junction was set for Greenwich. It is believed that this was first fixed signal used to control a junction. Greenwich trains ran every 15 minutes, Croydon trains were hourly. The first railway semaphore signal was erected by Charles Hutton Gregory on the railway at New Cross, about 1842. Atmospheric railway In 1844, the L&CR was given parliamentary authority to lay an additional line next to the existing track and test an atmospheric railway system. Pumping stations were built at Portland Road, Croydon and Dartmouth Arms, which created a vacuum in a pipe laid between the running rails. A free-running piston in the pipe was attached to the train through a slit sealed by a leather valve. The piston, and hence the train, was propelled towards the pumping station by atmospheric pressure. The pumping stations were built in a Gothic style, with a very tall ornate tower, which served both as a chimney and as an exhaust vent for air pumped from the propulsion pipe. As part of the construction works for the atmospheric system, the world's first railway flyover (overpass) was constructed south of Jolly Sailor, to carry the atmospheric line over the conventional steam line. The railway experienced many problems with the pumping engines and the valves during 1846, creating dissatisfaction among the shareholders with the directors. The added directors from the L&BR, after the amalgamation in August, were even less interested in continuing the experiment. In 1847, the atmospheric experiment was abandoned. The engine house at Dartmouth Arms was largely demolished in 1851 and an electricity sub-station was built on the site in 1928. Stone from the Croydon pumping station was reused in construction of the Surrey Street waterworks building, which still exists. According to one historian the use of the atmospheric system cost the railway £500,000 and was 'a sad fiasco'. Accidents The railway is not known to have suffered any serious accidents, which is remarkable given its early operation over shared lines. Amalgamation As a result of the poor financial performance of both the L&CR and the L&BR, a group of shareholders organised an amalgamation of these companies with the Brighton and Chichester Railway and the Brighton Lewes and Hastings Railway (both under construction) to form the London, Brighton and South Coast Railway on 27 February 1846. Notes Citations References Whishaw, F., (1840) The Railways of Great Britain and Ireland: Practically described and illustrated London: Simpkin,