The Hartley Colliery disaster (also known as the Hartley Pit disaster or Hester Pit disaster) was a coal mining accident in Northumberland, England, that occurred on 16 January 1862 and resulted in the deaths of 204 men and children. The beam of the pit's pumping engine broke and fell down the shaft, trapping the men below. The disaster prompted a change in British law that required all collieries to have at least two independent means of escape. Collieries Hartley old pit Hartley old pit was established in the coastal village of Hartley, Northumberland, (today part of Seaton Sluice) during the 13th century; the earliest extant records date from 1291. The colliery suffered increasingly from flooding as the seams were worked out under the sea and in 1760 the first atmospheric engine was installed, followed later by more powerful engines. Despite these efforts, the flooding became so severe that the old pit was abandoned in 1844. Hester pit The coal was sufficiently valuable that the following year a new shaft (A on the diagram alongside) was sunk about inland. The low main seam (F) was reached on 29 May 1846. The colliery was called the New Hartley Colliery and the shaft the Hester Pit. Around the pit a new village grew up that was called New Hartley. Women and very young children (they had to be aged 10 or above) were not employed in the pit and, according to E. Raper (Social and Working Conditions in the village of New Hartley 1845–1900), this gave a higher standard of life for the miners: "the miner in New Hartley would return home after a hard day's work to a warm, clean, comfortable home and usually a substantial hot meal". In common with many collieries of the period and locality, only one shaft was dug, which was of diameter, at a total cost of about £3,600. Coal, men, and materials travelled up and down the shaft, which also accommodated the pumps. In addition, the shaft provided the vitally important fresh air ventilation and extraction of firedamp. In collieries with two or more pits (for instance see the description of Felling), one pit was the "downcast pit" down which fresh air travelled, the other the "upcast pit" up which spent air escaped. Within the colliery the air was forced to traverse the whole of the workings by the use of walls of coal left in