The system was designed and patented by the Samuda Brothers. The pipe was laid in sections between the broad gauge rails with a continuous slot along the top that was sealed by a leather valve. The buildings that housed the boilers and engines were built in a decorative Italianate style with square chimneys and spaced at around intervals. The 1845 contract for 24 engines comprised sixteen of 33 inch cylinder diameter, and eight of 12HP, and was split between Boulton and Watt and 'Messrs Rennie', probably J. and G. Rennie. The engine that pumped each section was the one towards which the train was travelling, for example a train leaving Exeter was powered by the Countess Wear engine creating a partial vacuum in the pipe in front of the train which was then propelled forward by the normal atmospheric pressure in the pipe behind the train's piston. Pumping started up to eight minutes before the scheduled departure of the train so as to build up a sufficient vacuum. At stations a smaller pipe was laid alongside the track and a piston in this was connected to the train by a rope to start it moving. On arrival at the next station it was up to the driver to bring the train to a stop using its brakes. Engine houses were situated at every station except Exeter St Thomas where the driver had to hold the train against the atmospheric pressure with the brakes. The level portions used pipes but the steeper gradients west of Newton were to have used pipes. It is not clear how the change between the two pipe sizes would have been achieved unless the piston carriages were changed at Newton. It is also unclear how the level crossing at Turf was operated as the pipe projected some way above the rails. Speeds of up to 70 mph were achieved, but service speeds were usually around 40 mph. The timetable allowed 55 minutes for the journey, but records show that 36% of trains arrived more than five minutes early, some by more than ten minutes.
Engine house remains
Turf
The remains of Turf engine house can be seen on the river side of the line just where the railway comes alongside the River Exe near Turf Lock, the entrance to the Exeter Canal. The square pond surrounded by trees on the river side of the line was the main water reservoir. Just to the south of this, the foundations of some buildings can be seen. This was where the engine house itself was built, although some of the foundations are from later alterations. The building was demolished about 1860 and the stone used in a nearby farm.
Starcross
The most familiar engine house, and the most intact one which actually saw service, is situated on the landward side of the line at the south end of Starcross railway station. The chimney, reduced in height for safety many years ago, had for a while a new pitched roof, but it has since been removed. Unlike the other engine houses this one is built of Heavitree stone from Exeter, a coarse red sandstone that has not weathered well. The accompanying photograph from 2007 shows the original wall along the narrow street called The Strand, but within the next decade it had to be rebuilt with a concrete surface painted to resemble stones. After the engines ceased work, the boiler house was used by coal merchants until 1981. The engine area was used as a Wesleyan Church from 1867 to 1958, after which it was used as a youth club for a few years. The whole building was sold and reopened as a museum for the atmospheric railway in 1982. This has since closed and the building was developed internally for use by the local Starcross Fishing and Cruising Club.
Dawlish
Although largely demolished in 1873, part of the engine house wall can be seen at the back of Dawlish railway station car park.
By the time the railway opened to Torquay the decision had already been made to abandon atmospheric working, so this engine house was never used. However it was completed and is the surviving example with the least amount of exterior modification. It is also the one least easy to see from trains; it is about on the side of but is on a higher level above the line. It can be more easily viewed from a supermarket car park in Newton Road. The location so far from the terminal but uphill from it shows that southbound trains were intended to run the last mile by gravity.
Totnes
The engine house adjacent to Totnes railway station was never brought into use. It was converted for use as a milk processing plant for Dairy Crest but this has since closed. The original chimney, still present in a photograph of 1925, was removed many years ago.
