Location: SE 02631 64796
Dukes Level was a drainage adit driven from Hebden Gill and was approximately 1.5 miles in length. The level provided drainage for most of the deeper workings across Grassington Moor, reaching both Yarnbury and the Out Moor. Work started in 1796 and it was first designed as an underground boat level where ore and waste material could be transported out of the connecting mines, as well as to provide the vital function of drainage. Initially the level was constructed five feet wide by nine feet high, however in 1818, the new mining agent John Taylor instructed that the dimensions of the level were to be reduced down to four feet by six feet and six inches above the rails. Taylor’s reasoning for doing this was due to the cost of driving the level and the fact that once the ore was extracted by the boats it would need to be hauled back up to the mines to be dressed and smelted. As there was no room for a dressing floor and smelt mill at the levels portal from 1818, work was continued only to provide a drainage adit for the mines across the moor. Dukes Level took 20 years to reach the mines at Yarnbury and only reached Coalgrovebeck Engine Shaft on the Out Moor by 1830.