£550 (about £ today) each. This order was historically important as the first of these locomotives, Active (later renamed Locomotion No. 1), was the first steam locomotive to haul a passenger train on a public railway. Design The design of Locomotion combined and built on the improvements that George Stephenson had incorporated in his Killingworth locomotives. The locomotive weighed 6.6 tonnes, with many elements, including the boiler, cylinders and wheels, composed of cast iron, although the frame was timber. There were four diameter driving wheels. Locomotion No. 1 used high-pressure (50 psi) steam generated in a centre-flue boiler and driving a pair of vertical cylinders, in diameter, which were half embedded within the boiler. The boiler had a blastpipe in the chimney. The single flue boiler had a low heating surface-to-water ratio compared to later boiler designs. The maximum speed of Locomotion No. 1 was about . A pair of cross-heads above the cylinders transmitted the power through a pair of coupling rods, making use of a loose eccentric valve gear. Locomotion No. 1 is believed to have been the first locomotive to use coupling rods to connect its driving wheels together, an approach which considerably decreased the chance of slipping. According to author H. C. Casserley, Locomotion No. 1 is most notable for being the first locomotive to haul a passenger train on a public railway than for the innovations in its design. Operations The completed Locomotion No.1 was transported by road from Newcastle to Darlington in September 1825. On 26 September, the day before the opening of the Stockton and Darlington Railway, the locomotive was taken on a trial run between Shildon and Darlington, with a number of the railway's directors aboard the railway's first passenger coach, known as ‘’Experiment’’. The driver, who had to perch on a small platform beside the boiler, was James Stephenson, the elder brother to George Stephenson; the fireman, William Gowling, stood on a footplate between the engine and the tender. On 27 September 1825, Locomotion No.1 hauled the first train on the Stockton and Darlington Railway, driven by George Stephenson. The train consisted of Locomotion No.1, eleven wagons of coal, the carriage ‘’Experiment’’, and a further 20 wagons of passengers, guests, and workmen. Around 300 tickets had been sold but about twice as many people were believed to have been aboard. The train, which had an estimated weight of 80 tonnes was