but it may have been a development of a former pit called Kearsley's Pit mentioned in the company records from the 1860s, which lay at the other end of a geological fault from the Coity pits. A mines inspector report of 1881 is the first to describe a mine called the Big Pit due to its elliptical shape with dimensions of by , the first shaft in Wales large enough to allow two tramways. On completion it became the coal-winding shaft, while the older Coity shaft was used for upcast air ventilation. In 1878, the main shaft was deepened to reach the Old Coal seam at . By 1908, Big Pit provided employment for 1,122 people, and by 1923 at peak, there were 1,399 men employed, producing: House Coal, Steam Coal, Ironstone and Fireclay; from the Horn, No. 2 Yard, Old Coal and Elled seams. The peak of production was more than 250,000 tons of coal per year. During the height of production, coal from Big Pit was shipped as far as South America, and also to other points worldwide. Until 1908, when a conveyor became part of the mine equipment, everything at Big Pit was done by manpower - including cutting the coal. The mine was one of the first to install electricity and by 1910, fans, hauling systems and pumps were electric powered. In 1939, pithead baths were installed at the mine; it meant miners no longer needed to walk home dirty and wet, risking illness. The baths were also beneficial to miners' families; women no longer needed to carry hot jugs of water to fill tin baths and children were no longer accidentally scalded during this process. During the Second World War, surface extraction of coal began at Blaenavon in November 1941 using equipment and skilled men from the Canadian Army. On nationalisation in 1947, the National Coal Board took over the mine from the Blaenavon Co. Ltd, which employed 789 men. By 1970 the workforce numbered only 494, as operations had focused solely on the Garw seam, with a maximum thickness of only . The NCB agreed the development of a drift mine, which by 1973 meant that windings at Big Pit had ceased, with coal extracted close to the refurbished Black Lion coal washery. The Coity shaft was abandoned, with the Big Pit shaft used for upcast air ventilation and emergency extraction. The pit finally