[ 5 °+ ] 
not like thunder, but rather a dull rumbling even 
found, like deads running under ground. In the 
fmith’s fhop the window-leaves fhook, and the Hat- 
ing of the houfe cracked. The whim-houfe {hook 
fo terribly, that a man there at work ran out of it, 
concluding it to be falling. Several perfons then in 
the mine, working 60 fathom deep, thought they 
found the earth about them to move, and heard an 
uncommon noife : fome heard the noife, and felt no 
tremor ; others, working in a mine adjoining called 
Huel-breag, were fo frightened, that they called to 
their companions above to be drawn up from the 
bottoms. Their moor-houfe was lhaken, and the 
padlock of their candle-cheft was heard to ftrike 
againft the ftaples. To fhew, that this noife pro- 
ceeded from below, and not from any concuffion in 
the atmofphere above, this very intelligent captain of 
the mine (5) obferves, from his own experience, 
that thunder was never known to affed the air at 60 
fathoms deep, even in a {ingle {haft pierced into 
the hardeft Hone ; much lei's could it continue the 
found thro’ fuch workings as there are in this mine, 
impeded in all parts with deads, great quantities of 
timber, various noifes, fuch as the rattling of chains, 
fridtion of wheels and ropes, and dafhing of waters ; 
all which mull contribute to break the vibrations of 
the air as they defcend : and I intirely agree with 
this gentleman’s conclulion, that thunder, or any 
other noifes from above in the atmofphere, could not 
be heard at half the depth of this mine. This there- 
fore could be no other than a real tremor of the earth, 
(5) Mr. J. Nantcarrow. 
attended 
