SAMUDA/CLEGG PATENT
The patent obtained suggested the use of a hinge of leather, plated with iron, the lower plate convex to fit the circular tube, sealing composition and a heater, so providing what seemed like a practical solution to the problem of keeping an atmospheric tube reasonably free from leaks.1
The basic principle involved was that of a pipe which would have the air within pumped out, thereby creating a vacuum. As nature abhors a vacuum, anything in the pipe would move along the pipe in an attempt to close the vacuum. If this object was a piston, connected to the outside world through an otherwise sealed opening (apart from the small section necessary to allow this connection), carriages could be connected to the piston and thereby be moved by this act of pumping.
The Samuda's initial experiments were located at their ironworks in Southwark, followed by an experimental line at Wormwood Scrubs in London. But the idea needed a commercial line to prove its point.
DALKEY QUARRY TRAMWAY/ATMOSPHERIC RAILWAY.
The Kingstown Harbour Commissioners built a double track tramroad for a quarry tramway from Dalkey Quarry to their harbour under construction at Kingstown. This was opened in 1816 as a funicular railway, the weight of descending full wagons hauling back the empty wagons.
Principal work on the piers was completed in 1836. At this stage, the D&KR proposed to take one of the two tracks and works carriages by horse power. No Act of Parliament was sought and ultimately, the scheme was not proceeded with.
Atmospheric system.
Arising out of the Wormwood Scrubs trials, James Pim, the D&KR Treasurer became an Atmospheric enthusiast. The D&KR issued a pamphlet by Thomas Bergin, their Secretary, extolling the virtues of the system for extension of the D&KR line to Dalkey. No Act was sought as this prevented the public knowing too much about what was taking place and the extension was financed by D&KR out of their own resources. This led to problems which have ramifications to this day. 5 public roads had to be crossed en route to Dalkey. As there was no authority to cross these on the level, a cutting was necessary. The Treasury agreed that one track of the tramway could be surrendered.
On 6th April 1842, D&KR agreed that extension to Dalkey should be atmospheric. The agreement reached with the Samuda's was that the D&KR could install the atmospheric system free of royalty and would receive a percentage of any royalties from use elsewhere in the United Kingdom (then Britain and Ireland). On 26th September 1842, ceremonial handing over the line by Board of Works by solemn delivery of "sod and twig", as emblems of possession.
Vignoles was the engineer responsible for the design of the line and Dargan was the contractor, responsible for the cutting and associated bridges. The Samudas provided the mechanical equipment necessary for atmospheric operation. Construction started and residents objected to the making of a cutting along the harbour frontage. Correspondence ensued between the State institutions concerned, out of which, the public were advised that no legal right of access to the harbour existed.
Faced with this reality, the objectors altered their demand to that of a tunnel, to which the D&KR raised engineering problems which would ensue if they acceded to this request. The inevitable compromise reached was that part of the line, from Kingstown Station to the Harbour Master's house was covered in. This was not without incident as in January 1868, shortly after a train had passed by, part of the cover fell in. 7 years later, another section fell while a horse and cart was on it.
On 19th August 1843, the first public train ran from Glasthule (Sandycove) to Dalkey. As the line was unfinished and officially still being tested, no fares could be charged and passengers were carried free of charge. The full line opened on 29th March 1844 and closed 10 years later on 12th April 1854, to allow for conversion to a standard gauge (5'3") conventional railway.
Operation.
At Kingstown, prior to departure, the train was pushed by hand until the piston was contained within the tube. The train's brakes were then applied to hold it until departure. 5 minutes before departure time, the engineman in Dalkey was instructed to start pumping to create the necessary vacuum. When this had reached the necessary level, a starting signal was given and the driver released the brakes.
Engineering.
Clearance between the line and bridges overhead was only 8½ feet, achievable due to the fact that there were no locomotive chimneys to accommodate. The main pipe, through which the piston ran was only 2490 yards long, 560 yards short of the Dalkey terminus. Over this latter section, the train ran on its own momentum. Occasionally the train would either undershoot or overshoot the station. In the former instance, it was necessary for passengers to get out and push. The return journey from Dalkey was by gravity, the piston being lifted clear of the pipe for this run.
Notes:
1. Hadfield - Atmospheric Railways; David & Charles 1967.
