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 boys. 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.
Hartley old pit was established in the coastal village of Hartley, Northumberland, (today part of Seaton Sluice) during the 13th century; the earliest existing 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 1767.
The coal was sufficiently valuable that the following year a new shaft (A on the diagram) was sunk about 1 mile (1,600 m) 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 12-foot (3.7 m) 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 place, stoppings and traps. In this period, the normal means of creating the updraft needed was by using a furnace in the upcast pit.
With a single shaft colliery this simple arrangement could not be followed, and so a timber brattice (B) was built from the top of the shaft to the bottom. Men and materials passed up and down on the downcast side, the pumps worked in the upcast. At Hartley a furnace was kept burning in the yard seam (E) with the rising hot gases passing up the furnace drift (I) to join and draw foul air up the upcast side of the shaft.
The vulnerability of such an arrangement had already been identified and publicised before the colliery was sunk. An explosion at the St Hilda pit in South Shields in 1839 had led (as the result of a public meeting) to the formation of a committee to consider the prevention of accidents in mines. The Shields Committee issued their report in 1843; it had found that mines in the North-East were unnecessarily at risk of explosions because they were generally inadequately ventilated with too few shafts for the size of the underground workings (a view supported by evidence from George Stephenson, amongst others). The committee's report had specifically argued against the practice for all new works (which it thought Parliament should legislate against), of sinking a single shaft and sub-dividing it by bratticing to separate in- and out-flowing ventilation air (since any explosion destroying the bratticing would destroy the ventilation of the mine and ensure the death by asphyxiation of those underground). It was later estimated that sinking two 8.5-foot (2.6 m) shafts instead of one 12-foot (3.7 m) shaft would have cost an extra £900.
In 1852, the pit was flooded to a depth of 8 fathoms (48 ft; 15 m) by water from the old pit. A powerful steam engine, 'the largest in the county employed in mining purpose', was therefore installed in 1855 to operate pumps to recover the pit. Pumping began in September 1855 (in June 1856 the pumping engine was shown off to a visiting French prince) but two years later the pit was not yet in full production and advertised for sale as 'just reopened'.
The pumps were in three stages. The lowest stage lifted water from a sump connected to an adit below the low main seam up to the yard seam. There, a second stage lifted the water up to a sump in the high main. The pumps were driven by a nominal 300 horsepower (220 kW) beam engine working the pumps directly: the first two stages were driven by the main beam, and the third stage by a subsidiary beam above the pump staple (C). The pit was known as a wet pit and the engine (capable of nine to ten strokes a minute) normally ran at about seven strokes a minute to cope with the water ingress; on loss of pumping the low main would flood within little more than a day from seawater percolating through the roof of the seam from the North Sea above it. Three miners from Hartley were amongst the death toll of an explosion at Burradon in 1860 because (explained the Durham Chronicle) "little work has been doing at Hartley colliery lately owing to an accumulation of water".
At the time of the disaster, the high main had been worked out and was closed off; the yard seam was being worked, but only by a few men (and a pit pony); the workings in the low main seam at Hester Pit were being extended to meet those at the Mill Pit at Seaton Sluice; within the year it would have been possible to escape from Hester Pit via the Mill Pit. In the meantime, a staple was provided within which was a ladder; this allowed escape to the yard seam from the low main should there be a major inrush of water ("the only thing that was feared").
On Thursday 16 January 1862 the fore shift went on duty at 02:30. At 10:30 the same morning the back shift were taking over from the fore shift, so most men of both shifts were at the coal face. As the first eight men were ascending, the beam of the pumping engine snapped and fell down the shaft. Although much of the brattice was destroyed, the first part seems to have deflected the beam away from the cage. Other debris fell on the cage, snapping two of the four support chains. Four of the eight men fell; the others managed to cling on. The beam came to rest jammed in the shaft and other falling debris created a blockage 30 yards (27 m) deep between the yard seam and the high main.
One of the deputies, Matthew Chapman, had been on his way home when he heard the crash. Retracing his steps he had himself lowered on a rope and started to clear away some of the debris with an axe. Realising that the man was exhausted, having just come off shift, the under-viewer Joseph Humble sent him home to rest whilst the main rescue effort was organised.
The initial rescue attempt was carried out under the direction of Humble, Carr (owner and viewer), G B Hunter (Cowpen & North Seaton), Hugh Taylor (Backworth) and Matthias Dunn (HM Inspector of Mines). By midnight rescuers had reached the damaged cage and George Sharp Snr was brought up in a rope sling. However, he jammed against some overhanging timbers, came out of the sling and fell to his death. The rescuers (including the by then rested Chapman) then descended the pump staple and lowered a rope sling from the high main. William Shape and Ralph Robinson were brought up from the cage in this manner. Thomas Watson, a Primitive Methodist local preacher, had earlier descended from the cage to the men who had fallen. He remained with them to pray and comfort them until they died. Watson likewise ascended in a sling and was therefore the last man out alive.
With the pumps stopped, all knew that the low main would quickly flood. Those on the surface, therefore, assumed correctly that the men below would make their way via the staple up to the yard seam. Throughout the night men continued to work from ropes.