Tommy-knocker

Tommy-knocker is a North American appellation of Cornish derivation for a gnomish entity that is supposed to work unseen in mines, so-called for their "knocking" activity as they seek valuable ores, this being linked by certain sources to the creaking of support timbers and other sounds of the underground. Varied happenings in the lives of miners were attributed to the actions of the knockers, from benign (e.g. warning of impending cave-ins) to malicious (e.g. causing cave-ins).

Reading

• Ellis, Samuel B. (2 Oct. 1920), "The Tommy-Knockers", Engineering and Mining Journal 110: 675, https://babel.hathitrust.org/cgi/pt?id=uc1.c2537940&view=1up&seq=703 
  

  When I die (said the mining engineer) do not bury me at all;

  Cache me on the bottom level, with a pick beside my pall;

  Leave a candlestick and matches, then cave the stopes and drifts,

  And I'll be a tommy-knocker for a hundred thousand shifts.

  Yes, a jolly tommy-knock, always starting for a walk;

  Always pounding on the rock, scaring honest Hunkies with my little tap, tap, tap—

  Always listening for the blast 'till the pumps are pulled at last,

  And the bloody surface tenderfoots are routed from their nap;

  Then the depths of earth will be lighted and we can see right through,

  And all the lost bonanzas will be nuts for me and you.

  Then we'll dig, dig, dig (If we've been good engineers)

  Ore shot with chunks of metal, through all the happy years.

  We'll have angels for muckers, who'll never ask for pay,

  And the ore will stope itself, over—under—anyway—
  Anyway you say!
  Oh, boy! Don't wake me up

  And say the men are striking and the tax-collector's here,

  And the bottom of the metal market's gone,

  And how you've lost the ore-shoot, and all the other grief;

  Jest let me snooze 'till Gabriel blows his hawn!

• "A Divining Rod Improved", Engineering and Mining Journal 110: 801, 23 Oct. 1920, https://babel.hathitrust.org/cgi/pt?id=uc1.c2537940&view=1up&seq=829, "Romance has gone out of business, but not mining. We have the tommy-knocker, the busy little gnome woodpecker of the underground. We have heard him ourselves. And we have the divining rod, short-range and long-distance, as marvelous and intangible a fairy gift as seven league boots or cloak of invisibility. We have known several mines where the spirits instructed the owner in detail, periodically, what to do — 'turn your tunnel to the left and drive fifty feet, and then crosscut west sixty-three feet and six inches.' In one such case the patient owner, after driving like this for a year, broke into his own tunnel near the mouth — and who could do this without supernatural help?" 
• "The Tommy-Knockers", Notes and Queries, 12 7: 447, 4 Dec. 1920, https://babel.hathitrust.org/cgi/pt?id=uc1.b5580532&view=1up&seq=457, "American and Canadian mining papers have recently published a short poem under the above title by Samuel B. Ellis. In a foot-note we are told that the tommy-knocker is the gnome of the underground, who is often heard tapping the rock in mines, and superstitious miners do not like to work alone for fear of meeting him. In the 'N.E.D.' he is simply called 'knocker' and described as a spirit or goblin imagined to dwell in mines and to indicate the presence of ore by knocking. Judging by the personal description of him given in one of the three quotations in the 'N.E.D.', the superstition about him has evidently been imported into this country by German miners in past centuries. L.L.K." 
• Federal Writers' Project (1939), "Tommy-knocker", Montana: A State Guide Book, New York: Viking Press, p. 416, https://babel.hathitrust.org/cgi/pt?id=mdp.39015005748036&view=1up&seq=428, "Ghost of a man killed in a mine. Miners say he returns to work the shift on which he was killed. They thus explain the creaking of timbers and similar sounds." 
• Buchanan, John W.; Buchanan, Doris G. (1957), The Story of Ghost Town, Caribou, Boulder, Colo.: Printed by the Boulder Publishing, Inc., https://babel.hathitrust.org/cgi/pt?id=uc1.31822043016666&view=1up&seq=22, "They were a superstitious people, their imaginations fed by a folklore that was spawned in the legendary background of Cornwall. [...] They told about small imps, 'Tommy Knockers,' who in habited the mines. If anyone bothered these creatures, that brought on bad luck. The 'Tommy Knocker' rattled rocks onto their hard boiled hats; misplaced their hammers; put a puddle of water in an unexpected spot." 
• Baker, James C. (Summer 1971), "Oregon Gold Mining Folklore: Federal Writers' Project and Today", Keystone Folklore Quarterly 16: 75-76, https://babel.hathitrust.org/cgi/pt?id=uc1.b3638555&view=1up&seq=94, "Oregon metal miners of various ethnic backgrounds share Tommy Knocker lore, which folklorists consider Cornish in origin. Many mining districts around the world have folklore about underground gremlins who rattle through the mines. In the West, miners may have adopted 'knockers' from Cornish immigrants, and altered the name to 'Tommy Knockers.' Some Tommy Knockers cause accidents and disease (F456.1.2.1 Malicious actions of knockers); whereas others warn the miner of a cave-in or attract him to pay dirt (F456.1.2.2.4 Knockers appear to miners before accidents occur; F456.1.2.2.4 Knockers lead men to the richest lodes in the mines by knocking in those areas)." 
• Baker, James C. (April 1971), "Echoes of Tommy Knockers in Bohemia, Oregon Mines", Western Folklore 30 (2): 119-122