I saw the first episode of a new series on the SYFY channel, Ghost Mine, and it is basically about TommyKnockers. The only association I had for that term was a Stephen King book about extraterrestrial aliens so I started the search!
|That's an actual candle on the Cornish miner's helmet!|
Cornish miners emigrated to the U.S. and had a huge influence in the Pennsylvania coal mines and the California Gold Rush spreading the superstition of TommyKnockers. But over the years TommyKnockers changed and instead of being Fae creatures, they became the ghosts of dead miners.
Apparently, with modern technology, TommyKnockers are supposed to be fading into legend. But if this new show is any indication, people are just as superstitious as ever!