a tall chimney like structure, the tallest thing to emerge from the city's skyscape. The structure belongs to the Cambridge Museum of Technology. Jinx St Leger, the chief engineer, waits for Harry Lewis and James Tytko at the museum entrance... 

James - It's a special treat for us Jinx, this.

Jinx - Yes. Yeah. Well, you know, there's nobody else here.

James - So why is that? Why is it closed?

Jinx - The museum's actually only open at the weekends at the moment. We are really reliant on volunteers and we just don't have that many people that volunteer. So at the moment we are only open Saturdays and Sundays.

James - And can you tell me the Cambridge Museum of Technology - What's the story? Because this didn't look like it was originally built to be a museum.

Jinx - No, very much not. It was a very, very practical building. These two very beautiful engines, in this main engine hall, actually originally pumped sewage. So in the 1800's, there were several outbreaks of cholera in Cambridge because the Cam was an open sewer. So after several outbreaks of cholera, it was decided that they needed to treat the sewage somehow - get it out of the river. And this station was built to pump that sewage to Milton, where the sewage works still currently is, they're looking to move it, but it is still currently being treated in the same place it was over 120 years ago.

James - And could you talk me through what I'm looking at here? This is visually very impressive.

Jinx - Well, they're stationary steam engines. So we have two engines in here. These two, as far as we know are the only two left in the world and they both work. We also have around the room, some smaller engines that were originally used to pump water into the boiler from steam. So, originally, they would've pumped water from the river, but now we don't do that. We come from the mains and we then pump it that way.

James - If I were to come back another time, when might I be able to see these engines in action?

Jinx - So we have just got back into steam. We had our first steam event in many years in April because we'd had the boil refurb, so we couldn't produce steam before that. And then we had another one in June. We're looking to have another steam event in September.

James - But when you say a steam event -

Jinx - Oh, see, I'm using the terms of the community. So, a steam event is basically when the museum or any place that runs steam engines will raise steam, runs engines. And it's a bit of a family event really. And there is very much a steam community. So it's not just people running steam engines. We are like a small family and, and we work as a community together to do that. So the colloquialism is 'steam up'. So if you are a steamy, if you're in the steam community, you say we're having a steam up. <laugh>

James - I wonder if we could have a look at some of the components of these enormous engines.

Jinx - I'd like to show you this big wheel here. So, obviously there's one on each engine. So, when we run this, before we start the engine at a 'steam up', I will turn to the audience and say, "how do you think the steam engine works"? And pretty much 99 times out of a hundred, people will say that big wheel spins round. And it doesn't, because it's connected to a tiny beam. And actually that wheel only revolves 90 degrees. It rocks backwards and forwards. So we often say our engine is very beautiful, but not very dramatic. It's always kids that notice it. It's never grownups, grownups never notice that that doesn't spin. It's always the kids going well, there are two rods going through the floor.

James - So the engines that we can see right now, that's not everything that's going on here when the whole thing's operational.

Jinx - No, absolutely not. This is a very attractive tip of an iceberg. There are several floors below us. Some of them are now flooded with water.

James - Where next?

Jinx - I can show you through to the gas engine room.

James - Let's do that.

James - Okay. It looks kind of similar jinx to what's in the other room, but I'm sure it's, it's very different. What can you tell me about what I'm looking at right now?

Jinx - Right. So these are very different. These are gas engines. The problem with a steam engine is you can't just flick a switch and get it to go. It needs to be warmed through. It needs to sort of be prepared. It needs to also work under load. Not so with the gas engines, you can pretty much flick a switch on these and they will start working. They don't need to have a load on them. So as the size of Cambridge grew, there was more population, more sort of flash flooding because obviously the ground had been covered. So the ground and the water wasn't soaking away in the same way, and they needed more engines, and this was the ideal accompaniment to the steam engines, because basically you could flick a switch and off you go.

James - How much water did they need to move?

Jinx - Now that's a tough one. And obviously it depended on how much rain there'd been and how much sewage there was. So I can't really give you an exact answer off the top of my head, but it had to move three miles up a slight hill - as hilly as the Fens get - to the sewage pumping station. So it was quite an ask.

James - And what sort of effect did that have on the cholera outbreak?

Jinx - Well, just having the steam engines here basically stopped that because the Cam was no longer an open sewer. So, as soon as that was being dealt with, no more cholera. Wonderful.

James - Jinx, we've entered a bit of a cavernous expanse with bits of machine everywhere. What's going on in here?

Jinx - So this is the boiler house. So obviously you can't run steam engines without steam, and this is where the steam is generated. So it's a big old place. The biggest boiler is about the size, It's about the height of a house, and about half the width of a, sort of a fairly decent sized house. And we have two smaller boilers. The ceiling here is really, really high. It used to get extremely hot. So one of the reasons you would have tall ceilings is because of the heat in here as well. When the plant was working, the engine room would've been pristine. So nice, shiny ceramic tiles, very, very beautiful. Boilerhouse was very much the opposite. So you can tell it's dusty. You can tell that things were burnt in here. All the walls are kind of this off-white. It doesn't look run down, but it does look like it's the business end, it really does.

