It can hardly be cause for wonder that the miner should be superstitious. His life is passed in a dark and gloomy region, fathoms below the earth's green surface, surrounded by walls on which dim lamps shed a fitful light. It is not surprising that imagination (and the Welsh imagination is peculiarly vivid) should conjure up the faces and forms of gnomes and coblynau, of phantoms and fairy men. When they hear the mysterious thumping which they know is not produced by any human being, and when in examining the place where the noise was heard they find there are really valuable indications of ore, the sturdiest incredulity must sometimes be shaken. Science points out that the noise may be produced by the action of water upon the loose stones in fissures and pot-holes of the mountain limestone, and does actually suggest the presence of metals.
In the days before a Priestley had caught and bottled that demon which exists in the shape of carbonic acid gas, when the miner was smitten dead by an invisible foe in the deep bowels of the earth it was natural his awestruck companions should ascribe the mysterious blow to a supernatural enemy. When the workman was assailed suddenly by what we now call fire-damp, which hurled him and his companions right and left upon the dark rocks, scorching, burning, and killing, those who survived were not likely to question the existence of the mine fiend. Hence arose the superstition--now probably quite extinct--of basilisks in the mines, which destroyed with their terrible gaze. When the explanation came, that the thing which killed the miner was what he breathed, not what he saw; and when chemistry took the fire-damp from the domain of faerie, the basilisk and the fire fiend had not a leg to stand on. The explanation of the Knockers is more recent, and less palpable and convincing.
The Coblynau are always given the form of dwarfs, in the popular fancy; wherever seen or heard, they are believed to have escaped from the mines or the secret regions of the mountains. Their homes are hidden from mortal vision. When encountered, either in the mines or on the mountains, they have strayed from their special abodes, which are as spectral as themselves. There is at least one account extant of their secret territory having been revealed to mortal eyes. I find it in a quaint volume (of which I shall have more to say), printed at Newport, Monmouthshire, in 1813.[19] It relates that one William Evans, of Hafodafel, while crossing the Beacon Mountain very early in the morning, passed a fairy coal mine, where fairies were busily at work. Some were cutting the coal, some carrying it to fill the sacks, some raising the loads upon the horses' backs, and so on; but all in the completest silence. He thought this 'a wonderful extra natural thing,' and was considerably impressed by it, for well he knew that there really was no coal mine at that place. He was a person of 'undoubted veracity,' and what is more, 'a great man in the world--above telling an untruth.'