If someone knows a bit about the railways and Isambard Kingdom Brunel, they will have heard of his experimentation in atmospheric pressure on the South Devon Railway from Exeter to Plymouth[1]. This was not the only time that these sort of railways have been discussed or even used in Britain, or indeed the world. Ever since the use of railways and the introduction of the steam engine people have thought about how to move more goods faster. Due to the way rails were constructed at the turn of the nineteenth century, the use of a steam locomotive was not practical. As was seen with the testing of Trevithick’s locomotive at the Pen-y-Darren tramway in 1804 proved. The weight of the locomotive eventually broke the rails, and it was then used as a stationary engine[2]. So, in the true inventiveness style of the industrialist at the time. Other methods were sought out to try.

One method was using atmospheric pressure. This is simply using different levels of pressure to move the train along. Either by adding more behind or taking some away from the front of the plate to use air pressure to push the train along. Possibly the first to look at this was George Medford, who in 1799, proposed the idea of having a carriage in a tunnel which would fit the tunnel and having air blow it through, but this was later amended to having a pipe with a piston attached to the bottom of the carriage[3]. Although these ideas never left paper.

Henry Pinkus did build a working demonstration line using this system along the Kensington Canal, as first he used a square section of pipe, this was later changed to be a tubular one, again with a piston in the pipe and the groove would be sealed with the use of rope. He tried in vain to get investment, which was not forthcoming, particularly when the rope started to stretch compromising the seal[4].

Although it was not a success the idea of using a small bore pipe in the way Pinkus did seem to be the way forward. Ship builders and engineers Jacob and Joseph Samunda working with gas engineer Samual Clegg produced a solution to the problems that were evident in Pinkus’ design. Instead of utilising rope to seal the tube, they used a continuous flap to seal the tube, which would be pushed up by the piston set to the first carriage of the train and after it had past it would fall back down. The other difference was that instead of air being pushed in behind the piston, a partial vacuum would be created ahead of it so the train would be dragged as the air tried to equalise itself[5].

Other ideas on how the railway would work were also discussed and experimented with around this period. Some of them were using a canvas pie, a wooden pipe and using water pressure.

Despite these other ideas, probably the first to be used as a running railway rather than a demonstration was the two mile Dalkey Atmospheric Railway connecting the port of Dun Laoghaire to Dublin. Which took it up a steep gradient of 1 in 57 at its steepest part. This was the longest serving line of this type in the British Isles, attracting the attention of Isambard Kingdom Brunel, amongst others[6].

When designing the South Devon Railway (SDR), Brunel saw the sort of hills in his way, his first idea was to use countless viaducts and tunnels to create the line. After seeing the Dalkey Atmospheric Railway and talking with Messrs Samuda, Brunel decided to take a more direct route believing this type of propulsion would be the answer to the problem. However, the SDR was different situation. The Dalkey was only two miles long and the SDR was over one hundred and twenty and needed pressure both ways. This complicated things greatly, it suffered from lack of power at times due to problems with the pump house and the diameters of the tubes ad various places. Along side of this, there were the problems with the seals along the top of the pipes. The result of this was that the railway had to be converted to be used by steam locomotives, none of which could manage the gradients until Daniel Gooch, Chief Mechanical Engineer of the Great Western Railway designed new locomotives that could cope[7].

Historians and others have often used this experiment into this system of propulsion as a rod for Brunel’s back on many occasions. But the technology was tried and tested for short distances, and it worked. Perhaps it was a case of many innovators of that time. They had the ideas and were willing to push the boundaries, but the materials and technology had not caught up with their minds yet. The idea and use of the atmospheric railways have not died out. A Brazilian company had made successful lines in various places around the world, and both China and the United States are developing systems to be used to bring the technology to more common use, this could move the railways forward and keep them useful well up the end of this century[8].  

[1] Christian Wolmar, Fire and Steam: How the railways transformed Britain, (2007, London).

[2] Alun John Richards, The slate railways of Wales, (2001, Llanrwst).

[3] Howard Clayton, The atmospheric railways, (1966, Lichfield).

[4] Clayton, Atmospheric railways.

[5] J Samunda, A treatise on the adaption of atmospheric pressure to the purposes of locomotion on the railways, (1841, London)

[6] Clayton, Atmospheric railways.

[7] Colin Maggs, A history of the Great Western Railway, (2013, Stroud)

[8] Alan Whiston, Atmospheric railways: A look to the past and the future, ‘The Journal’ Issue 137, Vol 1 (2019).