to the risk of steam engine boiler explosions (then a very real possibility). Samuda also rebutted criticisms of his system that had become widespread: that if a pumping station failed the whole line would be closed because no train could pass that point; Samuda explained that a pipe arrangement would enable the next pumping station ahead to supply that section; if this was at reduced pressure, the train would nonetheless be able to pass, albeit with a small loss of time; that leakage of air at the flap or the pipe joints would critically weaken the vacuum effect; Samuda pointed to experience and test results on his demonstration line, where this was evidently not a problem; the capital cost of the engine houses was a huge burden; Samuda observed that the capital cost of steam locomotives was eliminated, and running costs for fuel and maintenance could be expected to be lower. A patent In April 1844, Jacob and Joseph Samuda took out a patent for their system. Soon after this, Joseph Samuda died and it was left to his brother Jacob to continue the work. The patent was in three parts: the first describing the atmospheric pipe and piston system, the second describing how in areas of plentiful water supply, the vacuum might be created by using tanks of water at differing levels; and the third section dealt with level crossings of an atmospheric railway. Dalkey Atmospheric Railway The Dublin and Kingstown Railway opened in 1834 connecting the port of Dún Laoghaire (then called Kingstown) to Dublin; it was a standard gauge line. In 1840, it was desired to extend the line to Dalkey, a distance of about two miles. A horse tramway on the route was acquired and converted: it had been used to bring stone from a quarry for the construction of the harbour. It was steeply graded (at 1 in 115 with a 440-yard stretch of 1 in 57) and heavily curved, the sharpest being 570 yards radius. This presented significant difficulties to the locomotives then in use. The treasurer of the company, James Pim, was visiting London and hearing of Samuda's project he viewed it. He considered it to be perfect for the requirements of his company, and after petitioning government for a loan of £26,000, it was agreed to install it on the Dalkey line. Thus became the Dalkey Atmospheric Railway. A 15-inch traction pipe