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| English
engineer who built the first successful steam locomotive. He also invented
a safety lamp independently of Humphrey Davy in 1815. He was appointed engineer
of the Stockton and Darlington Railway, the world's first public railway,
in 1821, and of the Liverpool and Manchester Railway in 1826. In 1829 he
won a prize with his locomotive Rocket. Experimenting with various gradients, Stephenson found that a slope of 1 in 200, common enough on roads, reduced the haulage power of a locomotive by 50% (on a completely even surface, a tractive force of less than 5 kg/11 lb would move a tonne). Friction was virtually independent of speed. It followed that railway gradients should always be as low as possible, and cuttings, tunnels, and embankments were therefore necessary. He also advocated the use of malleable iron rails instead of cast iron. The gauge for the Stockton and Darlington railway was set by Stephenson at 1.4 m/4 ft 8 in, which became the standard gauge for railways in most of the world. Stephenson was born near Newcastle-upon-Tyne and received no formal education. He worked at a coal mine, servicing the steam pumping engine, and it was there he built his first locomotive in 1814. After the Liverpool and Manchester railway opened 1830, he worked as a consultant engineer to several newly emerging railway companies, all in the north of England or the Midlands. In his first locomotive, Stephenson introduced a system by which exhaust steam was redirected into the chimney through a blast pipe, bringing in air with it and increasing the draught through the fire. This development made the locomotive truly practical. With his son Robert, he established locomotive works at Newcastle. The Stockton and Darlington Railway was opened 1825 by Stephenson's engine Locomotion, travelling at a top speed of 24 kph/15 mph. Stephenson was engaged to design the railway from Manchester to Liverpool, but there was an open competition for the most efficient locomotive. Three other engines were entered, but on day of the trials the Rocket was the only locomotive ready on time. It weighed 4.2 tonnes, half the weight of Locomotion. |