James - How does it work?

Jinx - All our boilers here are Babcock and Wilcox and that company has been going for a very, very long time. The boilers are all water tube boilers. So, inside the boilers, they have big tubes filled with water and you put fire under it and that creates a steam. Initially, fuel was pretty free. The council collected rubbish, the rubbish was sorted up that top area, which is called top bay. Anything with a high calorific value was burnt and other things could have been reused or recycled. Later on, the destructive boilers were adapted. When the calorific value of the rubbish went down, the fronts of the boilers were changed so they could be stoked with coal. And then the final, the grand lady of this area is boiler number four. So boiler number four was put in in 1923, so she's nearly a hundred years old. And she's really the reason that I ended up working at the museum.

James - Why is that?

Jinx - So I was a volunteer here for a while and they needed somebody to project manage the restoration of this historic boiler. She was in a bit of a bad state. The problem with industrial heritage is that when it's in its working life, it's constantly being used and maintained, and all those things that you do when you have a working plant. When you have something that then becomes static, it becomes prone to rust and decay because it's not being used all the time. She had basically failed at a steam up in 2014. Right in the middle of the steam up, some of her tubes bursts. The curator at the time, alongside with some of the trustees, applied for a heritage lottery grant and basically they needed somebody to run the project, to restore the boiler. So that's where I came into the museum.

James - What's the process of restoring something as complicated as this?

Jinx - Well, the thing is, it's not complicated. When I came here and I was talking to the subcontractors before we started work, they basically said ""oh, it's not complicated. It's a big kettle, which might be an oversimplification, but not by much. So, you're heating water, you're putting it into a drum and the steam's coming off the drum and powering the engines. But, unlike the boiler you might have at home, most of the walls of this boiler are made of brick. So the big complications we had to take the walls, one of the walls down before we could get inside to sort out the tubes that was complicated because we didn't know what was historic and what wasn't. Because this is a protected building, we had to establish how old the wall was. And then we found out it'd been rebuilt in the 1980's by the volunteers, so then it wasn't a problem anymore. We took the wall down, and we removed all the tubes. That sounds very easy, it took a long time, and then there were some innards that needed to be replaced. And then tubes went back in wall and went back up. The whole process took well over a year because we had to have different contractors on site at different points.

James - I'm desperate now to see the rest of that iceberg we talked about earlier.

Jinx - Well, Just because it's you guys, I can do that.

Harry - <laugh> Jinx, You're an angel <laugh>.

Harry - Through here?

Jinx - Yeah. Through here.

Harry - That's a slight on my sandals. Not really appropriate footwear for any engineering.

James - No, not for a place of work like this. Down the hatch. We've opened up a sort of cellar-type area. There's some ominous humming going on, emitting from it, and a sort of rusty looking ladder that we're about to climb down. I mean, after you, Harry.

Harry - It looks very traditional. That's what I will say Jinx.

Jinx - Yes. Yeah. It's not rusty and it's perfectly fine. But the ominous humming you can hear is the ventilation system, because this is a confined space. So, obviously we want to adhere to health and safety. So, even though this is a very old building, we've got modern engineering practice here. So we have it just to make sure the air's nice and fresh under the engines.

Harry - Oh, how slim are these people? Jinx? <Laugh>.

Jinx - Uhh, slimmer than you.

Harry - Yeah. Obviously. It really feels like the belly of the beast down here. Doesn't it? Yeah. What an absolute trip back in time, it feels like. Suddenly, we are surrounded by all these old components.

Jinx - So you've got two sets of pumps here. You've got what are called air pumps, and you have the actual main pumps that would be pumping the sewage. So, already where we are, it is a very high ceiling and there are several of those below us. Like I said before, a couple of them are actually flooded through. So this might look very unattractive and unappealing, but like with the beautiful engines at the top, we need to work on these. On the top of each section of the pump, we have these little yellow boxes, which you probably wouldn't notice, but every time we start the engines, we have to pour oil in there and we have wicks like you would have in a candle. And that helps the system all lubricate.

James - Wow.

Jinx - It's never ending. There's always something to do. Always something to prettify. I'm concerned, basically, with these engines in the main engine room, but there's a whole site with other things on it that need to be done. We also are looking to encourage more young people into engineering. So in the future, we're looking to have a program where young people can come and work alongside some of our volunteers and get some engineering experience as well. So I think that's one of the next big things and obviously steam ups.

James - We have to get ourselves down to the next one.

Harry - I will. Yeah. And what's fascinating is, later on, we've spoken about cholera and sewage in the Cam. Well, later on, we're speaking to Susanna and Anne as well, they're doing some real life time monitoring of the pathogens and bacteria that are in the river at the moment. So we are going literally from the history of the river Cam and sewage to the future. So, Jinx, thanks for grounding us in such good knowledge.

Jinx - Yeah, thanks for coming.


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