Lucy Melford: Brunel's Pumping House

The famous nineteenth-century engineer for the Great Western Railway, Isambard Kingdom Brunel, flirted with a novel means of train propulsion in the company's early years. This was 'atmospheric' propulsion. Brunel didn't invent it, but he thought he saw ways to improve it and make it practical for real-life use.

So far as I understand it, a pipe with a continuous slot in the top side was laid between the tracks (there was plenty of room, those being Broad Gauge days). The slot was sealed with a lubricated leather flap. The air inside the pipe was sucked out by coal-fired pumping stations at intervals along the line. Below each train was slung a piston that fitted the diameter of the pipe. As the train moved forward, the shaped rod that connected the piston to the train momentarily unsealed the flap, allowing air to rush in and push against the piston, propelling the train. When working properly, air pressure would push the piston (and the whole train) forward smoothly, and at speed.

I don't quite see how one got the train to start moving in the first place, nor what happened where lines joined or diverged, as that would mean smoothly combining two slotted pipes into one, and yet somehow preserving the vacuum. Tricky.

Brunel was however so confident of his atmospheric system's power to propel trains up quite steep gradients that he built the main line through South Devon with hillier sections than would otherwise be feasible for a single conventional locomotive. This of course saved money in construction costs, and must have been attractive to the GWR, and instrumental in their agreeing to adopt the system. It was up and running by 1847.

You'll have spotted the fatal flaw already: the leather flaps. At the time no better flexible material existed, and no weatherproof lubricant either. The pipes leaked air in, reducing the vacuum and therefore the system's efficiency. The leather quickly split with wear and tear. To cap it all, the fixed pumping stations consumed enormous quantities of coal - the vacuum had to be maintained whether or not trains were running - so what was saved in construction costs was more than cancelled out by mounting coal costs. Brunel had to admit defeat, and in 1848 reverted to conventional steam locomotives. The system had lasted only one year. Unwanted material was sold off at a colossal loss. And South Devon was now stuck with sections of steep railway line that were always a challenge until the diesel era.

Most of those pumping stations are long gone, but one remained at Starcross, on the main line south of Exeter, on the very banks of the River Exe estuary. I went to see it.

Approaching Starcross from the north, I was held up by roadworks. But a dark green GWR train (that's the modern company, not the original one), probably bound for Plymouth and beyond, passed by and relieved the tedium.

Having found a place to park, I first had a look at Starcross station, which is also the western destination of the hourly cross-estuary passenger ferry from Exmouth. This can be seen best in these 1998 shots of mine. You first have to cross the footbridge (from which the pictures were taken: not so easily accessible to me in 2022, with my knee being as it is), then proceed right to the end of the down platform and onwards to a pier, which you then walk to the end of. Quite a rigmarole really, and I wonder how mums with young children in buggies manage, or people with laden bicycles for that matter.

Things looked smarter in 2022, in particular the platforms were tarmacked and not wooden, but otherwise not much had changed. The Italianate roofs and tall tower mark the location of Brunel's Pumping House at Starcross.

Here are some modern (2022) views of the station and its signage.

Another station that would seem bleak and cheerless on a winter day. As it was, the brisk breeze encouraged me to keep moving. I walked along the road to the Pumping House, for a closer look.

I'm guessing that there was once a siding that enabled coal wagons to enter the Pumping House through that arched doorway, to discharge their loads within. The boilers to drive the pistons that sucked ait out of the atmospheric pipes would have been further inside, and the tall tower housed the chimney. By the looks of it, the tower part was the first built, and the rest were additions.

It's all very solidly constructed from stone, with ornate features abounding. But then railway architecture was often elaborate, even for workaday buildings that the public had no access to. Such impressive buildings couldn't have come cheap. But the railway wanted the investing public to know that their money wasn't wasted on flimsy constructions.

And of course, the Pumping House has lasted for 180-odd years, which shows how Brunel's designs typically stand the test of time. Nowadays the Pumping House is the headquarters of the local 'fishing and cruising' club. You'll notice a ramp leading down to a tunnel under the railway. I couldn't resist having a look.

Hmm. wet and uninviting! I didn't venture through.

Back at the Pumping House, I saw a red plaque and a nearby a panel that explained the history of this particular location. Amazingly, the underground reservoir of water needed to provide steam for the pumping engine was long forgotten and only recently rediscovered in 2018, perfectly preserved.