Coordinates: 55°5′15″N 1°31′42″W / 55.08750°N 1.52833°W
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 Thursday 16 January 1862 and resulted in the deaths of 204 men. The beam of the pit's pumping engine broke and fell down the shaft, trapping the men below. The disaster prompted a change in UK law that henceforth required all collieries to have at least two independent means of escape.
Hartley old pit was established in the coastal village of Hartley (now part of Seaton Sluice), Northumberland 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 by later, more powerful, engines. The flooding became so severe that the old pit was abandoned in 1844.
The coal was sufficiently valuable that the following year a new shaft (A on the diagram alongside) was sunk about a mile 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 young children 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 a single 12 feet (3.7 m) shaft was dug. Coal, men, and materials traveled up and down the shaft, which also accommodated the pumps. In addition, the shaft provided vitally important fresh air ventilation and extraction of the firedamp.