the last train which he introduced known as the Killingworth Billy ran until 1881. The first intercity railway between Liverpool and Manchester was built by Stephenson in 1830. These systems, which made use of the steam locomotive, were the first practical form of mechanized land transport, and they remained the primary form of mechanized land transport for the next 100 years. The first railroad built in Great Britain was the Stockton and Darlington, which opened in 1825. It used a steam locomotive built by George Stephenson and was practical only for hauling minerals. The Liverpool and Manchester Railway, which opened in 1830, was the first modern railroad. It was a public carrier of both passengers and freight. By 1870, Britain had about 13,500 miles (21,700 km) of railroad. In 1879, electric locomotive development was booming in Germany. In the late 19th century, Werner von Siemens demonstrated the first experimental electric passenger train. The train transported around 90,000 people and worked on the concept of insulated third rail to supply electricity. In 1881, Siemens built the world's first electric tram line in the Berlin suburb of Lichterfelde. Following this trend, many such initiatives were set up in Brighton and Vienna in 1883. Diesel locomotives A new type of railway locomotives was developed by Dr. Rudolf Diesel, which involved a new internal combustion method to propel the railway. In 1892, he proposed this method and soon sparked speculation on whether this type of engine would actually work. From the late 19th century to the early 20th century, Rudolf Diesel worked on putting diesel on track and tried to improve the power-to-weight ratio. He worked at a Swiss engineering firm Sulzer. Eventually, by the end of the Second World War, steam engines became obsolete and were rarely used in developed countries. At the system's greatest extent, in 1914, there were about 20,000 miles (32,000 km) of the track, run by 120 competing companies. The British government combined all these companies into four main groups in 1923 as an economic measure. British Railways, by name British Rail, the former national railway system of Great Britain, was created by the Transport Act of 1947, which inaugurated public ownership of the railways. The history of rail transport also includes the history of rapid transit and arguably history of monorail. Water In the Stone Age, primitive boats developed to permit navigation of rivers and for fishing in