Bearland flue was built in 1860 to remove foul and poisonous gases from the mines below. This method of mine ventilation was frequently used in the Welsh collieries up to the 1880s.
The ventilation of underground mines was and still is a significant safety concern for miners. Poor ventilation of the mines causes exposure to noxious gases, heat and dust.
How did it work?
From the base of the ca 5.6m circular stone chimney a ventilation duct of about 30 sq cm went down an air shaft (now visible as a depression in the ground) a few metres to the north, and at the bottom, turned along the roof to the working face of the long adit that was driven into the hillside.
A coal fire was lit on the firebars at the bottom of the chimney stack, and the rising hot air from the fire drew foul air through the duct out of the pit and fresh air into the adit from outside.
Once the fire drew well, the fire door was closed to make sure that the combustion air was only drawn from underground.
When by 1864 no iron ore had been found in the Bearland Wood adit, the flue was abandoned.
