The Oaks explosion, which happened at a coal mine in South Yorkshire on 12 December 1866, remains the worst mining disaster in England. A series of explosions caused by firedamp ripped through the underground workings at the Oaks Colliery at Hoyle Mill near Stairfoot in Barnsley killing 361 miners and rescuers. It was the worst mining disaster in the United Kingdom until the 1913 Senghenydd explosion in Wales.
The first shaft at the Oaks Colliery was sunk in the early 1830s. In 1845 two separate explosions occurred at the colliery. On both occasions few men were below ground and no more than three or four workers died. Two years later a more serious incident occurred after firedamp, which had accumulated in old workings, was ignited and exploded. Of the men underground, 73 were killed and 26 were rescued. Changes were then made to the colliery's ventilation. The downcast shaft was converted to upcast with a furnace at its foot. Two abandoned shafts were deepened to the lower seams and brought into use as the downcast and drawing shafts. The upcast shaft was close to the Dearne and Dove Canal and the downcast shafts were adjacent to the railway.
The colliery covered about 450 acres (180 ha), of which two-thirds had been worked out. It was worked on the longwall principle, there being about 60 miles (97 km) of wall at the time of the 1866 explosion. The Barnsley seam is about 8 feet (2.4 m) thick. It is 280 yards (260 m) below the surface at the pit bottom, but dips significantly, so that it reaches 400 yards (370 m). The Barnsley seam tended to experience outbursts of firedamp, and they were sometimes powerful enough to extinguish the Geordie lamps that were used at the time. On one occasion all the lamps for 1,500 yards (1,400 m) were extinguished. Gas built up in the uneven levels, and the goaves were full of firedamp. The air circuit was more than 3 miles (4.8 km) long. The induced draught was obtained from a pair of furnaces 70 yards (64 m) from the upcast shaft.
At the inquiry after the explosion, it was pointed out that the colliery had not been visited by government inspectors for some years.
The Oaks Colliery workings became part of Barnsley Main Colliery, which closed and re-opened several times between 1929 and 1966. Linked underground to Barrow Colliery, the No.2 shaft was used for man-riding in the 1970s. Production at Barnsley Main ceased in 1991. The colliery's winding engine house and pit-head structures are Grade II listed buildings. They are a rare survival of winding-shaft structures modernised in the 1950s by the National Coal Board, and their presence preserves a historical connection to past disasters.
The Oaks was considered to be one of the most dangerous pits in South Yorkshire and the workers were concerned for their own safety. Large emissions of firedamp were commonplace. Ten years earlier the 400-strong workforce had gone on strike for ten weeks because of alleged management incompetence, but had to resume work when starvation loomed. During a bitter dispute in 1864, blackleg labour was used, and striking miners and their families were evicted from their homes. Gas made men giddy and faint. Men would not take safety lamps near the goaves. According to Tomlinson, the underviewers had written the word "Fire" in chalk in certain places. Parkin Jeffcock, the mining engineer who attended after the explosion, agreed that the fireman had written "Fire" but said that this was not unusual.
In a meeting with the management at the beginning of December, the workers complained about an inadequacy in the pit's ventilation. To improve the ventilation and alleviate the problem of gas issuing from the seam, a drift through the rock was blasted from near the pit bottom towards the more remote workings. The drift was expected to be finished that day.
A critical aspect to the science of firedamp explosions is the afterdamp, the aftermath mix of gases, which can be equally dangerous, if not more so.
On Wednesday 12 December 1866, 340 men and boys were underground, 131 hewers who cut the coal, hurriers who moved the coal to the shaft bottom, horse-drivers, maintenance staff and trappers, boys who were employed to open and close ventilation doors to allow wagons to pass.
At 1:20 pm with less than an hour of the shift remaining, an explosion ripped through the workings. The whole neighbourhood for three miles (5 km) around shook as if an earthquake had occurred accompanied by a loud roar akin to thunder. Two dense columns of smoke and debris erupted from the downcast shafts. At No. 1 pit the blast damaged the winding engine and broke the cage, disconnecting it from its rope. At No. 2 pit the cage was blown up into the headgear breaking a coupling. After about five minutes the ventilation resumed and fresh air was drawn back the downcast pits.
Another cage was attached to the rope in the No. 1 pit. Thomas Dymond, the colliery owner, David Tewart (alternately spelled Towart or Tewert), the underground steward, and Christopher Siddons (alternately spelled Seddons), a deputy, bravely descended first. They found 20 badly burned casualties who were quickly sent up but 14 subsequently died of their injuries. After another rope was attached, rescue volunteers including P. Cooper, John Brown, William Porter Maddison, William Auboné Potter, Kell, John Platts, George Minto, the under-viewer from Mount Osborne Colliery (and previous under-viewer at the Oaks), and other engineers and deputies from surrounding collieries, along with seventy or eighty additional men, went down. By 4:00 pm a total of about 80 workers had been recovered, but only 19 of them barely alive. Of these 19, only 6 survived and one, William Hart, later died in a different colliery accident. The few survivors of the initial blast had made their way to the shaft bottom where there was some air; those in more distant areas succumbed to the afterdamp, principally carbon monoxide. The dead were taken to their homes.
At the time of the explosion the only rescuers were volunteers and officials who came from neighbouring collieries who worked in relays. Sixteen men forced to the surface because of the foul air were accused of cowardice by bystanders. The few police present could not control the crowd, which invaded the pithead and interfered with operations. A telegram to the chief constable brought reinforcements and the area was cleared. Meanwhile, Blackburn (with his assistant), as well as Smith Sr. and Jr. had arrived to give medical aid to the injured.
A message was sent to colliery engineer Thomas Woodhouse of Duffield near Derby. It said, "The Oaks Pit is on fire. Come directly." Woodhouse was in London but his partner, Parkin Jeffcock, responded and arrived by train before 10 pm.
The rescuers' progress was restricted because of roof falls and afterdamp. Where it was possible to penetrate further into the workings bodies were found damaged by the blast. During the day the rope and cage for the No. 1 shaft were repaired and brattice was sent down to repair the stoppings.
Jeffcock descended into the pit at 10 pm and met Minto, Brown, Potter, Cooper, and Platts who were finally coming up for rest. Jeffcock took charge of the operation to make the pit safe and worked to restore ventilation. Dymond and Brown, who were supervising operations, realised before the end of the first day that all the remaining men underground must be dead and from midnight underground operations were run down. At 1:30 am most of the men below ground came up due to a false alarm and Minto went with John Smith (the mining engineer from Lundhill Colliery) below to investigate. Minto and Smith found Tewart who gave them directions to Jeffcock's location at the end of the stone drift. Jeffcock, Minto, and Smith walked up the engine level checking stoppings. Part way up they encountered a strong blower of chokedamp (mainly carbon dioxide and nitrogen) which accounted for much of the foul air. Minto, Jeffcock, and several others remained in the mine and worked through the night into the next morning.