Sir William Armstrong's hydro-electric machine invented in the mid 19th century. It was the most powerful means of developing frictional electricity at the time and was one of the first machines capable of generating power on an industrial scale. During 1870-77 and 1883-85 Armstong rebuilt Cragside, the house he lived in, as a country estate. He created an artifical lake where a head of water was produced which powered a hydraulic ram used to provide water to the house and grounds. Later he created four additional lakes which were used to supply electricity to the house. Cragside was one of the first houses to be lit by electric light and was the first house in the world to be lit by hydro-electric power. In 1969 interest in steam electricty was renewed because of explosions caused by the ignition of chemical vapours during the washing of ships tanks with steam jets.