From The Illustrated London News of 6 January 1844.
There is a book by Arthur R Nicholls called 'The London and Portsmouth Direct Atmospheric Railway. A Mere Puff of Wind': the title tells you all you need to know about an ambitious and elaborate idea which swiftly evaporated.
What is an atmospheric system?
In basic terms an atmospheric system is one powered by a 'rope of air'. The underlying principle is as simple as a cylinder vacuum. In a vacuum cleaner a sweet wrapper is moved along the hose towards the fan partly by suction but mainly by the higher air pressure pushing from the nozzle end. In the railway scheme the sweet wrapper is replaced by a piston running in a pipe laid on the sleepers between the rails. The piston is connected to a rod that passes through a slit that runs along the top of the whole length of the tube to the first of a series of carriages that form the train. The air is sucked out of the tube by stationary engines at pumping stations spaced at several miles apart. The main technical difficulty at the time in question - roughly 1840 - was to perfect an air tight seal that would allow the rod to pass through the slot.
Jolly Sailor pumping station on the London to Croydon line, with atmospheric train. Image source: The Pictorial Times via Wikimedia Commons.
The initial impetus for the ultimately ill-fated venture came from a paper on atmospheric locomotion by Joseph d'Aguilar Samuda, who was then invited by the London & Croydon Railway to supply equipment for an atmospheric system between London Bridge and Epsom. Before we get into the evolution of this particular project, some general information about the state of the railway system at that point (early 1840s) would be timely.
The first public railway in the world to use steam locomotives was the Stockton & Darlington, which opened for business in 1825.
The opening of the Stockton & Darlington Railway in 1825. Image source: Wikimedia Commons.
From then on railway companies and sections of track proliferated. This was nothing like a fully 'joined-up' system, but a rambling collection of lines, run by enterprises which envisaged a handsome profit in their particular project. It was often a case of trying to run before they could walk, since there needed to be very substantial investment in land purchase and infrastructure (especially large-scale infrastructure, such as bridges) and in the early stages the locomotives were not that reliable or safe.
Locomotives were very heavy, compared to the carriages they pulled, and they needed lines a third heavier than those needed for atmospheric trains. Early locomotives needed help climbing steep hills so more engineering work was needed to build embankments and cuttings: this, together with the large support infrastructure, meant the cost implications were large (capital costs of £37,600 per mile with running costs of £4,130 per mile, as against capital of £15,120 and running costs of £1,626 per mile for an atmospheric system - 1839 figures). We will come to the accuracy of the figures shortly.
Example of an 1840 locomotive. Image source: Wikimedia Commons.
As for safety issues, only one train could work a section of atmospheric track at any one time and was more stable on sharper curves, so such trains were considered inherently safer than conventional systems. Environmentally the atmospheric system was to be quiet in operation and there was no risk of smoke or hot glowing sparks escaping along the track - something that worried farmers with hayricks and property owners. The static engine houses used cheap coal compared to the coke used by locomotives, they had tall chimneys so smoke was dissipated and the risk of sparks was eliminated. Additionally, there was no chance of the boiler on the locomotive blowing up! The viability of the new system sounded too good to be true and, of course, it was.
Amazingly it seems that the atmospheric cost claims were never subjected to close analysis and the actual costs were probably very much greater. On a Devon system the estimated cost for atmospheric equipment (i.e. not including the track) was £6,620 per mile, but in reality it was nearly three times as much - £21,700.
The technical details - how atmospheric systems worked (or were supposed to work)
The idea of using air pressure started with George Medford who in about 1810 proposed transporting goods and people through a pipe using compressed air. He carried out various experiments and realised that people did not like the pressure differentials or travelling in his windowless experimental carriages. He suggested that the passengers could be carried in carriages outside the pipe, connected by a rod to a piston in the pipe. He even came up with a couple of different ideas for the longitudinal valve. In 1834 an American living in England, Henry Pinkus, invented a different type of valve but the one that was to be used in the main experimental lines in the UK was invented by Samuel Clegg, a gas engineer, with Jacob and Joseph Samuda (boat builders and engineers).
One has to bear in mind that the materials we would think about using today to make a reliable airtight seal simply did not exist in the early 1800s. Charles Goodyear did not patent his rubber vulcanization process until 1844 and mineral oil only became available in large quantities after 1854, when the world's first oil refinery was opened in Poland (the first American oil well did not open until 1859) and flexible plastics only came in the 20th century.
Diagram of the leather flap at the top of the tube. Based on the original drawing by Joseph Samuda November 1846
So in the Clegg-Samuda system the slit was covered by a leather flap held along one long edge by bolt-hooks pulling on a retaining rod. The other long edge rested on a narrow bed of tallow and beeswax that helped to form the air tight seal. Above the sealing edge was riveted a series of 8 inch long metal strips resting on a second narrow strip of leather. The short metal strips let the leather flex sufficiently to allow the rod to move along the pipe and helped the flap fall back into place. The second layer of leather was used to reduce the risk of the metal strips cutting into the main leather of the flap.
The leather flap was lifted just ahead of the rod by two small wheels attached to the leading carriage. Behind the rod were two further wheels to let the flap fall back down in the correct position. The short metal strips helped to keep the flap flat and were used by a further sealing wheel running along the top of them.
