In the early years of steam railways one of the operational problems was the low power of the locomotives. The solution to this was to build the grades as level as possible. The massive embankments, cuttings, tunnels and bridges that were engineered to this end have, 160 years later, provided superb racetracks for present day high speed trains.

Isambard Kingdom Brunel, the engineer who was responsible for the Great Western Railway found himself in a quandary. The branch lines that fed these super mainlines could not generate enough returns to justify high standards and so were built with steeper grades etc. At that time the solution to steep grades was to install steam winches to drag the trains. This was barely cost effective and was an operational nightmare. Part of Brunel’s South Devon Railway posed such a problem and the famous engineer was sorely pressed for a solution.

The solution he chose was not unlike our Skytrain in that it did not rely on wheel adhesion for traction. Electricity and linear motors were unavailable but he was attracted to a patent held by the brothers Jacob and Joseph Samuda. In 1839 they patented an idea that had been around for a while, an atmospheric railway.

This consisted of a large cast iron pipe laid between the rails with a slot in the top. A piston inside the pipe was connected by a bar through the slot to the ‘hauling’ car. The slot was sealed by a long leather flap and when a vacuum was introduced into the pipe the car was sucked along the track. The demonstration track was laid at a 1.2 per cent grade and the contraption hauled 5 tons at 30 mph and 11 tons at 22 mph. Despite some criticism this caught the attention of a lot of people including the directors of the Dublin and Kingstown railway.

These gentlemen took the plunge in 1843. They built a passenger carrying atmospheric branch line between Kingstown and Dalkey. The Samuda brothers provided a 100hp steam vacuum pump with a thirty foot diameter flywheel fed by three boilers and a 15”dia. pipe was laid for 2490 yards, the last 100yds. being ‘coasted’. The average grade was 1.28 per cent, and in places was steeper. Five minutes before departure the engineman would start pumping down the pipe and the train brakes would be set. When the brakes were released the train glided smoothly up the hill, no smuts, no soot. The return was made by gravity. 30 mph was quite normal uphill, sometimes more.

The fastest ascent was made by Frank Ebrington, an engineering student and one of Ireland’s unsung heroes. Frank was seated on the hauling car waiting to do a test run when it was sucked away, someone having forgotten to hook up to the rest of the train! The train travelled the branch line in one and a quarter minutes at an average of 85 mph. Maximum speed was 100 mph. The track had considerable super elevation and of course the piston in the pipe helped keep the car on the track. It is not recorded whether Mr. Ebrington ever rode again or if he recovered from the trauma of being the fastest man on earth!

Brunel, however, was smitten. He decided this system would help solve some of his problems. He proceeded to fit a section of the South Devon Railway with the atmospheric system. Over the severely graded section from Exeter to Newton Abbot the 10ft. sections of 15in. pipe were laid between the 7 foot GWR rails. Pumping stations were built and upon opening trains of 28 tons travelled at 64-68 mph and those of 110 tons at 30 mph, all this with 16” of vacuum in the pipe. The speed capabilities enabled the lost time on the locomotive hauled sections to be recovered on the atmospheric section.

As one can imagine, there were many bugs to be sorted. The biggest problem was the leather flap. It froze in the winter, the rats (the line is by the sea) chewed on it also, and this caused leaks and then poor vacuum. Brunel of course had lots of solutions, as did the Samuda brothers, but the system was expensive and the GWR board stepped in and shut down the atmospheric system. Brunel had plans (and material on hand) to extend the system with 22” pipes on other subdivisions, but it was all for naught.

Other atmospheric systems went the same way except for one in France, 10km long from Nanterre to St. Germain. With its 25” pipe and 3 per cent grades it soldiered on until 1860. Here’s a thought! Imagine what size pipes it would take to move a 15,000 ton coal train!

If you are fascinated by excellence in imaginative engineering I recommend the many books on Isambard Brunel and his father Marc Brunel. The only limit to the genius of the Brunels was the materials available to them.