The Oaks explosion

The Oaks explosion occurred at the Oaks Colliery, near Stairfoot, Barnsley, West Riding of Yorkshire, England (now within the new county of South Yorkshire), on 12 December 1866 killing 361 miners and rescuers. The disaster happened after a series of explosions caused by firedamp (chiefly methane) igniting ripped through the workings. It remains the worst colliery or mining disaster in England, and the second worst mining accident in the United Kingdom, after the Welsh Senghenydd Colliery Disaster.

The first shaft at the Oaks Colliery was sunk in the early 1830s. For nearly a decade no notable accidents happened, but in 1845 two separate explosions occurred. On both occasions few men were below ground so that "only three or four lives were sacrificed". Two years later though there was an altogether more serious accident. It was "generally understood" that firedamp had accumulated in old workings and was somehow ignited leading to an explosion. Of the men underground at the time seventy-three were killed and only twenty-six rescued.

As a result of this, the following year changes were made in the colliery. The downcast shaft was converted to an upcast shaft with a furnace burning continuously at its foot. Two earlier shafts which only reached the topmost seam and had been abandoned earlier were brought into use as the downcast and "drawing" shaft. They were deepened to the lowest seams. Firedamp was collected in a gasometer from the upper workings and used to light the main roads underground.

The upcast pit was close to the Dearne and Dove Canal and was provided with coke ovens. Both were in the northern colliery site. The southern colliery site was the centre of activity with the two downcast pits. This latter was adjacent to the railway.

The colliery covered about 450 acres (180 ha) of which two thirds had already been worked out. The colliery was worked on the longwall principle, there being about 60 miles (97 km) of wall at the time of the 1866 explosion. The main or 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 to 400 yards (370 m) at some places. The Barnsley seam was known to be gassy. It was liable to sudden inrushes of firedamp, sometimes sufficient to put out the Geordie lamps used. On one occasion all the lamps for 1,500 yards (1,400 m) were put out. With all this gas and with the uneven levels of the seam there were pockets of gas building up, indeed it was recognised that the goaves were full of the firedamp.

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