Diagram based on the Clegg and Samuda Patent Click image to enlarge.
The piston was attached to a curved arm (sometimes described as a rod or a plate), which extended through a slot to the carriage.
That is probably enough technical stuff, so let's move on to the grand plan of the London & Croydon
London to Croydon with extension to Epsom
A Proposed Atmospheric Railway Station on the Croydon Epsom Line. From The Illustrated London News of 01 March 1845.
I am indebted to the book entitled 'Atmospheric Railways' by Charles Hadfield (David & Charles 1967) for a detailed narrative on this subject and I will attempt to pick out the salient points here.
As mentioned earlier, there were many companies and lots of bits and pieces of track and the first problem was that one part of the proposed route for the new atmospheric railway belonged to the London & Croydon (L&C) and another part was run by the London & Greenwich (L&G).
Route of the London Croydon Line. From The book 'Atmospheric Railways' by Charles Hadfield.
The L&G built London's first steam railway, which eventually ran from London Bridge to Greenwich, which is around 5 miles as the crow flies: this illustrates exactly how fragmented the railway 'system' was in that era. About halfway along this line was a station called Corbett's Lane, which had a junction with the L&C route into London. To cut a long story short, having announced their new project in the summer of 1844, L&C did a complicated deal with L&G, the outcome of which was that the latter would have an extra line for atmospheric trains between London Bridge and Corbett's Lane (funded by the former via a mixture of outright funding and loans), a distance of 1.75 miles.
I'm afraid that there is a further company to stir into this stew and that is the London and Brighton Railway (L&B), which ran into London via a junction called Jolly Sailor, subsequently re-named Norwood, and really it was the L&B who became the villains of this piece, aided and abetted by the deficiencies of the atmospheric system.
Various members of the Cubitt family (e.g. Sir William Cubitt and his son Joseph) were at the helm of this project which, if finished, would comprise 20 miles of tube and it started with construction of the section between Croydon and Forest Hill (then known as Dartmouth Arms). Despite the fact that there were problems with a lack of plans, to facilitate purchase of necessary land, work began in October 1844. In July 1845 a decision was taken that the Epsom extension would be double-tracked. Progress on the first section from Croydon to Forest Hill was so rapid that on 20 October 1845, ten piston carriages packed to the gunwales with 'ladies and gentlemen', replete from the L&C's corporate hospitality, travelled the five mile stretch in 8.75 minutes, reaching a maximum speed of 52 mph.
Two weeks later L&C announced an amalgamation with L&B, which was where the rot set in.
The L&B obviously had a much longer stretch of track than the other companies involved and had made heavy investment in locomotives, rolling stock, staff and infrastructure. In other words they had a very vested interest in steam and did not want competition or disruption from the upstart atmospheric system. Although there were now some L&C directors on the L&B board, it seems that information was withheld from them - principally that the L&B had an agreement with the London and South Western Railway concerning the Portsmouth line, which did not include provision for atmospheric traction.
There were plenty of hitches in the London to Croydon project and many disagreements among the principal players. Joseph Cubitt, the engineer, said that he did not want the Epsom extension begun until he was sure the rest of the system was reliable and commercially viable, whilst Joseph Samuda, who was supposed to be in sole charge, delivered a substantial amount of rails, valves etc for the extension.
Caricature of Joseph Samuda from Vanity Fair of 15 February 1873. Image source: Wikimedia Commons.
Cubitt realised that the traffic on the atmospheric line was already outgrowing the power available, the reason being that the tubes were too small in diameter. So, in August 1846 he decided to complete the existing work on the London to Croydon section and then establish what was needed in the way of improvements. In the meantime, he said, the Epsom extension would operate as a locomotive line.
As mentioned above, the L&B (now the London, Brighton and South Coast Railway - the LB&SCR) did not want to operate an atmospheric system at all, so produced figures showing how expensive it would be. Samuda responded with completely different costings. While all this wrangling was ongoing, the contractor building the Epsom extension (including new stations at Carshalton, Sutton, Cheam, Ewell and Epsom) needed to know what type of line it was! In December 1846 the board decided it would be for locomotives.
BUT … and you knew there would be one … there was the issue of locos running from Epsom to Croydon, piston carriages between Croydon and Forest Hill and then locos again into London. The LB&SCR had an idea and agreed to extending the atmospheric line another 2.5 miles from Forest Hill to New Cross. Why? Because they knew that it was impossible, since the tubes were too small to power the carriages up the incline at New Cross. Samuda was furious and was then told that the Epsom extension would not be an atmospheric line and it opened with locos on 10 May 1847. The entire atmospheric project was abandoned in that same year.
There were subsequent experiments with pneumatic railways, including a section of New York subway, but the system was plagued by problems and never caught on.
These days, technology has moved on and the Aeromovel company has devised an atmospheric system which is actually in operation over two very short (2 miles or less) stretches in Brazil and Indonesia. Fundamentally it works on a similar principle to the 1840s experiments but the train runs on an elevated track mounted on a concrete 'tube', which acts as the air duct, and the troublesome leather flaps are now made of rubber.
The Aeromovel of Porto Alegre, Brazil. Photo by Programa de Aceleracao do Crescimento via flickr and licensed under this creative commons licence.
Researched and written by Linda Jackson with help from Peter Reed. Jan. 2016